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Liu S, Bush WS, Miskimen K, Gonzalez-Vicente A, Bailey JNC, Konidari I, McCauley JL, Sedor JR, O'Toole JF, Crawford DC. T-cell receptor diversity in minimal change disease in the NEPTUNE study. Pediatr Nephrol 2023; 38:1115-1126. [PMID: 35943576 PMCID: PMC10037226 DOI: 10.1007/s00467-022-05696-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 07/15/2022] [Accepted: 07/15/2022] [Indexed: 11/28/2022]
Abstract
BACKGROUND Minimal change disease (MCD) is the major cause of childhood idiopathic nephrotic syndrome, which is characterized by massive proteinuria and debilitating edema. Proteinuria in MCD is typically rapidly reversible with corticosteroid therapy, but relapses are common, and children often have many adverse events from the repeated courses of immunosuppressive therapy. The pathobiology of MCD remains poorly understood. Prior clinical observations suggest that abnormal T-cell function may play a central role in MCD pathogenesis. Based on these observations, we hypothesized that T-cell responses to specific exposures or antigens lead to a clonal expansion of T-cell subsets, a restriction in the T-cell repertoire, and an elaboration of specific circulating factors that trigger disease onset and relapses. METHODS To test these hypotheses, we sequenced T-cell receptors in fourteen MCD, four focal segmental glomerulosclerosis (FSGS), and four membranous nephropathy (MN) patients with clinical data and blood samples drawn during active disease and during remission collected by the Nephrotic Syndrome Study Network (NEPTUNE). We calculated several T-cell receptor diversity metrics to assess possible differences between active disease and remission states in paired samples. RESULTS Median productive clonality did not differ between MCD active disease (0.0083; range: 0.0042, 0.0397) and remission (0.0088; range: 0.0038, 0.0369). We did not identify dominant clonotypes in MCD active disease, and few clonotypes were shared with FSGS and MN patients. CONCLUSIONS While these data do not support an obvious role of the adaptive immune system T-cells in MCD pathogenesis, further study is warranted given the limited sample size. A higher resolution version of the Graphical abstract is available as Supplementary information.
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Affiliation(s)
- Shiying Liu
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH, USA
- Cleveland Institute for Computational Biology, Case Western Reserve University, Cleveland, OH, USA
| | - William S Bush
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH, USA
- Cleveland Institute for Computational Biology, Case Western Reserve University, Cleveland, OH, USA
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, USA
| | - Kristy Miskimen
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH, USA
- Cleveland Institute for Computational Biology, Case Western Reserve University, Cleveland, OH, USA
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, USA
| | - Agustin Gonzalez-Vicente
- Glickman Urological and Kidney Disease and Lerner Research Institutes, Cleveland Clinic, Cleveland, OH, USA
| | - Jessica N Cooke Bailey
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH, USA
- Cleveland Institute for Computational Biology, Case Western Reserve University, Cleveland, OH, USA
| | - Ioanna Konidari
- John P. Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - Jacob L McCauley
- John P. Hussman Institute for Human Genomics, Miller School of Medicine, University of Miami, Miami, FL, USA
| | - John R Sedor
- Glickman Urological and Kidney Disease and Lerner Research Institutes, Cleveland Clinic, Cleveland, OH, USA
| | - John F O'Toole
- Glickman Urological and Kidney Disease and Lerner Research Institutes, Cleveland Clinic, Cleveland, OH, USA
| | - Dana C Crawford
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH, USA.
- Cleveland Institute for Computational Biology, Case Western Reserve University, Cleveland, OH, USA.
- Department of Genetics and Genome Sciences, Case Western Reserve University, Cleveland, OH, USA.
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Hong C, Eichinger F, Atta MG, Estrella MM, Fine DM, Ross MJ, Wyatt C, Hwang TH, Kretzler M, Sedor JR, O'Toole JF, Miller AW, Bruggeman LA. Viral associations with kidney disease diagnosis and altered kidney metatranscriptome by kidney function. Kidney Int 2023; 103:218-222. [PMID: 36356649 PMCID: PMC9822862 DOI: 10.1016/j.kint.2022.11.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 10/31/2022] [Accepted: 11/01/2022] [Indexed: 11/09/2022]
Affiliation(s)
- Changjin Hong
- Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio, USA
| | - Felix Eichinger
- Department of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Mohamed G Atta
- Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - Michelle M Estrella
- Kidney Health Research Collaborative, Department of Medicine, University of California San Francisco, San Francisco, California, USA; Division of Nephrology, San Francisco VA Health Care System, San Francisco, CA, USA
| | - Derek M Fine
- Department of Medicine, Johns Hopkins University, Baltimore, Maryland, USA
| | - Michael J Ross
- Department of Medicine, Albert Einstein College of Medicine, Bronx, New York, USA
| | - Christina Wyatt
- Department of Medicine, Duke University School of Medicine, Durham, North Carolina, USA
| | - Tae Hyun Hwang
- Department of Quantitative Health Sciences, Cleveland Clinic, Cleveland, Ohio, USA
| | - Matthias Kretzler
- Department of Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - John R Sedor
- Department of Inflammation and Immunity, Cleveland Clinic, Cleveland, Ohio, USA; Department of Kidney Medicine, Cleveland Clinic, Cleveland, Ohio, USA; Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - John F O'Toole
- Department of Inflammation and Immunity, Cleveland Clinic, Cleveland, Ohio, USA; Department of Kidney Medicine, Cleveland Clinic, Cleveland, Ohio, USA
| | - Aaron W Miller
- Department of Kidney Medicine, Cleveland Clinic, Cleveland, Ohio, USA; Department of Cardiovascular and Metabolic Sciences, Cleveland Clinic, Cleveland, Ohio, USA.
| | - Leslie A Bruggeman
- Department of Inflammation and Immunity, Cleveland Clinic, Cleveland, Ohio, USA; Department of Kidney Medicine, Cleveland Clinic, Cleveland, Ohio, USA.
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Madhavan SM, Konieczkowski M, Bruggeman LA, DeWalt M, Nguyen JK, O'Toole JF, Sedor JR. Essential role of Wtip in mouse development and maintenance of the glomerular filtration barrier. Am J Physiol Renal Physiol 2022; 323:F272-F287. [PMID: 35862649 PMCID: PMC9394782 DOI: 10.1152/ajprenal.00051.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 07/12/2022] [Accepted: 07/13/2022] [Indexed: 11/22/2022] Open
Abstract
Wilms' tumor interacting protein (Wtip) has been implicated in cell junction assembly and cell differentiation and interacts with proteins in the podocyte slit diaphragm, where it regulates podocyte phenotype. To define Wtip expression and function in the kidney, we created a Wtip-deleted mouse model using β-galactosidase-neomycin (β-geo) gene trap technology. Wtip gene trap mice were embryonic lethal, suggesting additional developmental roles outside kidney function. Using β-geo heterozygous and normal mice, Wtip expression was identified in the developing kidneys, heart, and eyes. In the kidney, expression was restricted to podocytes, which appeared initially at the capillary loop stage coinciding with terminal podocyte differentiation. Heterozygous mice had an expected lifespan and showed no evidence of proteinuria or glomerular pathology. However, heterozygous mice were more susceptible to glomerular injury than wild-type littermates and developed more significant and prolonged proteinuria in response to lipopolysaccharide or adriamycin. In normal human kidneys, WTIP expression patterns were consistent with observations in mice and were lost in glomeruli concurrent with loss of synaptopodin expression in disease. Mechanistically, we identified the Rho guanine nucleotide exchange factor 12 (ARHGEF12) as a binding partner for WTIP. ARHGEF12 was expressed in human podocytes and formed high-affinity interactions through their LIM- and PDZ-binding domains. Our findings suggest that Wtip is essential for early murine embryonic development and maintaining normal glomerular filtration barrier function, potentially regulating slit diaphragm and foot process function through Rho effector proteins.NEW & NOTEWORTHY This study characterized dynamic expression patterns of Wilms' tumor interacting protein (Wtip) and demonstrates the novel role of Wtip in murine development and maintenance of the glomerular filtration barrier.
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Affiliation(s)
- Sethu M Madhavan
- Department of Medicine, The Ohio State University, Columbus, Ohio
| | | | - Leslie A Bruggeman
- Department of Inflammation and Immunity, Cleveland Clinic, Cleveland, Ohio
- Department of Nephrology, Cleveland Clinic, Cleveland, Ohio
| | - Megan DeWalt
- Department of Medicine, The Ohio State University, Columbus, Ohio
| | - Jane K Nguyen
- Department of Pathology, Cleveland Clinic, Cleveland, Ohio
| | - John F O'Toole
- Department of Inflammation and Immunity, Cleveland Clinic, Cleveland, Ohio
- Department of Nephrology, Cleveland Clinic, Cleveland, Ohio
| | - John R Sedor
- Department of Inflammation and Immunity, Cleveland Clinic, Cleveland, Ohio
- Department of Nephrology, Cleveland Clinic, Cleveland, Ohio
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
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4
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Butler CR, Appelbaum PS, Ascani H, Aulisio M, Campbell CE, de Boer IH, Dighe AL, Hall DE, Himmelfarb J, Knight R, Mehl K, Murugan R, Rosas SE, Sedor JR, O'Toole JF, Tuttle KR, Waikar SS, Freeman M. A Participant-Centered Approach to Understanding Risks and Benefits of Participation in Research Informed by the Kidney Precision Medicine Project. Am J Kidney Dis 2022; 80:132-138. [PMID: 34871700 PMCID: PMC9166631 DOI: 10.1053/j.ajkd.2021.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 10/12/2021] [Indexed: 11/11/2022]
Abstract
An understanding of the ethical underpinnings of human subjects research that involves some risk to participants without anticipated direct clinical benefit-such as the kidney biopsy procedure as part of the Kidney Precision Medicine Project (KPMP)-requires a critical examination of the risks as well as the diverse set of countervailing potential benefits to participants. This kind of deliberation has been foundational to the development and conduct of the KPMP. Herein, we use illustrative features of this research paradigm to develop a more comprehensive conceptualization of the types of benefits that may be important to research participants, including respecting pluralistic values, supporting the opportunity to act altruistically, and enhancing benefits to a participant's community. This approach may serve as a model to help researchers, ethicists, and regulators to identify opportunities to better respect and support participants in future research that entails some risk to these participants as well as to improve the quality of research for people with kidney disease.
