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Juliar BA, Stanaway IB, Sano F, Fu H, Smith KD, Akilesh S, Scales SJ, El Saghir J, Bhatraju PK, Liu E, Yang J, Lin J, Eddy S, Kretzler M, Zheng Y, Himmelfarb J, Harder JL, Freedman BS. Interferon-γ induces combined pyroptotic angiopathy and APOL1 expression in human kidney disease. Cell Rep 2024; 43:114310. [PMID: 38838223 DOI: 10.1016/j.celrep.2024.114310] [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: 09/27/2023] [Revised: 03/18/2024] [Accepted: 05/16/2024] [Indexed: 06/07/2024] Open
Abstract
Elevated interferon (IFN) signaling is associated with kidney diseases including COVID-19, HIV, and apolipoprotein-L1 (APOL1) nephropathy, but whether IFNs directly contribute to nephrotoxicity remains unclear. Using human kidney organoids, primary endothelial cells, and patient samples, we demonstrate that IFN-γ induces pyroptotic angiopathy in combination with APOL1 expression. Single-cell RNA sequencing, immunoblotting, and quantitative fluorescence-based assays reveal that IFN-γ-mediated expression of APOL1 is accompanied by pyroptotic endothelial network degradation in organoids. Pharmacological blockade of IFN-γ signaling inhibits APOL1 expression, prevents upregulation of pyroptosis-associated genes, and rescues vascular networks. Multiomic analyses in patients with COVID-19, proteinuric kidney disease, and collapsing glomerulopathy similarly demonstrate increased IFN signaling and pyroptosis-associated gene expression correlating with accelerated renal disease progression. Our results reveal that IFN-γ signaling simultaneously induces endothelial injury and primes renal cells for pyroptosis, suggesting a combinatorial mechanism for APOL1-mediated collapsing glomerulopathy, which can be targeted therapeutically.
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Affiliation(s)
- Benjamin A Juliar
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98109, USA; Kidney Research Institute, University of Washington School of Medicine, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Ian B Stanaway
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98109, USA; Kidney Research Institute, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Fumika Sano
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Hongxia Fu
- Institute for Stem Cell and Regenerative Medicine, University of Washington School of Medicine, Seattle, WA 98109, USA; Division of Hematology, Department of Medicine, Seattle, WA 98109, USA; Department of Bioengineering, University of Washington School of Medicine, Seattle, WA 98109, USA; Bloodworks Northwest Research Institute, Seattle, WA 98102, USA; Plurexa, Seattle, WA 98109, USA
| | - Kelly D Smith
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98109, USA; Department of Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Shreeram Akilesh
- Kidney Research Institute, University of Washington School of Medicine, Seattle, WA 98109, USA; Department of Laboratory Medicine and Pathology, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Suzie J Scales
- Department of Immunology, Genentech, 1 DNA Way, South San Francisco, CA 94080, USA
| | - Jamal El Saghir
- Division of Nephrology, Department of Internal Medicine, and Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Pavan K Bhatraju
- Kidney Research Institute, University of Washington School of Medicine, Seattle, WA 98109, USA; Division of Pulmonary, Critical Care and Sleep Medicine, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Esther Liu
- Division of Nephrology and Hypertension, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Johnson Yang
- Division of Nephrology and Hypertension, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Jennie Lin
- Division of Nephrology and Hypertension, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Sean Eddy
- Division of Nephrology, Department of Internal Medicine, and Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Matthias Kretzler
- Division of Nephrology, Department of Internal Medicine, and Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Ying Zheng
- Kidney Research Institute, University of Washington School of Medicine, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington School of Medicine, Seattle, WA 98109, USA; Department of Bioengineering, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Jonathan Himmelfarb
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98109, USA; Kidney Research Institute, University of Washington School of Medicine, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington School of Medicine, Seattle, WA 98109, USA
| | - Jennifer L Harder
- Division of Nephrology, Department of Internal Medicine, and Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109, USA.
| | - Benjamin S Freedman
- Division of Nephrology, Department of Medicine, University of Washington School of Medicine, Seattle, WA 98109, USA; Kidney Research Institute, University of Washington School of Medicine, Seattle, WA 98109, USA; Institute for Stem Cell and Regenerative Medicine, University of Washington School of Medicine, Seattle, WA 98109, USA; Department of Bioengineering, University of Washington School of Medicine, Seattle, WA 98109, USA; Plurexa, Seattle, WA 98109, USA.
