Cholesterol enrichment in liver mitochondria impairs oxidative phosphorylation and disrupts the assembly of respiratory supercomplexes
Estel Solsona-Vilarrasa,
Raquel Fucho,
Sandra Torres,
Susana Nuñez,
Natalia Nuño-Lámbarri,
Carlos Enrich,
Carmen García-Ruiz,
José C. Fernández-Checa
Affiliations
Estel Solsona-Vilarrasa
Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigación Biomédica en Red (CIBEREHD), Barcelona, Spain; Department of Biomedical Sciences, Medicine Faculty, Universitat de Barcelona (UB), Spain
Raquel Fucho
Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigación Biomédica en Red (CIBEREHD), Barcelona, Spain
Sandra Torres
Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigación Biomédica en Red (CIBEREHD), Barcelona, Spain
Susana Nuñez
Centro de Investigación Biomédica en Red (CIBEREHD), Barcelona, Spain
Natalia Nuño-Lámbarri
Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Traslational Research Unit, Medica Sur Clinic & Foundation, Mexico City, Mexico
Carlos Enrich
Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Department of Biomedical Sciences, Medicine Faculty, Universitat de Barcelona (UB), Spain
Carmen García-Ruiz
Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigación Biomédica en Red (CIBEREHD), Barcelona, Spain; eResearch Center for ALPD, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States; Corresponding authors. Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain.
José C. Fernández-Checa
Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain; Liver Unit, Hospital Clinic I Provincial de Barcelona, Instituto de Investigaciones Biomédicas August Pi i Sunyer (IDIBAPS), Barcelona, Spain; Centro de Investigación Biomédica en Red (CIBEREHD), Barcelona, Spain; eResearch Center for ALPD, Keck School of Medicine, University of Southern California, Los Angeles, CA, United States; Corresponding authors. Department of Cell Death and Proliferation, Institute of Biomedical Research of Barcelona (IIBB), CSIC, Barcelona, Spain.
Mitochondrial cholesterol accumulation is a hallmark of alcoholic and non-alcoholic fatty liver diseases and impairs the function of specific solute carriers through changes in membrane physical properties. However, its impact on mitochondrial respiration and organization of respiratory supercomplexes has not been determined so far. Here we fed mice a cholesterol-enriched diet (HC) supplemented with sodium cholate to examine the effect of cholesterol in mitochondrial function. HC feeding increased liver cholesterol content, which downregulated Srebp2 and Hmgcr expression, while sodium cholate administration decreased Cyp7a1 and Cyp8b1 mRNA levels, suggesting the downregulation of bile acid synthesis through the classical pathway. HC-fed mice exhibited increased expression of Stard1 and Mln64 and enhanced mitochondrial free cholesterol levels (2–3 fold), leading to decreased membrane fluidity. Mitochondria from HC-fed mice displayed increased cholesterol loading in both outer and inner mitochondrial membranes. Cholesterol loading decreased complex I and complex II-driven state 3 respiration and mitochondrial membrane potential. Decreased respiratory and uncoupling control ratio from complex I was also observed after in situ enrichment of mouse liver mitochondria with cholesterol or enantiomer cholesterol, the mirror image of natural cholesterol. Moreover, in vivo cholesterol loading decreased the level of complex III2 and the assembly of respiratory supercomplexes I1+III2+IV and I1+III2. Moreover, HC feeding caused oxidative stress and mitochondrial GSH (mGSH) depletion, which translated in hepatic steatosis and liver injury, effects that were rescued by replenishing mGSH with GSH ethyl ester. Overall, mitochondrial cholesterol accumulation disrupts mitochondrial functional performance and the organization of respiratory supercomplexes assembly, which can contribute to oxidative stress and liver injury. Keywords: Mitochondria, Cholesterol, Liver, Hepatic diseases, Respiration, Oxidative stress
