1
|
Durand A, Winkler CA, Vince N, Douillard V, Geffard E, Binns-Roemer E, Ng DK, Gourraud PA, Reidy K, Warady B, Furth S, Kopp JB, Kaskel FJ, Limou S. Identification of Novel Genetic Risk Factors for Focal Segmental Glomerulosclerosis in Children: Results From the Chronic Kidney Disease in Children (CKiD) Cohort. Am J Kidney Dis 2023; 81:635-646.e1. [PMID: 36623684 DOI: 10.1053/j.ajkd.2022.11.003] [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: 04/28/2022] [Accepted: 11/02/2022] [Indexed: 01/09/2023]
Abstract
RATIONALE & OBJECTIVE Focal segmental glomerulosclerosis (FSGS) is a major cause of pediatric nephrotic syndrome, and African Americans exhibit an increased risk for developing FSGS compared with other populations. Predisposing genetic factors have previously been described in adults. Here we performed genomic screening of primary FSGS in a pediatric African American population. STUDY DESIGN Prospective cohort with case-control genetic association study design. SETTING & PARTICIPANTS 140 African American children with chronic kidney disease from the Chronic Kidney Disease in Children (CKiD) cohort, including 32 cases with FSGS. PREDICTORS Over 680,000 common single-nucleotide polymorphisms (SNPs) were tested for association. We also ran a pathway enrichment analysis and a human leucocyte antigen (HLA)-focused association study. OUTCOME Primary biopsy-proven pediatric FSGS. ANALYTICAL APPROACH Multivariate logistic regression models. RESULTS The genome-wide association study revealed 169 SNPs from 14 independent loci significantly associated with FSGS (false discovery rate [FDR]<5%). We observed notable signals for genetic variants within the APOL1 (P=8.6×10-7; OR, 25.8 [95% CI, 7.1-94.0]), ALMS1 (P=1.3×10-7; 13.0% in FSGS cases vs 0% in controls), and FGFR4 (P=4.3×10-6; OR, 24.8 [95% CI, 6.3-97.7]) genes, all of which had previously been associated with adult FSGS, kidney function, or chronic kidney disease. We also highlighted novel, functionally relevant genes, including GRB2 (which encodes a slit diaphragm protein promoting podocyte structure through actin polymerization) and ITGB1 (which is linked to renal injuries). Our results suggest a major role for immune responses and antigen presentation in pediatric FSGS through (1) associations with SNPs in PTPRJ (or CD148, P=3.5×10-7), which plays a role in T-cell receptor signaling, (2) HLA-DRB1∗11:01 association (P=6.1×10-3; OR, 4.5 [95% CI, 1.5-13.0]), and (3) signaling pathway enrichment (P=1.3×10-6). LIMITATIONS Sample size and no independent replication cohort with genomic data readily available. CONCLUSIONS Our genetic study has identified functionally relevant risk factors and the importance of immune regulation for pediatric primary FSGS, which contributes to a better description of its molecular pathophysiological mechanisms.
Collapse
Affiliation(s)
- Axelle Durand
- Center for Research in Transplantation and Translational Immunology (UMR 1064), Nantes Université, Ecole Centrale Nantes, CHU Nantes, INSERM, F-44000 Nantes, France
| | - Cheryl A Winkler
- Basic Research Laboratory, Center for Cancer Research, Frederick National Laboratory, National Cancer Institute, Frederick, Maryland
| | - Nicolas Vince
- Center for Research in Transplantation and Translational Immunology (UMR 1064), Nantes Université, Ecole Centrale Nantes, CHU Nantes, INSERM, F-44000 Nantes, France
| | - Venceslas Douillard
- Center for Research in Transplantation and Translational Immunology (UMR 1064), Nantes Université, Ecole Centrale Nantes, CHU Nantes, INSERM, F-44000 Nantes, France
| | - Estelle Geffard
- Center for Research in Transplantation and Translational Immunology (UMR 1064), Nantes Université, Ecole Centrale Nantes, CHU Nantes, INSERM, F-44000 Nantes, France
| | - Elizabeth Binns-Roemer
- Basic Research Laboratory, Center for Cancer Research, Frederick National Laboratory, National Cancer Institute, Frederick, Maryland
| | - Derek K Ng
- Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
| | - Pierre-Antoine Gourraud
- Center for Research in Transplantation and Translational Immunology (UMR 1064), Nantes Université, Ecole Centrale Nantes, CHU Nantes, INSERM, F-44000 Nantes, France
| | - Kimberley Reidy
- Children's Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, New York
| | | | - Susan Furth
- Children's Hospital of Pennsylvania, Philadelphia, Pennsylvania
| | - Jeffrey B Kopp
- Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Frederick J Kaskel
- Children's Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, New York
| | - Sophie Limou
- Center for Research in Transplantation and Translational Immunology (UMR 1064), Nantes Université, Ecole Centrale Nantes, CHU Nantes, INSERM, F-44000 Nantes, France.