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Affiliation(s)
- Catherine R Butler
- Division of Nephrology, Department of Medicine and the Kidney Research Institute, University of Washington, Seattle, Washington; Seattle-Denver Health Services Research and Development Center of Innovation, Veterans Affairs Puget Sound Health Care System, Seattle, Washington.
| | - Paul S Appelbaum
- Department of Psychiatry, Vagelos College of Physicians & Surgeons, Columbia University, New York, New York; New York State Psychiatric Institute, New York, New York
| | - Heather Ascani
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan
| | - Mark Aulisio
- Department of Bioethics, School of Medicine, Case Western Reserve University, Cleveland, Ohio; Center for Biomedical Ethics, MetroHealth System, Cleveland, Ohio
| | - Catherine E Campbell
- Kidney Precision Medicine Project Patient Partner, American Association of Kidney Patients, Tampa, Florida; Sigma Theta Tau International Honor Society, Case Management Society of America, AARP Volunteer Nursing Leadership Board
| | - Ian H de Boer
- Division of Nephrology, Department of Medicine and the Kidney Research Institute, University of Washington, Seattle, Washington
| | - Ashveena L Dighe
- Division of Nephrology, Department of Medicine and the Kidney Research Institute, University of Washington, Seattle, Washington
| | - Daniel E Hall
- Department of Surgery, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; Department of Anesthesiology and Perioperative Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania; Wolff Center at UPMC, Pittsburgh, Pennsylvania; Center for Health Equity Research and Promotion and Geriatric Research Education and Clinical Center, VA Pittsburgh Healthcare System, Pittsburgh, Pennsylvania
| | - Jonathan Himmelfarb
- Division of Nephrology, Department of Medicine and the Kidney Research Institute, University of Washington, Seattle, Washington
| | - Richard Knight
- Kidney Precision Medicine Project Patient Partner, American Association of Kidney Patients, Tampa, Florida; American Association of Kidney Patients, Pittsburgh, Pennsylvania
| | - Karla Mehl
- Division of Nephrology, Irving Medical Center, Columbia University, New York, New York
| | - Raghavan Murugan
- Center for Critical Care Nephrology, Department of Critical Care Medicine, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania
| | - Sylvia E Rosas
- Kidney and Hypertension Unit, Joslin Diabetes Center, Harvard Medical School, Boston, Massachusetts
| | - John R Sedor
- Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio; Department of Nephrology and Hypertension, Glickman Urological and Kidney and Lerner Research Institutes, Cleveland Clinic Foundation, Cleveland, Ohio
| | - John F O'Toole
- Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio; Department of Nephrology and Hypertension, Glickman Urological and Kidney and Lerner Research Institutes, Cleveland Clinic Foundation, Cleveland, Ohio
| | - Katherine R Tuttle
- Division of Nephrology, Department of Medicine and the Kidney Research Institute, University of Washington, Seattle, Washington
| | - Sushrut S Waikar
- Section of Nephrology, Boston University School of Medicine and Boston Medical Center, Boston, Massachusetts; Renal Division, Brigham & Women's Hospital, Boston, Massachusetts
| | - Michael Freeman
- Division of Pediatric Nephrology and Hypertension, Department of Pediatrics and Humanities, Penn State College of Medicine, Hershey, Pennsylvania
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5
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Bruggeman LA, Azhibekov T, O'Toole JF. Moving Toward a Common Pathogenic Mechanism and Therapeutic Targets for APOL1 Nephropathies. American Journal of Kidney Diseases 2022; 79:901-903. [DOI: 10.1053/j.ajkd.2022.02.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 02/05/2022] [Indexed: 11/11/2022]
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6
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de Boer IH, Alpers CE, Azeloglu EU, Balis UGJ, Barasch JM, Barisoni L, Blank KN, Bomback AS, Brown K, Dagher PC, Dighe AL, Eadon MT, El-Achkar TM, Gaut JP, Hacohen N, He Y, Hodgin JB, Jain S, Kellum JA, Kiryluk K, Knight R, Laszik ZG, Lienczewski C, Mariani LH, McClelland RL, Menez S, Moledina DG, Mooney SD, O'Toole JF, Palevsky PM, Parikh CR, Poggio ED, Rosas SE, Rosengart MR, Sarwal MM, Schaub JA, Sedor JR, Sharma K, Steck B, Toto RD, Troyanskaya OG, Tuttle KR, Vazquez MA, Waikar SS, Williams K, Wilson FP, Zhang K, Iyengar R, Kretzler M, Himmelfarb J. Rationale and design of the Kidney Precision Medicine Project. Kidney Int 2021; 99:498-510. [PMID: 33637194 PMCID: PMC8330551 DOI: 10.1016/j.kint.2020.08.039] [Citation(s) in RCA: 78] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Revised: 08/08/2020] [Accepted: 08/14/2020] [Indexed: 02/07/2023]
Abstract
Chronic kidney disease (CKD) and acute kidney injury (AKI) are common, heterogeneous, and morbid diseases. Mechanistic characterization of CKD and AKI in patients may facilitate a precision-medicine approach to prevention, diagnosis, and treatment. The Kidney Precision Medicine Project aims to ethically and safely obtain kidney biopsies from participants with CKD or AKI, create a reference kidney atlas, and characterize disease subgroups to stratify patients based on molecular features of disease, clinical characteristics, and associated outcomes. An additional aim is to identify critical cells, pathways, and targets for novel therapies and preventive strategies. This project is a multicenter prospective cohort study of adults with CKD or AKI who undergo a protocol kidney biopsy for research purposes. This investigation focuses on kidney diseases that are most prevalent and therefore substantially burden the public health, including CKD attributed to diabetes or hypertension and AKI attributed to ischemic and toxic injuries. Reference kidney tissues (for example, living-donor kidney biopsies) will also be evaluated. Traditional and digital pathology will be combined with transcriptomic, proteomic, and metabolomic analysis of the kidney tissue as well as deep clinical phenotyping for supervised and unsupervised subgroup analysis and systems biology analysis. Participants will be followed prospectively for 10 years to ascertain clinical outcomes. Cell types, locations, and functions will be characterized in health and disease in an open, searchable, online kidney tissue atlas. All data from the Kidney Precision Medicine Project will be made readily available for broad use by scientists, clinicians, and patients.
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Affiliation(s)
- Ian H de Boer
- Department of Medicine, University of Washington, Seattle, Washington, USA.
| | - Charles E Alpers
- Department of Pathology, University of Washington, Seattle, Washington, USA
| | - Evren U Azeloglu
- Department of Medicine, Icahn School of Medicine at Mt. Sinai, New York, New York, USA
| | - Ulysses G J Balis
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA
| | | | - Laura Barisoni
- Department of Pathology, Duke University, Durham, North Carolina, USA
| | - Kristina N Blank
- Department of Biostatistics, University of Washington, Seattle, Washington, USA
| | - Andrew S Bomback
- Department of Medicine, Columbia University, New York, New York, USA
| | - Keith Brown
- Patient Representative, Kidney Precision Medicine Project Steering Committee Member
| | - Pierre C Dagher
- Department of Medicine, Indiana University, Indianapolis, Indiana, USA
| | - Ashveena L Dighe
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Michael T Eadon
- Department of Medicine, Indiana University, Indianapolis, Indiana, USA
| | - Tarek M El-Achkar
- Department of Medicine, Indiana University, Indianapolis, Indiana, USA
| | - Joseph P Gaut
- Department of Pathology, Washington University School of Medicine, St. Louis, St. Louis, Missouri, USA
| | - Nir Hacohen
- Broad Institute, Cambridge, Massachusetts, USA
| | - Yongqun He
- Department of Microbiology and Immunology, University of Michigan, Ann Arbor, Michigan, USA
| | - Jeffrey B Hodgin
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA
| | - Sanjay Jain
- Department of Medicine, Washington University School of Medicine, St. Louis, St. Louis, Missouri, USA
| | - John A Kellum
- Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Krzysztof Kiryluk
- Department of Medicine, Columbia University, New York, New York, USA
| | - Richard Knight
- American Association of Kidney Patients, Kidney Precision Medicine Project Patient Partner
| | - Zoltan G Laszik
- Department of Pathology, University of California, San Francisco, San Francisco, California, USA
| | - Chrysta Lienczewski
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Laura H Mariani
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Robyn L McClelland
- Department of Biostatistics, University of Washington, Seattle, Washington, USA
| | - Steven Menez
- Department of Medicine, Johns Hopkins Medicine, Baltimore, Maryland, USA
| | - Dennis G Moledina
- Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - Sean D Mooney
- Department of Biomedical Informatics and Medical Education, University of Washington, Seattle, Washington, USA
| | - John F O'Toole
- Department of Nephrology and Hypertension, Cleveland Clinic, Cleveland, Ohio, USA
| | - Paul M Palevsky
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA; Renal Section, Veterans Administration Pittsburgh Healthcare System, Pittsburgh, Pennsylvania, USA
| | - Chirag R Parikh
- Department of Medicine, Johns Hopkins Medicine, Baltimore, Maryland, USA
| | - Emilio D Poggio
- Department of Nephrology and Hypertension, Cleveland Clinic, Cleveland, Ohio, USA
| | | | - Matthew R Rosengart
- Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
| | - Minnie M Sarwal
- Department of Surgery, University of California, San Francisco, San Francisco, California, USA
| | - Jennifer A Schaub
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - John R Sedor
- Department of Nephrology and Hypertension, Cleveland Clinic, Cleveland, Ohio, USA
| | - Kumar Sharma
- Department of Medicine, UT Health San Antonio, San Antonio, Texas, USA
| | - Becky Steck
- Department of Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
| | - Robert D Toto
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Olga G Troyanskaya
- Department of Computer Science, Princeton University, Princeton, New Jersey, USA
| | - Katherine R Tuttle
- Department of Medicine, University of Washington, Seattle, Washington, USA
| | - Miguel A Vazquez
- Department of Internal Medicine, UT Southwestern Medical Center, Dallas, Texas, USA
| | - Sushrut S Waikar
- Department of Medicine, Boston University Medical Center, Boston, Massachusetts, USA
| | - Kayleen Williams
- Department of Biostatistics, University of Washington, Seattle, Washington, USA
| | - Francis Perry Wilson
- Department of Internal Medicine, Yale School of Medicine, New Haven, Connecticut, USA
| | - Kun Zhang
- Institute for Genomic Sciences, University of California, San Diego, California, USA
| | - Ravi Iyengar
- Mount Sinai Institute for Systems Biomedicine, Mount Sinai, New York, New York, USA
| | - Matthias Kretzler
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA
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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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8
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Sedor JR, Bruggeman LA, O'Toole JF. APOL1 and Preeclampsia: Intriguing Links, Uncertain Causality, Troubling Implications. Am J Kidney Dis 2021; 77:863-865. [PMID: 33875279 DOI: 10.1053/j.ajkd.2021.01.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 01/31/2021] [Indexed: 11/11/2022]
Affiliation(s)
- John R Sedor
- Glickman Urology and Kidney Institute, Case Western Reserve University, Cleveland, OH; Lerner Research Institute, Cleveland Clinic, Case Western Reserve University, Cleveland, OH; Department of Molecular Medicine, Case Western Reserve University, Cleveland, OH; Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, OH.
| | - Leslie A Bruggeman
- Glickman Urology and Kidney Institute, Case Western Reserve University, Cleveland, OH; Lerner Research Institute, Cleveland Clinic, Case Western Reserve University, Cleveland, OH; Department of Molecular Medicine, Case Western Reserve University, Cleveland, OH
| | - John F O'Toole
- Glickman Urology and Kidney Institute, Case Western Reserve University, Cleveland, OH; Lerner Research Institute, Cleveland Clinic, Case Western Reserve University, Cleveland, OH; Department of Molecular Medicine, Case Western Reserve University, Cleveland, OH
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9
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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10
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Ong E, Wang LL, Schaub J, O'Toole JF, Steck B, Rosenberg AZ, Dowd F, Hansen J, Barisoni L, Jain S, de Boer IH, Valerius MT, Waikar SS, Park C, Crawford DC, Alexandrov T, Anderton CR, Stoeckert C, Weng C, Diehl AD, Mungall CJ, Haendel M, Robinson PN, Himmelfarb J, Iyengar R, Kretzler M, Mooney S, He Y. Modelling kidney disease using ontology: insights from the Kidney Precision Medicine Project. Nat Rev Nephrol 2020; 16:686-696. [PMID: 32939051 PMCID: PMC8012202 DOI: 10.1038/s41581-020-00335-w] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/24/2020] [Indexed: 12/29/2022]
Abstract
An important need exists to better understand and stratify kidney disease according to its underlying pathophysiology in order to develop more precise and effective therapeutic agents. National collaborative efforts such as the Kidney Precision Medicine Project are working towards this goal through the collection and integration of large, disparate clinical, biological and imaging data from patients with kidney disease. Ontologies are powerful tools that facilitate these efforts by enabling researchers to organize and make sense of different data elements and the relationships between them. Ontologies are critical to support the types of big data analysis necessary for kidney precision medicine, where heterogeneous clinical, imaging and biopsy data from diverse sources must be combined to define a patient's phenotype. The development of two new ontologies - the Kidney Tissue Atlas Ontology and the Ontology of Precision Medicine and Investigation - will support the creation of the Kidney Tissue Atlas, which aims to provide a comprehensive molecular, cellular and anatomical map of the kidney. These ontologies will improve the annotation of kidney-relevant data, and eventually lead to new definitions of kidney disease in support of precision medicine.
