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Zhu JY, Fu Y, van de Leemput J, Yu Y, Li J, Ray PE, Han Z. HIV-1 Nef acts in synergy with APOL1-G1 to induce nephrocyte cell death in a new Drosophila model of HIV-related kidney diseases. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.08.584069. [PMID: 38496548 PMCID: PMC10942446 DOI: 10.1101/2024.03.08.584069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Background: People carrying two APOL1 risk alleles (RA) G1 or G2 are at greater risk of developing HIV-associated nephropathy (HIVAN). Studies in transgenic mice showed that the expression of HIV-1 genes in podocytes, and nef in particular, led to HIVAN. However, it remains unclear whether APOL1-RA and HIV-1 Nef interact to induce podocyte cell death. Method: We generated transgenic (Tg) flies that express APOL1-G1 (derived from a child with HIVAN) and HIV-1 nef specifically in the nephrocytes, the fly equivalent of mammalian podocytes, and assessed their individual and combined effects on the nephrocyte filtration structure and function. Results: We found that HIV-1 Nef acts in synergy with APOL1-G1 resulting in nephrocyte structural and functional defects. Specifically, HIV-1 Nef itself can induce endoplasmic reticulum (ER) stress without affecting autophagy. Furthermore, Nef exacerbates the organelle acidification defects and autophagy reduction induced by APOL1-G1. The synergy between HIV-1 Nef and APOL1-G1 is built on their joint effects on elevating ER stress, triggering nephrocyte dysfunction and ultimately cell death. Conclusions: Using a new Drosophila model of HIV-1-related kidney diseases, we identified ER stress as the converging point for the synergy between HIV-1 Nef and APOL1-G1 in inducing nephrocyte cell death. Given the high relevance between Drosophila nephrocytes and human podocytes, this finding suggests ER stress as a new therapeutic target for HIV-1 and APOL1-associated nephropathies.
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Dogan M, Watkins C, Ingram H, Moore N, Rucker GM, Gower EG, Eason JD, Bhalla A, Talwar M, Nezakatgoo N, Eymard C, Helmick R, Vanatta J, Bajwa A, Kuscu C, Kuscu C. Unveiling APOL1 haplotypes in a predominantly African-American cohort of kidney transplant patients: a novel classification using probe-independent quantitative real-time PCR. Front Med (Lausanne) 2024; 11:1325128. [PMID: 38660426 PMCID: PMC11039853 DOI: 10.3389/fmed.2024.1325128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 03/20/2024] [Indexed: 04/26/2024] Open
Abstract
Introduction Apolipoprotein-L1 (APOL1) is a primate-specific protein component of high-density lipoprotein (HDL). Two variants of APOL1 (G1 and G2), provide resistance to parasitic infections in African Americans but are also implicated in kidney-related diseases and transplant outcomes in recipients. This study aims to identify these risk variants using a novel probe-independent quantitative real-time PCR method in a high African American recipient cohort. Additionally, it aims to develop a new stratification approach based on a haplotype-centric model. Methods Genomic DNA was extracted from recipient PBMCs using SDS lysis buffer and proteinase K. A quantitative PCR assay with modified forward primers and a common reverse primer enabled us to quantitatively identify single nucleotide polymorphisms (SNPs) and the 6-bp deletion. Additionally, we used Sanger sequencing to verify our QPCR findings. Results Our novel probe-independent qPCR effectively distinguished homozygous wild-type, heterozygous SNPs/deletions, and homozygous SNPs/deletions, with at least 4-fold differences. A high prevalence of APOL1 variants was observed (18% two-risk alleles, 34% one-risk allele) in our recipient cohort. Intriguingly, no significant impact of recipient APOL1 variants on transplant outcomes was observed up to 12-month of follow-ups. Ongoing research will encompass more time points and a larger patient cohort, allowing for a comprehensive evaluation of G1/G2 variant subgroups categorized by new haplotype scores, enriching our understanding. Conclusion Our cost-effective and rapid qPCR technique facilitates APOL1 genotyping within hours. Prospective and retrospective studies will enable comparisons with long-term allograft rejection, potentially predicting early/late-stage transplant outcomes based on haplotype evaluation in this diverse group of kidney transplant recipients.
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Affiliation(s)
- Murat Dogan
- Transplant Research Institute, Memphis, TN, United States
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Christine Watkins
- Transplant Research Institute, Memphis, TN, United States
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Holly Ingram
- Transplant Research Institute, Memphis, TN, United States
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Nicholas Moore
- Transplant Research Institute, Memphis, TN, United States
| | - Grace M. Rucker
- Transplant Research Institute, Memphis, TN, United States
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
| | | | | | - Anshul Bhalla
- Transplant Research Institute, Memphis, TN, United States
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
- Methodist Hospital, Memphis, TN, United States
| | - Manish Talwar
- Transplant Research Institute, Memphis, TN, United States
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
- Methodist Hospital, Memphis, TN, United States
| | - Nosratollah Nezakatgoo
- Transplant Research Institute, Memphis, TN, United States
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
- Methodist Hospital, Memphis, TN, United States
| | - Corey Eymard
- Transplant Research Institute, Memphis, TN, United States
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
- Methodist Hospital, Memphis, TN, United States
| | - Ryan Helmick
- Transplant Research Institute, Memphis, TN, United States
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
- Methodist Hospital, Memphis, TN, United States
| | - Jason Vanatta
- Transplant Research Institute, Memphis, TN, United States
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
- Methodist Hospital, Memphis, TN, United States
| | - Amandeep Bajwa
- Transplant Research Institute, Memphis, TN, United States
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Canan Kuscu
- Transplant Research Institute, Memphis, TN, United States
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
| | - Cem Kuscu
- Transplant Research Institute, Memphis, TN, United States
- Department of Surgery, College of Medicine, University of Tennessee Health Science Center, Memphis, TN, United States
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Pays E. The Janus-faced functions of Apolipoproteins L in membrane dynamics. Cell Mol Life Sci 2024; 81:134. [PMID: 38478101 PMCID: PMC10937811 DOI: 10.1007/s00018-024-05180-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 02/06/2024] [Accepted: 02/18/2024] [Indexed: 03/17/2024]
Abstract
The functions of human Apolipoproteins L (APOLs) are poorly understood, but involve diverse activities like lysis of bloodstream trypanosomes and intracellular bacteria, modulation of viral infection and induction of apoptosis, autophagy, and chronic kidney disease. Based on recent work, I propose that the basic function of APOLs is the control of membrane dynamics, at least in the Golgi and mitochondrion. Together with neuronal calcium sensor-1 (NCS1) and calneuron-1 (CALN1), APOL3 controls the activity of phosphatidylinositol-4-kinase-IIIB (PI4KB), involved in both Golgi and mitochondrion membrane fission. Whereas secreted APOL1 induces African trypanosome lysis through membrane permeabilization of the parasite mitochondrion, intracellular APOL1 conditions non-muscular myosin-2A (NM2A)-mediated transfer of PI4KB and APOL3 from the Golgi to the mitochondrion under conditions interfering with PI4KB-APOL3 interaction, such as APOL1 C-terminal variant expression or virus-induced inflammatory signalling. APOL3 controls mitophagy through complementary interactions with the membrane fission factor PI4KB and the membrane fusion factor vesicle-associated membrane protein-8 (VAMP8). In mice, the basic APOL1 and APOL3 activities could be exerted by mAPOL9 and mAPOL8, respectively. Perspectives regarding the mechanism and treatment of APOL1-related kidney disease are discussed, as well as speculations on additional APOLs functions, such as APOL6 involvement in adipocyte membrane dynamics through interaction with myosin-10 (MYH10).
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Affiliation(s)
- Etienne Pays
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 6041, Gosselies, Belgium.
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4
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Gupta N, Waas B, Austin D, De Mazière AM, Kujala P, Stockwell AD, Li T, Yaspan BL, Klumperman J, Scales SJ. Apolipoprotein L1 (APOL1) renal risk variant-mediated podocyte cytotoxicity depends on African haplotype and surface expression. Sci Rep 2024; 14:3765. [PMID: 38355600 PMCID: PMC10866943 DOI: 10.1038/s41598-024-53298-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 01/30/2024] [Indexed: 02/16/2024] Open
Abstract
Homozygous Apolipoprotein L1 (APOL1) variants G1 and G2 cause APOL1-mediated kidney disease, purportedly acting as surface cation channels in podocytes. APOL1-G0 exhibits various single nucleotide polymorphisms, most commonly haplotype E150K, M228I and R255K ("KIK"; the Reference Sequence is "EMR"), whereas variants G1 and G2 are mostly found in a single "African" haplotype background ("EIK"). Several labs reported cytotoxicity with risk variants G1 and G2 in KIK or EIK background haplotypes, but used HEK-293 cells and did not verify equal surface expression. To see if haplotype matters in a more relevant cell type, we induced APOL1-G0, G1 and G2 EIK, KIK and EMR at comparable surface levels in immortalized podocytes. G1 and G2 risk variants (but not G0) caused dose-dependent podocyte death within 48h only in their native African EIK haplotype and correlated with K+ conductance (thallium FLIPR). We ruled out differences in localization and trafficking, except for possibly greater surface clustering of cytotoxic haplotypes. APOL1 surface expression was required, since Brefeldin A rescued cytotoxicity; and cytoplasmic isoforms vB3 and vC were not cytotoxic. Thus, APOL1-EIK risk variants kill podocytes in a dose and haplotype-dependent manner (as in HEK-293 cells), whereas unlike in HEK-293 cells the KIK risk variants did not.
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Affiliation(s)
- Nidhi Gupta
- Department of Discovery Immunology, Genentech, 1 DNA Way, South San Francisco, CA, 94080, USA
- Department of Molecular Biology, Genentech, 1 DNA Way, South San Francisco, CA, 94080, USA
| | - Bridget Waas
- Department of Discovery Immunology, Genentech, 1 DNA Way, South San Francisco, CA, 94080, USA
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Daniel Austin
- Department of Biochemical and Cellular Pharmacology, Genentech, 1 DNA Way, South San Francisco, CA, 94080, USA
| | - Ann M De Mazière
- Section of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Pekka Kujala
- Section of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Amy D Stockwell
- Department of Human Genetics, Genentech, 1 DNA Way, South San Francisco, CA, 94080, USA
| | - Tianbo Li
- Department of Biochemical and Cellular Pharmacology, Genentech, 1 DNA Way, South San Francisco, CA, 94080, USA
| | - Brian L Yaspan
- Department of Human Genetics, Genentech, 1 DNA Way, South San Francisco, CA, 94080, USA.
| | - Judith Klumperman
- Section of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Suzie J Scales
- Department of Discovery Immunology, Genentech, 1 DNA Way, South San Francisco, CA, 94080, USA.
- Department of Molecular Biology, Genentech, 1 DNA Way, South San Francisco, CA, 94080, USA.
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Datta S, Antonio BM, Zahler NH, Theile JW, Krafte D, Zhang H, Rosenberg PB, Chaves AB, Muoio DM, Zhang G, Silas D, Li G, Soldano K, Nystrom S, Ferreira D, Miller SE, Bain JR, Muehlbauer MJ, Ilkayeva O, Becker TC, Hohmeier HE, Newgard CB, Olabisi OA. APOL1-mediated monovalent cation transport contributes to APOL1-mediated podocytopathy in kidney disease. J Clin Invest 2024; 134:e172262. [PMID: 38227370 PMCID: PMC10904047 DOI: 10.1172/jci172262] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2023] [Accepted: 01/09/2024] [Indexed: 01/17/2024] Open
Abstract
Two coding variants of apolipoprotein L1 (APOL1), called G1 and G2, explain much of the excess risk of kidney disease in African Americans. While various cytotoxic phenotypes have been reported in experimental models, the proximal mechanism by which G1 and G2 cause kidney disease is poorly understood. Here, we leveraged 3 experimental models and a recently reported small molecule blocker of APOL1 protein, VX-147, to identify the upstream mechanism of G1-induced cytotoxicity. In HEK293 cells, we demonstrated that G1-mediated Na+ import/K+ efflux triggered activation of GPCR/IP3-mediated calcium release from the ER, impaired mitochondrial ATP production, and impaired translation, which were all reversed by VX-147. In human urine-derived podocyte-like epithelial cells (HUPECs), we demonstrated that G1 caused cytotoxicity that was again reversible by VX-147. Finally, in podocytes isolated from APOL1 G1 transgenic mice, we showed that IFN-γ-mediated induction of G1 caused K+ efflux, activation of GPCR/IP3 signaling, and inhibition of translation, podocyte injury, and proteinuria, all reversed by VX-147. Together, these results establish APOL1-mediated Na+/K+ transport as the proximal driver of APOL1-mediated kidney disease.
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Affiliation(s)
- Somenath Datta
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Duke University School of Medicine, Department of Medicine, Division of Nephrology, Durham, North Carolina, USA
| | | | | | | | | | - Hengtao Zhang
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Division of Cardiology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Paul B. Rosenberg
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Division of Cardiology, Duke University School of Medicine, Durham, North Carolina, USA
| | - Alec B. Chaves
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
| | - Deborah M. Muoio
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Division of Endocrinology, Metabolism, and Nutrition, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA
| | - Guofang Zhang
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Division of Endocrinology, Metabolism, and Nutrition, Duke University School of Medicine, Durham, North Carolina, USA
| | - Daniel Silas
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Duke University School of Medicine, Department of Medicine, Division of Nephrology, Durham, North Carolina, USA
| | - Guojie Li
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Duke University School of Medicine, Department of Medicine, Division of Nephrology, Durham, North Carolina, USA
| | - Karen Soldano
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Duke University School of Medicine, Department of Medicine, Division of Nephrology, Durham, North Carolina, USA
| | - Sarah Nystrom
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Duke University School of Medicine, Department of Medicine, Division of Nephrology, Durham, North Carolina, USA
| | - Davis Ferreira
- Department of Pathology, Duke University Medical Center, Durham, North Carolina, USA
| | - Sara E. Miller
- Department of Pathology, Duke University Medical Center, Durham, North Carolina, USA
| | - James R. Bain
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Division of Endocrinology, Metabolism, and Nutrition, Duke University School of Medicine, Durham, North Carolina, USA
| | - Michael J. Muehlbauer
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
| | - Olga Ilkayeva
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Division of Endocrinology, Metabolism, and Nutrition, Duke University School of Medicine, Durham, North Carolina, USA
| | - Thomas C. Becker
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Division of Endocrinology, Metabolism, and Nutrition, Duke University School of Medicine, Durham, North Carolina, USA
| | - Hans-Ewald Hohmeier
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Division of Endocrinology, Metabolism, and Nutrition, Duke University School of Medicine, Durham, North Carolina, USA
| | - Christopher B. Newgard
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Medicine, Division of Endocrinology, Metabolism, and Nutrition, Duke University School of Medicine, Durham, North Carolina, USA
- Department of Pharmacology and Cancer Biology, Duke University Medical Center, Durham, North Carolina, USA
| | - Opeyemi A. Olabisi
- Duke Molecular Physiology Institute and Sarah W. Stedman Nutrition and Metabolism Center, Duke University School of Medicine, Durham, North Carolina, USA
- Duke University School of Medicine, Department of Medicine, Division of Nephrology, Durham, North Carolina, USA
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Zhu F, Li S, Gu Q, Xie N, Wu Y. APOL1 Induces Pyroptosis of Fibroblasts Through NLRP3/Caspase-1/GSDMD Signaling Pathway in Ulcerative Colitis. J Inflamm Res 2023; 16:6385-6396. [PMID: 38161356 PMCID: PMC10757784 DOI: 10.2147/jir.s437875] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Accepted: 12/19/2023] [Indexed: 01/03/2024] Open
Abstract
Background Pyroptosis is a form of proinfammatory gasdermin-mediated programmed cell death. Abnormal infammation in the intestine is a critical risk factor for Ulcerative colitis (UC). However, at present, it is not clear whether pyroptosis of colonic fibroblasts is involved in the pathogenesis and progression of UC. Methods In this study, key genes associated with UC were identified by bioinformatics analysis. Datasets were downloaded from the Gene Expression Omnibus (GEO) database (GSE193677). The differentially expressed genes were analyzed, and the hub genes were screened by weighted gene co-expression network analysis (WGCNA) and differentially expressed genes. We also downloaded the dataset from GEO for single-cell RNA sequencing (GSE231993). The expression of key genes was verified by immunohistochemistry, immunofluorescence and Western blot, and the specific pathways of key genes inducing pyroptosis in cell lines were explored. Results The results of bioinformatics analysis showed that the expression of APOL1 and CXCL1 in UC tissues was significantly higher than that in normal tissues. The results of single-cell analysis showed that the two genes were co-localized to fibroblasts. These results were consistent with the results of immunohistochemistry and immunofluorescence colocalization in human intestinal mucosa specimens. Furthermore, APOL1 overexpression induced NLRP3-caspase1-GSDMD-mediated pyroptosis of fibroblasts, which was confirmed by Western blot. Conclusion APOL1 induces pyroptosis of fibroblasts mediated by NLRP3-Caspase1-GSDMD signaling pathway and promote the release of chemokines CXCL1. Fibroblasts may play a crucial role in the pathogenesis and progression of UC.