| |
Collapse
|
2
|
Martin CE, Jones N. ShcA expression in podocytes is dispensable for glomerular development but its upregulation is associated with kidney disease. Am J Transl Res 2021; 13:9874-9882. [PMID: 34540124 PMCID: PMC8430102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2020] [Accepted: 03/18/2021] [Indexed: 06/13/2023]
Abstract
BACKGROUND ShcA (SHC1) is a phosphotyrosine adaptor protein which plays broad signaling roles within the cell. Systemic loss of ShcA during embryogenesis is lethal, while its aberrant expression contributes to disease. We recently demonstrated that ShcA is highly expressed during glomerular development and that it is upregulated within podocytes in experimental kidney injury and chronic kidney disease. The objective of this study was to analyze the in vivo role of ShcA in podocytes. METHODS We selectively deleted all three isoforms of ShcA from mouse kidney podocytes using the Cre/lox system driven by the podocyte-specific podocin promoter (Nphs2). Immunostaining of kidney sections was used to confirm ShcA deletion in podocytes. Coomassie blue staining of protein gels was used to detect urinary albumin. Light and electron microscopy were used to assess glomerular morphology. Transcript levels of SHC1 in human renal disease were assessed using the Nephroseq database. RESULTS Mice lacking podocyte ShcA were born at the expected Mendelian frequency and did not display overt renal impairment or changes in podocyte architecture beyond one year of age. In parallel, we correlated increased ShcA mRNA expression in the human kidney with proteinuria and reduced glomerular filtration rate. CONCLUSION Our studies reveal that ShcA is dispensable for normal kidney function, but its upregulation is associated with disease.
Collapse
Affiliation(s)
- Claire E Martin
- Department of Molecular and Cellular Biology, University of Guelph Guelph, ON, Canada
| | - Nina Jones
- Department of Molecular and Cellular Biology, University of Guelph Guelph, ON, Canada
| |
Collapse
|
3
|
Martin CE, Petersen KA, Aoudjit L, Tilak M, Eremina V, Hardy WR, Quaggin SE, Takano T, Jones N. ShcA Adaptor Protein Promotes Nephrin Endocytosis and Is Upregulated in Proteinuric Nephropathies. J Am Soc Nephrol 2017; 29:92-103. [PMID: 29018139 DOI: 10.1681/asn.2017030285] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2017] [Accepted: 07/23/2017] [Indexed: 11/03/2022] Open
Abstract
Nephrin is a key structural component of the podocyte slit diaphragm, and proper expression of nephrin on the cell surface is critical to ensure integrity of the blood filtration barrier. Maintenance of nephrin within this unique cell junction has been proposed to require dynamic phosphorylation events and endocytic recycling, although the molecular mechanisms that control this interplay are poorly understood. Here, we investigated the possibility that the phosphotyrosine adaptor protein ShcA regulates nephrin turnover. Western blotting and immunostaining analysis confirmed that ShcA is expressed in podocytes. In immunoprecipitation and pulldown assays, ShcA, via its SH2 domain, was associated with several phosphorylated tyrosine residues on nephrin. Overexpression of ShcA promoted nephrin tyrosine phosphorylation and reduced nephrin signaling and cell surface expression in vitro In a rat model of reversible podocyte injury and proteinuria, phosphorylated nephrin temporally colocalized with endocytic structures coincident with upregulation of ShcA expression. In vivo biotinylation assays confirmed that nephrin expression decreased at the cell surface and correspondingly increased in the cytosol during the injury time course. Finally, immunostaining in kidney biopsy specimens demonstrated overexpression of ShcA in several human proteinuric kidney diseases compared with normal conditions. Our results suggest that increases in ShcA perturb nephrin phosphosignaling dynamics, leading to aberrant nephrin turnover and slit diaphragm disassembly.