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Zhou L, Cai F, Li Y, Gao X, Wei Y, Fedorova A, Kirchhofer D, Hannoush RN, Zhang Y. Disulfide-constrained peptide scaffolds enable a robust peptide-therapeutic discovery platform. PLoS One 2024; 19:e0300135. [PMID: 38547109 PMCID: PMC10977697 DOI: 10.1371/journal.pone.0300135] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 02/21/2024] [Indexed: 04/02/2024] Open
Abstract
Peptides present an alternative modality to immunoglobulin domains or small molecules for developing therapeutics to either agonize or antagonize cellular pathways associated with diseases. However, peptides often suffer from poor chemical and physical stability, limiting their therapeutic potential. Disulfide-constrained peptides (DCP) are naturally occurring and possess numerous desirable properties, such as high stability, that qualify them as drug-like scaffolds for peptide therapeutics. DCPs contain loop regions protruding from the core of the molecule that are amenable to peptide engineering via direct evolution by use of phage display technology. In this study, we have established a robust platform for the discovery of peptide therapeutics using various DCPs as scaffolds. We created diverse libraries comprising seven different DCP scaffolds, resulting in an overall diversity of 2 x 1011. The effectiveness of this platform for functional hit discovery has been extensively evaluated, demonstrating a hit rate comparable to that of synthetic antibody libraries. By utilizing chemically synthesized and in vitro folded peptides derived from selections of phage displayed DCP libraries, we have successfully generated functional inhibitors targeting the HtrA1 protease. Through affinity maturation strategies, we have transformed initially weak binders against Notch2 with micromolar Kd values to high-affinity ligands in the nanomolar range. This process highlights a viable hit-to-lead progression. Overall, our platform holds significant potential to greatly enhance the discovery of peptide therapeutics.
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Affiliation(s)
- Lijuan Zhou
- Departments of Biological Chemistry, Genentech, Inc., South San Francisco, California, United States of America
| | - Fei Cai
- Departments of Biological Chemistry, Genentech, Inc., South San Francisco, California, United States of America
| | - Yanjie Li
- Department of Peptide Therapeutics, Genentech, Inc., South San Francisco, California, United States of America
| | - Xinxin Gao
- Department of Peptide Therapeutics, Genentech, Inc., South San Francisco, California, United States of America
| | - Yuehua Wei
- Departments of Biological Chemistry, Genentech, Inc., South San Francisco, California, United States of America
| | - Anna Fedorova
- Departments of Biological Chemistry, Genentech, Inc., South San Francisco, California, United States of America
| | - Daniel Kirchhofer
- Departments of Biological Chemistry, Genentech, Inc., South San Francisco, California, United States of America
| | - Rami N. Hannoush
- Department of Early Discovery Biochemistry, Genentech, Inc., South San Francisco, California, United States of America
| | - Yingnan Zhang
- Departments of Biological Chemistry, Genentech, Inc., South San Francisco, California, United States of America
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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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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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Andrews M, Yoshida T, Henderson CM, Pflaum H, McGregor A, Lieberman JA, de Boer IH, Vaisar T, Himmelfarb J, Kestenbaum B, Chung JY, Hewitt SM, Santo BA, Ginley B, Sarder P, Rosenberg AZ, Murakami T, Kopp JB, Kuklenyik Z, Hoofnagle AN. Variant APOL1 protein in plasma associates with larger particles in humans and mouse models of kidney injury. PLoS One 2022; 17:e0276649. [PMID: 36279295 PMCID: PMC9591058 DOI: 10.1371/journal.pone.0276649] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 10/11/2022] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND Genetic variants in apolipoprotein L1 (APOL1), a protein that protects humans from infection with African trypanosomes, explain a substantial proportion of the excess risk of chronic kidney disease affecting individuals with sub-Saharan ancestry. The mechanisms by which risk variants damage kidney cells remain incompletely understood. In preclinical models, APOL1 expressed in podocytes can lead to significant kidney injury. In humans, studies in kidney transplant suggest that the effects of APOL1 variants are predominantly driven by donor genotype. Less attention has been paid to a possible role for circulating APOL1 in kidney injury. METHODS Using liquid chromatography-tandem mass spectrometry, the concentrations of APOL1 were measured in plasma and urine from participants in the Seattle Kidney Study. Asymmetric flow field-flow fractionation was used to evaluate the size of APOL1-containing lipoprotein particles in plasma. Transgenic mice that express wild-type or risk variant APOL1 from an albumin promoter were treated to cause kidney injury and evaluated for renal disease and pathology. RESULTS In human participants, urine concentrations of APOL1 were correlated with plasma concentrations and reduced kidney function. Risk variant APOL1 was enriched in larger particles. In mice, circulating risk variant APOL1-G1 promoted kidney damage and reduced podocyte density without renal expression of APOL1. CONCLUSIONS These results suggest that plasma APOL1 is dynamic and contributes to the progression of kidney disease in humans, which may have implications for treatment of APOL1-associated kidney disease and for kidney transplantation.