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Affiliation(s)
- Fangqing Zhu
- Department of Gastroenterology, Ganzhou People’s Hospital, Ganzhou, Jiangxi, 341000, People’s Republic of China
| | - Sheng Li
- Department of Gastroenterology, Yuebei People’s Hospital, Shantou University Medical College, Shaoguan, Guangdong, 512026, People’s Republic of China
| | - Qiuping Gu
- Department of Gastroenterology, Ganzhou People’s Hospital, Ganzhou, Jiangxi, 341000, People’s Republic of China
| | - Ningsheng Xie
- Department of Gastroenterology, Ganzhou People’s Hospital, Ganzhou, Jiangxi, 341000, People’s Republic of China
| | - Yinxia Wu
- Department of Rehabilitation, Ganzhou People’s Hospital, Ganzhou, Jiangxi, 341000, People’s Republic of China
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Lee JG, Fu Y, Zhu JY, Wen P, van de Leemput J, Ray PE, Han Z. A SNARE protective pool antagonizes APOL1 renal toxicity in Drosophila nephrocytes. Cell Biosci 2023; 13:199. [PMID: 37925499 PMCID: PMC10625211 DOI: 10.1186/s13578-023-01147-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 10/12/2023] [Indexed: 11/06/2023] Open
Abstract
BACKGROUND People of Sub-Saharan African ancestry are at higher risk of developing chronic kidney disease (CKD), attributed to the Apolipoprotein L1 (APOL1) gene risk alleles (RA) G1 and G2. The underlying mechanisms by which the APOL1-RA precipitate CKD remain elusive, hindering the development of potential treatments. RESULTS Using a Drosophila genetic modifier screen, we found that SNARE proteins (Syx7, Ykt6, and Syb) play an important role in preventing APOL1 cytotoxicity. Reducing the expression of these SNARE proteins significantly increased APOL1 cytotoxicity in fly nephrocytes, the equivalent of mammalian podocytes, whereas overexpression of Syx7, Ykt6, or Syb attenuated their toxicity in nephrocytes. These SNARE proteins bound to APOL1-G0 with higher affinity than APOL1-G1/G2, and attenuated APOL1-G0 cytotoxicity to a greater extent than either APOL1-RA. CONCLUSIONS Using a Drosophila screen, we identified SNARE proteins (Syx7, Ykt6, and Syb) as antagonists of APOL1-induced cytotoxicity by directly binding APOL1. These data uncovered a new potential protective role for certain SNARE proteins in the pathogenesis of APOL1-CKD and provide novel therapeutic targets for APOL1-associated nephropathies.
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Affiliation(s)
- Jin-Gu Lee
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine (UMSOM), 670 West Baltimore Street, 4052 HSFIII, Baltimore, MD, 21201, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Yulong Fu
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine (UMSOM), 670 West Baltimore Street, 4052 HSFIII, Baltimore, MD, 21201, USA
- Department of Pathology, University of Alabama Birmingham, Birmingham, AL, 35249, USA
| | - Jun-Yi Zhu
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine (UMSOM), 670 West Baltimore Street, 4052 HSFIII, Baltimore, MD, 21201, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Pei Wen
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine (UMSOM), 670 West Baltimore Street, 4052 HSFIII, Baltimore, MD, 21201, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Joyce van de Leemput
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine (UMSOM), 670 West Baltimore Street, 4052 HSFIII, Baltimore, MD, 21201, USA
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA
| | - Patricio E Ray
- Child Health Research Center, Department of Pediatrics, University of Virginia School of Medicine, 409 Lane Road, Charlottesville, VA, 22908, USA.
| | - Zhe Han
- Center for Precision Disease Modeling, Department of Medicine, University of Maryland School of Medicine (UMSOM), 670 West Baltimore Street, 4052 HSFIII, Baltimore, MD, 21201, USA.
- Division of Endocrinology, Diabetes and Nutrition, Department of Medicine, University of Maryland School of Medicine, Baltimore, MD, 21201, USA.
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8
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Dogan M, Watkins C, Ingram H, Moore N, Rucker GM, Gower EG, Eason JD, Bhalla A, Talwar M, Nezakatgoo N, Eymard C, Helmick R, Vanatta J, Bajwa A, Kuscu C, Kuscu C. Unveiling APOL1 Haplotypes: A Novel Classification Through Probe-Independent Quantitative Real-Time PCR. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.10.16.562539. [PMID: 37905084 PMCID: PMC10614821 DOI: 10.1101/2023.10.16.562539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2023]
Abstract
Introduction Apolipoprotein-L1 (APOL1) is a primate-specific protein component of high- density lipoprotein (HDL). Two variants of APOL1 (G1 and G2), provide resistance to parasitic infections in African Americans but are also implicated in kidney-related diseases and transplant outcomes in recipients. This study aims to identify these risk variants using a novel probe- independent quantitative real-time PCR method in a high African American recipient cohort. Additionally, it aims to develop a new stratification approach based on haplotype-centric model. Methods Genomic DNA was extracted from recipient PBMCs using SDS lysis buffer and proteinase K. Quantitative PCR assay with modified forward primers and a common reverse primer enabled us to identify single nucleotide polymorphisms (SNPs) and the 6-bp deletion quantitatively. Additionally, we used sanger sequencing to verify our QPCR findings. Results Our novel probe-independent qPCR effectively distinguished homozygous wild-type, heterozygous SNPs/deletion, and homozygous SNPs/deletion, with at least 4-fold differences. High prevalence of APOL1 variants was observed (18% two-risk alleles, 34% one-risk allele) in our recipient cohort. Intriguingly, up to 12-month follow-up revealed no significant impact of recipient APOL1 variants on transplant outcomes. Ongoing research will encompass more time points and a larger patient cohort, allowing a comprehensive evaluation of G1/G2 variant subgroups categorized by new haplotype scores, enriching our understanding. Conclusions Our cost-effective and rapid qPCR technique facilitates APOL1 genotyping within hours. Prospective and retrospective studies will enable comparisons with long-term allograft rejection, potentially predicting early/late-stage transplant outcomes based on haplotype evaluation in this diverse group of kidney transplant recipients.
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9
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Vandorpe DH, Heneghan JF, Waitzman JS, McCarthy GM, Blasio A, Magraner JM, Donovan OG, Schaller LB, Shah SS, Subramanian B, Riella CV, Friedman DJ, Pollak MR, Alper SL. Apolipoprotein L1 (APOL1) cation current in HEK-293 cells and in human podocytes. Pflugers Arch 2023; 475:323-341. [PMID: 36449077 DOI: 10.1007/s00424-022-02767-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 10/14/2022] [Accepted: 10/25/2022] [Indexed: 12/05/2022]
Abstract
Two heterozygous missense variants (G1 and G2) of Apolipoprotein L1 (APOL1) found in individuals of recent African ancestry can attenuate the severity of infection by some forms of Trypanosoma brucei. However, these two variants within a broader African haplotype also increase the risk of kidney disease in Americans of African descent. Although overexpression of either variant G1 or G2 causes multiple pathogenic changes in cultured cells and transgenic mouse models, the mechanism(s) promoting kidney disease remain unclear. Human serum APOL1 kills trypanosomes through its cation channel activity, and cation channel activity of recombinant APOL1 has been reconstituted in lipid bilayers and proteoliposomes. Although APOL1 overexpression increases whole cell cation currents in HEK-293 cells, the ion channel activity of APOL1 has not been assessed in glomerular podocytes, the major site of APOL1-associated kidney diseases. We characterize APOL1-associated whole cell and on-cell cation currents in HEK-293 T-Rex cells and demonstrate partial inhibition of currents by anti-APOL antibodies. We detect in primary human podocytes a similar cation current inducible by interferon-γ (IFNγ) and sensitive to inhibition by anti-APOL antibody as well as by a fragment of T. brucei Serum Resistance-Associated protein (SRA). CRISPR knockout of APOL1 in human primary podocytes abrogates the IFNγ-induced, antibody-sensitive current. Our novel characterization in HEK-293 cells of heterologous APOL1-associated cation conductance inhibited by anti-APOL antibody and our documentation in primary human glomerular podocytes of endogenous IFNγ-stimulated, APOL1-mediated, SRA and anti-APOL-sensitive ion channel activity together support APOL1-mediated channel activity as a therapeutic target for treatment of APOL1-associated kidney diseases.
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Affiliation(s)
- David H Vandorpe
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA.,Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
| | - John F Heneghan
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA.,Department of Pathology, Brigham and Women's Hospital, Boston, MA, 02215, USA
| | - Joshua S Waitzman
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA.,Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
| | - Gizelle M McCarthy
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA.,Vertex Pharmaceuticals, Boston, MA, 02210, USA
| | - Angelo Blasio
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA.,Vertex Pharmaceuticals, Boston, MA, 02210, USA
| | - Jose M Magraner
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA.,, San Diego, CA, USA
| | - Olivia G Donovan
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA
| | - Lena B Schaller
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA.,Ludwig-Maximilians-Universitaet, 80336, Munich, Germany
| | - Shrijal S Shah
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA.,Chroma Medicine, Cambridge, MA, 02142, USA
| | - Balajikarthick Subramanian
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA.,Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
| | - Cristian V Riella
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA.,Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA
| | - David J Friedman
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA.,Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA.,Broad Institute of Harvard and MIT, Cambridge, MA, 02139, USA
| | - Martin R Pollak
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA.,Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA.,Broad Institute of Harvard and MIT, Cambridge, MA, 02139, USA
| | - Seth L Alper
- Division of Nephrology and Department of Medicine, Beth Israel Deaconess Medical Center RN380F, 99 Brookline Ave, Boston, MA, 02215, USA. .,Department of Medicine, Harvard Medical School, Boston, MA, 02115, USA. .,Broad Institute of Harvard and MIT, Cambridge, MA, 02139, USA.
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10
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Abstract
African trypanosomes are bloodstream protozoan parasites that infect mammals including humans, where they cause sleeping sickness. Long-lasting infection is required to favor parasite transmission between hosts. Therefore, trypanosomes have developed strategies to continuously escape innate and adaptive responses of the immune system, while also preventing premature death of the host. The pathology linked to infection mainly results from inflammation and includes anemia and brain dysfunction in addition to loss of specificity and memory of the antibody response. The serum of humans contains an efficient trypanolytic factor, the membrane pore-forming protein apolipoprotein L1 (APOL1). In the two human-infective trypanosomes, specific parasite resistance factors inhibit APOL1 activity. In turn, many African individuals express APOL1 variants that counteract these resistance factors, enabling them to avoid sleeping sickness. However, these variants are associated with chronic kidney disease, particularly in the context of virus-induced inflammation such as coronavirus disease 2019. Vaccination perspectives are discussed.
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Affiliation(s)
- Etienne Pays
- Laboratory of Molecular Parasitology, Université Libre de Bruxelles, Gosselies, Belgium;
| | - Magdalena Radwanska
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea.,Department of Biomedical Molecular Biology, Ghent University, Ghent, Belgium;
| | - Stefan Magez
- Laboratory for Biomedical Research, Ghent University Global Campus, Incheon, South Korea.,Laboratory of Cellular and Molecular Immunology, Vrije Universiteit Brussel, Brussels, Belgium; .,Department of Biochemistry and Microbiology, Ghent University, Ghent, Belgium
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11
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McNulty MT, Fermin D, Eichinger F, Jang D, Kretzler M, Burtt NP, Pollak MR, Flannick J, Weins A, Friedman DJ, Sampson MG. A glomerular transcriptomic landscape of apolipoprotein L1 in Black patients with focal segmental glomerulosclerosis. Kidney Int 2022; 102:136-148. [PMID: 34929253 PMCID: PMC9206042 DOI: 10.1016/j.kint.2021.10.041] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Revised: 10/20/2021] [Accepted: 10/29/2021] [Indexed: 12/26/2022]
Abstract
Apolipoprotein L1 (APOL1)-associated focal segmental glomerulosclerosis (FSGS) is the dominant form of FSGS in Black individuals. There are no targeted therapies for this condition, in part because the molecular mechanisms underlying APOL1's pathogenic contribution to FSGS are incompletely understood. Studying the transcriptomic landscape of APOL1 FSGS in patient kidneys is an important way to discover genes and molecular behaviors that are unique or most relevant to the human disease. With the hypothesis that the pathology driven by the high-risk APOL1 genotype is reflected in alteration of gene expression across the glomerular transcriptome, we compared expression and co-expression profiles of 15,703 genes in 16 Black patients with FSGS at high-risk vs 14 Black patients with a low-risk APOL1 genotype. Expression data from APOL1-inducible HEK293 cells and normal human glomeruli were used to pursue genes and molecular pathways uncovered in these studies. We discovered increased expression of APOL1 and nine other significant differentially expressed genes in high-risk patients. This included stanniocalcin, which has a role in mitochondrial and calcium-related processes along with differential correlations between high- and low-risk APOL1 and metabolism pathway genes. There were similar correlations with extracellular matrix- and immune-related genes, but significant loss of co-expression of mitochondrial genes in high-risk FSGS, and an NF-κB-down regulating gene, NKIRAS1, as the most significant hub gene with strong differential correlations with NDUF family (mitochondrial respiratory genes) and immune-related (JAK-STAT) genes. Thus, differences in mitochondrial gene regulation appear to underlie many differences observed between high- and low-risk Black patients with FSGS.
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Affiliation(s)
- Michelle T McNulty
- Division of Pediatric Nephrology, Boston Children's Hospital, Boston, Massachusetts, USA; Kidney Disease Initiative, Broad Institute, Cambridge, Massachusetts, USA
| | - Damian Fermin
- Division of Nephrology, Department of Internal Medicine, Michigan Medicine, Ann Arbor, Michigan, USA
| | - Felix Eichinger
- Division of Nephrology, Department of Internal Medicine, Michigan Medicine, Ann Arbor, Michigan, USA
| | - Dongkeun Jang
- Program in Medical and Population Genetics, Broad Institute, Cambridge, Massachusetts, USA
| | - Matthias Kretzler
- Division of Nephrology, Department of Internal Medicine, Michigan Medicine, Ann Arbor, Michigan, USA
| | - Noël P Burtt
- Program in Medical and Population Genetics, Broad Institute, Cambridge, Massachusetts, USA; Metabolism Program, Broad Institute, Cambridge, Massachusetts, USA
| | - Martin R Pollak
- Harvard Medical School, Boston, Massachusetts, USA; Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Jason Flannick
- Program in Medical and Population Genetics, Broad Institute, Cambridge, Massachusetts, USA; Metabolism Program, Broad Institute, Cambridge, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA; Division of Genetics, Department of Pediatrics, Boston Children's Hospital, Boston, Massachusetts, USA
| | - Astrid Weins
- Harvard Medical School, Boston, Massachusetts, USA
| | - David J Friedman
- Harvard Medical School, Boston, Massachusetts, USA; Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Matthew G Sampson
- Division of Pediatric Nephrology, Boston Children's Hospital, Boston, Massachusetts, USA; Kidney Disease Initiative, Broad Institute, Cambridge, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA.
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12
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Adebayo OC, Van den Heuvel LP, Olowu WA, Levtchenko EN, Labarque V. Sickle cell nephropathy: insights into the pediatric population. Pediatr Nephrol 2022; 37:1231-1243. [PMID: 34050806 DOI: 10.1007/s00467-021-05126-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Revised: 04/10/2021] [Accepted: 05/06/2021] [Indexed: 12/13/2022]
Abstract
The life expectancy of individuals with sickle cell disease has increased over the years, majorly due to an overall improvement in diagnosis and medical care. Nevertheless, this improved longevity has resulted in an increased prevalence of chronic complications such as sickle cell nephropathy (SCN), which poses a challenge to the medical care of the patient, shortening the lifespan of patients by 20-30 years. Clinical presentation of SCN is age-dependent, with kidney dysfunction slowly beginning to develop from childhood, progressing to chronic kidney disease and kidney failure during the third and fourth decades of life. This review explores the epidemiology, pathology, pathophysiology, clinical presentation, and management of SCN by focusing on the pediatric population. It also discusses the factors that can modify SCN susceptibility.