Collapse
Affiliation(s)
- Claire E Martin
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Kelly A Petersen
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Lamine Aoudjit
- Department of Medicine, McGill University Health Centre, Montreal, Quebec, Canada
| | - Manali Tilak
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada
| | - Vera Eremina
- The Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada; and
| | - W Rod Hardy
- The Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada; and
| | - Susan E Quaggin
- The Lunenfeld-Tanenbaum Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada; and.,Feinberg Cardiovascular Research Institute and Division of Nephrology and Hypertension, Northwestern University of Chicago, Illinois
| | - Tomoko Takano
- Department of Medicine, McGill University Health Centre, Montreal, Quebec, Canada
| | - Nina Jones
- Department of Molecular and Cellular Biology, University of Guelph, Guelph, Ontario, Canada;
| |
Collapse
|
4
|
Grb2 regulates the proliferation of hematopoietic stem and progenitors cells. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017; 1864:2449-2459. [PMID: 28964849 DOI: 10.1016/j.bbamcr.2017.09.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Revised: 08/31/2017] [Accepted: 09/26/2017] [Indexed: 01/13/2023]
Abstract
Although Hematopoietic Stem and Progenitor Cell (HSPC) proliferation, survival and expansion have been shown to be supported by the cooperative action of different cytokines, little is known about the intracellular signaling pathways that are activated by cytokines upon binding to their receptors. Our study showed that Growth factor receptor-bound protein 2 (Grb2) mRNAs are preferentially expressed in HSC compared to progenitors and differentiated cells of the myeloid and erythroid lineages. Conditional deletion of Grb2 induced a rapid decline of erythroid and myeloid progenitors and a progressive decline of HSC numbers in steady state conditions. We showed that when transplanted, Grb2 deleted bone marrow cells could not reconstitute irradiated recipients. Strinkingly, Grb2 deletion did not modify HSPC quiescence, but impaired LT-HSC and progenitors ability to respond a proliferative signal induced by 5FU in vivo and by various cytokines in vitro. We showed finally that Grb2 links IL3 signaling to the ERK/MAPK proliferative pathway and that both SH2 and SH3 domains of Grb2 are crucial for IL3 signaling in progenitor cells. Our findings position Grb2 as a key adaptor that integrates various cytokines response in cycling HSPC.
Collapse
|
5
|
Abstract
Genetic studies of hereditary forms of nephrotic syndrome have identified several proteins that are involved in regulating the permselective properties of the glomerular filtration system. Further extensive research has elucidated the complex molecular basis of the glomerular filtration barrier and clearly established the pivotal role of podocytes in the pathophysiology of glomerular diseases. Podocyte architecture is centred on focal adhesions and slit diaphragms - multiprotein signalling hubs that regulate cell morphology and function. A highly interconnected actin cytoskeleton enables podocytes to adapt in order to accommodate environmental changes and maintain an intact glomerular filtration barrier. Actin-based endocytosis has now emerged as a regulator of podocyte integrity, providing an impetus for understanding the precise mechanisms that underlie the steady-state control of focal adhesion and slit diaphragm components. This Review outlines the role of actin dynamics and endocytosis in podocyte biology, and discusses how molecular heterogeneity in glomerular disorders could be exploited to deliver more rational therapeutic interventions, paving the way for targeted medicine in nephrology.