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Affiliation(s)
- Michael Andrews
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Teruhiko Yoshida
- Kidney Disease Section, Kidney Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Clark M. Henderson
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Hannah Pflaum
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Ayako McGregor
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Joshua A. Lieberman
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
| | - Ian H. de Boer
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
- Kidney Research Institute, University of Washington, Seattle, Washington, United States of America
| | - Tomas Vaisar
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
| | - Jonathan Himmelfarb
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
- Kidney Research Institute, University of Washington, Seattle, Washington, United States of America
| | - Bryan Kestenbaum
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
- Kidney Research Institute, University of Washington, Seattle, Washington, United States of America
| | - Joon-Yong Chung
- Center for Cancer Research, NCI, NIH, Bethesda, Maryland, United States of America
| | - Stephen M. Hewitt
- Center for Cancer Research, NCI, NIH, Bethesda, Maryland, United States of America
| | - Briana A. Santo
- Department of Pathology and Anatomical Sciences, Jacobs School of Medicine & Biomedical Sciences, University at Buffalo, Buffalo, New York, United States of America
| | - Brandon Ginley
- Department of Pathology and Anatomical Sciences, Jacobs School of Medicine & Biomedical Sciences, University at Buffalo, Buffalo, New York, United States of America
| | - Pinaki Sarder
- Department of Pathology and Anatomical Sciences, Jacobs School of Medicine & Biomedical Sciences, University at Buffalo, Buffalo, New York, United States of America
| | - Avi Z. Rosenberg
- Department of Pathology, Johns Hopkins Medical Institutions, Baltimore, Maryland, United States of America
| | - Taichi Murakami
- Kidney Disease Section, Kidney Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
- Department of Nephrology, Ehime Prefectural Central Hospital, Ehime, Japan
| | - Jeffrey B. Kopp
- Kidney Disease Section, Kidney Diseases Branch, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland, United States of America
| | - Zsuzsanna Kuklenyik
- Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America
| | - Andrew N. Hoofnagle
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, Washington, United States of America
- Department of Medicine, University of Washington, Seattle, Washington, United States of America
- Kidney Research Institute, University of Washington, Seattle, Washington, United States of America
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6
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Chun J, Riella CV, Chung H, Shah SS, Wang M, Magraner JM, Ribas GT, Ribas HT, Zhang JY, Alper SL, Friedman DJ, Pollak MR. DGAT2 Inhibition Potentiates Lipid Droplet Formation To Reduce Cytotoxicity in APOL1 Kidney Risk Variants. J Am Soc Nephrol 2022; 33:889-907. [PMID: 35232775 PMCID: PMC9063887 DOI: 10.1681/asn.2021050723] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2021] [Accepted: 01/22/2022] [Indexed: 11/03/2022] Open
Abstract
BACKGROUND Two variants in the gene encoding apolipoprotein L1 (APOL1) that are highly associated with African ancestry are major contributors to the large racial disparity in rates of human kidney disease. We previously demonstrated that recruitment of APOL1 risk variants G1 and G2 from the endoplasmic reticulum to lipid droplets leads to reduced APOL1-mediated cytotoxicity in human podocytes. METHODS We used CRISPR-Cas9 gene editing of induced pluripotent stem cells to develop human-derived APOL1G0/G0 and APOL1G2/G2 kidney organoids on an isogenic background, and performed bulk RNA sequencing of organoids before and after treatment with IFN-γ. We examined the number and distribution of lipid droplets in response to treatment with inhibitors of diacylglycerol O-acyltransferases 1 and 2 (DGAT1 and DGAT2) in kidney cells and organoids. RESULTS APOL1 was highly upregulated in response to IFN-γ in human kidney organoids, with greater increases in organoids of high-risk G1 and G2 genotypes compared with wild-type (G0) organoids. RNA sequencing of organoids revealed that high-risk APOL1G2/G2 organoids exhibited downregulation of a number of genes involved in lipogenesis and lipid droplet biogenesis, as well as upregulation of genes involved in fatty acid oxidation. There were fewer lipid droplets in unstimulated high-risk APOL1G2/G2 kidney organoids than in wild-type APOL1G0/G0 organoids. Whereas DGAT1 inhibition reduced kidney organoid lipid droplet number, DGAT2 inhibition unexpectedly increased organoid lipid droplet number. DGAT2 inhibition promoted the recruitment of APOL1 to lipid droplets, with associated reduction in cytotoxicity. CONCLUSIONS Lipogenesis and lipid droplet formation are important modulators of APOL1-associated cytotoxicity. Inhibition of DGAT2 may offer a potential therapeutic strategy to attenuate cytotoxic effects of APOL1 risk variants.