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Affiliation(s)
- Edison Ong
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Lucy L Wang
- Allen Institute for Artificial Intelligence, Seattle, WA, USA
| | - Jennifer Schaub
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - John F O'Toole
- Department of Nephrology and Hypertension, Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, OH, USA
- Department of Inflammation and Immunity, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA
| | - Becky Steck
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Avi Z Rosenberg
- Department of Pathology, Johns Hopkins University, Baltimore, MD, USA
| | - Frederick Dowd
- UW Medicine Research IT, University of Washington, Seattle, WA, USA
| | - Jens Hansen
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Laura Barisoni
- Division of AI/Computational Pathology, Department of Pathology, and Division of Nephrology, Department of Medicine, Duke University, Durham, NC, USA
| | - Sanjay Jain
- Division of Nephrology, School of Medicine, Washington University in St. Louis, St Louis, MO, USA
| | - Ian H de Boer
- Division of Nephrology, Department of Medicine, University of Washington, Seattle, WA, USA
| | - M Todd Valerius
- Division of Renal Medicine, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA
| | - Sushrut S Waikar
- Section of Nephrology, Boston University Medical Center, Boston, MA, USA
| | - Christopher Park
- Kidney Research Institute, University of Washington, Seattle, WA, USA
| | - Dana C Crawford
- Department of Population and Quantitative Health Sciences, Case Western Reserve University, Cleveland, OH, USA
- Department of Genetics and Genome Sciences, School of Medicine, Case Western Reserve University, Cleveland, OH, USA
- Cleveland Institute for Computational Biology, Cleveland, OH, USA
| | - Theodore Alexandrov
- Structural and Computational Biology, European Molecular Biology Laboratory, Heidelberg, Germany
- Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, La Jolla, CA, USA
| | | | - Christian Stoeckert
- Department of Genetics, Perelman School of Medicine, University of Pennsylvania Philadelphia, Philadelphia, PA, USA
| | - Chunhua Weng
- Department of Biomedical Informatics, Columbia University, New York, NY, USA
| | - Alexander D Diehl
- Department of Biomedical Informatics, Jacobs School of Medicine and Biomedical Sciences, University at Buffalo, Buffalo, NY, USA
| | - Christopher J Mungall
- Environmental Genomics and Systems Biology, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | - Melissa Haendel
- Department of Environmental and Molecular Toxicology, Oregon State University, Corvallis, OR, USA
| | - Peter N Robinson
- The Jackson Laboratory for Genomic Medicine, Farmington, CT, USA
| | - Jonathan Himmelfarb
- Division of Nephrology, Department of Medicine, University of Washington, Seattle, WA, USA
- Kidney Research Institute, University of Washington, Seattle, WA, USA
| | - Ravi Iyengar
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA
- Institute for Systems Biomedicine, Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Matthias Kretzler
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA
- Division of Nephrology, Department of Internal Medicine, University of Michigan, Ann Arbor, MI, USA
| | - Sean Mooney
- Department of Biomedical Informatics and Medical Education, University of Washington, Seattle, WA, USA.
| | - Yongqun He
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI, USA.
- Unit for Laboratory Animal Medicine, University of Michigan Medical School, Ann Arbor, MI, USA.
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA.
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11
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Miller AK, Azhibekov T, O'Toole JF, Sedor JR, Williams SM, Redline RW, Bruggeman LA. Association of preeclampsia with infant APOL1 genotype in African Americans. BMC Med Genet 2020; 21:110. [PMID: 32434471 PMCID: PMC7238556 DOI: 10.1186/s12881-020-01048-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Accepted: 05/10/2020] [Indexed: 12/26/2022]
Abstract
Background Black women in the United States and Africa are at an increased risk for preeclampsia. Allelic variants in the gene for apolipoprotein LI, APOL1, are found only in populations of African ancestry, and have been shown to contribute significant risk for kidney disease. Recent studies suggest these APOL1 variants also may contribute risk for preeclampsia. Methods The association of preeclampsia with carriage of APOL1 risk alleles was evaluated in a case-control study of deliveries from black women at a single center in Cleveland, Ohio that included gross and histopathologic evaluations of placental tissues (395 cases and 282 controls). Using logistic regression models, associations between fetal APOL1 genotype and preeclampsia were evaluated using several case definitions based on prematurity and severity of preeclampsia, with uncomplicated term pregnancies as controls. Associations between APOL1 genotype and pathological features were also examined. Results The infant APOL1 genotype was significantly associated with preeclampsia in a dominant inheritance pattern with odds ratio of 1.41 (P=0.029, 95% CI 1.037, 1.926). Stratifying preeclampsia cases by preterm birth, significant associations were detected for both recessive (O.R.=1.70, P=0.038) and additive (O.R.=1.33, P=0.028) inheritance patterns. APOL1 genotype, however, was not significantly associated with pathological changes or other perinatal observations. Conclusions Preeclampsia appears to be another disease associated with APOL1 variants, however, further studies are needed to increase confidence in the mode of inheritance. By understanding the association of APOL1 variants with preeclampsia, genetic screening tests for APOL1 may be useful to predict at-risk pregnancies and targeted interventions may be developed to improve pregnancy outcomes.
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Affiliation(s)
- Anna K Miller
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, USA
| | - Timur Azhibekov
- Division of Neonatology, Department of Pediatrics, Metro Health Medical Center, Case Western Reserve University School of Medicine, Cleveland, USA
| | - John F O'Toole
- Departments of Inflammation and Immunity and Nephrology, Cleveland Clinic, Case Western Reserve University School of Medicine, Cleveland, USA
| | - John R Sedor
- Departments of Inflammation and Immunity and Nephrology, Cleveland Clinic, Case Western Reserve University School of Medicine, Cleveland, USA.,Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, USA
| | - Scott M Williams
- Department of Genetics and Genome Sciences, Case Western Reserve University School of Medicine, Cleveland, USA.,Department of Population and Quantitative Health Sciences, Case Western Reserve University School of Medicine, Cleveland, USA
| | - Raymond W Redline
- Departments of Pathology and Reproductive Biology, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, OH, USA
| | - Leslie A Bruggeman
- Departments of Inflammation and Immunity and Nephrology, Cleveland Clinic, Case Western Reserve University School of Medicine, Cleveland, USA.
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12
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Bruggeman LA, Wu Z, Luo L, Madhavan S, Drawz PE, Thomas DB, Barisoni L, O'Toole JF, Sedor JR. APOL1-G0 protects podocytes in a mouse model of HIV-associated nephropathy. PLoS One 2019; 14:e0224408. [PMID: 31661509 PMCID: PMC6818796 DOI: 10.1371/journal.pone.0224408] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 10/11/2019] [Indexed: 11/21/2022] Open
Abstract
African polymorphisms in the gene for Apolipoprotein L1 (APOL1) confer a survival advantage against lethal trypanosomiasis but also an increased risk for several chronic kidney diseases (CKD) including HIV-associated nephropathy (HIVAN). APOL1 is expressed in renal cells, however, the pathogenic events that lead to renal cell damage and kidney disease are not fully understood. The podocyte function of APOL1-G0 versus APOL1-G2 in the setting of a known disease stressor was assessed using transgenic mouse models. Transgene expression, survival, renal pathology and function, and podocyte density were assessed in an intercross of a mouse model of HIVAN (Tg26) with two mouse models that express either APOL1-G0 or APOL1-G2 in podocytes. Mice that expressed HIV genes developed heavy proteinuria and glomerulosclerosis, and had significant losses in podocyte numbers and reductions in podocyte densities. Mice that co-expressed APOL1-G0 and HIV had preserved podocyte numbers and densities, with fewer morphologic manifestations typical of HIVAN pathology. Podocyte losses and pathology in mice co-expressing APOL1-G2 and HIV were not significantly different from mice expressing only HIV. Podocyte hypertrophy, a known compensatory event to stress, was increased in the mice co-expressing HIV and APOL1-G0, but absent in the mice co-expressing HIV and APOL1-G2. Mortality and renal function tests were not significantly different between groups. APOL1-G0 expressed in podocytes may have a protective function against podocyte loss or injury when exposed to an environmental stressor. This was absent with APOL1-G2 expression, suggesting APOL1-G2 may have lost this protective function.
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Affiliation(s)
- Leslie A. Bruggeman
- Departments of Inflammation & Immunity and Nephrology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
- * E-mail:
| | - Zhenzhen Wu
- Departments of Inflammation & Immunity and Nephrology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Liping Luo
- Departments of Inflammation & Immunity and Nephrology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - Sethu Madhavan
- Department of Medicine, Ohio State University, Columbus, Ohio, United States of America
| | - Paul E. Drawz
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota, United States of America
| | - David B. Thomas
- Departments of Pathology, University of Miami, Miami, Florida, United States of America
| | - Laura Barisoni
- Departments of Pathology and Medicine, Duke University, Durham, North Carolina, United States of America
| | - John F. O'Toole
- Departments of Inflammation & Immunity and Nephrology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
| | - John R. Sedor
- Departments of Inflammation & Immunity and Nephrology, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Case Western Reserve University, Cleveland, Ohio, United States of America
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13
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Abstract
The mechanism that explains the association of APOL1 variants with nondiabetic kidney diseases in African Americans remains unclear. Kidney disease risk is inherited as a recessive trait, and many studies investigating the intracellular function of APOL1 have indicated the APOL1 variants G1 and G2 are associated with cytotoxicity. Whether cytotoxicity results from the absence of a protective effect conferred by the G0 allele or is induced by a deleterious effect of variant allele expression has not be conclusively established. A central issue hampering basic biology studies is the lack of model systems that authentically replicate APOL1 expression patterns. APOL1 is present in humans and a few other primates and appears to have important functions in the kidney, as the kidney is the primary target for disease associated with the genetic variance. There have been no studies to date assessing the function of untagged APOL1 protein under native expression in human or primate kidney cells, and no studies have examined the heterozygous state, a disease-free condition in humans. A second major issue is the chronic kidney disease (CKD)-associated APOL1 variants are conditional mutations, where the disease-inducing function is only evident under the appropriate environmental stimulus. In addition, it is possible there may be more than one mechanism of pathogenesis that is dependent on the nature of the stressor or other genetic variabilities. Studies addressing the function of APOL1 and how the CKD-associated APOL1 variants cause kidney disease are challenging and remain to be fully investigated under conditions that faithfully model known human genetics and physiology.
