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Xiao H, Qu Y, Li H, Zhang Y, Fei M, Liang C, Yang H, Zhang X. HIF-2α/LINC02609/APOL1-mediated lipid storage promotes endoplasmic reticulum homeostasis and regulates tumor progression in clear-cell renal cell carcinoma. J Exp Clin Cancer Res 2024; 43:29. [PMID: 38263248 PMCID: PMC10804485 DOI: 10.1186/s13046-023-02940-6] [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: 06/26/2023] [Accepted: 12/26/2023] [Indexed: 01/25/2024] Open
Abstract
BACKGROUND The VHL-HIF pathway and lipid droplet accumulation are the main characteristics of clear cell renal cell carcinoma (ccRCC). However, the connection between the two features is largely unknown. METHODS We used transcriptional sequencing and TCGA database analysis to identify APOL1 as a novel therapeutic target for ccRCC. The oncogenic functions of APOL1 were investigated by cell proliferation, colony formation, migration and invasion assays in ccRCC cells in vitro and xenografts derived from ccRCC cells in vivo. Oil red O staining and quantification were used to detect lipid droplets. Chromatin immunoprecipitation (ChIP) assays and luciferase reporter assays were carried out to identify HIF-2α bound to the promoter of APOL1 and lncRNA LINC02609. RNA-FISH and luciferase reporter assays were performed to determine that LncRNA LINC02609 functions as a competing endogenous RNA to regulate APOL1 expression by sponging miR-149-5p. FINDINGS RNA-seq data revealed that HIF2α can regulate APOL1 and lncRNA LINC02609 expression. We also found that HIF-2α can bind to the promoter of APOL1 and lncRNA LINC02609 and transcriptionally regulate their expression directly. We further demonstrated that LncRNA LINC02609 functions as a competing endogenous RNA to regulate APOL1 expression by sponging miR-149-5p in ccRCC. Mechanistically, APOL1-dependent lipid storage is required for endoplasmic reticulum (ER) homeostasis and cell viability and metastasis in ccRCC. We also showed that high APOL1 expression correlated with worse clinical outcomes, and knockdown of APOL1 inhibited tumor cell lipid droplet formation, proliferation, metastasis and xenograft tumor formation abilities. Together, our studies identify that HIF2α can regulate the expression of the lipid metabolism related gene APOL1 by direct and indirect means, which are essential for ccRCC tumorigenesis. INTERPRETATION Based on the experimental data, in ccRCC, the HIF-2α/LINC02609/APOL1 axis can regulate the expression of APOL1, thus interfering with lipid storage, promoting endoplasmic reticulum homeostasis and regulating tumor progression in ccRCC. Together, our findings provide potential biomarkers and novel therapeutic targets for future studies in ccRCC.
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Affiliation(s)
- Haibing Xiao
- Department of Urology, Institute of Urology, Anhui Province Key Laboratory of Genitourinary Diseases, The First Affiliated Hospital of Anhui Medical University, Anhui Medical University, Hefei, 230022, China
- Department of Urology, Tongji Medical College, Union Hospital, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei Province, 430022, China
- Department of Pathogenic Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China
| | - Yan Qu
- College of Basic Medicine, Xinxiang Medical University, Xinxiang, Henan, 453000, China
| | - Haolin Li
- Department of Urology, Institute of Urology, Anhui Province Key Laboratory of Genitourinary Diseases, The First Affiliated Hospital of Anhui Medical University, Anhui Medical University, Hefei, 230022, China
| | - Yi Zhang
- Department of Urology, Institute of Urology, Anhui Province Key Laboratory of Genitourinary Diseases, The First Affiliated Hospital of Anhui Medical University, Anhui Medical University, Hefei, 230022, China
| | - Mintian Fei
- Department of Urology, Institute of Urology, Anhui Province Key Laboratory of Genitourinary Diseases, The First Affiliated Hospital of Anhui Medical University, Anhui Medical University, Hefei, 230022, China
| | - Chaozhao Liang
- Department of Urology, Institute of Urology, Anhui Province Key Laboratory of Genitourinary Diseases, The First Affiliated Hospital of Anhui Medical University, Anhui Medical University, Hefei, 230022, China.
| | - Hongmei Yang
- Department of Pathogenic Biology, School of Basic Medicine, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430030, China.
| | - Xiaoping Zhang
- Department of Urology, Tongji Medical College, Union Hospital, Huazhong University of Science and Technology, 1277 Jiefang Avenue, Wuhan, Hubei Province, 430022, China.