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Affiliation(s)
- Justin Chun
- Department of Medicine, Division of Nephrology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
- Department of Medicine, Division of Nephrology, University of Calgary, Cumming School of Medicine, Calgary, Alberta, Canada
| | - Cristian V. Riella
- Department of Medicine, Division of Nephrology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Hyunjae Chung
- Department of Medicine, Division of Nephrology, University of Calgary, Cumming School of Medicine, Calgary, Alberta, Canada
| | - Shrijal S. Shah
- Department of Medicine, Division of Nephrology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Minxian Wang
- Cardiovascular Disease Initiative and the Program in Medical and Population Genetics, Broad Institute of Harvard and Massachusetts Institute of Technology, Cambridge, Massachusetts
| | - Jose M. Magraner
- Department of Medicine, Division of Nephrology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Guilherme T. Ribas
- Professional and Technological Education Sector, Federal University of Paraná, Curitiba, Paraná, Brazil
| | - Hennrique T. Ribas
- Professional and Technological Education Sector, Federal University of Paraná, Curitiba, Paraná, Brazil
| | - Jia-Yue Zhang
- Department of Medicine, Division of Nephrology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Seth. L. Alper
- Department of Medicine, Division of Nephrology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - David J. Friedman
- Department of Medicine, Division of Nephrology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
| | - Martin R. Pollak
- Department of Medicine, Division of Nephrology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, Massachusetts
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7
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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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8
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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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9
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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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10
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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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11
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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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12
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Pant J, Giovinazzo JA, Tuka LS, Peña D, Raper J, Thomson R. Apolipoproteins L1-6 share key cation channel-regulating residues but have different membrane insertion and ion conductance properties. J Biol Chem 2021; 297:100951. [PMID: 34252458 PMCID: PMC8358165 DOI: 10.1016/j.jbc.2021.100951] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Revised: 06/29/2021] [Accepted: 07/08/2021] [Indexed: 01/01/2023] Open
Abstract
The human apolipoprotein L gene family encodes the apolipoprotein L1–6 (APOL1–6) proteins, which are effectors of the innate immune response to viruses, bacteria and protozoan parasites. Due to a high degree of similarity between APOL proteins, it is often assumed that they have similar functions to APOL1, which forms cation channels in planar lipid bilayers and membranes resulting in cytolytic activity. However, the channel properties of the remaining APOL proteins have not been reported. Here, we used transient overexpression and a planar lipid bilayer system to study the function of APOL proteins. By measuring lactate dehydrogenase release, we found that APOL1, APOL3, and APOL6 were cytolytic, whereas APOL2, APOL4, and APOL5 were not. Cells expressing APOL1 or APOL3, but not APOL6, developed a distinctive swollen morphology. In planar lipid bilayers, recombinant APOL1 and APOL2 required an acidic environment for the insertion of each protein into the membrane bilayer to form an ion conductance channel. In contrast, recombinant APOL3, APOL4, and APOL5 readily inserted into bilayers to form ion conductance at neutral pH, but required a positive voltage on the side of insertion. Despite these differences in membrane insertion properties, the ion conductances formed by APOL1-4 were similarly pH-dependent and cation-selective, consistent with conservation of the pore-lining region in each protein. Thus, despite structural conservation, the APOL proteins are functionally different. We propose that these proteins interact with different membranes and under different voltage and pH conditions within a cell to effect innate immunity to different microbial pathogens.