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Affiliation(s)
- Leslie A Bruggeman
- Department of Inflammation and Immunity, Cleveland Clinic , Cleveland, Ohio.,Department of Nephrology, Cleveland Clinic , Cleveland, Ohio
| | - John F O'Toole
- Department of Inflammation and Immunity, Cleveland Clinic , Cleveland, Ohio.,Department of Nephrology, Cleveland Clinic , Cleveland, Ohio
| | - John R Sedor
- Department of Inflammation and Immunity, Cleveland Clinic , Cleveland, Ohio.,Department of Nephrology, Cleveland Clinic , Cleveland, Ohio.,Department of Physiology and Biophysics, Case Western Reserve University School of Medicine , Cleveland, Ohio
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14
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O'Toole JF, Sedor JR. CKD, Genetic Variation, and the Epigenome: Decrypting the Code. Am J Kidney Dis 2018; 72:164-167. [PMID: 29728315 DOI: 10.1053/j.ajkd.2018.03.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 03/06/2018] [Indexed: 11/11/2022]
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15
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O'Toole JF, Schilling W, Kunze D, Madhavan SM, Konieczkowski M, Gu Y, Luo L, Wu Z, Bruggeman LA, Sedor JR. ApoL1 Overexpression Drives Variant-Independent Cytotoxicity. J Am Soc Nephrol 2017; 29:869-879. [PMID: 29180397 DOI: 10.1681/asn.2016121322] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 10/31/2017] [Indexed: 12/16/2022] Open
Abstract
Coding variants in the APOL1 gene are associated with kidney diseases in African ancestral populations; yet, the underlying biologic mechanisms remain uncertain. Variant-dependent autophagic and cytotoxic cell death have been proposed as pathogenic pathways mediating kidney injury. To examine this possibility, we conditionally expressed APOL1-G0 (reference), -G1, and -G2 (variants) using a tetracycline-regulated system in HEK293 cells. Autophagy was monitored biochemically and cell death was measured using multiple assays. We measured intracellular Na+ and K+ content with atomic absorption spectroscopy and APOL1-dependent currents with whole-cell patch clamping. Neither reference nor variant APOL1s induced autophagy. At high expression levels, APOL1-G0, -G1, and -G2 inserted into the plasma membrane and formed pH-sensitive cation channels, causing collapse of cellular Na+ and K+ gradients, phosphorylation of p38 mitogen-activated protein kinase, and cell death, without variant-dependent differences. APOL1-G0 and -G2 exhibited similar channel properties in whole-cell patch clamp experiments. At low expression levels, neither reference nor variant APOL1s localized on the plasma membrane, Na+ and K+ gradients were maintained, and cells remained viable. Our results indicate that APOL1-mediated pore formation is critical for the trypanolytic activity of APOL1 and drives APOL1-mediated cytotoxicity in overexpression systems. The absence of cytotoxicity at physiologic expression levels suggests variant-dependent intracellular K+ loss and cytotoxicity does not drive kidney disease progression.
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Affiliation(s)
- John F O'Toole
- Department of Nephrology and Hypertension, Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, Ohio.,Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio; and
| | - William Schilling
- Rammelkamp Center, MetroHealth System.,Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | | | | | | | - Yaping Gu
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - Liping Luo
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - Zhenzhen Wu
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - Leslie A Bruggeman
- Department of Nephrology and Hypertension, Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, Ohio.,Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio; and
| | - John R Sedor
- Department of Nephrology and Hypertension, Glickman Urological and Kidney Institute, Cleveland Clinic, Cleveland, Ohio.,Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio.,Department of Molecular Medicine, Cleveland Clinic Lerner College of Medicine, Case Western Reserve University, Cleveland, Ohio; and.,Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
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16
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Affiliation(s)
- John F O'Toole
- Department of Nephrology and Hypertension, Glickman Urological and Kidney Institute and
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - Leslie A Bruggeman
- Department of Nephrology and Hypertension, Glickman Urological and Kidney Institute and
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
| | - John R Sedor
- Department of Nephrology and Hypertension, Glickman Urological and Kidney Institute and
- Department of Pathobiology, Lerner Research Institute, Cleveland Clinic, Cleveland, Ohio
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17
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Madhavan SM, O'Toole JF, Konieczkowski M, Barisoni L, Thomas DB, Ganesan S, Bruggeman LA, Buck M, Sedor JR. APOL1 variants change C-terminal conformational dynamics and binding to SNARE protein VAMP8. JCI Insight 2017; 2:92581. [PMID: 28724794 DOI: 10.1172/jci.insight.92581] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 06/13/2017] [Indexed: 12/11/2022] Open
Abstract
APOL1 variants in African populations mediate resistance to trypanosomal infection but increase risk for kidney diseases through unknown mechanisms. APOL1 is expressed in glomerular podocytes and does not vary with underlying kidney disease diagnoses or APOL1 genotypes, suggesting that the kidney disease-associated variants dysregulate its function rather than its localization or abundance. Structural homology searches identified vesicle-associated membrane protein 8 (VAMP8) as an APOL1 protein interactor. VAMP8 colocalizes with APOL1 in the podocyte, and the APOL1:VAMP8 interaction was confirmed biochemically and with surface plasmon resonance. APOL1 variants attenuate this interaction. Computational modeling of APOL1's 3-dimensional structure, followed by molecular dynamics simulations, revealed increased motion of the C-terminal domain of reference APOL1 compared with either variant, suggesting that the variants stabilize a closed or autoinhibited state that diminishes protein interactions with VAMP8. Changes in ellipticity with increasing urea concentrations, as assessed by circular dichroism spectroscopy, showed higher conformational stability of the C-terminal helix of the variants compared with the reference protein. These results suggest that reference APOL1 interacts with VAMP8-coated vesicles, a process attenuated by variant-induced reduction in local dynamics of the C-terminal. Disordered vesicular trafficking in the podocyte may cause injury and progressive chronic kidney diseases in susceptible African Americans subjects.
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Affiliation(s)
- Sethu M Madhavan
- Department of Medicine and Rammelkamp Center for Education and Research, MetroHealth System Campus, and
| | - John F O'Toole
- Department of Medicine and Rammelkamp Center for Education and Research, MetroHealth System Campus, and
| | - Martha Konieczkowski
- Department of Medicine and Rammelkamp Center for Education and Research, MetroHealth System Campus, and
| | - Laura Barisoni
- Department of Pathology, University of Miami, Miami, Florida, USA
| | - David B Thomas
- Department of Pathology, University of Miami, Miami, Florida, USA
| | | | - Leslie A Bruggeman
- Department of Medicine and Rammelkamp Center for Education and Research, MetroHealth System Campus, and
| | - Matthias Buck
- Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - John R Sedor
- Department of Medicine and Rammelkamp Center for Education and Research, MetroHealth System Campus, and.,Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
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18
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Affiliation(s)
| | | | - John R Sedor
- Department of Medicine, MetroHealth Medical Center and.,Department of Physiology, Case Western Reserve University School of Medicine, Cleveland, Ohio
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19
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Bruggeman LA, Wu Z, Luo L, Madhavan SM, Konieczkowski M, Drawz PE, Thomas DB, Barisoni L, Sedor JR, O'Toole JF. APOL1-G0 or APOL1-G2 Transgenic Models Develop Preeclampsia but Not Kidney Disease. J Am Soc Nephrol 2016; 27:3600-3610. [PMID: 27026370 DOI: 10.1681/asn.2015111220] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 02/15/2016] [Indexed: 11/03/2022] Open
Abstract
APOL1 risk variants are associated with kidney disease in blacks, but the mechanisms of renal injury associated with APOL1 risk variants are unknown. Because APOL1 is unique to humans and some primates, we created transgenic (Tg) mice using the promoter of nephrin-encoding Nphs1 to express the APOL1 reference sequence (G0) or the G2 risk variant in podocytes, establishing Tg lines with a spectrum of APOL1 expression levels. Podocytes from Tg-G0 and Tg-G2 mice did not undergo necrosis, apoptosis, or autophagic cell death in vivo, even in lines with highly expressed transgenes. Further, Tg-G0 and Tg-G2 mice did not develop kidney pathology, proteinuria, or azotemia as of 300 days of age. However, by 200 days of age, Tg-G2 mice had significantly lower podocyte density than age-matched WT and Tg-G0 mice had, a difference that was not evident at weaning. Notably, a pregnancy-associated phenotype that encompassed eclampsia, preeclampsia, fetal/neonatal deaths, and small litter sizes occurred in some Tg-G0 mice and more severely in Tg-G2 mice. Similar to human placenta, placentas of Tg mice expressed APOL1. Overall, these results suggest podocyte depletion could predispose individuals with APOL1 risk genotypes to kidney disease in response to a second stressor, and add to other published evidence associating APOL1 expression with preeclampsia.
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Affiliation(s)
- Leslie A Bruggeman
- Division of Nephrology, Department of Medicine, MetroHealth Medical Center and
| | - Zhenzhen Wu
- Division of Nephrology, Department of Medicine, MetroHealth Medical Center and
| | - Liping Luo
- Division of Nephrology, Department of Medicine, MetroHealth Medical Center and
| | - Sethu M Madhavan
- Division of Nephrology, Department of Medicine, MetroHealth Medical Center and
| | | | - Paul E Drawz
- Department of Medicine, University of Minnesota, Minneapolis, Minnesota; and
| | - David B Thomas
- Department of Pathology, University of Miami, Miami, Florida
| | - Laura Barisoni
- Department of Pathology, University of Miami, Miami, Florida
| | - John R Sedor
- Division of Nephrology, Department of Medicine, MetroHealth Medical Center and.,Department of Physiology and Biophysics, Case Western Reserve University School of Medicine, Cleveland, Ohio
| | - John F O'Toole
- Division of Nephrology, Department of Medicine, MetroHealth Medical Center and
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20
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Sampson MG, Robertson CC, Martini S, Mariani LH, Lemley KV, Gillies CE, Otto EA, Kopp JB, Randolph A, Vega-Warner V, Eichinger F, Nair V, Gipson DS, Cattran DC, Johnstone DB, O'Toole JF, Bagnasco SM, Song PX, Barisoni L, Troost JP, Kretzler M, Sedor JR. Integrative Genomics Identifies Novel Associations with APOL1 Risk Genotypes in Black NEPTUNE Subjects. J Am Soc Nephrol 2015; 27:814-23. [PMID: 26150607 DOI: 10.1681/asn.2014111131] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 05/31/2015] [Indexed: 01/13/2023] Open
Abstract
APOL1 variants have been associated with renal phenotypes in blacks. To refine clinical outcomes and discover mechanisms of APOL1-associated kidney injury, we analyzed clinical and genomic datasets derived from 90 black subjects in the Nephrotic Syndrome Study Network (NEPTUNE), stratified by APOL1 risk genotype. Ninety subjects with proteinuria ≥0.5 g/d were enrolled at first biopsy for primary nephrotic syndrome and followed. Clinical outcomes were determined, and renal histomorphometry and sequencing of Mendelian nephrotic syndrome genes were performed. APOL1 variants were genotyped, and glomerular and tubulointerstitial transcriptomes from protocol renal biopsy cores were analyzed for differential and correlative gene expression. Analyses were performed under the recessive model (high-risk genotype defined by two risk alleles). APOL1 high-risk genotype was significantly associated with a 17 ml/min per 1.73 m(2) lower eGFR and a 69% reduction in the probability of complete remission at any time, independent of histologic diagnosis. Neither APOL1 risk group was enriched for Mendelian mutations. On renal biopsy, high-risk genotype was associated with increased fractional interstitial area, interstitial fibrosis, and tubular atrophy. Risk genotype was not associated with intrarenal APOL1 mRNA expression levels. Differential expression analysis demonstrated an increased steady-state level of five genes associated with the high-risk genotype (CXCL9, CXCL11, and UBD in glomerulus; SNOR14B and MUC13 in tubulointerstitium). APOL1 tubulointerstitial coexpression analysis showed coexpression of APOL1 mRNA levels with a group of intrarenal transcripts that together were associated with increased interstitial fibrosis and tubular atrophy. These data indicate the high-risk APOL1 genotype confers renal risk across histopathologic diagnoses.
