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 August 1, 2019; First 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 3

ABCA1 deficiency is a susceptibility factor for podocyte injury contributing to worsened DKD.

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ABCA1 deficiency is a susceptibility factor for podocyte injury contribu...
(A) Quantification for cytotoxicity normalized to viability for NP (n = 16) and P (n = 15) sera–treated, or untreated (NT, n = 3) siRNA ABCA1 knockdown podocytes (siABCA1) compared with scramble control (siCO) podocytes. (B–F) Ob/+, ob/ob, and Abca1fl/fl ob/ob mice were analyzed for the following: (B) albumin-to-creatinine ratios at 12 and 16 weeks (time of sacrifice) (n = 4–5 per group); (C) TC, FC, and CEs (n = 3–5 per group); (D) mesangial expansion score using PAS-stained kidney cortex sections (n = 7 per group); (E) podocyte foot processes (marked with orange arrows in H) per μm of GBM (n = 3 per group); and (F) podocyte number per glomerular cross section as determined via WT1 antibody. (G–I) Representative images for (G) PAS-stained kidney cortex (scale bars: 25 μm); (H) TEM podocyte foot process measurements (mitochondria marked with yellow asterisks; scale bars: 200 nm); and (I) WT1-stained kidney cortex sections (scale bars: 25 μm). (J) Correlation analysis between BUN and kidney cortex CEs (μM cholesterol/mg protein) (n = 3–5 per group). (K) Quantification of albumin-to-creatinine ratios comparing WT (n = 4–5), Abca1fl/+ (HET) (n = 4–6), and Abcafl/fl (KO) (n = 4) mice injected with vehicle or STZ. (L) Quantification of kidney cortex TC, FC, and CEs content in KO and STZ-treated WT and KO mice (n = 3–5 per group). Two-tailed t test (A, D, E) or 1-way ANOVA followed by Tukey’s multiple comparisons test (B, C, F, K, L) and linear regression used for correlation analyses (J) with r2 and P values shown. *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.