Focal segmental glomerulosclerosis (FSGS) is a clinical-pathologic syndromes characterized by the accumulation of fibrotic proteins in glomeruli, initially involving only some glomeruli (focal) and involving portions (segments) of the affected glomeruli. FSGS can be classified as follows: idiopathic FSGS, genetic FSGS and post-adaptive FSGS (associated with glomerular hypertrophy and hyperfiltration, and due to reduced renal mass, renal toxins, obesity, and sickle cell disease). A related syndrome is collapsing glomerulopathy, associated with podocyte hyperplasia whereas FSGS is associated with podocyte depletion. Collapsing glomerulopathy can be classified as HIV-associated or idiopathic. In order to define the molecular mechanisms responsible for HIV-associated collapsing glomerulopathy, we have established mice in which transgene expression can be regulated in the glomerular podocyte using an tetracycline-regulated system. We have used this system to express the HIV-1 accessory protein Vpr in the podocyte. These mice develop proteinuria beginning 4 weeks after treatment with tetracycline. Collapsing glomerulopathy appears at 8 weeks, progressing to global glomerulosclerosis and end-stage kidney disease. Podocyte phenotype is abnormal, with reduced expression of the differentiation marker synaptopodin and de novo expression of the injury marker desmin. Increased cell proliferation is present in the glomerular tuft, parietal epithelum, and tubular epithelium. These results demonstrate that Vpr is sufficient to induce HIV-associated collapsing glomerulopathy in transgenic mice. 1) Using these transgenic mice, we have established double transgenic podocyte cell lines, which bear the podocin/rtTA, and temperature-sensitive SV40 Tag transgenes to confer conditional immortalization. These cells were found to express characteristic podocyte markers, including podocin, nephrin, and WT1. We have introduced the Vpr gene into these cells to understand Vpr-induced cell injury. Our preliminary results indicate increased apoptosis with 12 hours of Vpr expression induced by doxycycline. The mechanisms appear to involve both caspase dependent and caspase independent pathways.

Project Start
Project End
Budget Start
Budget End
Support Year
8
Fiscal Year
2014
Total Cost
Indirect Cost
Name
U.S. National Inst Diabetes/Digst/Kidney
Department
Type
DUNS #
City
State
Country
Zip Code
Kopp, Jeffrey B (2017) Chronic Kidney Disease in the Aging Human Immunodeficiency Virus-Infected Population. J Infect Dis :
Kopp, Jeffrey B; Heymann, Jurgen; Winkler, Cheryl A (2017) APOL1 Renal Risk Variants: Fertile Soil for HIV-Associated Nephropathy. Semin Nephrol 37:514-519
Purswani, Murli U; Patel, Kunjal; Winkler, Cheryl A et al. (2016) Brief Report: APOL1 Renal Risk Variants Are Associated With Chronic Kidney Disease in Children and Youth With Perinatal HIV Infection. J Acquir Immune Defic Syndr 73:63-8
Atta, Mohamed G; Estrella, Michelle M; Skorecki, Karl L et al. (2016) Association of APOL1 Genotype with Renal Histology among Black HIV-Positive Patients Undergoing Kidney Biopsy. Clin J Am Soc Nephrol 11:262-70
Kasembeli, Alex N; Duarte, Raquel; Ramsay, Michèle et al. (2015) APOL1 Risk Variants Are Strongly Associated with HIV-Associated Nephropathy in Black South Africans. J Am Soc Nephrol 26:2882-90
Kopp, Jeffrey B (2013) JC viruria and kidney disease in APOL1 risk genotype individuals: is this a clue to a gene × environment interaction? Kidney Int 84:1069-72
Hadigan, Colleen; Edwards, Elizabeth; Rosenberg, Alice et al. (2013) Microalbuminuria in HIV disease. Am J Nephrol 37:443-51
Kopp, Jeffrey B (2013) Rethinking hypertensive kidney disease: arterionephrosclerosis as a genetic, metabolic, and inflammatory disorder. Curr Opin Nephrol Hypertens 22:266-72
Purswani, Murli; Patel, Kunjal; Kopp, Jeffrey B et al. (2013) Tenofovir treatment duration predicts proteinuria in a multiethnic United States Cohort of children and adolescents with perinatal HIV-1 infection. Pediatr Infect Dis J 32:495-500
Shrivastav, Shashi; Zhang, Liyan; Okamoto, Koji et al. (2013) HIV-1 Vpr enhances PPAR?/?-mediated transcription, increases PDK4 expression, and reduces PDC activity. Mol Endocrinol 27:1564-76

Showing the most recent 10 out of 17 publications