Collapse
|
6
|
Levy-Apter E, Finkelshtein E, Vemulapalli V, Li SSC, Bedford MT, Elson A. Adaptor protein GRB2 promotes Src tyrosine kinase activation and podosomal organization by protein-tyrosine phosphatase ϵ in osteoclasts. J Biol Chem 2014; 289:36048-58. [PMID: 25381250 DOI: 10.1074/jbc.m114.603548] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The non-receptor isoform of protein-tyrosine phosphatase ϵ (cyt-PTPe) supports adhesion of bone-resorbing osteoclasts by activating Src downstream of integrins. Loss of cyt-PTPe reduces Src activity in osteoclasts, reduces resorption of mineralized matrix both in vivo and in cell culture, and induces mild osteopetrosis in young female PTPe KO mice. Activation of Src by cyt-PTPe is dependent upon this phosphatase undergoing phosphorylation at its C-terminal Tyr-638 by partially active Src. To understand how cyt-PTPe activates Src, we screened 73 Src homology 2 (SH2) domains for binding to Tyr(P)-638 of cyt-PTPe. The SH2 domain of GRB2 bound Tyr(P)-638 of cyt-PTPe most prominently, whereas the Src SH2 domain did not bind at all, suggesting that GRB2 may link PTPe with downstream molecules. Further studies indicated that GRB2 is required for activation of Src by cyt-PTPe in osteoclast-like cells (OCLs) in culture. Overexpression of GRB2 in OCLs increased activating phosphorylation of Src at Tyr-416 and of cyt-PTPe at Tyr-638; opposite results were obtained when GRB2 expression was reduced by shRNA or by gene inactivation. Phosphorylation of cyt-PTPe at Tyr-683 and its association with GRB2 are integrin-driven processes in OCLs, and cyt-PTPe undergoes autodephosphorylation at Tyr-683, thus limiting Src activation by integrins. Reduced GRB2 expression also reduced the ability of bone marrow precursors to differentiate into OCLs and reduced the fraction of OCLs in which podosomal adhesion structures assume organization typical of active, resorbing cells. We conclude that GRB2 physically links cyt-PTPe with Src and enables cyt-PTPe to activate Src downstream of activated integrins in OCLs.
Collapse
Affiliation(s)
- Einat Levy-Apter
- From the Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Eynat Finkelshtein
- From the Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Vidyasiri Vemulapalli
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas M. D. Anderson Cancer Center, Smithville, Texas 78957, and
| | - Shawn S-C Li
- Department of Biochemistry and the Siebens-Drake Medical Research Institute, Schulich School of Medicine and Dentistry, University of Western Ontario, London, Ontario N6A 5C1, Canada
| | - Mark T Bedford
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas M. D. Anderson Cancer Center, Smithville, Texas 78957, and
| | - Ari Elson
- From the Department of Molecular Genetics, The Weizmann Institute of Science, Rehovot 76100, Israel,
| |
Collapse
|
7
|
|
8
|
Lennon R, Randles MJ, Humphries MJ. The importance of podocyte adhesion for a healthy glomerulus. Front Endocrinol (Lausanne) 2014; 5:160. [PMID: 25352829 PMCID: PMC4196579 DOI: 10.3389/fendo.2014.00160] [Citation(s) in RCA: 84] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2014] [Accepted: 09/21/2014] [Indexed: 12/23/2022] Open
Abstract
Podocytes are specialized epithelial cells that cover the outer surfaces of glomerular capillaries. Unique cell junctions, known as slit diaphragms, which feature nephrin and Neph family proteins in addition to components of adherens, tight, and gap junctions, connect adjacent podocyte foot processes. Single gene disorders affecting the slit diaphragm result in nephrotic syndrome in humans, characterized by massive loss of protein across the capillary wall. In addition to specialized cell junctions, interconnecting podocytes also adhere to the glomerular basement membrane (GBM) of the capillary wall. The GBM is a dense network of secreted, extracellular matrix (ECM) components and contains tissue-restricted isoforms of collagen IV and laminin in addition to other structural proteins and ECM regulators such as proteases and growth factors. The specialized niche of the GBM provides a scaffold for endothelial cells and podocytes to support their unique functions and human genetic mutations in GBM components lead to renal failure, thus highlighting the importance of cell-matrix interactions in the glomerulus. Cells adhere to ECM via adhesion receptors, including integrins, syndecans, and dystroglycan and in particular the integrin heterodimer α3β1 is required to maintain barrier integrity. Therefore, the sophisticated function of glomerular filtration relies on podocyte adhesion both at cell junctions and at the interface with the ECM. In health, the podocyte coordinates signals from cell junctions and cell-matrix interactions, in response to environmental cues in order to regulate filtration and as our understanding of mechanisms that control cell adhesion in the glomerulus develops, then insight into the effects of disease will improve. The ultimate goal will be to develop targeted therapies to prevent or repair defects in the filtration barrier and to restore glomerular function.
