A role for genetic susceptibility in sporadic focal segmental glomerulosclerosis
Haiyang Yu, … , Mark J. Daly, Andrey S. Shaw
Haiyang Yu, … , Mark J. Daly, Andrey S. Shaw
Published February 22, 2016
Citation Information: J Clin Invest. 2016;126(3):1067-1078. https://doi.org/10.1172/JCI82592.
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Research Article Nephrology

A role for genetic susceptibility in sporadic focal segmental glomerulosclerosis

Abstract

Focal segmental glomerulosclerosis (FSGS) is a syndrome that involves kidney podocyte dysfunction and causes chronic kidney disease. Multiple factors including chemical toxicity, inflammation, and infection underlie FSGS; however, highly penetrant disease genes have been identified in a small fraction of patients with a family history of FSGS. Variants of apolipoprotein L1 (APOL1) have been linked to FSGS in African Americans with HIV or hypertension, supporting the proposal that genetic factors enhance FSGS susceptibility. Here, we used sequencing to investigate whether genetics plays a role in the majority of FSGS cases that are identified as primary or sporadic FSGS and have no known cause. Given the limited number of biopsy-proven cases with ethnically matched controls, we devised an analytic strategy to identify and rank potential candidate genes and used an animal model for validation. Nine candidate FSGS susceptibility genes were identified in our patient cohort, and three were validated using a high-throughput mouse method that we developed. Specifically, we introduced a podocyte-specific, doxycycline-inducible transactivator into a murine embryonic stem cell line with an FSGS-susceptible genetic background that allows shRNA-mediated targeting of candidate genes in the adult kidney. Our analysis supports a broader role for genetic susceptibility of both sporadic and familial cases of FSGS and provides a tool to rapidly evaluate candidate FSGS-associated genes.

Authors

Haiyang Yu, Mykyta Artomov, Sebastian Brähler, M. Christine Stander, Ghaidan Shamsan, Matthew G. Sampson, J. Michael White, Matthias Kretzler, Jeffrey H. Miner, Sanjay Jain, Cheryl A. Winkler, Robi D. Mitra, Jeffrey B. Kopp, Mark J. Daly, Andrey S. Shaw

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Figure 3

Validation of the system using CD2AP knockdown.

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Validation of the system using CD2AP knockdown. (A) Targeting strategy u...
(A) Targeting strategy used to integrate a miR30-shRNA transgene into the Hprt1 locus. (B) Knockdown efficiency of a miR30-shRNA for Cd2ap (sh877). Immunoblot shows endogenous CD2AP in NIH3T3 cells stably transduced with FF3 (control shRNA) or sh877. The validation of sh877 is shown in Supplemental Figure 2A. Panel B represents multiple experiments (n = 3) conducted to test the efficiency of the RNAi. (C) Sixteen mice generated with ES cells with the Cd2ap shRNA that was targeted to the Hprt1 locus were treated with or without DOX, and urine was analyzed by measuring the urine albumin/creatinine ratio at 4 and 8 weeks. (D) Histology from a representative Cd2ap RNAi mouse treated with DOX showing protein casts (indicated with asterisks; n >5). (E) Representative electron microscopic image from a Cd2ap RNAi mouse treated with DOX shows podocyte foot process (FP) effacement. En, endothelial cells (n = 9). (F) Thirteen control mice were generated with a control luciferase RNAi targeted to the Hgprt locus. Mice were treated with (n = 6) or without (n = 7) DOX, and urine was analyzed by measuring the albumin/creatinine ratio at 4 and 8 weeks. A 2-tailed Mann-Whitney U test was used to calculate the P values in C and F. A P value of less than 0.05 was considered statistically significant.