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2
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Mayanja R, Kintu C, Diabate O, Soremekun O, Oluwagbemi OO, Wele M, Kalyesubula R, Jjingo D, Chikowore T, Fatumo S. Molecular Dynamic Simulation Reveals Structure Differences in APOL1 Variants and Implication in Pathogenesis of Chronic Kidney Disease. Genes (Basel) 2022; 13:1460. [PMID: 36011371 PMCID: PMC9408642 DOI: 10.3390/genes13081460] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Revised: 07/28/2022] [Accepted: 08/08/2022] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND According to observational studies, two polymorphisms in the apolipoprotein L1 (APOL1) gene have been linked to an increased risk of chronic kidney disease (CKD) in Africans. One polymorphism involves the substitution of two amino-acid residues (S342G and I384M; known as G1), while the other involves the deletion of two amino-acid residues in a row (N388 and Y389; termed G2). Despite the strong link between APOL1 polymorphisms and kidney disease, the molecular mechanisms via which these APOL1 mutations influence the onset and progression of CKD remain unknown. METHODS To predict the active site and allosteric site on the APOL1 protein, we used the Computed Atlas of Surface Topography of Proteins (CASTp) and the Protein Allosteric Sites Server (PASSer). Using an extended molecular dynamics simulation, we investigated the characteristic structural perturbations in the 3D structures of APOL1 variants. RESULTS According to CASTp's active site characterization, the topmost predicted site had a surface area of 964.892 Å2 and a pocket volume of 900.792 Å3. For the top three allosteric pockets, the allostery probability was 52.44%, 46.30%, and 38.50%, respectively. The systems reached equilibrium in about 125 ns. From 0-100 ns, there was also significant structural instability. When compared to G1 and G2, the wildtype protein (G0) had overall high stability throughout the simulation. The root-mean-square fluctuation (RMSF) of wildtype and variant protein backbone Cα fluctuations revealed that the Cα of the variants had a large structural fluctuation when compared to the wildtype. CONCLUSION Using a combination of different computational techniques, we identified binding sites within the APOL1 protein that could be an attractive site for potential inhibitors of APOL1. Furthermore, the G1 and G2 mutations reduced the structural stability of APOL1.
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Affiliation(s)
- Richard Mayanja
- The African Computational Genomics (TACG) Research Group, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe 31405, Uganda
- Department of Immunology and Molecular Biology, College of Health Sciences, Makerere University, Kampala 10101, Uganda
| | - Christopher Kintu
- The African Computational Genomics (TACG) Research Group, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe 31405, Uganda
- Department of Immunology and Molecular Biology, College of Health Sciences, Makerere University, Kampala 10101, Uganda
| | - Oudou Diabate
- The African Computational Genomics (TACG) Research Group, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe 31405, Uganda
- African Center of Excellence in Bioinformatics (ACE-B), University of Science, Technique and Technologies of Bamako (USTTB), Bamako 3206, Mali
| | - Opeyemi Soremekun
- The African Computational Genomics (TACG) Research Group, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe 31405, Uganda
- Molecular Bio-Computation and Drug Design Laboratory, School of Health Sciences, University of KwaZulu-Natal, Durban 4041, South Africa
| | | | - Mamadou Wele
- African Center of Excellence in Bioinformatics (ACE-B), University of Science, Technique and Technologies of Bamako (USTTB), Bamako 3206, Mali
| | - Robert Kalyesubula
- Department of Internal Medicine and Department of Physiology, Makerere University, Kampala 10101, Uganda
| | - Daudi Jjingo
- African Center of Excellence in Bioinformatics (ACE-B), Makerere University, Kampala 10101, Uganda
| | - Tinashe Chikowore
- MRC/Wits Developmental Pathways for Health Research Unit, Department of Paediatrics, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2050, South Africa
- Sydney Brenner Institute for Molecular Bioscience, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg 2193, South Africa
| | - Segun Fatumo
- The African Computational Genomics (TACG) Research Group, Medical Research Council/Uganda Virus Research Institute and London School of Hygiene & Tropical Medicine Uganda Research Unit, Entebbe 31405, Uganda
- Department of Non-Communicable Disease Epidemiology (NCDE), London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
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3
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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: 46] [Impact Index Per Article: 23.0] [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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4