Collapse
Affiliation(s)
- Rachel Lennon
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
- Institute of Human Development, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK
- Department of Paediatric Nephrology, Manchester Academic Health Science Centre, Central Manchester University Hospitals NHS Foundation Trust, Manchester, UK
- *Correspondence: Rachel Lennon, Wellcome Trust Centre for Cell-Matrix Research, The University of Manchester, Michael Smith Building, Manchester M13 9PT, UK e-mail:
| | - Michael J. Randles
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
- Institute of Human Development, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, UK
| | - Martin J. Humphries
- Wellcome Trust Centre for Cell-Matrix Research, Faculty of Life Sciences, The University of Manchester, Manchester, UK
| |
Collapse
|
9
|
Laurin M, Dumouchel A, Fukui Y, Côté JF. The Rac-specific exchange factors Dock1 and Dock5 are dispensable for the establishment of the glomerular filtration barrier in vivo. Small GTPases 2013; 4:221-30. [PMID: 24365888 DOI: 10.4161/sgtp.27430] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Podocytes are specialized kidney cells that form the kidney filtration barrier through the connection of their foot processes. Nephrin and Neph family transmembrane molecules at the surface of podocytes interconnect to form a unique type of cell-cell junction, the slit diaphragm, which acts as a molecular sieve. The cytoplasmic tails of Nephrin and Neph mediate cytoskeletal rearrangement that contributes to the maintenance of the filtration barrier. Nephrin and Neph1 orthologs are essential to regulate cell-cell adhesion and Rac-dependent actin rearrangement during Drosophila myoblast fusion. We hypothesized here that molecules regulating myoblast fusion in Drosophila could contribute to signaling downstream of Nephrin and Neph1 in podocytes. We found that Nephrin engagement promoted recruitment of the Rac exchange factor Dock1 to the membrane. Furthermore, Nephrin overexpression led to lamellipodia formation that could be blocked by inhibiting Rac1 activity. We generated in vivo mouse models to investigate whether Dock1 and Dock5 contribute to the formation and maintenance of the kidney filtration barrier. Our results indicate that while Dock1 and Dock5 are expressed in podocytes, their functions are not essential for the development of the glomerular filtration barrier. Furthermore, mice lacking Dock1 were not protected from LPS-induced podocyte effacement. Our data suggest that Dock1 and Dock5 are not the important exchange factors regulating Rac activity during the establishment and maintenance of the glomerular barrier.
Collapse
Affiliation(s)
- Mélanie Laurin
- Institut de Recherches Cliniques de Montréal (IRCM); Montréal, QC, Canada; Département de Médecine (Programmes de Biologie Moléculaire); Université de Montréal; Montréal, QC, Canada
| | - Annie Dumouchel
- Institut de Recherches Cliniques de Montréal (IRCM); Montréal, QC, Canada
| | - Yoshinori Fukui
- Division of Immunogenetics; Department of Immunobiology and Neuroscience; Medical Institute of Bioregulation; Kyushu University; Fukuoda, Japan
| | - Jean-François Côté
- Institut de Recherches Cliniques de Montréal (IRCM); Montréal, QC, Canada; Département de Médecine (Programmes de Biologie Moléculaire); Université de Montréal; Montréal, QC, Canada; Département de Biochimie; Université de Montréal; Montréal, QC, Canada; Division of Experimental Medicine; McGill University; Montréal, QC, Canada
| |
Collapse
|
10
|
Lay A, Coward RJ. Recent advances in our understanding of insulin signalling to the podocyte. Nephrol Dial Transplant 2013; 29:1127-33. [PMID: 24286976 DOI: 10.1093/ndt/gft471] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
It is becoming increasingly clear that the insulin responses of a number of different cell types within the kidney are important in the maintenance of normal renal function. This review summarizes our current understanding of renal insulin signalling, with specific focus on the podocyte, presenting recent evidence that suggests these responses are altered in systemic insulin-resistant states and chronic kidney disease via a number of different mechanisms.
Collapse
Affiliation(s)
- Abigail Lay
- Academic Renal Unit, Learning and Research Building, Southmead Hospital, School of Clinical Sciences, University of Bristol, Bristol BS10 5NB, UK
| | - Richard J Coward
- Academic Renal Unit, Learning and Research Building, Southmead Hospital, School of Clinical Sciences, University of Bristol, Bristol BS10 5NB, UK
| |
Collapse
|