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Affiliation(s)
- Oyindamola C Adebayo
- Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium.,Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Lambertus P Van den Heuvel
- Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Pediatric Nephrology, Radboud University Medical Centre, Nijmegen, Netherlands
| | - Wasiu A Olowu
- Pediatric Nephrology and Hypertension Unit, Obafemi Awolowo University Teaching Hospitals Complex, Ile-Ife, Nigeria
| | - Elena N Levtchenko
- Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium. .,Department of Pediatric Nephrology, University Hospital Leuven, Herestraat 49, Bus 817, 3000, Leuven, Belgium.
| | - Veerle Labarque
- Center for Molecular and Vascular Biology, Department of Cardiovascular Sciences, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Pediatric Hematology, University Hospital Leuven, Leuven, Belgium
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13
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Nystrom SE, Li G, Datta S, Soldano K, Silas D, Weins A, Hall G, Thomas DB, Olabisi OA. JAK inhibitor blocks COVID-19-cytokine-induced JAK-STAT-APOL1 signaling in glomerular cells and podocytopathy in human kidney organoids. JCI Insight 2022; 7:157432. [PMID: 35472001 PMCID: PMC9220952 DOI: 10.1172/jci.insight.157432] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2021] [Accepted: 04/20/2022] [Indexed: 11/17/2022] Open
Abstract
COVID-19 infection causes collapse of glomerular capillaries and loss of podocytes, culminating in a severe kidney disease called COVID-19–associated nephropathy (COVAN). The underlying mechanism of COVAN is unknown. We hypothesized that cytokines induced by COVID-19 trigger expression of pathogenic APOL1 via JAK/STAT signaling, resulting in podocyte loss and COVAN phenotype. Here, based on 9 biopsy-proven COVAN cases, we demonstrated for the first time, to the best of our knowledge, that APOL1 protein was abundantly expressed in podocytes and glomerular endothelial cells (GECs) of COVAN kidneys but not in controls. Moreover, a majority of patients with COVAN carried 2 APOL1 risk alleles. We show that recombinant cytokines induced by SARS-CoV-2 acted synergistically to drive APOL1 expression through the JAK/STAT pathway in primary human podocytes, GECs, and kidney micro-organoids derived from a carrier of 2 APOL1 risk alleles, but expression was blocked by a JAK1/2 inhibitor, baricitinib. We demonstrate that cytokine-induced JAK/STAT/APOL1 signaling reduced the viability of kidney organoid podocytes but was rescued by baricitinib. Together, our results support the conclusion that COVID-19–induced cytokines are sufficient to drive COVAN-associated podocytopathy via JAK/STAT/APOL1 signaling and that JAK inhibitors could block this pathogenic process. These findings suggest JAK inhibitors may have therapeutic benefits for managing cytokine-induced, APOL1-mediated podocytopathy.
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Affiliation(s)
- Sarah E Nystrom
- Division of Nephrology, Duke University School of Medicine, Durham, United States of America
| | - Guojie Li
- Division of Nephrology, Duke University School of Medicine, Durham, United States of America
| | - Somenath Datta
- Division of Nephrology, Duke University School of Medicine, Durham, United States of America
| | - Karen Soldano
- Division of Nephrology, Duke University School of Medicine, Durham, United States of America
| | - Daniel Silas
- Division of Nephrology, Duke University School of Medicine, Durham, United States of America
| | - Astrid Weins
- Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, United States of America
| | - Gentzon Hall
- Division of Nephrology, Duke University School of Medicine, Durham, United States of America
| | - David B Thomas
- Department of Pathology, Nephrocor, Memphis, United States of America
| | - Opeyemi A Olabisi
- Division of Nephrology, Duke University School of Medicine, Durham, United States of America
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14
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Yang YW, Poudel B, Frederick J, Dhillon P, Shrestha R, Ma Z, Wu J, Okamoto K, Kopp JB, Booten SL, Gattis D, Watt AT, Palmer M, Aghajan M, Susztak K. Antisense oligonucleotides ameliorate kidney dysfunction in podocyte specific APOL1 risk variant mice. Mol Ther 2022; 30:2491-2504. [PMID: 35450819 DOI: 10.1016/j.ymthe.2022.04.007] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Revised: 03/23/2022] [Accepted: 04/14/2022] [Indexed: 10/18/2022] Open
Abstract
Coding variants (named G1 and G2) in Apolipoprotein L1 (APOL1) can explain the most excess risk of kidney disease observed in African Americans. It has been proposed that risk variant APOL1 dose, such as increased risk variant APOL1 level serves as a trigger (second hit) for disease development. The goal of this study was to determine whether lowering risk variant APOL1 levels protects from disease development in podocyte specific transgenic mouse disease model. We administered antisense oligonucleotides (ASO) targeting APOL1 to podocyte specific G2APOL1 mice and observed efficient reduction of APOL1 levels. APOL1 ASO1, which more efficiently lowered APOL1 transcript levels, protected mice from albuminuria, glomerulosclerosis, tubulointerstitial fibrosis, and renal failure. The administration of APOL1 ASO1 was effective even for established disease in the NEFTA-rtTA/TRE-G2APOL1 (NEFTA/G2APOL1) mice. We observed a strong correlation between APOL1 transcript level and disease severity. We concluded that an APOL1 ASO1 may be an effective therapeutic approach for APOL1-associated glomerular disease.
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Affiliation(s)
- Ya-Wen Yang
- Division of Nephrology, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA; Department of Surgery, National Taiwan University Hospital, Taipei, Taiwan
| | - Bibek Poudel
- Division of Nephrology, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Julia Frederick
- Division of Nephrology, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Poonam Dhillon
- Division of Nephrology, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Rojesh Shrestha
- Division of Nephrology, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Ziyuan Ma
- Division of Nephrology, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Junnan Wu
- Division of Nephrology, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | - Koji Okamoto
- Kidney Disease Section, NIDDK, NIH, Bethesda, MD, USA
| | | | | | | | | | - Matthew Palmer
- Department of Pathology, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA
| | | | - Katalin Susztak
- Division of Nephrology, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA.
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15
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Daneshpajouhnejad P, Kopp JB, Winkler CA, Rosenberg AZ. The evolving story of apolipoprotein L1 nephropathy: the end of the beginning. Nat Rev Nephrol 2022; 18:307-320. [PMID: 35217848 PMCID: PMC8877744 DOI: 10.1038/s41581-022-00538-3] [Citation(s) in RCA: 34] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2022] [Indexed: 01/13/2023]
Abstract
Genetic coding variants in APOL1, which encodes apolipoprotein L1 (APOL1), were identified in 2010 and are relatively common among individuals of sub-Saharan African ancestry. Approximately 13% of African Americans carry two APOL1 risk alleles. These variants, termed G1 and G2, are a frequent cause of kidney disease — termed APOL1 nephropathy — that typically manifests as focal segmental glomerulosclerosis and the clinical syndrome of hypertension and arterionephrosclerosis. Cell culture studies suggest that APOL1 variants cause cell dysfunction through several processes, including alterations in cation channel activity, inflammasome activation, increased endoplasmic reticulum stress, activation of protein kinase R, mitochondrial dysfunction and disruption of APOL1 ubiquitinylation. Risk of APOL1 nephropathy is mostly confined to individuals with two APOL1 risk variants. However, only a minority of individuals with two APOL1 risk alleles develop kidney disease, suggesting the need for a ‘second hit’. The best recognized factor responsible for this ‘second hit’ is a chronic viral infection, particularly HIV-1, resulting in interferon-mediated activation of the APOL1 promoter, although most individuals with APOL1 nephropathy do not have an obvious cofactor. Current therapies for APOL1 nephropathies are not adequate to halt progression of chronic kidney disease, and new targeted molecular therapies are in clinical trials. This Review summarizes current understanding of the role of APOL1 variants in kidney disease. The authors discuss the genetics, protein structure and biological functions of APOL1 variants and provide an overview of promising therapeutic strategies. In contrast to other APOL family members, which are primarily intracellular, APOL1 contains a unique secretory signal peptide, resulting in its secretion into plasma. APOL1 renal risk alleles provide protection from African human trypanosomiasis but are a risk factor for progressive kidney disease in those carrying two risk alleles. APOL1 risk allele frequency is ~35% in the African American population in the United States, with ~13% of individuals having two risk alleles; the highest allele frequencies are found in West African populations and their descendants. Cell and mouse models implicate endolysosomal and mitochondrial dysfunction, altered ion channel activity, altered autophagy, and activation of protein kinase R in the pathogenesis of APOL1-associated kidney disease; however, the relevance of these injury pathways to human disease has not been resolved. APOL1 kidney disease tends to be progressive, and current standard therapies are generally ineffective; targeted therapeutic strategies hold the most promise.
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Affiliation(s)
- Parnaz Daneshpajouhnejad
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.,Department of Pathology, University of Pennsylvania Hospital, Philadelphia, PA, USA
| | | | - Cheryl A Winkler
- Basic Research Program, Frederick National Laboratory for Cancer Research, Frederick, MD, USA
| | - Avi Z Rosenberg
- Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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16
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Comparative Analysis of the APOL1 Variants in the Genetic Landscape of Renal Carcinoma Cells. Cancers (Basel) 2022; 14:cancers14030733. [PMID: 35159001 PMCID: PMC8833631 DOI: 10.3390/cancers14030733] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2021] [Revised: 01/11/2022] [Accepted: 01/26/2022] [Indexed: 11/21/2022] Open
Abstract
Simple Summary Renal cell carcinoma (RCC) occurs at higher frequency in individuals of African ancestry, with well-recorded documentation in this community. This is most prominent in the context of chronic kidney disease. In turn, many forms of progressive chronic kidney disease are more common in populations of Sub-Saharan African ancestry. This disparity has been attributed to well-defined allelic variants and has risen in the parental populations to high frequency under evolutionary pressure. Mechanisms of increased kidney disease risk and cell injury, causally associated with these APOL1 gene variants, have been extensively studied. Most studies have compared the effects of ectopic overexpression of the parental non-risk APOL1 with the mutated risk variants in cellular and organismal platforms. In the current study, we have used CRISPR/Cas9 genetic engineering to knock out or modify the sequence of endogenous APOL1 in RCC to mimic and examine the effects of these naturally occurring kidney disease risk allelic variants. Remarkably, these modifications to endogenous APOL1 genes in RCC resulted in a set of prominent effects on mitochondrial integrity and metabolic pathways and disrupted tumorigenesis. These findings both clarify pathways of cell injury of APOL1 risk variants in cells of kidney origin and motivate further studies to examine the potential central role of APOL1 in the pathogenesis of renal cell carcinoma and its relation to chronic kidney disease in genotypically at-risk African ancestry individuals. Abstract Although the relative risk of renal cell carcinoma associated with chronic kidney injury is particularly high among sub-Saharan African ancestry populations, it is unclear yet whether the APOL1 gene risk variants (RV) for kidney disease additionally elevate this risk. APOL1 G1 and G2 RV contribute to increased risk for kidney disease in black populations, although the disease mechanism has still not been fully deciphered. While high expression levels of all three APOL1 allelic variants, G0 (the wild type allele), G1, and G2 are injurious to normal human cells, renal carcinoma cells (RCC) naturally tolerate inherent high expression levels of APOL1. We utilized CRISPR/Cas9 gene editing to generate isogenic RCC clones expressing APOL1 G1 or G2 risk variants on a similar genetic background, thus enabling a reliable comparison between the phenotypes elicited in RCC by each of the APOL1 variants. Here, we demonstrate that knocking in the G1 or G2 APOL1 alleles, or complete elimination of APOL1 expression, has major effects on proliferation capacity, mitochondrial morphology, cell metabolism, autophagy levels, and the tumorigenic potential of RCC cells. The most striking effect of the APOL1 RV effect was demonstrated in vivo by the complete abolishment of tumor growth in immunodeficient mice. Our findings suggest that, in contrast to the WT APOL1 variant, APOL1 RV are toxic for RCC cells and may act to suppress cancer cell growth. We conclude that the inherent expression of non-risk APOL1 G0 is required for RCC tumorigenicity. RCC cancer cells can hardly tolerate increased APOL1 risk variants expression levels as opposed to APOL1 G0.
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17
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Kruzel-Davila E, Bavli-Kertselli I, Ofir A, Cheatham AM, Shemer R, Zaknoun E, Chornyy S, Tabachnikov O, Davis SE, Khatua AK, Skorecki K, Popik W. Endoplasmic reticulum-translocation is essential for APOL1 cellular toxicity. iScience 2022; 25:103717. [PMID: 35072009 PMCID: PMC8762391 DOI: 10.1016/j.isci.2021.103717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 11/17/2021] [Accepted: 12/29/2021] [Indexed: 11/28/2022] Open
Abstract
Two variants at the APOL1 gene, encoding apolipoprotein L1, account for more than 70% of the increased risk for chronic kidney disease in individuals of African ancestry. While the initiating event for APOL1 risk variant cell injury remains to be clarified, we explored the possibility of blocking APOL1 toxicity at a more upstream level. We demonstrate that deletion of the first six amino acids of exon 4 abrogates APOL1 cytotoxicity by impairing APOL1 translocation to the lumen of ER and splicing of the signal peptide. Likewise, in orthologous systems, APOL1 lethality was partially abrogated in yeast strains and flies with reduced dosage of genes encoding ER translocon proteins. An inhibitor of ER to Golgi trafficking reduced lethality as well. We suggest that targeting the MSALFL sequence or exon 4 skipping may serve as potential therapeutic approaches to mitigate the risk of CKD caused by APOL1 renal risk variants.
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Affiliation(s)
- Etty Kruzel-Davila
- Department of Nephrology, Rambam Health Care Campus, Haifa, Israel
- Departments of Genetics and Developmental Biology and Rappaport Faculty of Medicine and Research Institute, Technion—Israel Institute of Technology, Haifa, Israel
| | | | - Ayala Ofir
- Department of Nephrology, Rambam Health Care Campus, Haifa, Israel
| | - Amber M. Cheatham
- Meharry Medical College, Center for AIDS Health Disparities Research, Department of Microbiology and Immunology, 1005 D. B. Todd Boulevard, Nashville, TN 37028, USA
| | - Revital Shemer
- Departments of Genetics and Developmental Biology and Rappaport Faculty of Medicine and Research Institute, Technion—Israel Institute of Technology, Haifa, Israel
| | - Eid Zaknoun
- Departments of Genetics and Developmental Biology and Rappaport Faculty of Medicine and Research Institute, Technion—Israel Institute of Technology, Haifa, Israel
| | - Sergiy Chornyy
- Departments of Genetics and Developmental Biology and Rappaport Faculty of Medicine and Research Institute, Technion—Israel Institute of Technology, Haifa, Israel
| | - Orly Tabachnikov
- Department of Nephrology, Rambam Health Care Campus, Haifa, Israel
| | - Shamara E. Davis
- Meharry Medical College, Center for AIDS Health Disparities Research, Department of Microbiology and Immunology, 1005 D. B. Todd Boulevard, Nashville, TN 37028, USA
| | - Atanu K. Khatua
- Meharry Medical College, Center for AIDS Health Disparities Research, Department of Microbiology and Immunology, 1005 D. B. Todd Boulevard, Nashville, TN 37028, USA
| | - Karl Skorecki
- Department of Nephrology, Rambam Health Care Campus, Haifa, Israel
- Departments of Genetics and Developmental Biology and Rappaport Faculty of Medicine and Research Institute, Technion—Israel Institute of Technology, Haifa, Israel
| | - Waldemar Popik
- Meharry Medical College, Center for AIDS Health Disparities Research, Department of Microbiology and Immunology, 1005 D. B. Todd Boulevard, Nashville, TN 37028, USA
- Department of Internal Medicine, 1005 D. B. Todd Boulevard, Nashville, TN 37028, USA
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18
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Steers NJ, Gupta Y, D’Agati VD, Lim TY, DeMaria N, Mo A, Liang J, Stevens KO, Ahram DF, Lam WY, Gagea M, Nagarajan L, Sanna-Cherchi S, Gharavi AG. GWAS in Mice Maps Susceptibility to HIV-Associated Nephropathy to the Ssbp2 Locus. J Am Soc Nephrol 2022; 33:108-120. [PMID: 34893534 PMCID: PMC8763192 DOI: 10.1681/asn.2021040543] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2021] [Accepted: 09/27/2021] [Indexed: 02/04/2023] Open
Abstract
BACKGROUND To gain insight into the pathogenesis of collapsing glomerulopathy, a rare form of FSGS that often arises in the setting of viral infections, we performed a genome-wide association study (GWAS) among inbred mouse strains using a murine model of HIV-1 associated nephropathy (HIVAN). METHODS We first generated F1 hybrids between HIV-1 transgenic mice on the FVB/NJ background and 20 inbred laboratory strains. Analysis of histology, BUN, and urinary NGAL demonstrated marked phenotypic variation among the transgenic F1 hybrids, providing strong evidence for host genetic factors in the predisposition to nephropathy. A GWAS in 365 transgenic F1 hybrids generated from these 20 inbred strains was performed. RESULTS We identified a genome-wide significant locus on chromosome 13-C3 and multiple additional suggestive loci. Crossannotation of the Chr. 13 locus, including single-cell transcriptomic analysis of wildtype and HIV-1 transgenic mouse kidneys, nominated Ssbp2 as the most likely candidate gene. Ssbp2 is highly expressed in podocytes, encodes a transcriptional cofactor that interacts with LDB1 and LMX1B, which are both previously implicated in FSGS. Consistent with these data, older Ssbp2 null mice spontaneously develop glomerulosclerosis, tubular casts, interstitial fibrosis, and inflammation, similar to the HIVAN mouse model. CONCLUSIONS These findings demonstrate the utility of GWAS in mice to uncover host genetic factors for rare kidney traits and suggest Ssbp2 as susceptibility gene for HIVAN, potentially acting via the LDB1-LMX1B transcriptional network.
