Human iPSC-derived Podocytes to Study APOL1 High-Risk Variants

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PROJECT SUMMARY/ABSTRACT. . Kidney disease status is characterized by how efficiently the kidney is able to remove excess fluids and waste. Podocytes within the glomerulus are integral to forming the barrier needed for this filtration. An estimated 15% of adults in the US have chronic kidney disease (CKD), but there are no curative treatment options for CKD and patients must resort to time-consuming dialysis or undergoing a kidney transplant to maintain a quality of life during disease progression. The African American population of sub-Saharan descent has a 3.5-fold increased risk for end-stage kidney disease compared to populations of European descent. This incidence discrepancy is, in part, due to two pathogenic variants G1 and G2 in the apolipoprotein L1 (APOL1) gene. Individuals with the presence of one high-risk allele are resistant to African sleeping sickness, but the presence of two high-risk alleles significantly predisposes to kidney disease. As APOL1 is only found in humans and some primates, this work utilizes isogenic human iPSC lines genetically engineered to contain APOL1 variant genotypes. The mechanism of APOL1-mediated kidney diseases is not known but correlates with podocyte population depletion. This depletion is thought to be linked to foot process effacement, a podocyte stress response dictated by cytoskeletal rearrangements that cause the processes to simplify and flatten to flatten, leading to decreased kidney function. This study proposes high-risk APOL1 podocytes are intrinsically different compared to reference APOL1 podocytes. Variant APOL1 iPSC lines will be directly differentiated into pure podocyte populations and will be used to determine if the presence of high-risk APOL1 interferes with podocyte cytoskeleton dynamics. Further, this work will utilize a Design of Experiment (DoE) approach to detect the effects of synergistic inputs involved in podocyte biology to determine if high-risk APOL1 podocytes are intrinsically different. This research will assess human-specific aspects of podocyte biology in a representative and homogenous cell population, providing an opportunity to gain an understanding of the mechanism of APOL1-mediated diseases. Data generated will provide directly translatable and desperately needed therapeutic intervention to kidney disease injury and progression.