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Affiliation(s)
- Matthew G Sampson
- Division of Nephrology, Department of Pediatrics and Communicable Diseases,
| | | | - Sebastian Martini
- Division of Nephrology, Departments of Internal Medicine and Computational Medicine and Bioinformatics, and
| | - Laura H Mariani
- Division of Nephrology, Departments of Internal Medicine and Computational Medicine and Bioinformatics, and
| | - Kevin V Lemley
- Division of Nephrology, Department of Pediatrics, Children's Hospital of Los Angeles, University of Southern California School of Medicine, Los Angeles, California
| | | | - Edgar A Otto
- Division of Nephrology, Department of Pediatrics and Communicable Diseases
| | - Jeffrey B Kopp
- Kidney Diseases Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland
| | - Anne Randolph
- Division of Nephrology, Departments of Internal Medicine and Computational Medicine and Bioinformatics, and
| | | | - Felix Eichinger
- Division of Nephrology, Departments of Internal Medicine and Computational Medicine and Bioinformatics, and
| | - Viji Nair
- Division of Nephrology, Departments of Internal Medicine and Computational Medicine and Bioinformatics, and
| | - Debbie S Gipson
- Division of Nephrology, Department of Pediatrics and Communicable Diseases
| | - Daniel C Cattran
- Department of Nephrology, University Health Network, University of Toronto, Toronto, Ontario, Canada
| | - Duncan B Johnstone
- Division of Nephrology, Department of Internal Medicine, Temple University School of Medicine, Philadelphia, Pennsylvania
| | - John F O'Toole
- Division of Nephrology, Department of Internal Medicine and
| | - Serena M Bagnasco
- Department of Pathology, Johns Hopkins School of Medicine, Baltimore, Maryland
| | - Peter X Song
- Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, Michigan; and
| | - Laura Barisoni
- Department of Pathology, University of Miami, Miller School of Medicine, Miami, Florida
| | - Jonathan P Troost
- Division of Nephrology, Department of Pediatrics and Communicable Diseases
| | - Matthias Kretzler
- Division of Nephrology, Departments of Internal Medicine and Computational Medicine and Bioinformatics, and Department of Computational Medicine and Bioinformatics, University of Michigan School of Medicine, Ann Arbor, Michigan
| | - John R Sedor
- Division of Nephrology, Department of Internal Medicine and Department of Physiology and Biophysics, Case Western Reserve University and Rammelkamp Center for Education and Research, MetroHealth System, Cleveland, Ohio
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21
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Madhavan SM, O'Toole JF. The biology of APOL1 with insights into the association between APOL1 variants and chronic kidney disease. Clin Exp Nephrol 2014; 18:238-42. [PMID: 24233469 DOI: 10.1007/s10157-013-0907-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 10/29/2013] [Indexed: 12/15/2022]
Abstract
Recent studies have identified genetic variants in APOL1 that may contribute to the increased incidence of kidney disease in populations with African ancestry. Here, we review the biology of APOL1 present in the circulation and localized to the kidney as it may contribute to the pathogenesis of APOL1-associated kidney disease.
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Abstract
Kidney disease is one of the most prevalent chronic conditions and is a frequent complication of diabetes, cardiovascular disease, and obesity. Recent advances in biomedical research and novel technologies have created opportunities to study kidney disease in a variety of platforms, applied to human populations. The Reviews in this series discuss the kidney in hypertension, diabetes, and monogenic forms of kidney disease, as well as the cellular and molecular mediators of acute kidney injury and fibrosis, IgA nephropathy and idiopathic membranous nephropathy, and kidney transplantation. In this introduction, we briefly review new insights into focal segmental glomerulosclerosis and the role of podocytes in health and disease. Additionally, we discuss how new technologies, therapeutics, and the availability of patient data can help shape the study of kidney disease and ultimately inform policies concerning biomedical research and health care.
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23
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Abstract
Mitochondrial diseases can be related to mutations in either the nuclear or mitochondrial genome. Childhood presentations are commonly associated with renal tubular dysfunction, but renal involvement is less commonly reported outside of this age-group. Mitochondrial diseases are notable for the significant variability in their clinical presentation and the broad spectrum of genes implicated in their etiology. These features contribute to the challenges of establishing a definitive diagnosis and understanding the pathogenetic mechanisms leading to kidney involvement in these diseases. Here, we review the deoxyribonucleic acid variants in the mitochondrial and nuclear genomes that have been associated with a kidney phenotype, and examine some of the possible pathogenic mechanisms that may contribute to the expression of a renal phenotype.
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Affiliation(s)
- John F O'Toole
- Department of Internal Medicine, Division of Nephrology, MetroHealth Medical System, Case Western Reserve University School of Medicine, Cleveland, OH, USA
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Bruggeman LA, O'Toole JF, Ross MD, Madhavan SM, Smurzynski M, Wu K, Bosch RJ, Gupta S, Pollak MR, Sedor JR, Kalayjian RC. Plasma apolipoprotein L1 levels do not correlate with CKD. J Am Soc Nephrol 2013; 25:634-44. [PMID: 24231663 DOI: 10.1681/asn.2013070700] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Polymorphisms in APOL1 are associated with CKD, including HIV-related CKD, in individuals of African ancestry. The apolipoprotein L1 (APOL1) protein circulates and is localized in kidney cells, but the contribution of APOL1 location to CKD pathogenesis is unclear. We examined associations of plasma APOL1 levels with plasma cytokine levels, dyslipidemia, and APOL1 genotype in a nested case-control study (n=270) of HIV-infected African Americans enrolled in a multicenter prospective observational study. Patients were designated as having CKD when estimated GFR (eGFR) decreased to <60 ml/min per 1.73 m(2) (eGFR<60 cohort) or protein-to-creatinine ratios became >3.5 g/g (nephrotic proteinuria cohort). Circulating APOL1 levels did not associate with APOL1 genotype, CKD status, or levels of proinflammatory cytokines, but did correlate with fasting cholesterol, LDL cholesterol, and triglyceride levels. At ascertainment, CKD-associated polymorphisms (risk variants) in APOL1 associated with the eGFR<60 cohort, but not the nephrotic-range proteinuria cohort. Of note, in both the eGFR<60 and nephrotic proteinuria cohorts, CKD cases with two APOL1 risk variants had significant declines in eGFR over a median of 4 years compared with individuals with one or no risk variants. APOL1 risk genotype was not associated with changes in proteinuria. Higher circulating proinflammatory cytokine levels were independently associated with CKD but not APOL1 genotype. In conclusion, the function of variant APOL1 proteins derived from circulation or synthesized in the kidney, but not the level of circulating APOL1, probably mediates APOL1-associated kidney disease in HIV-infected African Americans.
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Stames EM, O'Toole JF. Mitochondrial aminopeptidase deletion increases chronological lifespan and oxidative stress resistance while decreasing respiratory metabolism in S. cerevisiae. PLoS One 2013; 8:e77234. [PMID: 24116217 PMCID: PMC3792884 DOI: 10.1371/journal.pone.0077234] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2012] [Accepted: 09/05/2013] [Indexed: 12/15/2022] Open
Abstract
Recessive mutations in XPNPEP3, encoding a mitochondrial x-prolyl aminopeptidase, have been identified in families with a rare hereditary tubulointerstitial kidney disease. The yeast ortholog of XPNPEP3, Icp55p, participates in the proteolytic processing and stabilization of mitochondrial proteins and its deletion accelerates the degradation of its protein targets. We used icp55 deletion strains of S. cerevisiae to model loss of XPNPEP3 enzymatic function and study its phenotypic consequences on mitochondrial function. We found that Icp55p is not required for respiratory competence; however, compared to controls deletion strains had reduced mitochondrial oxygen consumption when grown in glucose containing media. The reduced mitochondrial respiration of icp55 deletion strains in glucose media requires the mitochondrial peptide transporter, Mdl1p, and was corrected by Tor1p inhibition with rapamycin. Under similar growth conditions the abundance of the mitochondrial ATP synthase complex was decreased in the icp55 deletion strain and was corrected by concurrent deletion of tor1. The icp55 deletion strain demonstrated an increased chronological lifespan and decreased reactive oxygen species. These changes were additive to similar changes known to occur in tor1 deletion strains suggesting independent mechanisms. Together, these results demonstrate that loss of Icp55p function reduces mitochondrial oxygen consumption and ATP synthase complex assembly in glucose media, while also promoting stress resistance, decreasing reactive oxygen species and increasing chronological lifespan through mechanisms that are distinct from decreased Tor1p activity.
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Affiliation(s)
- Erine M. Stames
- Department of Medicine, Division of Nephrology MetroHealth Medical System and Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
| | - John F. O'Toole
- Department of Medicine, Division of Nephrology MetroHealth Medical System and Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America
- * E-mail:
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Chaki M, Airik R, Ghosh AK, Giles RH, Chen R, Slaats GG, Wang H, Hurd TW, Zhou W, Cluckey A, Gee HY, Ramaswami G, Hong CJ, Hamilton BA, Cervenka I, Ganji RS, Bryja V, Arts HH, van Reeuwijk J, Oud MM, Letteboer SJF, Roepman R, Husson H, Ibraghimov-Beskrovnaya O, Yasunaga T, Walz G, Eley L, Sayer JA, Schermer B, Liebau MC, Benzing T, Le Corre S, Drummond I, Janssen S, Allen SJ, Natarajan S, O'Toole JF, Attanasio M, Saunier S, Antignac C, Koenekoop RK, Ren H, Lopez I, Nayir A, Stoetzel C, Dollfus H, Massoudi R, Gleeson JG, Andreoli SP, Doherty DG, Lindstrad A, Golzio C, Katsanis N, Pape L, Abboud EB, Al-Rajhi AA, Lewis RA, Omran H, Lee EYHP, Wang S, Sekiguchi JM, Saunders R, Johnson CA, Garner E, Vanselow K, Andersen JS, Shlomai J, Nurnberg G, Nurnberg P, Levy S, Smogorzewska A, Otto EA, Hildebrandt F. Exome capture reveals ZNF423 and CEP164 mutations, linking renal ciliopathies to DNA damage response signaling. Cell 2012; 150:533-48. [PMID: 22863007 DOI: 10.1016/j.cell.2012.06.028] [Citation(s) in RCA: 287] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Revised: 02/01/2012] [Accepted: 06/25/2012] [Indexed: 01/03/2023]
Abstract
Nephronophthisis-related ciliopathies (NPHP-RC) are degenerative recessive diseases that affect kidney, retina, and brain. Genetic defects in NPHP gene products that localize to cilia and centrosomes defined them as "ciliopathies." However, disease mechanisms remain poorly understood. Here, we identify by whole-exome resequencing, mutations of MRE11, ZNF423, and CEP164 as causing NPHP-RC. All three genes function within the DNA damage response (DDR) pathway. We demonstrate that, upon induced DNA damage, the NPHP-RC proteins ZNF423, CEP164, and NPHP10 colocalize to nuclear foci positive for TIP60, known to activate ATM at sites of DNA damage. We show that knockdown of CEP164 or ZNF423 causes sensitivity to DNA damaging agents and that cep164 knockdown in zebrafish results in dysregulated DDR and an NPHP-RC phenotype. Our findings link degenerative diseases of the kidney and retina, disorders of increasing prevalence, to mechanisms of DDR.