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Affiliation(s)
- Nicholas J. Steers
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Yask Gupta
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Vivette D. D’Agati
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, New York
| | - Tze Y. Lim
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Natalia DeMaria
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Anna Mo
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Judy Liang
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Kelsey O. Stevens
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Dina F. Ahram
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Wan Yee Lam
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Mihai Gagea
- Department of Veterinary Medicine and Surgery, University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Lalitha Nagarajan
- Department of Genetics, University of Texas M.D. Anderson Cancer Center, Houston, Texas
| | - Simone Sanna-Cherchi
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
| | - Ali G. Gharavi
- Division of Nephrology, Department of Medicine, Columbia University Irving Medical Center, New York, New York
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19
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Pays E. Distinct APOL1 functions in trypanosomes and kidney podocytes. Trends Parasitol 2021; 38:104-108. [PMID: 34887168 DOI: 10.1016/j.pt.2021.11.005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 11/10/2021] [Accepted: 11/15/2021] [Indexed: 10/19/2022]
Abstract
The human serum protein apolipoprotein L1 (APOL1) kills Trypanosoma brucei but not the sleeping sickness agent Trypanosoma rhodesiense. APOL1 C-terminal variants can kill T. rhodesiense but they also induce kidney disease. Given topological and functional differences between intracellular and extracellular APOL1 isoforms, I propose that trypanolysis and kidney disease result from distinct APOL1 activities.
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Affiliation(s)
- Etienne Pays
- Laboratory of Molecular Parasitology, Institute of Molecular Biology and Medicine, Université Libre de Bruxelles, Gosselies, Belgium.
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20
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Dhande IS, Braun MC, Doris PA. Emerging Insights Into Chronic Renal Disease Pathogenesis in Hypertension From Human and Animal Genomic Studies. Hypertension 2021; 78:1689-1700. [PMID: 34757770 PMCID: PMC8577298 DOI: 10.1161/hypertensionaha.121.18112] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
The pathogenic links between elevated blood pressure and chronic kidney disease remain obscure. This article examines progress in population genetics and in animal models of hypertension and chronic kidney disease. It also provides a critique of the application of genome-wide association studies to understanding the heritability of renal function. Emerging themes identified indicate that heritable risk of chronic kidney disease in hypertension can arise from genetic variation in (1) glomerular and tubular protein handling mechanisms; (2) autoregulatory capacity of the renal vasculature; and (3) innate and adaptive immune mechanisms. Increased prevalence of hypertension-associated chronic kidney disease that occurs with aging may reflect amplification of heritable risks by normal aging processes affecting immunity and autoregulation.
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Affiliation(s)
- Isha S. Dhande
- Center for Human Genetics, Brown Foundation Institute of Molecular Medicine, McGovern Medical School, University of Texas HSC, Houston (I.S.D., P.A.D.)
| | - Michael C. Braun
- Department of Pediatrics, Baylor College of Medicine, Texas Children's Hospital, Houston (M.C.B.)
| | - Peter A. Doris
- Center for Human Genetics, Brown Foundation Institute of Molecular Medicine, McGovern Medical School, University of Texas HSC, Houston (I.S.D., P.A.D.)
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21
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Wu J, Raman A, Coffey NJ, Sheng X, Wahba J, Seasock MJ, Ma Z, Beckerman P, Laczkó D, Palmer MB, Kopp JB, Kuo JJ, Pullen SS, Boustany-Kari CM, Linkermann A, Susztak K. The key role of NLRP3 and STING in APOL1-associated podocytopathy. J Clin Invest 2021; 131:136329. [PMID: 34651582 DOI: 10.1172/jci136329] [Citation(s) in RCA: 57] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2020] [Accepted: 09/02/2021] [Indexed: 12/13/2022] Open
Abstract
Coding variants in apolipoprotein L1 (APOL1), termed G1 and G2, can explain most excess kidney disease risk in African Americans; however, the molecular pathways of APOL1-induced kidney dysfunction remain poorly understood. Here, we report that expression of G2 APOL1 in the podocytes of Nphs1rtTA/TRE-G2APOL1 (G2APOL1) mice leads to early activation of the cytosolic nucleotide sensor, stimulator of interferon genes (STING), and the NLR family pyrin domain-containing 3 (NLRP3) inflammasome. STING and NLRP3 expression was increased in podocytes from patients with high-risk APOL1 genotypes, and expression of APOL1 correlated with caspase-1 and gasdermin D (GSDMD) levels. To demonstrate the role of NLRP3 and STING in APOL1-associated kidney disease, we generated transgenic mice with the G2 APOL1 risk variant and genetic deletion of Nlrp3 (G2APOL1/Nlrp3 KO), Gsdmd (G2APOL1/Gsdmd KO), and STING (G2APOL1/STING KO). Knockout mice displayed marked reduction in albuminuria, azotemia, and kidney fibrosis compared with G2APOL1 mice. To evaluate the therapeutic potential of targeting NLRP3, GSDMD, and STING, we treated mice with MCC950, disulfiram, and C176, potent and selective inhibitors of NLRP3, GSDMD, and STING, respectively. G2APOL1 mice treated with MCC950, disulfiram, and C176 showed lower albuminuria and improved kidney function even when inhibitor treatment was initiated after the development of albuminuria.
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Affiliation(s)
- Junnan Wu
- Department of Medicine, Renal-Electrolyte and Hypertension Division, and Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.,Department of Nephrology, Shanghai Jiao Tong University Affiliated Sixth People's Hospital, Shanghai, China
| | - Archana Raman
- Department of Medicine, Renal-Electrolyte and Hypertension Division, and Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Nathan J Coffey
- Department of Medicine, Renal-Electrolyte and Hypertension Division, and Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Xin Sheng
- Department of Medicine, Renal-Electrolyte and Hypertension Division, and Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Joseph Wahba
- Department of Medicine, Renal-Electrolyte and Hypertension Division, and Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Matthew J Seasock
- Department of Medicine, Renal-Electrolyte and Hypertension Division, and Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ziyuan Ma
- Department of Medicine, Renal-Electrolyte and Hypertension Division, and Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Pazit Beckerman
- Department of Medicine, Renal-Electrolyte and Hypertension Division, and Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Dorottya Laczkó
- Department of Medicine, Renal-Electrolyte and Hypertension Division, and Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Matthew B Palmer
- Department of Pathology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jeffrey B Kopp
- Kidney Disease Section, Kidney Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, USA
| | - Jay J Kuo
- Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut, USA
| | - Steven S Pullen
- Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, Connecticut, USA
| | | | - Andreas Linkermann
- Division of Nephrology, Department of Internal Medicine III, University Hospital Carl Gustav Carus at the Technische Universität Dresden, Dresden, Germany
| | - Katalin Susztak
- Department of Medicine, Renal-Electrolyte and Hypertension Division, and Department of Genetics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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22
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Adebayo OC, Betukumesu DK, Nkoy AB, Adesoji OM, Ekulu PM, Van den Heuvel LP, Levtchenko EN, Labarque V. Clinical and genetic factors are associated with kidney complications in African children with sickle cell anaemia. Br J Haematol 2021; 196:204-214. [PMID: 34545573 DOI: 10.1111/bjh.17832] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 08/19/2021] [Accepted: 09/02/2021] [Indexed: 12/11/2022]
Abstract
Clinical and genetic factors have been reported as influencing the development of sickle cell nephropathy (SCN). However, such data remain limited in the paediatric population. In this cross-sectional study, we enrolled 361 sickle cell disease children from the Democratic Republic of Congo. Participants were genotyped for the beta (β)-globin gene, apolipoprotein L1 (APOL1) risk variants, and haem oxygenase-1 (HMOX1) GT-dinucleotide repeats. As markers of kidney damage, albuminuria, hyperfiltration and decreased estimated glomerular filtration with creatinine (eGFRcr) were measured. An association of independent clinical and genetic factors with these markers of kidney damage were assessed via regression analysis. Genetic sequencing confirmed sickle cell anaemia in 326 participants. Albuminuria, hyperfiltration and decreased eGFRcr were present in 65 (20%), 52 (16%) and 18 (5·5%) patients, respectively. Regression analysis revealed frequent blood transfusions, indirect bilirubin and male gender as clinical predictors of SCN. APOL1 high-risk genotype (G1/G1, G2/G2 and G1/G2) was significantly associated with albuminuria (P = 0·04) and hyperfiltration (P = 0·001). HMOX1 GT-dinucleotide long repeats were significantly associated with lower eGFRcr. The study revealed a high burden of kidney damage among Congolese children and provided evidence of the possible role of APOL1 and HMOX1 in making children more susceptible to kidney complications.
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Affiliation(s)
- Oyindamola Christiana Adebayo
- Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium
| | - DieuMerci Kabasele Betukumesu
- Division of Nephrology, Department of Paediatrics, Faculty of Medicine, University Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Agathe Bikupe Nkoy
- Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium.,Division of Nephrology, Department of Paediatrics, Faculty of Medicine, University Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | | | - Pepe Mfutu Ekulu
- Division of Nephrology, Department of Paediatrics, Faculty of Medicine, University Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of Congo
| | - Lambertus P Van den Heuvel
- Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Paediatric Nephrology, Radboud University Medical Centre, Nijmegen, the Netherlands
| | - Elena N Levtchenko
- Department of Development and Regeneration, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Paediatric Nephrology, University Hospitals Leuven, Leuven, Belgium
| | - Veerle Labarque
- Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences, Katholieke Universiteit Leuven, Leuven, Belgium.,Department of Paediatric Haemato-Oncology, University Hospitals Leuven, Leuven, Belgium
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23
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APOL1 genotype-associated morphologic changes among patients with focal segmental glomerulosclerosis. Pediatr Nephrol 2021; 36:2747-2757. [PMID: 33646395 PMCID: PMC8524347 DOI: 10.1007/s00467-021-04990-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 01/25/2021] [Accepted: 02/05/2021] [Indexed: 10/22/2022]
Abstract
BACKGROUND The G1 and G2 alleles of apolipoprotein L1 (APOL1) are common in the Black population and associated with increased risk of focal segmental glomerulosclerosis (FSGS). The molecular mechanisms linking APOL1 risk variants with FSGS are not clearly understood, and APOL1's natural absence in laboratory animals makes studying its pathobiology challenging. METHODS In a cohort of 90 Black patients with either FSGS or minimal change disease (MCD) enrolled in the Nephrotic Syndrome Study Network (58% pediatric onset), we used kidney biopsy traits as an intermediate outcome to help illuminate tissue-based consequences of APOL1 risk variants and expression. We tested associations between APOL1 risk alleles or glomerular APOL1 mRNA expression and 83 light- or electron-microscopy traits measuring structural and cellular kidney changes. RESULTS Under both recessive and dominant models in the FSGS patient subgroup (61%), APOL1 risk variants were significantly correlated (defined as FDR <0.1) with decreased global mesangial hypercellularity, decreased condensation of cytoskeleton, and increased tubular microcysts. No significant correlations were detected in MCD cohort. Independent of risk alleles, glomerular APOL1 expression in FSGS patients was not correlated with morphologic features. CONCLUSIONS While APOL1-associated FSGS is associated with two risk alleles, both one and two risk alleles are associated with cellular/tissue changes in this study of FSGS patients. Our lack of discovery of a large group of tissue differences in FSGS and no significant difference in MCD may be due to the lack of power but also supports investigating whether machine learning methods may more sensitively detect APOL1-associated changes.
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24
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McCarthy GM, Blasio A, Donovan OG, Schaller LB, Bock-Hughes A, Magraner JM, Suh JH, Tattersfield CF, Stillman IE, Shah SS, Zsengeller ZK, Subramanian B, Friedman DJ, Pollak MR. Recessive, gain-of-function toxicity in an APOL1 BAC transgenic mouse model mirrors human APOL1 kidney disease. Dis Model Mech 2021; 14:dmm048952. [PMID: 34350953 PMCID: PMC8353097 DOI: 10.1242/dmm.048952] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 06/21/2021] [Indexed: 12/26/2022] Open
Abstract
People of recent sub-Saharan African ancestry develop kidney failure much more frequently than other groups. A large fraction of this disparity is due to two coding sequence variants in the APOL1 gene. Inheriting two copies of these APOL1 risk variants, known as G1 and G2, causes high rates of focal segmental glomerulosclerosis (FSGS), HIV-associated nephropathy and hypertension-associated end-stage kidney disease. Disease risk follows a recessive mode of inheritance, which is puzzling given the considerable data that G1 and G2 are toxic gain-of-function variants. We developed coisogenic bacterial artificial chromosome (BAC) transgenic mice harboring either the wild-type (G0), G1 or G2 forms of human APOL1. Expression of interferon gamma (IFN-γ) via plasmid tail vein injection results in upregulation of APOL1 protein levels together with robust induction of heavy proteinuria and glomerulosclerosis in G1/G1 and G2/G2 but not G0/G0 mice. The disease phenotype was greater in G2/G2 mice. Neither heterozygous (G1/G0 or G2/G0) risk variant mice nor hemizygous (G1/-, G2/-) mice had significant kidney injury in response to IFN-γ, although the heterozygous mice had a greater proteinuric response than the hemizygous mice, suggesting that the lack of significant disease in humans heterozygous for G1 or G2 is not due to G0 rescue of G1 or G2 toxicity. Studies using additional mice (multicopy G2 and a non-isogenic G0 mouse) supported the notion that disease is largely a function of the level of risk variant APOL1 expression. Together, these findings shed light on the recessive nature of APOL1-nephropathy and present an important model for future studies.