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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: 4] [Impact Index Per Article: 2.0] [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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5
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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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6
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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: 9] [Impact Index Per Article: 3.0] [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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7
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Goyal R, Singhal PC. APOL1 risk variants and the development of HIV-associated nephropathy. FEBS J 2020; 288:5586-5597. [PMID: 33340240 DOI: 10.1111/febs.15677] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2020] [Revised: 12/08/2020] [Accepted: 12/16/2020] [Indexed: 01/03/2023]
Abstract
HIV-associated nephropathy (HIVAN) remains a concern among untreated HIV patients, notably of African descent, as patients can reach end-stage renal disease within 3 years. Two variants (G1 and G2) of the APOL1 gene, common in African populations to protect against African sleeping sickness, have been associated with an increased risk of several glomerular disorders including HIVAN, hypertension-attributed chronic kidney disease, and idiopathic focal segmental glomerulosclerosis and are accordingly named renal risk variants (RRVs). This review examines the mechanisms by which APOL1 RRVs drive glomerular injury in the setting of HIV infection and their potential application to patient management. Innate antiviral mechanisms activated by chronic HIV infection, especially those involving type 1 interferons, are of particular interest as they have been shown to upregulate APOL1 expression. Additionally, the downregulation of miRNA 193a (a repressor of APOL1) is also associated with the upregulation of APOL1. Interestingly, glomerular damage affected by APOL1 RRVs is caused by both loss- and gain-of-function changes in the protein, explicitly characterizing these effects. Their intracellular localization offers a further understanding of the nuances of APOL1 variant effects in promoting renal disease. Finally, although APOL1 variants have been recognized as a critical genetic player in mediating kidney disease, there are significant gaps in their application to patient management for screening, diagnosis, and treatment.
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Affiliation(s)
- Rohan Goyal
- SUNY Downstate Health Sciences University, New York, NY, USA
| | - Pravin C Singhal
- Institute of Molecular Medicine, Feinstein Institute for Medical Research and Zucker School of Medicine at Hofstra-Northwell, Manhasset, NY, USA
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8
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Gribouval O, Boyer O, Knebelmann B, Karras A, Dantal J, Fourrage C, Alibeu O, Hogan J, Dossier C, Tête MJ, Antignac C, Servais A. APOL1 risk genotype in European steroid-resistant nephrotic syndrome and/or focal segmental glomerulosclerosis patients of different African ancestries. Nephrol Dial Transplant 2020; 34:1885-1893. [PMID: 29992269 DOI: 10.1093/ndt/gfy176] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2018] [Accepted: 05/03/2018] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Apolipoprotein L1 (APOL1) risk variants are strongly associated with sporadic focal segmental glomerulosclerosis (FSGS) in populations with African ancestry. We determined the frequency of G1/G2 variants in steroid-resistant nephrotic syndrome (SRNS)/FSGS patients with African or French West Indies ancestry in France and its relationships with other SRNS genes. METHODS In a cohort of 152 patients (139 families), the APOL1 risk variants were genotyped by direct Sanger sequencing and pathogenic mutations were screened by next-generation sequencing with a panel including 35 SRNS genes. RESULTS The two risk allele [high-risk (HR)] genotypes were found in 43.1% (66/152) of subjects compared with 18.9% (106/562) in a control population (P < 0.0001): 33 patients homozygous for APOL1 G1 alleles, 4 homozygous for G2 and 29 compound heterozygous for G1 and G2. Compared with patients in the low-risk (LR) group, patients in the HR group were more likely to originate from the French West Indies than from Africa [45/66 (68.2%) versus 30/86 (34.9%); P < 0.0001]. There were more familial cases in the HR group [27 (41.5%) versus 8 (11.4%); P < 0.0001]. However, causative mutations in monogenic SRNS genes were found in only 1 patient in the HR group compared with 16 patients (14 families) in the LR group (P = 0.0006). At diagnosis, patients in the HR group without other mutations were more often adults [35 (53.8%) versus 19 (27.1%); P = 0.003] and had a lower estimated glomerular filtration rate (78.9 versus 98.8 mL/min/1.73 m2; P = 0.02). CONCLUSIONS The HR genotype is frequent in FSGS patients with African ancestry in our cohort, especially in those originating from the West Indies, and confer a poor renal prognosis. It is usually not associated with other causative mutations in monogenic SRNS genes.