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Affiliation(s)
- Moumita Chaki
- Department of Pediatrics and Communicable Diseases, University of Michigan, Ann Arbor, MI 48109, USA
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Madhavan SM, O'Toole JF, Konieczkowski M, Ganesan S, Bruggeman LA, Sedor JR. APOL1 localization in normal kidney and nondiabetic kidney disease. J Am Soc Nephrol 2011; 22:2119-28. [PMID: 21997392 DOI: 10.1681/asn.2011010069] [Citation(s) in RCA: 190] [Impact Index Per Article: 14.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In patients of African ancestry, genetic variants in APOL1, which encodes apolipoprotein L1, associate with the nondiabetic kidney diseases, focal segmental glomerulosclerosis (FSGS), HIV-associated nephropathy (HIVAN), and hypertensive nephropathy. Understanding the renal localization of APOL1 may provide clues that will ultimately help elucidate the mechanisms by which APOL1 variants promote nephropathy. Here, we used immunohistology to examine APOL1 localization in normal human kidney sections and in biopsies demonstrating either FSGS (n = 8) or HIVAN (n = 2). Within normal glomeruli, APOL1 only localized to podocytes. Compared with normal glomeruli, fewer cells stained for APOL1 in FSGS and HIVAN glomeruli, even when expression of the podocyte markers GLEPP1 and synaptopodin appeared normal. APOL1 localized to proximal tubular epithelia in normal kidneys, FSGS, and HIVAN. We detected APOL1 in the arteriolar endothelium of normal and diseased kidney sections. Unexpectedly, in both FSGS and HIVAN but not normal kidneys, the media of medium artery and arterioles contained a subset of α-smooth muscle actin-positive cells that stained for APOL1. Comparing the renal distribution of APOL1 in nondiabetic kidney disease to normal kidney suggests that a previously unrecognized arteriopathy may contribute to disease pathogenesis in patients of African ancestry.
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Affiliation(s)
- Sethu M Madhavan
- Department of Medicine and the Rammel kamp Center for Education and Research, Metro Health System Campus, Cleveland, Ohio, USA
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Sang L, Miller JJ, Corbit KC, Giles RH, Brauer MJ, Otto EA, Baye LM, Wen X, Scales SJ, Kwong M, Huntzicker EG, Sfakianos MK, Sandoval W, Bazan JF, Kulkarni P, Garcia-Gonzalo FR, Seol AD, O'Toole JF, Held S, Reutter HM, Lane WS, Rafiq MA, Noor A, Ansar M, Devi ARR, Sheffield VC, Slusarski DC, Vincent JB, Doherty DA, Hildebrandt F, Reiter JF, Jackson PK. Mapping the NPHP-JBTS-MKS protein network reveals ciliopathy disease genes and pathways. Cell 2011; 145:513-28. [PMID: 21565611 DOI: 10.1016/j.cell.2011.04.019] [Citation(s) in RCA: 454] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 03/16/2011] [Accepted: 04/27/2011] [Indexed: 12/18/2022]
Abstract
Nephronophthisis (NPHP), Joubert (JBTS), and Meckel-Gruber (MKS) syndromes are autosomal-recessive ciliopathies presenting with cystic kidneys, retinal degeneration, and cerebellar/neural tube malformation. Whether defects in kidney, retinal, or neural disease primarily involve ciliary, Hedgehog, or cell polarity pathways remains unclear. Using high-confidence proteomics, we identified 850 interactors copurifying with nine NPHP/JBTS/MKS proteins and discovered three connected modules: "NPHP1-4-8" functioning at the apical surface, "NPHP5-6" at centrosomes, and "MKS" linked to Hedgehog signaling. Assays for ciliogenesis and epithelial morphogenesis in 3D renal cultures link renal cystic disease to apical organization defects, whereas ciliary and Hedgehog pathway defects lead to retinal or neural deficits. Using 38 interactors as candidates, linkage and sequencing analysis of 250 patients identified ATXN10 and TCTN2 as new NPHP-JBTS genes, and our Tctn2 mouse knockout shows neural tube and Hedgehog signaling defects. Our study further illustrates the power of linking proteomic networks and human genetics to uncover critical disease pathways.
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Affiliation(s)
- Liyun Sang
- Genentech Inc., South San Francisco, CA 94080, USA
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Abstract
The genetic contribution to calcium metabolism is well recognized. Many of the proteins that contribute to calcium homeostasis through intestinal absorption, bone deposition and resorption, renal reabsorption and the molecules regulating these processes have been identified. Mutations in many of the genes coding for these proteins have been identified and often have clear clinical phenotypes. These mutations are generally rare with large effect sizes and a high degree of penetrance. As monogenetic diseases, they have a mendelian inheritance pattern and have been identified with traditional family-based linkage studies. A great deal of progress has been made in the understanding of the physiology of calcium metabolism; however, it remains an evolving field. The identification of the monogenetic etiology of disease has contributed greatly to our understanding of calcium handling and homeostasis. Transgenic animal models of these diseases continue to offer new insights into the mechanisms of calcium metabolism and its regulation. The purpose of this review is to briefly outline calcium metabolism focusing on the mechanisms of intestinal absorption and renal reabsorption as a framework to review the monogenic causes of dysregulated calcium metabolism.
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Affiliation(s)
- John F O'Toole
- Division of Nephrology, Department of Internal Medicine, MetroHealth Medical Center, and Case Western Reserve University School of Medicine, Cleveland, Ohio 44109-1998, USA.
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O'Toole JF, Liu Y, Davis EE, Westlake CJ, Attanasio M, Otto EA, Seelow D, Nurnberg G, Becker C, Nuutinen M, Kärppä M, Ignatius J, Uusimaa J, Pakanen S, Jaakkola E, van den Heuvel LP, Fehrenbach H, Wiggins R, Goyal M, Zhou W, Wolf MTF, Wise E, Helou J, Allen SJ, Murga-Zamalloa CA, Ashraf S, Chaki M, Heeringa S, Chernin G, Hoskins BE, Chaib H, Gleeson J, Kusakabe T, Suzuki T, Isaac RE, Quarmby LM, Tennant B, Fujioka H, Tuominen H, Hassinen I, Lohi H, van Houten JL, Rotig A, Sayer JA, Rolinski B, Freisinger P, Madhavan SM, Herzer M, Madignier F, Prokisch H, Nurnberg P, Jackson PK, Jackson P, Khanna H, Katsanis N, Hildebrandt F. Individuals with mutations in XPNPEP3, which encodes a mitochondrial protein, develop a nephronophthisis-like nephropathy. J Clin Invest 2010; 120:791-802. [PMID: 20179356 DOI: 10.1172/jci40076] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Accepted: 01/06/2010] [Indexed: 01/06/2023] Open
Abstract
The autosomal recessive kidney disease nephronophthisis (NPHP) constitutes the most frequent genetic cause of terminal renal failure in the first 3 decades of life. Ten causative genes (NPHP1-NPHP9 and NPHP11), whose products localize to the primary cilia-centrosome complex, support the unifying concept that cystic kidney diseases are "ciliopathies". Using genome-wide homozygosity mapping, we report here what we believe to be a new locus (NPHP-like 1 [NPHPL1]) for an NPHP-like nephropathy. In 2 families with an NPHP-like phenotype, we detected homozygous frameshift and splice-site mutations, respectively, in the X-prolyl aminopeptidase 3 (XPNPEP3) gene. In contrast to all known NPHP proteins, XPNPEP3 localizes to mitochondria of renal cells. However, in vivo analyses also revealed a likely cilia-related function; suppression of zebrafish xpnpep3 phenocopied the developmental phenotypes of ciliopathy morphants, and this effect was rescued by human XPNPEP3 that was devoid of a mitochondrial localization signal. Consistent with a role for XPNPEP3 in ciliary function, several ciliary cystogenic proteins were found to be XPNPEP3 substrates, for which resistance to N-terminal proline cleavage resulted in attenuated protein function in vivo in zebrafish. Our data highlight an emerging link between mitochondria and ciliary dysfunction, and suggest that further understanding the enzymatic activity and substrates of XPNPEP3 will illuminate novel cystogenic pathways.
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Affiliation(s)
- John F O'Toole
- Department of Pediatrics, University of Michigan, Ann Arbor, 48109-5646, USA
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32
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Louie CM, Caridi G, Lopes VS, Brancati F, Kispert A, Lancaster MA, Schlossman AM, Otto EA, Leitges M, Gröne HJ, Lopez I, Gudiseva HV, O'Toole JF, Vallespin E, Ayyagari R, Ayuso C, Cremers FPM, den Hollander AI, Koenekoop RK, Dallapiccola B, Ghiggeri GM, Hildebrandt F, Valente EM, Williams DS, Gleeson JG. AHI1 is required for photoreceptor outer segment development and is a modifier for retinal degeneration in nephronophthisis. Nat Genet 2010; 42:175-80. [PMID: 20081859 PMCID: PMC2884967 DOI: 10.1038/ng.519] [Citation(s) in RCA: 143] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2009] [Accepted: 12/03/2009] [Indexed: 12/13/2022]
Abstract
Photoreceptor degeneration is a common feature of ciliopathies, owing to the importance of the highly specialized ciliary structure of these cells. Absence of AHI1, which encodes a cilium-localized protein, has been shown to cause a form of Joubert syndrome highly penetrant for retinal degeneration1,2. We show that Ahi1 knockout mice fail to form outer segments (OS), and show abnormal distribution of opsin throughout photoreceptors. Apoptotic cell death occurs rapidly between 2-4 weeks of age and is significantly delayed by reduced dosage of opsin. This phenotype also displays dosage-sensitive genetic interactions with Nphp1, another ciliopathy gene. Although not a primary cause of retinal blindness in humans, an allele of AHI1 modifies the relative risk of retinal degeneration greater than 7 fold within a nephronophthisis cohort. Our data support context-specific roles for AHI1 as a contributor to retinopathy and may explain a proportion of the variability of retinal phenotypes observed in nephronophthisis.