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Affiliation(s)
- Gizelle M. McCarthy
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Angelo Blasio
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Olivia G. Donovan
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Lena B. Schaller
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Althea Bock-Hughes
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Jose M. Magraner
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Jung Hee Suh
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Calum F. Tattersfield
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Isaac E. Stillman
- Dept. of Pathology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Shrijal S. Shah
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Zsuzsanna K. Zsengeller
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Balajikarthick Subramanian
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - David J. Friedman
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
| | - Martin R. Pollak
- Nephrology Division, Department of Medicine, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02215, USA
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25
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Müller D, Schmitz J, Fischer K, Granado D, Groh AC, Krausel V, Lüttgenau SM, Amelung TM, Pavenstädt H, Weide T. Evolution of renal-disease factor APOL1 results in cis and trans orientations at the endoplasmic reticulum that both show cytotoxic effects. Mol Biol Evol 2021; 38:4962-4976. [PMID: 34323996 PMCID: PMC8557400 DOI: 10.1093/molbev/msab220] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The recent and exclusively in humans and a few other higher primates expressed APOL1 (apolipoprotein L1) gene is linked to African human trypanosomiasis (also known as African sleeping sickness) as well as to different forms of kidney diseases. Whereas APOL1’s role as a trypanolytic factor is well established, pathobiological mechanisms explaining its cytotoxicity in renal cells remain unclear. In this study, we compared the APOL family members using a combination of evolutionary studies and cell biological experiments to detect unique features causal for APOL1 nephrotoxic effects. We investigated available primate and mouse genome and transcriptome data to apply comparative phylogenetic and maximum likelihood selection analyses. We suggest that the APOL gene family evolved early in vertebrates and initial splitting occurred in ancestral mammals. Diversification and differentiation of functional domains continued in primates, including developing the two members APOL1 and APOL2. Their close relationship could be diagnosed by sequence similarity and a shared ancestral insertion of an AluY transposable element. Live-cell imaging analyses showed that both expressed proteins show a strong preference to localize at the endoplasmic reticulum (ER). However, glycosylation and secretion assays revealed that—unlike APOL2—APOL1 membrane insertion or association occurs in different orientations at the ER, with the disease-associated mutants facing either the luminal (cis) or cytoplasmic (trans) side of the ER. The various pools of APOL1 at the ER offer a novel perspective in explaining the broad spectrum of its observed toxic effects.
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Affiliation(s)
- Daria Müller
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, Münster, 48149, Germany
| | - Jürgen Schmitz
- Institute of Experimental Pathology, ZMBE, University of Münster, Von-Esmarch-Str. 56, Münster, D-48149, Germany
| | - Katharina Fischer
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, Münster, 48149, Germany
| | - Daniel Granado
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, Münster, 48149, Germany
| | - Ann-Christin Groh
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, Münster, 48149, Germany
| | - Vanessa Krausel
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, Münster, 48149, Germany
| | - Simona Mareike Lüttgenau
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, Münster, 48149, Germany
| | - Till Maximilian Amelung
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, Münster, 48149, Germany
| | - Hermann Pavenstädt
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, Münster, 48149, Germany
| | - Thomas Weide
- University Hospital of Münster (UKM), Internal Medicine D (MedD), Molecular Nephrology, Albert-Schweitzer-Campus 1 Building A14, Münster, 48149, Germany
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26
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Schaub C, Lee P, Racho-Jansen A, Giovinazzo J, Terra N, Raper J, Thomson R. Coiled-coil binding of the leucine zipper domains of APOL1 is necessary for the open cation channel conformation. J Biol Chem 2021; 297:101009. [PMID: 34331942 PMCID: PMC8446801 DOI: 10.1016/j.jbc.2021.101009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 07/12/2021] [Accepted: 07/23/2021] [Indexed: 11/17/2022] Open
Abstract
Apolipoprotein L-I (APOL1) is a channel-forming effector of innate immunity. The common human APOL1 variant G0 provides protection against infection with certain Trypanosoma and Leishmania parasite species, but it cannot protect against the trypanosomes responsible for human African trypanosomiasis. Human APOL1 variants G1 and G2 protect against human-infective trypanosomes but also confer a higher risk of developing chronic kidney disease. Trypanosome-killing activity is dependent on the ability of APOL1 to insert into membranes at acidic pH and form pH-gated cation channels. We previously mapped the channel’s pore-lining region to the C-terminal domain (residues 332–398) and identified a membrane-insertion domain (MID, residues 177–228) that facilitates acidic pH-dependent membrane insertion. In this article, we further investigate structural determinants of cation channel formation by APOL1. Using a combination of site-directed mutagenesis and targeted chemical modification, our data indicate that the C-terminal heptad-repeat sequence (residues 368–395) is a bona fide leucine zipper domain (ZIP) that is required for cation channel formation as well as lysis of trypanosomes and mammalian cells. Using protein-wide cysteine-scanning mutagenesis, coupled with the substituted cysteine accessibility method, we determined that, in the open channel state, both the N-terminal domain and the C-terminal ZIP domain are exposed on the intralumenal/extracellular side of the membrane and provide evidence that each APOL1 monomer contributes four transmembrane domains to the open cation channel conformation. Based on these data, we propose an oligomeric topology model in which the open APOL1 cation channel is assembled from the coiled-coil association of C-terminal ZIP domains.
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Affiliation(s)
- Charles Schaub
- Department of Biological sciences, Hunter College, City University of New York, USA; The Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York; Vanderbilt University, Nashville, Tennessee, USA
| | - Penny Lee
- Department of Biological sciences, Hunter College, City University of New York, USA; John Jay College, City University of New York, USA
| | - Alisha Racho-Jansen
- Department of Biological sciences, Hunter College, City University of New York, USA
| | - Joe Giovinazzo
- Department of Biological sciences, Hunter College, City University of New York, USA; University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Nada Terra
- Department of Biological sciences, Hunter College, City University of New York, USA; Icahn School of Medicine at Mount Sinai, New York, USA
| | - Jayne Raper
- Department of Biological sciences, Hunter College, City University of New York, USA; The Ph.D. Program in Biochemistry, The Graduate Center of the City University of New York.
| | - Russell Thomson
- Department of Biological sciences, Hunter College, City University of New York, USA.
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Ekulu PM, Adebayo OC, Decuypere JP, Bellucci L, Elmonem MA, Nkoy AB, Mekahli D, Bussolati B, van den Heuvel LP, Arcolino FO, Levtchenko EN. Novel Human Podocyte Cell Model Carrying G2/G2 APOL1 High-Risk Genotype. Cells 2021; 10:cells10081914. [PMID: 34440683 PMCID: PMC8391400 DOI: 10.3390/cells10081914] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Revised: 07/20/2021] [Accepted: 07/23/2021] [Indexed: 02/01/2023] Open
Abstract
Apolipoprotein L1 (APOL1) high-risk genotypes (HRG), G1 and G2, increase the risk of various non-diabetic kidney diseases in the African population. To date, the precise mechanisms by which APOL1 risk variants induce injury on podocytes and other kidney cells remain unclear. Trying to unravel these mechanisms, most studies have used animal or cell models created by gene editing. We developed and characterised conditionally immortalised human podocyte cell lines derived from urine of a donor carrying APOL1 HRG G2/G2. Following induction of APOL1 expression by polyinosinic-polycytidylic acid (poly(I:C)), we assessed functional features of APOL1-induced podocyte dysfunction. As control, APOL1 wild type (G0/G0) podocyte cell line previously generated from a Caucasian donor was used. Upon exposure to poly(I:C), G2/G2 and G0/G0 podocytes upregulated APOL1 expression resulting in podocytes detachment, decreased cells viability and increased apoptosis rate in a genotype-independent manner. Nevertheless, G2/G2 podocyte cell lines exhibited altered features, including upregulation of CD2AP, alteration of cytoskeleton, reduction of autophagic flux and increased permeability in an in vitro model under continuous perfusion. The human APOL1 G2/G2 podocyte cell model is a useful tool for unravelling the mechanisms of APOL1-induced podocyte injury and the cellular functions of APOL1.
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Affiliation(s)
- Pepe M. Ekulu
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Department of Paediatrics, Division of Nephrology, Faculty of Medicine, University Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Oyindamola C. Adebayo
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Centre for Molecular and Vascular Biology, Department of Cardiovascular Sciences, Katholieke Universiteit Leuven, 3000 Leuven, Belgium
| | - Jean-Paul Decuypere
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
| | - Linda Bellucci
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10124 Turin, Italy; (L.B.); (B.B.)
| | - Mohamed A. Elmonem
- Department of Clinical and Chemical Pathology, Faculty of Medicine, Cairo University, Cairo 11628, Egypt;
| | - Agathe B. Nkoy
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Department of Paediatrics, Division of Nephrology, Faculty of Medicine, University Hospital of Kinshasa, University of Kinshasa, Kinshasa, Democratic Republic of the Congo
| | - Djalila Mekahli
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Department of Paediatrics, Division of Nephrology, University Hospitals Leuven, 3000 Leuven, Belgium
| | - Benedetta Bussolati
- Department of Molecular Biotechnology and Health Sciences, University of Turin, 10124 Turin, Italy; (L.B.); (B.B.)
| | - Lambertus P. van den Heuvel
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Department of Paediatric Nephrology, Radboud University Medical Centre, 6500 Nijmegen, The Netherlands
| | - Fanny O. Arcolino
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Correspondence: ; Tel.: +32-16372647
| | - Elena N. Levtchenko
- Department of Development and Regeneration, Katholieke Universiteit Leuven, 3000 Leuven, Belgium; (P.M.E.); (O.C.A.); (J.-P.D.); (A.B.N.); (D.M.); (L.P.v.d.H.); (E.N.L.)
- Department of Paediatrics, Division of Nephrology, University Hospitals Leuven, 3000 Leuven, Belgium
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Ultsch M, Holliday MJ, Gerhardy S, Moran P, Scales SJ, Gupta N, Oltrabella F, Chiu C, Fairbrother W, Eigenbrot C, Kirchhofer D. Structures of the ApoL1 and ApoL2 N-terminal domains reveal a non-classical four-helix bundle motif. Commun Biol 2021; 4:916. [PMID: 34316015 PMCID: PMC8316464 DOI: 10.1038/s42003-021-02387-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2021] [Accepted: 06/23/2021] [Indexed: 02/07/2023] Open
Abstract
Apolipoprotein L1 (ApoL1) is a circulating innate immunity protein protecting against trypanosome infection. However, two ApoL1 coding variants are associated with a highly increased risk of chronic kidney disease. Here we present X-ray and NMR structures of the N-terminal domain (NTD) of ApoL1 and of its closest relative ApoL2. In both proteins, four of the five NTD helices form a four-helix core structure which is different from the classical four-helix bundle and from the pore-forming domain of colicin A. The reactivity with a conformation-specific antibody and structural models predict that this four-helix motif is also present in the NTDs of ApoL3 and ApoL4, suggesting related functions within the small ApoL family. The long helix 5 of ApoL1 is conformationally flexible and contains the BH3-like region. This BH3-like α-helix resembles true BH3 domains only in sequence and structure but not in function, since it does not bind to the pro-survival members of the Bcl-2 family, suggesting a Bcl-2-independent role in cytotoxicity. These findings should expedite a more comprehensive structural and functional understanding of the ApoL immune protein family.
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Affiliation(s)
- Mark Ultsch
- Department of Structural Biology, Genentech Inc., South San Francisco, CA, USA
| | - Michael J Holliday
- Department of Early Discovery Biochemistry, Genentech Inc., South San Francisco, CA, USA
| | - Stefan Gerhardy
- Department of Early Discovery Biochemistry, Genentech Inc., South San Francisco, CA, USA
| | - Paul Moran
- Department of Early Discovery Biochemistry, Genentech Inc., South San Francisco, CA, USA
| | - Suzie J Scales
- Department of Immunology, Genentech Inc., South San Francisco, CA, USA
| | - Nidhi Gupta
- Department of Immunology, Genentech Inc., South San Francisco, CA, USA
| | | | - Cecilia Chiu
- Department of Antibody Engineering, Genentech Inc., South San Francisco, CA, USA
| | - Wayne Fairbrother
- Department of Early Discovery Biochemistry, Genentech Inc., South San Francisco, CA, USA
| | - Charles Eigenbrot
- Department of Structural Biology, Genentech Inc., South San Francisco, CA, USA
| | - Daniel Kirchhofer
- Department of Early Discovery Biochemistry, Genentech Inc., South San Francisco, CA, USA.
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29
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Chen DP, Zaky ZS, Schold JD, Herlitz LC, El-Rifai R, Drawz PE, Bruggeman LA, Barisoni L, Hogan SL, Hu Y, O'Toole JF, Poggio ED, Sedor JR. Podocyte density is reduced in kidney allografts with high-risk APOL1 genotypes at transplantation. Clin Transplant 2021; 35:e14234. [PMID: 33511679 DOI: 10.1111/ctr.14234] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2020] [Revised: 11/25/2020] [Accepted: 01/20/2021] [Indexed: 01/23/2023]
Abstract
Variants in apolipoprotein L1 (APOL1) gene are associated with nondiabetic kidney diseases in black subjects and reduced kidney transplant graft survival. Living and deceased black kidney donors (n = 107) were genotyped for APOL1 variants. To determine whether allografts from high-risk APOL1 donors have reduced podocyte densities contributing to allograft failure, we morphometrically estimated podocyte number, glomerular volume, and podocyte density. We compared allograft loss and eGFR trajectories stratified by APOL1 high-risk and low-risk genotypes. Demographic characteristics were similar in high-risk (n = 16) and low-risk (n = 91) donors. Podocyte density was significantly lower in high-risk than low-risk donors (108 ± 26 vs 127 ± 40 podocytes/106 um3 , P = .03). Kaplan-Meier graft survival (high-risk 61% vs. low-risk 91%, p-value = 0.049) and multivariable Cox models (hazard ratio = 2.6; 95% CI, 0.9-7.8) revealed higher graft loss in recipients of APOL1 high-risk allografts over 48 months. More rapid eGFR decline was seen in recipients of high-risk APOL1 allografts (P < .001). At 60 months, eGFR was 27 vs. 51 mL/min/1.73 min2 in recipients of APOL1 high-risk vs low-risk kidney allografts, respectively. Kidneys from high-risk APOL1 donors had worse outcomes versus low-risk APOL1 genotypes. Lower podocyte density in kidneys from high-risk APOL1 donors may increase susceptibility to CKD from subsequent stresses in both the recipients and donors.
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Affiliation(s)
- Dhruti P Chen
- Division of Nephrology, UNC Kidney Center, University of North Carolina, Chapel Hill, NC, USA
| | - Ziad S Zaky
- Glickman Urology and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Jesse D Schold
- Glickman Urology and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA.,Quantitative Health Sciences, Cleveland Clinic, Cleveland, OH, USA
| | - Leal C Herlitz
- Pathology and Lab Medicine Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Rasha El-Rifai
- Division of Renal Diseases and Hypertension, University of Minnesota, Minneapolis, MN, USA
| | - Paul E Drawz
- Division of Renal Diseases and Hypertension, University of Minnesota, Minneapolis, MN, USA
| | - Leslie A Bruggeman
- Glickman Urology and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA.,Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Laura Barisoni
- Departments of Pathology and Medicine, Division of Nephrology, Duke University School of Medicine, Durham, NC, USA
| | - Susan L Hogan
- Division of Nephrology, UNC Kidney Center, University of North Carolina, Chapel Hill, NC, USA
| | - Yichun Hu
- Division of Nephrology, UNC Kidney Center, University of North Carolina, Chapel Hill, NC, USA
| | - John F O'Toole
- Glickman Urology and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA.,Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Emilio D Poggio
- Glickman Urology and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA.,Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - John R Sedor
- Glickman Urology and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA.,Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
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30
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Bruno J, Edwards JC. Kidney-disease-associated variants of Apolipoprotein L1 show gain of function in cation channel activity. J Biol Chem 2021; 296:100238. [PMID: 33380423 PMCID: PMC7948812 DOI: 10.1074/jbc.ra120.013943] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 12/23/2020] [Accepted: 12/30/2020] [Indexed: 11/08/2022] Open
Abstract
Variants in Apolipoprotein L1 (ApoL1) are known to be responsible for increased risk of some progressive kidney diseases among people of African ancestry. ApoL1 is an amphitropic protein that can insert into phospholipid membranes and confer anion- or cation-selective permeability to phospholipid membranes depending on pH. Whether these activities differ among the variants or whether they contribute to disease pathogenesis is unknown. We used assays of voltage-driven ion flux from phospholipid vesicles and of stable membrane association to assess differences among ApoL1 isoforms. There is a significant (approximately twofold) increase in the cation-selective ion permease activity of the two kidney-disease-associated variants compared with the reference protein. In contrast, we find no difference in the anion-selective permease activity at low pH among the isoforms. Compared with the reference sequence, the two disease-associated variants show increased stable association with phospholipid vesicles under conditions that support the cation permease activity, suggesting that the increased activity may be due to more efficient membrane association and insertion. There is no difference in membrane association among isoforms under optimal conditions for the anion permease activity. These data support a model in which enhanced cation permeability may contribute to the progressive kidney diseases associated with high-risk ApoL1 alleles.
