APOL1 RVs depolarize mitochondrial potential and induce cytotoxicity, reversible with pharmacologic inhibition or knockdown of mPTP components. (A) TMRM dye accumulates in the mitochondrial matrix on the basis of the hyperpolarized mitochondrial transmembrane potential. Compared with EV and G0 cells, TMRM fluorescence is much lower in APOL1 RV-expressing cells, indicating reduced mitochondrial transmembrane potential in RV cells. Original magnification, X630. (B) CYPD inhibitor CsA blocks mPTP formation and reduces APOL1 RV–induced cell death. Each dot represents an independent experiment. For both G1 and G2 cell lines, DMSO versus 0.1 µM CsA and DMSO versus 1 µM CsA; P<0.001. (C) NIM811, a CsA analog that can inhibit MPTP by binding to CYPD but cannot bind to calcineurin, blocks APOL1 RV induced cell death. Each dot represents an independent experiment. For both G1 and G2 cell lines, DMSO versus 0.1 µM NIM811 and DMSO versus 1 µM NIM811; P<0.001. (D) Knockdown of individual MPTP pore components or modulators blocks APOL1-induced cell death. Supplemental Figure 8 includes immunoprecipitation Western blots demonstrating interaction between APOL1 and MPTP components. Each dot represents an independent experiment. **P<0.001 comparing each siRNA to siNT-treated cells.