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Affiliation(s)
- Carrie M Louie
- Howard Hughes Medical Institute, Department of Pediatrics, University of California, San Diego, La Jolla, USA
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Hildebrandt F, Heeringa SF, Rüschendorf F, Attanasio M, Nürnberg G, Becker C, Seelow D, Huebner N, Chernin G, Vlangos CN, Zhou W, O'Toole JF, Hoskins BE, Wolf MTF, Hinkes BG, Chaib H, Ashraf S, Schoeb DS, Ovunc B, Allen SJ, Vega-Warner V, Wise E, Harville HM, Lyons RH, Washburn J, MacDonald J, Nürnberg P, Otto EA. A systematic approach to mapping recessive disease genes in individuals from outbred populations. PLoS Genet 2009; 5:e1000353. [PMID: 19165332 PMCID: PMC2621355 DOI: 10.1371/journal.pgen.1000353] [Citation(s) in RCA: 132] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2008] [Accepted: 12/22/2008] [Indexed: 12/29/2022] Open
Abstract
The identification of recessive disease-causing genes by homozygosity mapping is often restricted by lack of suitable consanguineous families. To overcome these limitations, we apply homozygosity mapping to single affected individuals from outbred populations. In 72 individuals of 54 kindred ascertained worldwide with known homozygous mutations in 13 different recessive disease genes, we performed total genome homozygosity mapping using 250,000 SNP arrays. Likelihood ratio Z-scores (ZLR) were plotted across the genome to detect ZLR peaks that reflect segments of homozygosity by descent, which may harbor the mutated gene. In 93% of cases, the causative gene was positioned within a consistent ZLR peak of homozygosity. The number of peaks reflected the degree of inbreeding. We demonstrate that disease-causing homozygous mutations can be detected in single cases from outbred populations within a single ZLR peak of homozygosity as short as 2 Mb, containing an average of only 16 candidate genes. As many specialty clinics have access to cohorts of individuals from outbred populations, and as our approach will result in smaller genetic candidate regions, the new strategy of homozygosity mapping in single outbred individuals will strongly accelerate the discovery of novel recessive disease genes. Many childhood diseases are caused by single-gene mutations of recessive genes, in which a child has inherited one mutated gene copy from each parent causing disease in the child, but not in the parents who are healthy heterozygous carriers. As the two mutations represent the disease cause, gene mapping helped understand disease mechanisms. “Homozygosity mapping” has been particularly useful. It assumes that the parents are related and that a disease-causing mutation together with a chromosomal segment of identical markers (i.e., homozygous markers) is transmitted to the affected child through the paternal and the maternal line from an ancestor common to both parents. Homozygosity mapping seeks out those homozygous regions to map the disease-causing gene. Homozygosity mapping requires families, in which the parents are knowingly related, and have multiple affected children. To overcome these limitations, we applied homozygosity mapping to single affected individuals from outbred populations. In 72 individuals with known homozygous mutations in 13 different recessive disease genes, we performed homozygosity mapping. In 93% we detected the causative gene in a segment of homozygosity. We demonstrate that disease-causing homozygous mutations can be detected in single cases from outbred populations. This will strongly accelerate the discovery of novel recessive disease genes.
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Affiliation(s)
- Friedhelm Hildebrandt
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
- Department of Human Genetics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
- Howard Hughes Medical Institute, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
- * E-mail:
| | - Saskia F. Heeringa
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | | | - Massimo Attanasio
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Gudrun Nürnberg
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - Christian Becker
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - Dominik Seelow
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
- Institute for Genetics, University of Cologne, Cologne, Germany
- Department of Neuropaediatrics, Charite, Berlin, Germany
| | | | - Gil Chernin
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Christopher N. Vlangos
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Weibin Zhou
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - John F. O'Toole
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Bethan E. Hoskins
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Matthias T. F. Wolf
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Bernward G. Hinkes
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Hassan Chaib
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Shazia Ashraf
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Dominik S. Schoeb
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Bugsu Ovunc
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Susan J. Allen
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Virginia Vega-Warner
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Eric Wise
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Heather M. Harville
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
- Department of Human Genetics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Robert H. Lyons
- Department of Human Genetics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
| | - Joseph Washburn
- University of Michigan Cancer Center, Ann Arbor, Michigan, United States of America
| | - James MacDonald
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
- University of Michigan Cancer Center, Ann Arbor, Michigan, United States of America
| | - Peter Nürnberg
- Cologne Center for Genomics, University of Cologne, Cologne, Germany
- Institute for Genetics, University of Cologne, Cologne, Germany
| | - Edgar A. Otto
- Department of Pediatrics, University of Michigan School of Medicine, Ann Arbor, Michigan, United States of America
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Otto EA, Helou J, Allen SJ, O'Toole JF, Wise EL, Ashraf S, Attanasio M, Zhou W, Wolf MTF, Hildebrandt F. Mutation analysis in nephronophthisis using a combined approach of homozygosity mapping, CEL I endonuclease cleavage, and direct sequencing. Hum Mutat 2008; 29:418-26. [PMID: 18076122 DOI: 10.1002/humu.20669] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
Nephronophthisis (NPHP), an autosomal recessive kidney disease, is the most frequent genetic cause of chronic renal failure in the first three decades of life. Mutations in eight genes (NPHP1-8) have been identified. We here describe a combined approach for mutation screening of NPHP1, NPHP2, NPHP3, NPHP4, and NPHP5 in a worldwide cohort of 470 unrelated patients with NPHP. First, homozygous NPHP1 deletions were detected in 97 patients (21%) by multiplex PCR. Second, 25 patients with infantile NPHP were screened for mutations in inversin (NPHP2/INVS). We detected a novel compound heterozygous frameshift mutation (p.[Q485fs]+[R687fs]), and a homozygous nonsense mutation (p.R899X). Third, 37 patients presenting with NPHP and retinitis pigmentosa (Senior-Løken syndrome [SLS]) were screened for NPHP5/IQCB1 mutations by direct sequencing. We discovered five different (three novel) homozygous premature termination codon (PTC) mutations (p.F142fsX; p.R461X; p.R489X; p.W444X; and c.488-1G>A). The remaining 366 patients were further investigated for mutations in NPHP1, NPHP3, and NPHP4. We applied a "homozygosity only" strategy and typed three highly polymorphic microsatellite markers at the respective loci. A total of 32, eight, and 14 patients showed homozygosity, and were screened by heteroduplex crude celery extract (CEL I) endonuclease digests. The sensitivity of CEL I was established as 92%, as it detected 73 out of 79 different known mutations simply on agarose gels. A total of 10 novel PTC mutations were found in NPHP1 (p.P186fs, p.R347X, p.V492fs, p.Y509X, and c.1884+1G>A), in NPHP3 (c.3812+2T>C and p.R1259X), and in NPHP4 (p.R59X, p.T1004fs, and p.V1091fs). The combined homozygosity mapping and CEL I endonuclease mutation analysis approach allowed us to identify rare mutations in a large cohort of patients at low cost.
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Affiliation(s)
- Edgar A Otto
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
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Hoefele J, Wolf MTF, O'Toole JF, Otto EA, Schultheiss U, Dêschenes G, Attanasio M, Utsch B, Antignac C, Hildebrandt F. Evidence of oligogenic inheritance in nephronophthisis. J Am Soc Nephrol 2007; 18:2789-95. [PMID: 17855640 DOI: 10.1681/asn.2007020243] [Citation(s) in RCA: 109] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022] Open
Abstract
Nephronophthisis is a recessive cystic renal disease that leads to end-stage renal failure in the first two decades of life. Twenty-five percent of nephronophthisis cases are caused by large homozygous deletions of NPHP1, but six genes responsible for nephronophthisis have been identified. Because oligogenic inheritance has been described for the related Bardet-Biedl syndrome, we evaluated whether mutations in more than one gene may also be detected in cases of nephronophthisis. Because the nephrocystins 1 to 4 are known to interact, we examined patients with nephronophthisis from 94 different families and sequenced all exons of the NPHP1, NPHP2, NPHP3, and NPHP4 genes. In our previous studies involving 44 families, we detected two mutations in one of the NPHP1-4 genes. Here, we detected in six families two mutations in either NPHP1, NPHP3, or NPHP4, and identified a third mutation in one of the other NPHP genes. Furthermore, we found possible digenic disease by detecting one individual who carried one mutation in NPHP2 and a second mutation in NPHP3. Finally, we detected the presence of a single mutation in nine families, suggesting that the second recessive mutation may be in another as yet unidentified NPHP gene. Our findings suggest that oligogenicity may occur in cases of nephronophthisis.
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Affiliation(s)
- Julia Hoefele
- Departments of Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
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Attanasio M, Uhlenhaut NH, Sousa VH, O'Toole JF, Otto E, Anlag K, Klugmann C, Treier AC, Helou J, Sayer JA, Seelow D, Nürnberg G, Becker C, Chudley AE, Nürnberg P, Hildebrandt F, Treier M. Loss of GLIS2 causes nephronophthisis in humans and mice by increased apoptosis and fibrosis. Nat Genet 2007; 39:1018-24. [PMID: 17618285 DOI: 10.1038/ng2072] [Citation(s) in RCA: 183] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2006] [Accepted: 05/17/2007] [Indexed: 01/16/2023]
Abstract
Nephronophthisis (NPHP), an autosomal recessive kidney disease, is the most frequent genetic cause of end-stage renal failure in the first three decades of life. Positional cloning of the six known NPHP genes has linked its pathogenesis to primary cilia function. Here we identify mutation of GLIS2 as causing an NPHP-like phenotype in humans and mice, using positional cloning and mouse transgenics, respectively. Kidneys of Glis2 mutant mice show severe renal atrophy and fibrosis starting at 8 weeks of age. Differential gene expression studies on Glis2 mutant kidneys demonstrate that genes promoting epithelial-to-mesenchymal transition and fibrosis are upregulated in the absence of Glis2. Thus, we identify Glis2 as a transcription factor mutated in NPHP and demonstrate its essential role for the maintenance of renal tissue architecture through prevention of apoptosis and fibrosis.
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Affiliation(s)
- Massimo Attanasio
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan 48109, USA
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Helou J, Otto EA, Attanasio M, Allen SJ, Parisi MA, Glass I, Utsch B, Hashmi S, Fazzi E, Omran H, O'Toole JF, Sayer JA, Hildebrandt F. Mutation analysis of NPHP6/CEP290 in patients with Joubert syndrome and Senior-Løken syndrome. J Med Genet 2007; 44:657-63. [PMID: 17617513 PMCID: PMC2597962 DOI: 10.1136/jmg.2007.052027] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
BACKGROUND Nephronophthisis (NPHP) is an autosomal recessive cystic kidney disease that constitutes the most common genetic cause of renal failure in the first three decades of life. Using positional cloning, six genes (NPHP1-6) have been identified as mutated in NPHP. In Joubert syndrome (JBTS), NPHP may be associated with cerebellar vermis aplasia/hypoplasia, retinal degeneration and mental retardation. In Senior-Løken syndrome (SLSN), NPHP is associated with retinal degeneration. Recently, mutations in NPHP6/CEP290 were identified as a new cause of JBTS. METHODS Mutational analysis was performed on a worldwide cohort of 75 families with SLSN, 99 families with JBTS and 21 families with isolated nephronophthisis. RESULTS Six novel and six known truncating mutations, one known missense mutation and one novel 3 bp pair in-frame deletion were identified in a total of seven families with JBTS, two families with SLSN and one family with isolated NPHP.
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O'Toole JF, Otto EA, Hoefele J, Helou J, Hildebrandt F. Mutational analysis in 119 families with nephronophthisis. Pediatr Nephrol 2007; 22:366-70. [PMID: 17061121 DOI: 10.1007/s00467-006-0334-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/22/2006] [Revised: 09/14/2006] [Accepted: 09/15/2006] [Indexed: 11/25/2022]
Abstract
Nephronophthisis (NPHP) is the most common genetic cause of end-stage renal disease (ESRD) in the first three decades of life. Six genes, NPHP1-6, have been reported, which when mutated result in NPHP. Our aim was to examine 119 families with NPHP and absence of homozygous NPHP1 deletions for mutations in NPHP2-6 and the two candidate genes BCL2 and CYS1. The 119 individuals affected with NPHP were selected from unrelated families, in which homozygous NPHP1 deletions were excluded. A combination of CEL-1 endonuclease digestion and direct sequencing was used for focused mutational analysis in this cohort. All individuals were examined for homozygous deletions in NPHP1 and directly sequenced for BCL2 and CYS1. As selected by appropriate phenotype, 9%, 38%, 97%, 20% and 20% of individuals were examined for mutations in NPHP2, 3, 4, 5, and 6 respectively. No mutations in known NPHP genes or in the candidate genes, BCL2 and CYS1, were found sufficient to explain NPHP in affected individuals. These findings demonstrate the need to evaluate additional candidate genes as the cause of NPHP.