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Affiliation(s)
- Olivier Gribouval
- Inserm U1163, Institut Imagine, University Paris Descartes, Paris, France
| | - Olivia Boyer
- Inserm U1163, Institut Imagine, University Paris Descartes, Paris, France.,Pediatric Nephrology Department, Necker Hospital, APHP, Paris, France
| | - Bertrand Knebelmann
- Nephrology and Transplantation Department, Necker Hospital, APHP, Paris, France
| | - Alexandre Karras
- Nephrology Department, European Georges Pompidou Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Jacques Dantal
- Nephrology Department, Centre Hospitalier Universitaire de Nantes, Nantes, France
| | - Cécile Fourrage
- Bioinformatic Platform, Paris Descartes Sorbonne Paris Cité University, Imagine Institute, Paris, France
| | - Olivier Alibeu
- Genomic Platform, Inserm UMR1163, Paris Descartes Sorbonne Paris Cité University, Paris, France
| | - Julien Hogan
- Pediatric Nephrology Department, Robert Debré Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Claire Dossier
- Pediatric Nephrology Department, Robert Debré Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Marie Josèphe Tête
- Inserm U1163, Institut Imagine, University Paris Descartes, Paris, France
| | - Corinne Antignac
- Inserm U1163, Institut Imagine, University Paris Descartes, Paris, France.,Genetic Department, Necker Hospital, Assistance Publique-Hôpitaux de Paris, Paris, France
| | - Aude Servais
- Inserm U1163, Institut Imagine, University Paris Descartes, Paris, France.,Nephrology and Transplantation Department, Necker Hospital, APHP, Paris, France
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9
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Bajaj A, Ihegword A, Qiu C, Small AM, Wei WQ, Bastarache L, Feng Q, Kember RL, Risman M, Bloom RD, Birtwell DL, Williams H, Shaffer CM, Chen J, Center RG, Denny JC, Rader DJ, Stein CM, Damrauer SM, Susztak K. Phenome-wide association analysis suggests the APOL1 linked disease spectrum primarily drives kidney-specific pathways. Kidney Int 2020; 97:1032-1041. [PMID: 32247630 DOI: 10.1016/j.kint.2020.01.027] [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: 04/09/2019] [Revised: 01/13/2020] [Accepted: 01/17/2020] [Indexed: 01/13/2023]
Abstract
The relationship between commonly occurring genetic variants (G1 and G2) in the APOL1 gene in African Americans and different disease traits, such as kidney disease, cardiovascular disease, and pre-eclampsia, remains the subject of controversy. Here we took a genotype-first approach, a phenome-wide association study, to define the spectrum of phenotypes associated with APOL1 high-risk variants in 1,837 African American participants of Penn Medicine Biobank and 4,742 African American participants of Vanderbilt BioVU. In the Penn Medicine Biobank, outpatient creatinine measurement-based estimated glomerular filtration rate and multivariable regression models were used to evaluate the association between high-risk APOL1 status and renal outcomes. In meta-analysis of both cohorts, the strongest phenome-wide association study associations were for the high-risk APOL1 variants and diagnoses codes were highly significant for "kidney dialysis" (odds ratio 3.75) and "end stage kidney disease" (odds ratio 3.42). A number of phenotypes were associated with APOL1 high-risk genotypes in an analysis adjusted only for demographic variables. However, no associations were detected with non-renal phenotypes after controlling for chronic/end stage kidney disease status. Using calculated estimated glomerular filtration rate -based phenotype analysis in the Penn Medicine Biobank, APOL1 high-risk status was associated with prevalent chronic/end stage kidney disease /kidney transplant (odds ratio 2.27, 95% confidence interval 1.67-3.08). In high-risk participants, the estimated glomerular filtration rate was 15.4 mL/min/1.73m2; significantly lower than in low-risk participants. Thus, although APOL1 high-risk variants are associated with a range of phenotypes, the risks for other associated phenotypes appear much lower and in our dataset are driven by a primary effect on renal disease.