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Affiliation(s)
- Jyoti Pant
- Department of Biological Sciences, Hunter College, City University of New York, New York, New York, USA.
| | - Joseph A Giovinazzo
- Department of Biological Sciences, Hunter College, City University of New York, New York, New York, USA; Department of Biochemistry and Molecular Genetics, School of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Lilit S Tuka
- Department of Biological Sciences, Hunter College, City University of New York, New York, New York, USA
| | - Darwin Peña
- Department of Biological Sciences, Hunter College, City University of New York, New York, New York, USA
| | - Jayne Raper
- Department of Biological Sciences, Hunter College, City University of New York, New York, New York, USA; PhD Program in Biochemistry, The Graduate Center of the City University of New York, New York, New York, USA
| | - Russell Thomson
- Department of Biological Sciences, Hunter College, City University of New York, New York, New York, USA.
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13
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Bruggeman LA, Sedor JR, O'Toole JF. Apolipoprotein L1 and mechanisms of kidney disease susceptibility. Curr Opin Nephrol Hypertens 2021; 30:317-323. [PMID: 33767059 PMCID: PMC8211384 DOI: 10.1097/mnh.0000000000000704] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
PURPOSE OF REVIEW Allelic variants in the gene for apolipoprotein L1 (APOL1), found only in individuals of African ancestry, explain a majority of the excess risk of kidney disease in African Americans. However, a clear understanding how the disease-associated APOL1 variants cause kidney injury and the identity of environmental stressors that trigger the injury process have not been determined. RECENT FINDINGS Basic mechanistic studies of APOL1 biochemistry and cell biology, bolstered by new antibody reagents and inducible pluripotent stem cell-derived cell systems, have focused on the cytotoxic effect of the risk variants when APOL1 gene expression is induced. Since the APOL1 variants evolved to alter a key protein-protein interaction with the trypanosome serum resistance-associated protein, additional studies have begun to address differences in APOL1 interactions with other proteins expressed in podocytes, including new observations that APOL1 variants may alter podocyte cytoskeleton dynamics. SUMMARY A unified mechanism of pathogenesis for the various APOL1 nephropathies still remains unclear and controversial. As ongoing studies have consistently implicated the pathogenic gain-of-function effects of the variant proteins, novel therapeutic development inhibiting the synthesis or function of APOL1 proteins is moving toward clinical trials.
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Affiliation(s)
| | - John R Sedor
- Departments of Nephrology and Inflammation & Immunity, Cleveland Clinic
- Department of Physiology & Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - John F O'Toole
- Departments of Nephrology and Inflammation & Immunity, Cleveland Clinic
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14
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Freedman BI, Kopp JB, Sampson MG, Susztak K. APOL1 at 10 years: progress and next steps. Kidney Int 2021; 99:1296-1302. [PMID: 33794228 DOI: 10.1016/j.kint.2021.03.013] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 02/17/2021] [Accepted: 02/25/2021] [Indexed: 12/29/2022]
Abstract
APOL1 kidney risk variants (RVs) were identified in 2010 as major drivers of glomerular, tubulointerstitial, and renal microvascular disease in individuals with sub-Saharan African ancestry. In December 2020, the "APOL1 at Ten" conference summarized the first decade of progress and discussed controversies and uncertainties that remain to be addressed. Topics included trypanosome infection and its role in the evolution of APOL1 kidney RVs, clinical phenotypes in APOL1-associated nephropathy, relationships between APOL1 RVs and background haplotypes on cell injury and molecular mechanisms initiating disease, the role of clinical APOL1 genotyping, and development of novel therapies for kidney disease. Future goals were defined, including improved characterization of various APOL1 RV phenotypes in patients and experimental preclinical models; further dissection of APOL1-mediated pathways to cellular injury and dysfunction in kidney (and other) cells; clarification of gene-gene and gene-environment interactions; and evaluation of the role for existing and novel therapies.