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Affiliation(s)
- Jonathan Bruno
- Nephrology Division, Department of Internal Medicine, Saint Louis University, St Louis, Missouri, USA
| | - John C Edwards
- Nephrology Division, Department of Internal Medicine, Saint Louis University, St Louis, Missouri, USA.
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31
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Pays E. The function of apolipoproteins L (APOLs): relevance for kidney disease, neurotransmission disorders, cancer and viral infection. FEBS J 2021; 288:360-381. [PMID: 32530132 PMCID: PMC7891394 DOI: 10.1111/febs.15444] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Revised: 05/24/2020] [Accepted: 06/03/2020] [Indexed: 12/17/2022]
Abstract
The discovery that apolipoprotein L1 (APOL1) is the trypanolytic factor of human serum raised interest about the function of APOLs, especially following the unexpected finding that in addition to their protective action against sleeping sickness, APOL1 C-terminal variants also cause kidney disease. Based on the analysis of the structure and trypanolytic activity of APOL1, it was proposed that APOLs could function as ion channels of intracellular membranes and be involved in mechanisms triggering programmed cell death. In this review, the recent finding that APOL1 and APOL3 inversely control the synthesis of phosphatidylinositol-4-phosphate (PI(4)P) by the Golgi PI(4)-kinase IIIB (PI4KB) is commented. APOL3 promotes Ca2+ -dependent activation of PI4KB, but due to their increased interaction with APOL3, APOL1 C-terminal variants can inactivate APOL3, leading to reduction of Golgi PI(4)P synthesis. The impact of APOLs on several pathological processes that depend on Golgi PI(4)P levels is discussed. I propose that through their effect on PI4KB activity, APOLs control not only actomyosin activities related to vesicular trafficking, but also the generation and elongation of autophagosomes induced by inflammation.
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Affiliation(s)
- Etienne Pays
- Laboratory of Molecular ParasitologyIBMMUniversité Libre de BruxellesGosseliesBelgium
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32
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Hong X, Rosenberg AZ, Zhang B, Binns-Roemer E, David V, Lv Y, Hjorten RC, Reidy KJ, Chen TK, Wang G, Ji Y, Simpson CL, Davis RL, Kopp JB, Wang X, Winkler CA. Joint Associations of Maternal-Fetal APOL1 Genotypes and Maternal Country of Origin With Preeclampsia Risk. Am J Kidney Dis 2020; 77:879-888.e1. [PMID: 33359152 DOI: 10.1053/j.ajkd.2020.10.020] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 10/24/2020] [Indexed: 12/25/2022]
Abstract
RATIONALE & OBJECTIVES Preeclampsia, which disproportionately affects Black women, is a leading cause of preterm delivery and risk for future hypertension and chronic kidney disease (CKD). Apolipoprotein L1 (APOL1) kidney risk alleles, common among Black individuals, contribute substantially to CKD disparities. Given the strong link between preeclampsia and CKD, we investigated whether maternal and fetal APOL1 risk alleles can jointly influence preeclampsia risk, and explored potential modifiers of the association between APOL1 and preeclampsia. STUDY DESIGN Nested case-control study. SETTING & PARTICIPANTS 426 Black mother-infant pairs (275 African Americans and 151 Haitians) from the Boston Birth Cohort. EXPOSURE Maternal and fetal APOL1 risk alleles. OUTCOMES Preeclampsia. ANALYTICAL APPROACH Logistic regression models with adjustment for demographic characteristics were applied to analyze associations between fetal and maternal APOL1 risk alleles and risk of preeclampsia and to investigate the effects of modification by maternal country of origin. RESULTS Fetal APOL1 risk alleles tended to be associated with an increased risk of preeclampsia, which was not statistically significant in the total genotyped population. However, this association was modified by maternal country of origin (P<0.05 for interaction tests): fetal APOL1 risk alleles were significantly associated with an increased risk of preeclampsia among African Americans under recessive (odds ratio [OR], 3.6 [95% CI, 1.3-9.7]; P=0.01) and additive (OR, 1.7 [95% CI, 1.1-2.6]; P=0.01) genetic models but not in Haitian Americans. Also, maternal-fetal genotype discordance at the APOL1 locus was associated with a 2.6-fold higher risk of preeclampsia (P<0.001) in African Americans. LIMITATIONS Limited sample size in stratified analyses; self-reported maternal country of origin; pre-pregnancy estimated glomerular filtration rate (eGFR) and proteinuria data in mothers were not collected; unmeasured confounding social and/or environmental factors; no replication study. CONCLUSIONS This study supports the hypothesis that fetal APOL1 kidney risk alleles are associated with increased risk for preeclampsia in a recessive mode of inheritance in African Americans and suggests that maternal-fetal genotype discordance is also associated with this risk. These conclusions underscore the need to better understand maternal-fetal interaction and their genetic and environmental factors as contributors to ethnic disparities in preeclampsia.
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Affiliation(s)
- Xiumei Hong
- Department of Population, Family and Reproductive Health, Center for the Early Life Origins of Disease, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD
| | - Avi Z Rosenberg
- Department of Pathology, Johns Hopkins University, Baltimore, MD
| | - Boyang Zhang
- Department of Biostatistics, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD
| | - Elizabeth Binns-Roemer
- Molecular Genetic Epidemiology Section, Frederick National Laboratory for Cancer Research in the Basic Research Laboratory, National Cancer Institute, Frederick, MD
| | - Victor David
- Basic Research Laboratory, Center for Cancer Research, National Cancer Institute, Frederick, MD
| | - Yiming Lv
- Department of Population, Family and Reproductive Health, Center for the Early Life Origins of Disease, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD
| | - Rebecca C Hjorten
- Department of Medicine, Division of Nephrology, University of Washington, Seattle, WA
| | - Kimberly J Reidy
- Department of Pediatrics, Division of Pediatric Nephrology, Children's Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, NY
| | - Teresa K Chen
- Department of Medicine, Division of Nephrology and Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins Medical Institutions, Baltimore, MD
| | - Guoying Wang
- Department of Population, Family and Reproductive Health, Center for the Early Life Origins of Disease, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD
| | - Yuelong Ji
- Department of Population, Family and Reproductive Health, Center for the Early Life Origins of Disease, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD
| | - Claire L Simpson
- Department of Genetics, Genomics, and Informatics, University of Tennessee Health Science Center, Memphis, TN
| | - Robert L Davis
- Center for Biomedical Informatics, Department of Pediatrics, University of Tennessee Health Science Center, Memphis, TN
| | - Jeffrey B Kopp
- Kidney Diseases Section, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD
| | - Xiaobin Wang
- Department of Population, Family and Reproductive Health, Center for the Early Life Origins of Disease, Johns Hopkins University Bloomberg School of Public Health, Baltimore, MD; Division of General Pediatrics and Adolescent Medicine, Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD.
| | - Cheryl A Winkler
- Molecular Genetic Epidemiology Section, Frederick National Laboratory for Cancer Research in the Basic Research Laboratory, National Cancer Institute, Frederick, MD.
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33
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Madhavan SM, Buck M. The Relationship between APOL1 Structure and Function: Clinical Implications. KIDNEY360 2020; 2:134-140. [PMID: 35368828 PMCID: PMC8785724 DOI: 10.34067/kid.0002482020] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 11/04/2020] [Indexed: 02/04/2023]
Abstract
Common variants in the APOL1 gene are associated with an increased risk of nondiabetic kidney disease in individuals of African ancestry. Mechanisms by which APOL1 variants mediate kidney disease pathogenesis are not well understood. Amino acid changes resulting from the kidney disease-associated APOL1 variants alter the three-dimensional structure and conformational dynamics of the C-terminal α-helical domain of the protein, which can rationalize the functional consequences. Understanding the three-dimensional structure of the protein, with and without the risk variants, can provide insights into the pathogenesis of kidney diseases mediated by APOL1 variants.
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Affiliation(s)
| | - Matthias Buck
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
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34
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Zhong F, Lu HP, Chen G, Dang YW, Zhang XG, Liang Y, Li MX, Li GS, Chen XY, Yao YX, Qin YY, Mo M, Zhang KL, Ding H, Huang ZG, Wei ZX. The clinical significance of apolipoprotein L1 in head and neck squamous cell carcinoma. Oncol Lett 2020; 20:377. [PMID: 33154775 PMCID: PMC7608033 DOI: 10.3892/ol.2020.12240] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2019] [Accepted: 08/18/2020] [Indexed: 12/20/2022] Open
Abstract
Approximately 500,000 new head and neck squamous cell carcinoma (HNSCC) cases are detected every year around the world, and its incidence ranks sixth among all cancer types globally. Among these cases, oral squamous cell carcinoma (OSCC) and laryngeal squamous cell carcinoma (LSCC) are HNSCC subtypes with high incidence rates, especially in China. The present study examines the association between the apolipoprotein L1 (APOL1) mRNA and protein expression and clinical parameters in HNSCC. The two most common types (oral and larynx) of HNSCC were selected for subgroup analyses. Immunohistochemistry (IHC) was used to detect APOL1 protein expression levels in HNSCC clinical specimens. It was demonstrated that APOL1 protein expression in 221 cases of HNSCC was higher compared with that in normal tissues. Consistent upregulation of APOL1 protein was also found in subgroups of OSCC and LSCC. Through mining the ArrayExpress, The Cancer Genome Atlas and the Gene Expression Omnibus databases, microarrays and RNA sequencing data for HNSCC were retrieved, which were used to analyze APOL1 mRNA expression levels. The results showed that APOL1 expression was higher in both OSCC and LSCC subtypes, as well as in HNSCC, compared with that in non-cancerous squamous epithelium. The summary receiver operating characteristic analysis showed that APOL1 had potential as a diagnostic biomarker for HNSCC, OSCC and LSCC. Thus, upregulation of APOL1 may contribute to the tumorigenesis of HNSCC.
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Affiliation(s)
- Feng Zhong
- Department of Pathology, Hengxian People's Hospital, Nanning, Guangxi Zhuang Autonomous Region 530300, P.R. China
| | - Hui-Ping Lu
- Department of Pathology, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Gang Chen
- Department of Pathology, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Yi-Wu Dang
- Department of Pathology, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Xiao-Guohui Zhang
- Department of Pathology, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Yao Liang
- Department of Pathology, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Ming-Xuan Li
- Department of Pathology, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Guo-Sheng Li
- Department of Pathology, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Xiao-Yi Chen
- Department of Pathology, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Yu-Xuan Yao
- Department of Pathology, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Yong-Ying Qin
- Department of Pathology, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Miao Mo
- Department of Radiotherapy, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Kai-Lang Zhang
- Department of Radiotherapy, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Hua Ding
- Department of Radiotherapy, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Zhi-Guang Huang
- Department of Pathology, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
| | - Zhu-Xin Wei
- Department of Radiotherapy, First Affiliated Hospital of Guangxi Medical University, Nanning, Guangxi Zhuang Autonomous Region 530021, P.R. China
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35
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Affiliation(s)
- Etienne Pays
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, Gosselies, Belgium
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36
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Datta S, Kataria R, Zhang JY, Moore S, Petitpas K, Mohamed A, Zahler N, Pollak MR, Olabisi OA. Kidney Disease-Associated APOL1 Variants Have Dose-Dependent, Dominant Toxic Gain-of-Function. J Am Soc Nephrol 2020; 31:2083-2096. [PMID: 32675303 PMCID: PMC7461666 DOI: 10.1681/asn.2020010079] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Accepted: 05/12/2020] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Two coding renal risk variants (RRVs) of the APOL1 gene (G1 and G2) are associated with large increases in CKD rates among populations of recent African descent, but the underlying molecular mechanisms are unknown. Mammalian cell culture models are widely used to study cytotoxicity of RRVs, but results have been contradictory. It remains unclear whether cytotoxicity is RRV-dependent or driven solely by variant-independent overexpression. It is also unknown whether expression of the reference APOL1 allele, the wild-type G0, could prevent cytotoxicity of RRVs. METHODS We generated tetracycline-inducible APOL1 expression in human embryonic kidney HEK293 cells and examined the effects of increased expression of APOL1 (G0, G1, G2, G0G0, G0G1, or G0G2) on known cytotoxicity phenotypes, including reduced viability, increased swelling, potassium loss, aberrant protein phosphorylation, and dysregulated energy metabolism. Furthermore, whole-genome transcriptome analysis examined deregulated canonical pathways. RESULTS At moderate expression, RRVs but not G0 caused cytotoxicity in a dose-dependent manner that coexpression of G0 did not reduce. RRVs also have dominant effects on canonical pathways relevant for the cellular stress response. CONCLUSIONS In HEK293 cells, RRVs exhibit a dominant toxic gain-of-function phenotype that worsens with increasing expression. These observations suggest that high steady-state levels of RRVs may underlie cellular injury in APOL1 nephropathy, and that interventions that reduce RRV expression in kidney compartments may mitigate APOL1 nephropathy.
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Affiliation(s)
- Somenath Datta
- Division of Nephrology and Duke Molecular Physiology Institute, Duke University, Durham, North Carolina
- Division of Nephrology, Massachusetts General Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | - Rama Kataria
- Division of Nephrology, Massachusetts General Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | - Jia-Yue Zhang
- Harvard Medical School, Boston, Massachusetts
- Division of Nephrology, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Savannah Moore
- Division of Nephrology, Massachusetts General Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | - Kaitlyn Petitpas
- Division of Nephrology, Massachusetts General Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | - Adam Mohamed
- Division of Nephrology, Massachusetts General Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
| | | | - Martin R Pollak
- Harvard Medical School, Boston, Massachusetts
- Division of Nephrology, Beth Israel Deaconess Medical Center, Boston, Massachusetts
| | - Opeyemi A Olabisi
- Division of Nephrology and Duke Molecular Physiology Institute, Duke University, Durham, North Carolina
- Division of Nephrology, Massachusetts General Hospital, Boston, Massachusetts
- Harvard Medical School, Boston, Massachusetts
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APOL1 variant-associated kidney disease: from trypanosomes to podocyte cytoskeleton. Kidney Int 2020; 98:1373-1377. [PMID: 32835731 DOI: 10.1016/j.kint.2020.07.034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 07/15/2020] [Accepted: 07/23/2020] [Indexed: 12/21/2022]
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Scales SJ, Gupta N, De Mazière AM, Posthuma G, Chiu CP, Pierce AA, Hötzel K, Tao J, Foreman O, Koukos G, Oltrabella F, Klumperman J, Lin W, Peterson AS. Apolipoprotein L1-Specific Antibodies Detect Endogenous APOL1 inside the Endoplasmic Reticulum and on the Plasma Membrane of Podocytes. J Am Soc Nephrol 2020; 31:2044-2064. [PMID: 32764142 DOI: 10.1681/asn.2019080829] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 05/10/2020] [Indexed: 12/29/2022] Open
Abstract
BACKGROUND APOL1 is found in human kidney podocytes and endothelia. Variants G1 and G2 of the APOL1 gene account for the high frequency of nondiabetic CKD among African Americans. Proposed mechanisms of kidney podocyte cytotoxicity resulting from APOL1 variant overexpression implicate different subcellular compartments. It is unclear where endogenous podocyte APOL1 resides, because previous immunolocalization studies utilized overexpressed protein or commercially available antibodies that crossreact with APOL2. This study describes and distinguishes the locations of both APOLs. METHODS Immunohistochemistry, confocal and immunoelectron microscopy, and podocyte fractionation localized endogenous and transfected APOL1 using a large panel of novel APOL1-specific mouse and rabbit monoclonal antibodies. RESULTS Both endogenous podocyte and transfected APOL1 isoforms vA and vB1 (and a little of isoform vC) localize to the luminal face of the endoplasmic reticulum (ER) and to the cell surface, but not to mitochondria, endosomes, or lipid droplets. In contrast, APOL2, isoform vB3, and most vC of APOL1 localize to the cytoplasmic face of the ER and are consequently absent from the cell surface. APOL1 knockout podocytes do not stain for APOL1, attesting to the APOL1-specificity of the antibodies. Stable re-transfection of knockout podocytes with inducible APOL1-G0, -G1, and -G2 showed no differences in localization among variants. CONCLUSIONS APOL1 is found in the ER and plasma membrane, consistent with either the ER stress or surface cation channel models of APOL1-mediated cytotoxicity. The surface localization of APOL1 variants potentially opens new therapeutic targeting avenues.