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Affiliation(s)
- Archna Bajaj
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Andrea Ihegword
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Chengxiang Qiu
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Renal Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Aeron M Small
- Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Medicine, Yale-New Haven Hospital, New Haven, Connecticut, USA
| | - Wei-Qi Wei
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Lisa Bastarache
- Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - QiPing Feng
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Rachel L Kember
- Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania, USA; VISN 4 Mental Illness Research, Education, and Clinical Center, Corporal Michael Crescenz Veterans Affairs Medical Center, Philadelphia, Pennsylvania, USA
| | - Marjorie Risman
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Roy D Bloom
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Renal Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - David L Birtwell
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Heather Williams
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Christian M Shaffer
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jinbo Chen
- Center for Clinical Epidemiology and Biostatistics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | | | - Joshua C Denny
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Biomedical Informatics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Daniel J Rader
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Genetics, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - C Michael Stein
- Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Pharmacology, Vanderbilt University, Nashville, Tennessee, USA
| | - Scott M Damrauer
- Department of Surgery, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Department of Surgery, Corporal Michael Crescenz Veterans Affairs Medical Center, Philadelphia, Pennsylvania, USA.
| | - Katalin Susztak
- Department of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Renal Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA; Cardiovascular Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, 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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11
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APOL1 risk genotype in Europe: Data in patients with focal segmental glomerulosclerosis and after renal transplantation. Nephrol Ther 2019; 15 Suppl 1:S85-S89. [DOI: 10.1016/j.nephro.2019.02.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2019] [Accepted: 02/14/2019] [Indexed: 12/11/2022]
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12
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Abstract
People of recent African ancestry develop kidney disease at much higher rates than most other groups. Two specific coding variants in the Apolipoprotein-L1 gene APOL1 termed G1 and G2 are the causal drivers of much of this difference in risk, following a recessive pattern of inheritance. However, most individuals with a high-risk APOL1 genotype do not develop overt kidney disease, prompting interest in identifying those factors that interact with APOL1 We performed an admixture mapping study to identify genetic modifiers of APOL1-associated kidney disease. Individuals with two APOL1 risk alleles and focal segmental glomerulosclerosis (FSGS) have significantly increased African ancestry at the UBD (also known as FAT10) locus. UBD is a ubiquitin-like protein modifier that targets proteins for proteasomal degradation. African ancestry at the UBD locus correlates with lower levels of UBD expression. In cell-based experiments, the disease-associated APOL1 alleles (known as G1 and G2) lead to increased abundance of UBD mRNA but to decreased levels of UBD protein. UBD gene expression inversely correlates with G1 and G2 APOL1-mediated cell toxicity, as well as with levels of G1 and G2 APOL1 protein in cells. These studies support a model whereby inflammatory stimuli up-regulate both UBD and APOL1, which interact in a functionally important manner. UBD appears to mitigate APOL1-mediated toxicity by targeting it for destruction. Thus, genetically encoded differences in UBD and UBD expression appear to modify the APOL1-associated kidney phenotype.
