ATP-binding cassette A1 deficiency causes cardiolipin-driven mitochondrial dysfunction in podocytes
G. Michelle Ducasa, … , Flavia Fontanesi, Alessia Fornoni
G. Michelle Ducasa, … , Flavia Fontanesi, Alessia Fornoni
Published July 22, 2019
Citation Information: J Clin Invest. 2019;129(8):3387-3400. https://doi.org/10.1172/JCI125316.
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Research Article Metabolism Nephrology

ATP-binding cassette A1 deficiency causes cardiolipin-driven mitochondrial dysfunction in podocytes

Abstract

Fibroblasts from patients with Tangier disease carrying ATP-binding cassette A1 (ABCA1) loss-of-function mutations are characterized by cardiolipin accumulation, a mitochondrial-specific phospholipid. Suppression of ABCA1 expression occurs in glomeruli from patients with diabetic kidney disease (DKD) and in human podocytes exposed to DKD sera collected prior to the development of DKD. We demonstrated that siRNA ABCA1 knockdown in podocytes led to reduced oxygen consumption capabilities associated with alterations in the oxidative phosphorylation (OXPHOS) complexes and with cardiolipin accumulation. Podocyte-specific deletion of Abca1 (Abca1fl/fl) rendered mice susceptible to DKD, and pharmacological induction of ABCA1 improved established DKD. This was not mediated by free cholesterol, as genetic deletion of sterol-o-acyltransferase-1 (SOAT1) in Abca1fl/fl mice was sufficient to cause free cholesterol accumulation but did not cause glomerular injury. Instead, cardiolipin mediates ABCA1-dependent susceptibility to podocyte injury, as inhibition of cardiolipin peroxidation with elamipretide improved DKD in vivo and prevented ABCA1-dependent podocyte injury in vitro and in vivo. Collectively, we describe a pathway definitively linking ABCA1 deficiency to cardiolipin-driven mitochondrial dysfunction. We demonstrated that this pathway is relevant to DKD and that ABCA1 inducers or inhibitors of cardiolipin peroxidation may each represent therapeutic strategies for the treatment of established DKD.

Authors

G. Michelle Ducasa, Alla Mitrofanova, Shamroop K. Mallela, Xiaochen Liu, Judith Molina, Alexis Sloan, Christopher E. Pedigo, Mengyuan Ge, Javier Varona Santos, Yanio Hernandez, Jin-Ju Kim, Cyrille Maugeais, Armando J. Mendez, Viji Nair, Matthias Kretzler, George W. Burke, Robert G. Nelson, Yu Ishimoto, Reiko Inagi, Santanu Banerjee, Shaoyi Liu, Hazel H. Szeto, Sandra Merscher, Flavia Fontanesi, Alessia Fornoni

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Figure 4

ABCA1 deficiency leads to cardiolipin accumulation associated with reduced mitochondrial function and oxygen consumption.

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ABCA1 deficiency leads to cardiolipin accumulation associated with reduc...
(A and B) siABCA1 compared with siCO podocytes were analyzed for (A) endogenous (unpermeabilized cells) and substrate-driven (permeabilized cells + glutamate-malate [CI] or succinate [CII]) oxygen consumption rates (OCR; nmol oxygen consumed per minute normalized to mg protein) (n = 3–4 per group); (B) maximal enzymatic activity for complex I (CI), complex III (CIII), and complex IV (CIV) (n = 3–4 per group). (C) Representative Western blot image of BN-PAGE analysis of mitochondrial extracts obtained with digitonin sequentially probed for core 2 antibody (CIII), Cox I antibody (CIV), and SDHA (CII). Samples were also resolved by SDS-PAGE and probed with VDAC as loading control. (D) Densiometric quantification of Western blot analysis of digitonin extract shown in C (n = 3–4 per group). (E) Representative Western blot images of BN-PAGE analysis of mitochondrial extracts obtained with lauryl maltoside and probed for NDUFA9 (CI), SDHA (CII), CORE2 (CIII), COXI (CIV), and ATPα5 (CV). Samples were also resolved by SDS-PAGE and VDAC was detected as loading control. (F) Densiometric quantification of Western blot analysis of lauryl maltoside extraction shown in E (n = 3 per group). (G) Quantification of the relative cardiolipin and (H) monoglycerides (MG) and fatty acids (FA) content normalized to total lipids extracted from isolated mitochondria of siABCA1 compared with siCO podocytes (n = 3 per group). Two-tailed t test. *P < 0.05; **P < 0.01; ***P < 0.001.