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Affiliation(s)
- Suzie J Scales
- Department of Molecular Biology, Genentech, South San Francisco, California .,Department of Immunology, Genentech, South San Francisco, California
| | - Nidhi Gupta
- Department of Molecular Biology, Genentech, South San Francisco, California.,Department of Immunology, Genentech, South San Francisco, California
| | - Ann M De Mazière
- Section of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - George Posthuma
- Section of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - Cecilia P Chiu
- Department of Antibody Engineering, Genentech, South San Francisco, California
| | - Andrew A Pierce
- Department of Pathology, Genentech, South San Francisco, California
| | - Kathy Hötzel
- Department of Pathology, Genentech, South San Francisco, California
| | - Jianhua Tao
- Department of Pathology, Genentech, South San Francisco, California
| | - Oded Foreman
- Department of Pathology, Genentech, South San Francisco, California
| | - Georgios Koukos
- Department of Molecular Biology, Genentech, South San Francisco, California
| | | | - Judith Klumperman
- Section of Cell Biology, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands
| | - WeiYu Lin
- Department of Antibody Engineering, Genentech, South San Francisco, California
| | - Andrew S Peterson
- Department of Molecular Biology, Genentech, South San Francisco, California
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39
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Gupta N, Wang X, Wen X, Moran P, Paluch M, Hass PE, Heidersbach A, Haley B, Kirchhofer D, Brezski RJ, Peterson AS, Scales SJ. Domain-Specific Antibodies Reveal Differences in the Membrane Topologies of Apolipoprotein L1 in Serum and Podocytes. J Am Soc Nephrol 2020; 31:2065-2082. [PMID: 32764138 DOI: 10.1681/asn.2019080830] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 05/10/2020] [Indexed: 01/13/2023] Open
Abstract
BACKGROUND Circulating APOL1 lyses trypanosomes, protecting against human sleeping sickness. Two common African gene variants of APOL1, G1 and G2, protect against infection by species of trypanosomes that resist wild-type APOL1. At the same time, the protection predisposes humans to CKD, an elegant example of balanced polymorphism. However, the exact mechanism of APOL1-mediated podocyte damage is not clear, including APOL1's subcellular localization, topology, and whether the damage is related to trypanolysis. METHODS APOL1 topology in serum (HDL particles) and in kidney podocytes was mapped with flow cytometry, immunoprecipitation, and trypanolysis assays that tracked 170 APOL1 domain-specific monoclonal antibodies. APOL1 knockout podocytes confirmed antibody specificity. RESULTS APOL1 localizes to the surface of podocytes, with most of the pore-forming domain (PFD) and C terminus of the Serum Resistance Associated-interacting domain (SRA-ID), but not the membrane-addressing domain (MAD), being exposed. In contrast, differential trypanolytic blocking activity reveals that the MAD is exposed in serum APOL1, with less of the PFD accessible. Low pH did not detectably alter the gross topology of APOL1, as determined by antibody accessibility, in serum or on podocytes. CONCLUSIONS Our antibodies highlighted different conformations of native APOL1 topology in serum (HDL particles) and at the podocyte surface. Our findings support the surface ion channel model for APOL1 risk variant-mediated podocyte injury, as well as providing domain accessibility information for designing APOL1-targeted therapeutics.
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Affiliation(s)
- Nidhi Gupta
- Department of Molecular Biology, Genentech, South San Francisco, California.,Department of Immunology, Genentech, South San Francisco, California
| | - Xinhua Wang
- Department of Antibody Engineering, Genentech, South San Francisco, California
| | - Xiaohui Wen
- Department of Molecular Biology, Genentech, South San Francisco, California
| | - Paul Moran
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, California
| | - Maciej Paluch
- Department of Protein Chemistry, Genentech, South San Francisco, California
| | - Philip E Hass
- Department of Protein Chemistry, Genentech, South San Francisco, California
| | - Amy Heidersbach
- Department of Molecular Biology, Genentech, South San Francisco, California
| | - Benjamin Haley
- Department of Molecular Biology, Genentech, South San Francisco, California
| | - Daniel Kirchhofer
- Department of Early Discovery Biochemistry, Genentech, South San Francisco, California
| | - Randall J Brezski
- Department of Antibody Engineering, Genentech, South San Francisco, California
| | - Andrew S Peterson
- Department of Molecular Biology, Genentech, South San Francisco, California
| | - Suzie J Scales
- Department of Molecular Biology, Genentech, South San Francisco, California .,Department of Immunology, Genentech, South San Francisco, California
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40
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Giovinazzo JA, Thomson RP, Khalizova N, Zager PJ, Malani N, Rodriguez-Boulan E, Raper J, Schreiner R. Apolipoprotein L-1 renal risk variants form active channels at the plasma membrane driving cytotoxicity. eLife 2020; 9:51185. [PMID: 32427098 PMCID: PMC7292663 DOI: 10.7554/elife.51185] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 05/14/2020] [Indexed: 12/25/2022] Open
Abstract
Recently evolved alleles of Apolipoprotein L-1 (APOL1) provide increased protection against African trypanosome parasites while also significantly increasing the risk of developing kidney disease in humans. APOL1 protects against trypanosome infections by forming ion channels within the parasite, causing lysis. While the correlation to kidney disease is robust, there is little consensus concerning the underlying disease mechanism. We show in human cells that the APOL1 renal risk variants have a population of active channels at the plasma membrane, which results in an influx of both Na+ and Ca2+. We propose a model wherein APOL1 channel activity is the upstream event causing cell death, and that the activate-state, plasma membrane-localized channel represents the ideal drug target to combat APOL1-mediated kidney disease.
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Affiliation(s)
- Joseph A Giovinazzo
- Department of Biological Sciences, Hunter College at City University of New York, New York, United States
| | - Russell P Thomson
- Department of Biological Sciences, Hunter College at City University of New York, New York, United States
| | - Nailya Khalizova
- Department of Biological Sciences, Hunter College at City University of New York, New York, United States
| | - Patrick J Zager
- Department of Ophthalmology, Margaret Dyson Vision Research Institute, Weill Cornell Medicine, New York, United States
| | | | - Enrique Rodriguez-Boulan
- Department of Ophthalmology, Margaret Dyson Vision Research Institute, Weill Cornell Medicine, New York, United States
| | - Jayne Raper
- Department of Biological Sciences, Hunter College at City University of New York, New York, United States
| | - Ryan Schreiner
- Department of Ophthalmology, Margaret Dyson Vision Research Institute, Weill Cornell Medicine, New York, United States
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41
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Uzureau S, Lecordier L, Uzureau P, Hennig D, Graversen JH, Homblé F, Mfutu PE, Oliveira Arcolino F, Ramos AR, La Rovere RM, Luyten T, Vermeersch M, Tebabi P, Dieu M, Cuypers B, Deborggraeve S, Rabant M, Legendre C, Moestrup SK, Levtchenko E, Bultynck G, Erneux C, Pérez-Morga D, Pays E. APOL1 C-Terminal Variants May Trigger Kidney Disease through Interference with APOL3 Control of Actomyosin. Cell Rep 2020; 30:3821-3836.e13. [PMID: 32187552 PMCID: PMC7090385 DOI: 10.1016/j.celrep.2020.02.064] [Citation(s) in RCA: 43] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 01/17/2020] [Accepted: 02/14/2020] [Indexed: 11/18/2022] Open
Abstract
The C-terminal variants G1 and G2 of apolipoprotein L1 (APOL1) confer human resistance to the sleeping sickness parasite Trypanosoma rhodesiense, but they also increase the risk of kidney disease. APOL1 and APOL3 are death-promoting proteins that are partially associated with the endoplasmic reticulum and Golgi membranes. We report that in podocytes, either APOL1 C-terminal helix truncation (APOL1Δ) or APOL3 deletion (APOL3KO) induces similar actomyosin reorganization linked to the inhibition of phosphatidylinositol-4-phosphate [PI(4)P] synthesis by the Golgi PI(4)-kinase IIIB (PI4KB). Both APOL1 and APOL3 can form K+ channels, but only APOL3 exhibits Ca2+-dependent binding of high affinity to neuronal calcium sensor-1 (NCS-1), promoting NCS-1-PI4KB interaction and stimulating PI4KB activity. Alteration of the APOL1 C-terminal helix triggers APOL1 unfolding and increased binding to APOL3, affecting APOL3-NCS-1 interaction. Since the podocytes of G1 and G2 patients exhibit an APOL1Δ or APOL3KO-like phenotype, APOL1 C-terminal variants may induce kidney disease by preventing APOL3 from activating PI4KB, with consecutive actomyosin reorganization of podocytes.
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Affiliation(s)
- Sophie Uzureau
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 6041 Gosselies, Belgium
| | - Laurence Lecordier
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 6041 Gosselies, Belgium
| | - Pierrick Uzureau
- Laboratory of Experimental Medicine (ULB222), CHU Charleroi, Université Libre de Bruxelles, Montigny le Tilleul, Belgium
| | - Dorle Hennig
- Department of Molecular Medicine, Cancer and Inflammation Research, University of Southern Denmark, 5000 Odense C, Denmark
| | - Jonas H Graversen
- Department of Molecular Medicine, Cancer and Inflammation Research, University of Southern Denmark, 5000 Odense C, Denmark
| | - Fabrice Homblé
- Laboratory of Structure and Function of Biological Membranes, Université Libre de Bruxelles, 1050 Brussels, Belgium
| | - Pepe Ekulu Mfutu
- Pediatric Nephrology, University Hospital Leuven, 3000 Leuven, Belgium
| | | | - Ana Raquel Ramos
- Institute of Interdisciplinary Research in Human and Molecular Biology, Campus Erasme, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - Rita M La Rovere
- Laboratory of Molecular and Cellular Signalling, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Tomas Luyten
- Laboratory of Molecular and Cellular Signalling, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Marjorie Vermeersch
- Center for Microscopy and Molecular Imaging (CMMI), Université Libre de Bruxelles, 6041 Gosselies, Belgium
| | - Patricia Tebabi
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 6041 Gosselies, Belgium
| | - Marc Dieu
- URBC-Narilis, University of Namur, 5000 Namur, Belgium
| | - Bart Cuypers
- Biomedical Sciences Department, Institute of Tropical Medicine, 2000 Antwerpen, Belgium; Adrem Data Lab, Department of Mathematics and Computer Science, University of Antwerp, 2000 Antwerpen, Belgium
| | - Stijn Deborggraeve
- Biomedical Sciences Department, Institute of Tropical Medicine, 2000 Antwerpen, Belgium
| | - Marion Rabant
- Adult Nephrology-Transplantation Department, Paris Hospitals and Paris Descartes University, 75006 Paris, France
| | - Christophe Legendre
- Pathology Department, Paris Hospitals and Paris Descartes University, 75006 Paris, France
| | - Søren K Moestrup
- Department of Molecular Medicine, Cancer and Inflammation Research, University of Southern Denmark, 5000 Odense C, Denmark; Department of Biomedicine, University of Aarhus, 8000 Aarhus, Denmark
| | - Elena Levtchenko
- Pediatric Nephrology, University Hospital Leuven, 3000 Leuven, Belgium
| | - Geert Bultynck
- Laboratory of Molecular and Cellular Signalling, KU Leuven, Herestraat 49, 3000 Leuven, Belgium
| | - Christophe Erneux
- Institute of Interdisciplinary Research in Human and Molecular Biology, Campus Erasme, Université Libre de Bruxelles, 1070 Brussels, Belgium
| | - David Pérez-Morga
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 6041 Gosselies, Belgium; Center for Microscopy and Molecular Imaging (CMMI), Université Libre de Bruxelles, 6041 Gosselies, Belgium
| | - Etienne Pays
- Laboratory of Molecular Parasitology, IBMM, Université Libre de Bruxelles, 6041 Gosselies, Belgium.
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Liu E, Radmanesh B, Chung BH, Donnan MD, Yi D, Dadi A, Smith KD, Himmelfarb J, Li M, Freedman BS, Lin J. Profiling APOL1 Nephropathy Risk Variants in Genome-Edited Kidney Organoids with Single-Cell Transcriptomics. KIDNEY360 2020; 1:203-215. [PMID: 32656538 PMCID: PMC7351353 DOI: 10.34067/kid.0000422019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Accepted: 02/12/2020] [Indexed: 12/20/2022]
Abstract
BACKGROUND DNA variants in APOL1 associate with kidney disease, but the pathophysiologic mechanisms remain incompletely understood. Model organisms lack the APOL1 gene, limiting the degree to which disease states can be recapitulated. Here we present single-cell RNA sequencing (scRNA-seq) of genome-edited human kidney organoids as a platform for profiling effects of APOL1 risk variants in diverse nephron cell types. METHODS We performed footprint-free CRISPR-Cas9 genome editing of human induced pluripotent stem cells (iPSCs) to knock in APOL1 high-risk G1 variants at the native genomic locus. iPSCs were differentiated into kidney organoids, treated with vehicle, IFN-γ, or the combination of IFN-γ and tunicamycin, and analyzed with scRNA-seq to profile cell-specific changes in differential gene expression patterns, compared with isogenic G0 controls. RESULTS Both G0 and G1 iPSCs differentiated into kidney organoids containing nephron-like structures with glomerular epithelial cells, proximal tubules, distal tubules, and endothelial cells. Organoids expressed detectable APOL1 only after exposure to IFN-γ. scRNA-seq revealed cell type-specific differences in G1 organoid response to APOL1 induction. Additional stress of tunicamycin exposure led to increased glomerular epithelial cell dedifferentiation in G1 organoids. CONCLUSIONS Single-cell transcriptomic profiling of human genome-edited kidney organoids expressing APOL1 risk variants provides a novel platform for studying the pathophysiology of APOL1-mediated kidney disease.
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Affiliation(s)
- Esther Liu
- Division of Nephrology and Hypertension, Department of Medicine, Feinberg Cardiovascular and Renal Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Behram Radmanesh
- Division of Nephrology and Hypertension, Department of Medicine, Feinberg Cardiovascular and Renal Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Byungha H. Chung
- Division of Nephrology, Department of Medicine, Kidney Research Institute, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
| | - Michael D. Donnan
- Division of Nephrology and Hypertension, Department of Medicine, Feinberg Cardiovascular and Renal Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Dan Yi
- Division of Nephrology and Hypertension, Department of Medicine, Feinberg Cardiovascular and Renal Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Amal Dadi
- Division of Nephrology and Hypertension, Department of Medicine, Feinberg Cardiovascular and Renal Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
| | - Kelly D. Smith
- Department of Pathology, University of Washington, Seattle, Washington
| | - Jonathan Himmelfarb
- Division of Nephrology, Department of Medicine, Kidney Research Institute, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
| | - Mingyao Li
- Department of Biostatistics, Epidemiology, and Informatics, University of Pennsylvania, Philadelphia, Pennsylvania; and
| | - Benjamin S. Freedman
- Division of Nephrology, Department of Medicine, Kidney Research Institute, Institute for Stem Cell and Regenerative Medicine, University of Washington, Seattle, Washington
- Department of Pathology, University of Washington, Seattle, Washington
| | - Jennie Lin
- Division of Nephrology and Hypertension, Department of Medicine, Feinberg Cardiovascular and Renal Research Institute, Northwestern University Feinberg School of Medicine, Chicago, Illinois
- Section of Nephrology, Jesse Brown Veterans Affairs Medical Center, Chicago, Illinois
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43
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Jha A, Kumar V, Haque S, Ayasolla K, Saha S, Lan X, Malhotra A, Saleem MA, Skorecki K, Singhal PC. Alterations in plasma membrane ion channel structures stimulate NLRP3 inflammasome activation in APOL1 risk milieu. FEBS J 2019; 287:2000-2022. [PMID: 31714001 DOI: 10.1111/febs.15133] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 09/23/2019] [Accepted: 11/09/2019] [Indexed: 12/01/2022]
Abstract
We evaluated alterations in the structural configurations of channels and activation of nucleotide-binding domain, leucine-rich-containing family, pyrin domain-containing-3 (NLRP3) inflammasome formation in apolipoprotein L1 (APOL1) risk and nonrisk milieus. APOL1G1- and APOL1G2-expressing podocytes (PD) displayed enhanced K+ efflux, induction of pyroptosis, and escalated transcription of interleukin (IL)-1β and IL-18. APOL1G1- and APOL1G2-expressing PD promoted the transcription as well as translation of proteins involved in the formation of inflammasomes. Since glyburide (a specific inhibitor of K+ efflux channels) inhibited the transcription of NLRP3, IL-1β, and IL-18, the role of K+ efflux in the activation of inflammasomes in APOL1 risk milieu was implicated. To evaluate the role of structural alterations in K+ channels in plasma membranes, bioinformatics studies, including molecular dynamic simulation, were carried out. Superimposition of bioinformatics reconstructions of APOL1G0, G1, and G2 showed several aligned regions. The analysis of pore-lining residues revealed that Ser342 and Tyr389 are involved in APOL1G0 pore formation and the altered conformations resulting from the Ser342Gly and Ile384Met mutation in the case of APOLG1 and deletion of the Tyr389 residue in the case of APOL1G2 are expected to alter pore characteristics, including K+ ion selectivity. Analysis of multiple membrane (lipid bilayer) models of interaction with the peripheral protein, integral membrane protein, and multimer protein revealed that for an APOL1 multimer model, APOL1G0 is not energetically favorable while the APOL1G1 and APOL1G2 moieties favor the insertion of multiple ion channels into the lipid bilayer. We conclude that altered pore configurations carry the potential to facilitate K+ ion transport in APOL1 risk milieu.