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13
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Kruzel-Davila E, Wasser WG, Skorecki K. APOL1 Nephropathy: A Population Genetics and Evolutionary Medicine Detective Story. Semin Nephrol 2017; 37:490-507. [PMID: 29110756 DOI: 10.1016/j.semnephrol.2017.07.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Common DNA sequence variants rarely have a high-risk association with a common disease. When such associations do occur, evolutionary forces must be sought, such as in the association of apolipoprotein L1 (APOL1) gene risk variants with nondiabetic kidney diseases in populations of African ancestry. The variants originated in West Africa and provided pathogenic resistance in the heterozygous state that led to high allele frequencies owing to an adaptive evolutionary selective sweep. However, the homozygous state is disadvantageous and is associated with a markedly increased risk of a spectrum of kidney diseases encompassing hypertension-attributed kidney disease, focal segmental glomerulosclerosis, human immunodeficiency virus nephropathy, sickle cell nephropathy, and progressive lupus nephritis. This scientific success story emerged with the help of the tools developed over the past 2 decades in human genome sequencing and population genomic databases. In this introductory article to a timely issue dedicated to illuminating progress in this area, we describe this unique population genetics and evolutionary medicine detective story. We emphasize the paradox of the inheritance mode, the missing heritability, and unresolved associations, including cardiovascular risk and diabetic nephropathy. We also highlight how genetic epidemiology elucidates mechanisms and how the principles of evolution can be used to unravel conserved pathways affected by APOL1 that may lead to novel therapies. The APOL1 gene provides a compelling example of a common variant association with common forms of nondiabetic kidney disease occurring in a continental population isolate with subsequent global admixture. Scientific collaboration using multiple experimental model systems and approaches should further clarify pathomechanisms further, leading to novel therapies.
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Affiliation(s)
| | - Walter G Wasser
- Department of Nephrology, Rambam Health Care Campus, Haifa, Israel; Department of Nephrology, Mayanei HaYeshua Medical Center, Bnei Brak, Israel
| | - Karl Skorecki
- Department of Nephrology, Rambam Health Care Campus, Haifa, Israel; Department of Genetics and Developmental Biology, Rappaport Faculty of Medicine and Research Institute Technion-Israel Institute of Technology, Rambam Health Care Campus, Haifa, Israel.
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14
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Bruno J, Pozzi N, Oliva J, Edwards JC. Apolipoprotein L1 confers pH-switchable ion permeability to phospholipid vesicles. J Biol Chem 2017; 292:18344-18353. [PMID: 28918394 DOI: 10.1074/jbc.m117.813444] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 09/08/2017] [Indexed: 01/13/2023] Open
Abstract
Apolipoprotein L1 (ApoL1) is a human serum protein conferring resistance to African trypanosomes, and certain ApoL1 variants increase susceptibility to some progressive kidney diseases. ApoL1 has been hypothesized to function like a pore-forming colicin and has been reported to have permeability effects on both intracellular and plasma membranes. Here, to gain insight into how ApoL1 may function in vivo, we used vesicle-based ion permeability, direct membrane association, and intrinsic fluorescence to study the activities of purified recombinant ApoL1. We found that ApoL1 confers chloride-selective permeability to preformed phospholipid vesicles and that this selectivity is strongly pH-sensitive, with maximal activity at pH 5 and little activity above pH 7. When ApoL1 and lipid were allowed to interact at low pH and were then brought to neutral pH, chloride permeability was suppressed, and potassium permeability was activated. Both chloride and potassium permeability linearly correlated with the mass of ApoL1 in the reaction mixture, and both exhibited lipid selectivity, requiring the presence of negatively charged lipids for activity. Potassium, but not chloride, permease activity required the presence of calcium ions in both the association and activation steps. Direct assessment of ApoL1-lipid associations confirmed that ApoL1 stably associates with phospholipid vesicles, requiring low pH and the presence of negatively charged phospholipids for maximal binding. Intrinsic fluorescence of ApoL1 supported the presence of a significant structural transition when ApoL1 is mixed with lipids at low pH. This pH-switchable ion-selective permeability may explain the different effects of ApoL1 reported in intracellular and plasma membrane environments.
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Affiliation(s)
| | - Nicola Pozzi
- Biochemistry and Molecular Biology, Saint Louis University, St. Louis, Missouri 63110
| | - Jonathan Oliva
- Biochemistry and Molecular Biology, Saint Louis University, St. Louis, Missouri 63110
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