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Affiliation(s)
- Barry I Freedman
- Section on Nephrology, Department of Internal Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
| | - Jeffrey B Kopp
- Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, Maryland, USA
| | - Matthew G Sampson
- Division of Pediatric Nephrology, Boston Children's Hospital, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA; Broad Institute, Cambridge, Massachusetts, USA
| | - Katalin Susztak
- Renal Electrolyte and Hypertension Division, Department of Medicine, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, USA; Department of Genetics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, USA; Institute for Diabetes, Obesity and Metabolism, University of Pennsylvania, Perelman School of Medicine, Philadelphia, Pennsylvania, USA.
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15
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Blazer A, Dey ID, Nwaukoni J, Reynolds M, Ankrah F, Algasas H, Ahmed T, Divers J. Apolipoprotein L1 risk genotypes in Ghanaian patients with systemic lupus erythematosus: a prospective cohort study. Lupus Sci Med 2021; 8:8/1/e000460. [PMID: 33461980 PMCID: PMC7816898 DOI: 10.1136/lupus-2020-000460] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 12/13/2020] [Accepted: 12/23/2020] [Indexed: 01/13/2023]
Abstract
Objective Two apolipoprotein L1 (APOL1) risk variants (RV) are enriched in sub-Saharan African populations due to conferred resistance to Trypanosoma brucei. These variants associate with adverse renal outcomes by multiple causes including SLE. Despite emerging reports that SLE is common in Ghana, where APOL1 variant allelic frequencies are high, the regional contribution to SLE outcomes has not been described. Accordingly, this prospective longitudinal cohort study tested the associations between APOL1 high-risk genotypes and kidney outcomes, organ damage accrual and death in 100 Ghanaian patients with SLE. Methods This was a prospective cohort study of 100 SLE outpatients who sought care at Korle bu Teaching Hospital in Accra, Ghana. Adult patients who met 4 American College of Rheumatology criteria for SLE were genotyped for APOL1 and followed longitudinally for SLE activity as measured by the Safety of Estrogens in Lupus National Assessment-Systemic Lupus Erythematosus Disease Activity Index (SELENA-SLEDAI) hybrid and organ injury as measured by the Systemic Lupus International Collaborating Clinics Damage Index (SDI) at baseline and every 6 months for 1 year. Outcomes of interest were kidney function, SDI and case fatality. Results Assuming a recessive inheritance, the APOL1 high-risk genotype (2RV) associated with end-stage renal disease (ESRD) at an OR of 14 (p=0.008). These patients accrued more SDI points particularly in renal and neurological domains. The SDI was 81.3% higher in 2RV patients compared with 0RV or 1RV patients despite no difference in SLE activity (p=0.01). After a 12-month period of observation, 3/12 (25%) of the 2RV patients died compared with 2/88 (2.3%) of the 0RV or 1RV carriers (OR=13.6, p=0.01). Deaths were due to end-stage kidney disease and heart failure. Conclusion APOL1 RVs were heritable risk factors for morbidity and mortality in this Ghanaian SLE cohort. Despite no appreciable differences in SLE activity, APOL1 high-risk patients exhibited progressive renal disease, organ damage accrual and a 13-fold higher case fatality.
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Affiliation(s)
- Ashira Blazer
- Department of Medicine, Division of Rheumatology, NYU Langone Health, New York, New York, USA
| | - Ida Dzifa Dey
- Department of Medicine, Division of Rheumatology, University of Ghana, Legon, Greater Accra, Ghana
| | - Janet Nwaukoni
- Philadelphia College of Osteopathic Medicine, Philadelphia, Pennsylvania, USA
| | | | - Festus Ankrah
- Internal Medicine, University of Ghana, Legon, Greater Accra, Ghana
| | | | - Tasneem Ahmed
- Department of Medicine, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | - Jasmin Divers
- Department of Biostatistics, Division of Health Sciences Research, NYU Winthrop Hospital, Mineola, New York, USA
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16
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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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