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Affiliation(s)
- John F O'Toole
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109-0676, USA
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Hoefele J, Sudbrak R, Reinhardt R, Lehrack S, Hennig S, Imm A, Muerb U, Utsch B, Attanasio M, O'Toole JF, Otto E, Hildebrandt F. Mutational analysis of the NPHP4 gene in 250 patients with nephronophthisis. Hum Mutat 2006; 25:411. [PMID: 15776426 DOI: 10.1002/humu.9326] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Nephronophthisis (NPH), a recessive cystic kidney disease, is the most frequent genetic cause for end-stage renal disease in the first two decades of life. Mutations in three genes (NPHP1, 2, and 3) were identified as causative. Extrarenal manifestations are known, such as retinitis pigmentosa (Senior-Loken syndrome, SLS) and ocular motor apraxia type Cogan. Recently, we identified a novel gene (NPHP4) as mutated in NPH. To date, a total of only 13 different NPHP4 mutations have been described. To determine the frequency of NPHP4 mutations, we performed mutational analysis by direct sequencing of all 30 NPHP4 exons in 250 different patients with isolated NPH, SLS, or Cogan syndrome ascertained worldwide over 14 years. We identified 23 novel NPHP4 sequence variants in 26/250 different patients (10%). Interestingly, we detected homozygous or compound heterozygous mutations of NPHP4 in only 6/250 different patients (2.4%), but only one heterozygous NPHP4 sequence variant in 20/250 different patients (8%). In the six patients with two NPHP4 mutations, 5/8 mutations (63%) were likely loss-of-function mutations, whereas in the 20 patients with only one sequence variant, only 1/20 (5%) was a likely loss-of-function (i.e., truncating) mutation. We conclude that: i) two recessive mutations in NPHP4 are a rare cause of nephronophthisis; ii) single heterozygous NPHP4 sequence variants are three times more prevalent than two recessive mutations; iii) there is no genotype/phenotype correlation; iv) there must exist further genes causing nephronophthisis, since in 224/250 (90%) patients, no sequence variants in either of the four NPH genes were detected.
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Affiliation(s)
- Julia Hoefele
- Department of Pediatrics, Human Genetics, University of Michigan, Ann Arbor, Michigan, USA
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Sayer JA, Otto EA, O'Toole JF, Nurnberg G, Kennedy MA, Becker C, Hennies HC, Helou J, Attanasio M, Fausett BV, Utsch B, Khanna H, Liu Y, Drummond I, Kawakami I, Kusakabe T, Tsuda M, Ma L, Lee H, Larson RG, Allen SJ, Wilkinson CJ, Nigg EA, Shou C, Lillo C, Williams DS, Hoppe B, Kemper MJ, Neuhaus T, Parisi MA, Glass IA, Petry M, Kispert A, Gloy J, Ganner A, Walz G, Zhu X, Goldman D, Nurnberg P, Swaroop A, Leroux MR, Hildebrandt F. The centrosomal protein nephrocystin-6 is mutated in Joubert syndrome and activates transcription factor ATF4. Nat Genet 2006; 38:674-81. [PMID: 16682973 DOI: 10.1038/ng1786] [Citation(s) in RCA: 413] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2005] [Accepted: 03/21/2006] [Indexed: 01/30/2023]
Abstract
The molecular basis of nephronophthisis, the most frequent genetic cause of renal failure in children and young adults, and its association with retinal degeneration and cerebellar vermis aplasia in Joubert syndrome are poorly understood. Using positional cloning, we here identify mutations in the gene CEP290 as causing nephronophthisis. It encodes a protein with several domains also present in CENPF, a protein involved in chromosome segregation. CEP290 (also known as NPHP6) interacts with and modulates the activity of ATF4, a transcription factor implicated in cAMP-dependent renal cyst formation. NPHP6 is found at centrosomes and in the nucleus of renal epithelial cells in a cell cycle-dependent manner and in connecting cilia of photoreceptors. Abrogation of its function in zebrafish recapitulates the renal, retinal and cerebellar phenotypes of Joubert syndrome. Our findings help establish the link between centrosome function, tissue architecture and transcriptional control in the pathogenesis of cystic kidney disease, retinal degeneration, and central nervous system development.
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Affiliation(s)
- John A Sayer
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan 48109, USA
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Abstract
BACKGROUND Nephronophthisis (NPHP) is an autosomal recessive disease, which is the most common genetic cause of end-stage renal disease in the first three decades of life. The disease is caused by mutations in the NPHP 1-5 genes, and is referred to as NPHP types 1-5, respectively. The association of NPHP and retinitis pigmentosa (RP) is known as Senior-Loken syndrome (SLS). The RP is associated with 10% of cases of NPHP types 1, 3 and 4, and all cases of NPHP type 5, but never in NPHP type 2, the infantile form of NPHP. The NPHP type 2 is distinguished from other types of NPHP by its early age of onset and by cystic enlargement of the kidneys. METHODS Mutational analysis of all five NPHP genes was performed by exon sequencing in a child with infantile NPHP and RP from a consanguineous kindred. RESULTS A homozygous mutation was identified in exon 13 of inversin (INVS) (C2719T, R907X) in this child. CONCLUSIONS This is the first report of the presence of RP in a patient with NPHP type 2 and INVS mutations. This report now extends the association of RP with NPHP to NPHP type 2.
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Affiliation(s)
- John F O'Toole
- Department of Internal Medicine, University of Michigan, Ann Arbor, MI 48109-0676, USA
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Otto EA, Loeys B, Khanna H, Hellemans J, Sudbrak R, Fan S, Muerb U, O'Toole JF, Helou J, Attanasio M, Utsch B, Sayer JA, Lillo C, Jimeno D, Coucke P, De Paepe A, Reinhardt R, Klages S, Tsuda M, Kawakami I, Kusakabe T, Omran H, Imm A, Tippens M, Raymond PA, Hill J, Beales P, He S, Kispert A, Margolis B, Williams DS, Swaroop A, Hildebrandt F. Nephrocystin-5, a ciliary IQ domain protein, is mutated in Senior-Loken syndrome and interacts with RPGR and calmodulin. Nat Genet 2005; 37:282-8. [PMID: 15723066 DOI: 10.1038/ng1520] [Citation(s) in RCA: 285] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2004] [Accepted: 01/14/2005] [Indexed: 02/07/2023]
Abstract
Nephronophthisis (NPHP) is the most frequent genetic cause of chronic renal failure in children. Identification of four genes mutated in NPHP subtypes 1-4 (refs. 4-9) has linked the pathogenesis of NPHP to ciliary functions. Ten percent of affected individuals have retinitis pigmentosa, constituting the renal-retinal Senior-Loken syndrome (SLSN). Here we identify, by positional cloning, mutations in an evolutionarily conserved gene, IQCB1 (also called NPHP5), as the most frequent cause of SLSN. IQCB1 encodes an IQ-domain protein, nephrocystin-5. All individuals with IQCB1 mutations have retinitis pigmentosa. Hence, we examined the interaction of nephrocystin-5 with RPGR (retinitis pigmentosa GTPase regulator), which is expressed in photoreceptor cilia and associated with 10-20% of retinitis pigmentosa. We show that nephrocystin-5, RPGR and calmodulin can be coimmunoprecipitated from retinal extracts, and that these proteins localize to connecting cilia of photoreceptors and to primary cilia of renal epithelial cells. Our studies emphasize the central role of ciliary dysfunction in the pathogenesis of SLSN.
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Affiliation(s)
- Edgar A Otto
- Department of Pediatrics, University of Michigan, Ann Arbor, Michigan 48109, USA
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Otto EA, Schermer B, Obara T, O'Toole JF, Hiller KS, Mueller AM, Ruf RG, Hoefele J, Beekmann F, Landau D, Foreman JW, Goodship JA, Strachan T, Kispert A, Wolf MT, Gagnadoux MF, Nivet H, Antignac C, Walz G, Drummond IA, Benzing T, Hildebrandt F. Mutations in INVS encoding inversin cause nephronophthisis type 2, linking renal cystic disease to the function of primary cilia and left-right axis determination. Nat Genet 2003; 34:413-20. [PMID: 12872123 PMCID: PMC3732175 DOI: 10.1038/ng1217] [Citation(s) in RCA: 464] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2003] [Accepted: 06/26/2003] [Indexed: 01/06/2023]
Abstract
Nephronophthisis (NPHP), an autosomal recessive cystic kidney disease, leads to chronic renal failure in children. The genes mutated in NPHP1 and NPHP4 have been identified, and a gene locus associated with infantile nephronophthisis (NPHP2) was mapped. The kidney phenotype of NPHP2 combines clinical features of NPHP and polycystic kidney disease (PKD). Here, we identify inversin (INVS) as the gene mutated in NPHP2 with and without situs inversus. We show molecular interaction of inversin with nephrocystin, the product of the gene mutated in NPHP1 and interaction of nephrocystin with beta-tubulin, a main component of primary cilia. We show that nephrocystin, inversin and beta-tubulin colocalize to primary cilia of renal tubular cells. Furthermore, we produce a PKD-like renal cystic phenotype and randomization of heart looping by knockdown of invs expression in zebrafish. The interaction and colocalization in cilia of inversin, nephrocystin and beta-tubulin connect pathogenetic aspects of NPHP to PKD, to primary cilia function and to left-right axis determination.
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Affiliation(s)
- Edgar A Otto
- Department of Pediatrics, 8220C MSRB III, 1150 West Medical Center Drive, University of Michigan, Ann Arbor, Michigan 48109, USA
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Abstract
The topology of Escherichia coli diacylglycerol kinase (DAGK) within the cytoplasmic membrane was elucidated by a combined approach involving both multiple aligned sequence analysis and fusion protein experiments. Hydropathy plots of the five prokaryotic DAGK sequences available were uniform in their prediction of three transmembrane segments. The hydropathy predictions were experimentally tested genetically by fusing C-terminal deletion derivatives of DAGK to beta-lactamase and beta-galactosidase. Following expression, the enzymatic activities of the chimeric proteins were measured and used to determine the cellular location of the fusion junction. These studies confirmed the hydropathy predictions for DAGK with respect to the number and approximate sequence locations of the transmembrane segments. Further analysis of the aligned DAGK sequences detected probable alpha-helical N-terminal capping motifs and two amphipathic alpha-helices within the enzyme. The combined fusion and sequence data indicate that DAGK is a polytopic integral membrane protein with three transmembrane segments with the N terminus of the protein in the cytoplasm, the C terminus in the periplasmic space, and two amphipathic helices near the cytoplasmic surface.
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Affiliation(s)
- R L Smith
- Department of Pharmacology, School of Medicine, Case Western Reserve University, Cleveland, Ohio 44106-4965
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