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Affiliation(s)
- Alok Jha
- Institute of Molecular Medicine, Feinstein Institute for Medical Research, Zucker School of Medicine at Hofstra-North Well, Manhasset, NY, USA
| | - Vinod Kumar
- Institute of Molecular Medicine, Feinstein Institute for Medical Research, Zucker School of Medicine at Hofstra-North Well, Manhasset, NY, USA
| | - Shabirul Haque
- Institute of Molecular Medicine, Feinstein Institute for Medical Research, Zucker School of Medicine at Hofstra-North Well, Manhasset, NY, USA
| | - Kamesh Ayasolla
- Institute of Molecular Medicine, Feinstein Institute for Medical Research, Zucker School of Medicine at Hofstra-North Well, Manhasset, NY, USA
| | - Shourav Saha
- Institute of Molecular Medicine, Feinstein Institute for Medical Research, Zucker School of Medicine at Hofstra-North Well, Manhasset, NY, USA
| | - Xiqian Lan
- Institute of Molecular Medicine, Feinstein Institute for Medical Research, Zucker School of Medicine at Hofstra-North Well, Manhasset, NY, USA
| | - Ashwani Malhotra
- Institute of Molecular Medicine, Feinstein Institute for Medical Research, Zucker School of Medicine at Hofstra-North Well, Manhasset, NY, USA
| | | | - Karl Skorecki
- Technion - Israel Institute of Technology, Rambam Health Care Campus, Haifa, Israel
| | - Pravin C Singhal
- Institute of Molecular Medicine, Feinstein Institute for Medical Research, Zucker School of Medicine at Hofstra-North Well, Manhasset, NY, USA
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Abstract
Genetic variants in the APOL1 gene, found only in individuals of recent African ancestry, greatly increase risk of multiple types of kidney disease. These APOL1 kidney risk alleles are a rare example of genetic variants that are common but also have a powerful effect on disease susceptibility. These alleles rose to high frequency in sub-Saharan Africa because they conferred protection against pathogenic trypanosomes that cause African sleeping sickness. We consider the genetic evidence supporting the association between APOL1 and kidney disease across the range of clinical phenotypes in the APOL1 nephropathy spectrum. We then explore the origins of the APOL1 risk variants and evolutionary struggle between humans and trypanosomes at both the molecular and population genetic level. Finally, we survey the rapidly growing literature investigating APOL1 biology as elucidated from experiments in cell-based systems, cell-free systems, mouse and lower organism models of disease, and through illuminating natural experiments in humans.
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Affiliation(s)
- David J Friedman
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA; ,
| | - Martin R Pollak
- Division of Nephrology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts 02215, USA; ,
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45
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Shah SS, Lannon H, Dias L, Zhang JY, Alper SL, Pollak MR, Friedman DJ. APOL1 Kidney Risk Variants Induce Cell Death via Mitochondrial Translocation and Opening of the Mitochondrial Permeability Transition Pore. J Am Soc Nephrol 2019; 30:2355-2368. [PMID: 31558683 DOI: 10.1681/asn.2019020114] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2019] [Accepted: 08/15/2019] [Indexed: 01/09/2023] Open
Abstract
BACKGROUND Genetic Variants in Apolipoprotein L1 (APOL1) are associated with large increases in CKD rates among African Americans. Experiments in cell and mouse models suggest that these risk-related polymorphisms are toxic gain-of-function variants that cause kidney dysfunction, following a recessive mode of inheritance. Recent data in trypanosomes and in human cells indicate that such variants may cause toxicity through their effects on mitochondria. METHODS To examine the molecular mechanisms underlying APOL1 risk variant-induced mitochondrial dysfunction, we generated tetracycline-inducible HEK293 T-REx cells stably expressing the APOL1 nonrisk G0 variant or APOL1 risk variants. Using these cells, we mapped the molecular pathway from mitochondrial import of APOL1 protein to APOL1-induced cell death with small interfering RNA knockdowns, pharmacologic inhibitors, blue native PAGE, mass spectrometry, and assessment of mitochondrial permeability transition pore function. RESULTS We found that the APOL1 G0 and risk variant proteins shared the same import pathway into the mitochondrial matrix. Once inside, G0 remained monomeric, whereas risk variant proteins were prone to forming higher-order oligomers. Both nonrisk G0 and risk variant proteins bound components of the mitochondrial permeability transition pore, but only risk variant proteins activated pore opening. Blocking mitochondrial import of APOL1 risk variants largely eliminated oligomer formation and also rescued toxicity. CONCLUSIONS Our study illuminates important differences in the molecular behavior of APOL1 nonrisk and risk variants, and our observations suggest a mechanism that may explain the very different functional effects of these variants, despite the lack of consistently observed differences in trafficking patterns, intracellular localization, or binding partners. Variant-dependent differences in oligomerization pattern may underlie APOL1's recessive, gain-of-function biology.
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Affiliation(s)
- Shrijal S Shah
- Renal Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Herbert Lannon
- Renal Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Leny Dias
- Renal Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Jia-Yue Zhang
- Renal Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Seth L Alper
- Renal Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - Martin R Pollak
- Renal Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
| | - David J Friedman
- Renal Division, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts
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Lannon H, Shah SS, Dias L, Blackler D, Alper SL, Pollak MR, Friedman DJ. Apolipoprotein L1 (APOL1) risk variant toxicity depends on the haplotype background. Kidney Int 2019; 96:1303-1307. [PMID: 31611067 DOI: 10.1016/j.kint.2019.07.010] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 06/27/2019] [Accepted: 07/03/2019] [Indexed: 01/01/2023]
Abstract
The Apolipoprotein L1 (APOL1) risk variants G1 and G2 are associated with high rates of kidney disease in African Americans in genetic studies. However, our understanding of APOL1 biology has lagged far behind. Here we report that engineering G1 and G2 mutations on unnatural haplotype backgrounds instead of on the specific G1 and G2 haplotype backgrounds that occur in nature profoundly alters APOL1-mediated cytotoxicity in experimental systems. Thus, in addition to helping resolve some important controversies in the APOL1 field, our demonstration of the critical influence of haplotype background may apply more generally to the study of other genetic variants that cause or predispose to human disease.
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Affiliation(s)
- Herbert Lannon
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Shrijal S Shah
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Leny Dias
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Daniel Blackler
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA
| | - Seth L Alper
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA; Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Martin R Pollak
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA; Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - David J Friedman
- Division of Nephrology, Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, USA.
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Abstract
PURPOSE OF REVIEW The purpose of this mini-review is to highlight some unresolved questions and controversies in the evolving story of apolipoprotein L1 (APOL1) nephropathy. RECENT FINDINGS We highlight studies that introduce complexity in unraveling the mechanisms whereby APOL1 risk variant alleles cause disease. These include studies which support a possible protective role for the APOL1 GO nonrisk ancestral allele, and studies which explore the initiating events that may trigger other downstream pathways mediating APOL1 cellular injury. We also review studies that reconcile the perplexing findings regarding APOL1 anionic or cationic conductance, and pH dependency, and also studies that attempt to characterize the 3-dimensional structure of APOL1 C-terminal in APOL1 variants, as well as that of the serum resistance-associated protein. We also attempt to convey new insights from in-vivo and in-vitro models, including studies that do not support the differential toxicity of APOL1 renal risk variants and recapitulate the clinical variability of individuals at genotypic risk. SUMMARY Along with major progress that had been achieved in the field of APOL1 nephropathy, controversies and enigmatic issues persist. It remains to be determined which of the pathways which have been demonstrated to mediate cell injury by ectopically expressed APOL1 risk variants in cellular and organismal models are relevant to human disease and can pave the way to potential therapy.
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Abstract
The apolipoprotein L1 (APOL1) gene is unique to humans and gorillas and appeared ~33 million years ago. Since the majority of the mammals do not carry APOL1, it seems to be dispensable for kidney function. APOL1 renal risk variants (RRVs; G1 and G2) are associated with the development as well as progression of chronic kidney diseases (CKDs) at higher rates in populations with African ancestry. Cellular expression of two APOL1 RRVs has been demonstrated to induce cytotoxicity, including necrosis, apoptosis, and pyroptosis, in several cell types including podocytes; mechanistically, these toxicities were attributed to lysosomal swelling, K+ depletion, mitochondrial dysfunction, autophagy blockade, protein kinase receptor activation, ubiquitin D degradation, and endoplasmic reticulum stress; notably, these effects were found to be dose dependent and occurred only in overtly APOL1 RRV-expressing cells. However, cellular protein expressions as well as circulating blood levels of APOL1 RRVs were not elevated in patients suffering from APOL1 RRV-associated CKDs. Therefore, the question arises as to whether it is gain or loss of function on the part of APOL1 RRVs contributing to kidney cell injury. The question seems to be more pertinent after the recognition of the role of APOL1 nonrisk (G0) in the transition of parietal epithelial cells and preservation of the podocyte molecular phenotype through modulation of the APOL1-miR-193a axis. With this background, the present review analyzed the available literature in terms of the known function of APOL1 nonrisk and how the loss of these functions could have contributed to two APOL1 RRV-associated CKDs.
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Affiliation(s)
- Vinod Kumar
- Institute of Molecular Medicine, Feinstein Institute for Medical Research and Department of Medicine, Zucker School of Medicine at Hofstra-Northwell, Hempstead, New York
| | - Pravin C Singhal
- Institute of Molecular Medicine, Feinstein Institute for Medical Research and Department of Medicine, Zucker School of Medicine at Hofstra-Northwell, Hempstead, New York
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RNA sequencing of isolated cell populations expressing human APOL1 G2 risk variant reveals molecular correlates of sickle cell nephropathy in zebrafish podocytes. PLoS One 2019; 14:e0217042. [PMID: 31158233 PMCID: PMC6546218 DOI: 10.1371/journal.pone.0217042] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 05/05/2019] [Indexed: 12/04/2022] Open
Abstract
Kidney failure occurs in 5–13% of individuals with sickle cell disease and is associated with early mortality. Two APOL1 alleles (G1 and G2) have been identified as risk factors for sickle cell disease nephropathy. Both risk alleles are prevalent in individuals with recent African ancestry and have been associated with nephropathic complications in other diseases. Despite the association of G1 and G2 with kidney dysfunction, the mechanisms by which these variants contribute to increased risk remain poorly understood. Previous work in zebrafish models suggest that the G2 risk allele functions as a dominant negative, whereas the G1 allele is a functional null. To understand better the cellular pathology attributed to APOL1 G2, we investigated the in vivo effects of the G2 risk variant on distinct cell types using RNA sequencing. We surveyed APOL1 G2 associated transcriptomic alterations in podocytes and vascular endothelial cells isolated from zebrafish larvae expressing cell-type specific reporters. Our analysis identified many transcripts (n = 7,523) showing differential expression between APOL1 G0 (human wild-type) and APOL1 G2 exposed podocytes. Conversely, relatively few transcripts (n = 107) were differentially expressed when comparing APOL1 G0 and APOL1 G2 exposed endothelial cells. Pathway analysis of differentially expressed transcripts in podocytes showed enrichment for autophagy associated terms such as “Lysosome” and “Phagosome”, implicating these pathways in APOL1 G2 associated kidney dysfunction. This work provides insight into the molecular pathology of APOL1 G2 nephropathy which may offer new therapeutic strategies for multiple disease contexts such as sickle cell nephropathy.
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Kumar V, Ayasolla K, Jha A, Mishra A, Vashistha H, Lan X, Qayyum M, Chinnapaka S, Purohit R, Mikulak J, Saleem MA, Malhotra A, Skorecki K, Singhal PC. Disrupted apolipoprotein L1-miR193a axis dedifferentiates podocytes through autophagy blockade in an APOL1 risk milieu. Am J Physiol Cell Physiol 2019; 317:C209-C225. [PMID: 31116585 DOI: 10.1152/ajpcell.00538.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We hypothesized that a functional apolipoprotein LI (APOL1)-miR193a axis (inverse relationship) preserves, but disruption alters, the podocyte molecular phenotype through the modulation of autophagy flux. Podocyte-expressing APOL1G0 (G0-podocytes) showed downregulation but podocyte-expressing APOL1G1 (G1-podocytes) and APOL1G2 (G2-podocytes) displayed enhanced miR193a expression. G0-, G1-, and G2-podocytes showed enhanced expression of light chain (LC) 3-II and beclin-1, but a disparate expression of p62 (low in wild-type but high in risk alleles). G0-podocytes showed enhanced, whereas G1- and G2-podocytes displayed decreased, phosphorylation of Unc-51-like autophagy-activating kinase (ULK)1 and class III phosphatidylinositol 3-kinase (PI3KC3). Podocytes overexpressing miR193a (miR193a-podocytes), G1, and G2 showed decreased transcription of PIK3R3 (PI3KC3's regulatory unit). Since 3-methyladenine (3-MA) enhanced miR193a expression but inhibited PIK3R3 transcription, it appears that 3-MA inhibits autophagy and induces podocyte dedifferentiation via miR193a generation. miR193a-, G1-, and G2-podocytes also showed decreased phosphorylation of mammalian target of rapamycin (mTOR) that could repress lysosome reformation. G1- and G2-podocytes showed enhanced expression of run domain beclin-1-interacting and cysteine-rich domain-containing protein (Rubicon); however, its silencing prevented their dedifferentiation. Docking, protein-protein interaction, and immunoprecipitation studies with antiautophagy-related gene (ATG)14L, anti-UV radiation resistance-associated gene (UVRAG), or Rubicon antibodies suggested the formation of ATG14L complex I and UVRAG complex II in G0-podocytes and the formation of Rubicon complex III in G1- and G2-podocytes. These findings suggest that the APOL1 risk alleles favor podocyte dedifferentiation through blockade of multiple autophagy pathways.
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Affiliation(s)
- Vinod Kumar
- Feinstein Institute and Zucker School of Medicine at Hofstra-Northwell , Hempstead, New York
| | - Kamesh Ayasolla
- Feinstein Institute and Zucker School of Medicine at Hofstra-Northwell , Hempstead, New York
| | - Alok Jha
- Feinstein Institute and Zucker School of Medicine at Hofstra-Northwell , Hempstead, New York
| | - Abheepsa Mishra
- Feinstein Institute and Zucker School of Medicine at Hofstra-Northwell , Hempstead, New York
| | | | - Xiqian Lan
- Feinstein Institute and Zucker School of Medicine at Hofstra-Northwell , Hempstead, New York
| | - Maleeha Qayyum
- Feinstein Institute and Zucker School of Medicine at Hofstra-Northwell , Hempstead, New York
| | - Sushma Chinnapaka
- Feinstein Institute and Zucker School of Medicine at Hofstra-Northwell , Hempstead, New York
| | - Richa Purohit
- Feinstein Institute and Zucker School of Medicine at Hofstra-Northwell , Hempstead, New York
| | - Joanna Mikulak
- Humanitas Clinical and Research Center, Rozzano, Milan , Italy
| | - Moin A Saleem
- Academic Renal Unit, University of Bristol , Bristol , United Kingdom
| | - Ashwani Malhotra
- Feinstein Institute and Zucker School of Medicine at Hofstra-Northwell , Hempstead, New York
| | - Karl Skorecki
- Technion-Israel Institute of Technology, Rambam Health Care Campus, Haifa , Israel
| | - Pravin C Singhal
- Feinstein Institute and Zucker School of Medicine at Hofstra-Northwell , Hempstead, New York
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