title: Reduced cardiolipin content decreases respiratory chain capacities and increases ATP synthesis yield in the human HepaRG cells.
abstract: Cardiolipin (CL) is a unique mitochondrial phospholipid potentially affecting many aspects of mitochondrial function/processes, i.e. energy production through oxidative phosphorylation. Most data focusing on implication of CL content and mitochondrial bioenergetics were performed in yeast or in cellular models of Barth syndrome. Previous work reported that increase in CL content leads to decrease in liver mitochondrial ATP synthesis yield. Therefore the aim of this study was to determine the effects of moderate decrease in CL content on mitochondrial bioenergetics in human hepatocytes. For this purpose, we generated a cardiolipin synthase knockdown (shCLS) in HepaRG hepatoma cells showing bioenergetics features similar to primary human hepatocytes. shCLS cells exhibited a 55% reduction in CLS gene and a 40% decrease in protein expression resulting in a 45% lower content in CL compared to control (shCTL) cells. Oxygen consumption was significantly reduced in shCLS cells compared to shCTL regardless of substrate used and energy state analyzed. Mitochondrial low molecular weight supercomplex content was higher in shCLS cells (+60%) compared to shCTL. Significant fragmentation of the mitochondrial network was observed in shCLS cells compared to shCTL cells. Surprisingly, mitochondrial ATP synthesis was unchanged in shCLS compared to shCTL cells but exhibited a higher ATP:O ratio (+46%) in shCLS cells. Our results suggest that lowered respiratory chain activity induced by moderate reduction in CL content may be due to both destabilization of supercomplexes and mitochondrial network fragmentation. In addition, CL content may regulate mitochondrial ATP synthesis yield.
authors.affiliation: Inserm UMR1069, Nutrition, Croissance et Cancer, Université François Rabelais de Tours, 10, bd Tonnellé, 37032 Tours, Cedex, France. Electronic address: laure.peyta@etu.univ-tours.fr.
authors.forename: Laure
authors.initials: L
authors.lastname: Peyta
authors.affiliation: Inserm UMR S-991, Foie, Métabolismes et Cancer, CHU Pontchaillou, 2 rue Henri Le Guilloux, 35033 Rennes, France; Université de Rennes 1, 2 rue du Thabor CS46510, 35065 Rennes, Cedex, France. Electronic address: kathleen.jarnouen@univ-rennes1.fr.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Jarnouen
authors.affiliation: Inserm UMR1069, Nutrition, Croissance et Cancer, Université François Rabelais de Tours, 10, bd Tonnellé, 37032 Tours, Cedex, France. Electronic address: michelle.pinault@univ-tours.fr.
authors.forename: Michelle
authors.initials: M
authors.lastname: Pinault
authors.affiliation: Inserm UMR1069, Nutrition, Croissance et Cancer, Université François Rabelais de Tours, 10, bd Tonnellé, 37032 Tours, Cedex, France. Electronic address: cyrille.guimaraes@gmail.com.
authors.forename: Cyrille
authors.initials: C
authors.lastname: Guimaraes
authors.affiliation: Plateforme de Lipidomique, INSERM UMR866/LabEx LipSTIC, 15 Bd Mal de Lattre de Tassigny, 21000 Dijon, France. Electronic address: jppais@u-bourgogne.fr.
authors.forename: Jean-Paul
authors.initials: JP
authors.lastname: Pais de Barros
authors.affiliation: Inserm UMR1069, Nutrition, Croissance et Cancer, Université François Rabelais de Tours, 10, bd Tonnellé, 37032 Tours, Cedex, France. Electronic address: stephan.chevalier@univ-tours.fr.
authors.forename: Stephan
authors.initials: S
authors.lastname: Chevalier
authors.affiliation: Inserm UMR1069, Nutrition, Croissance et Cancer, Université François Rabelais de Tours, 10, bd Tonnellé, 37032 Tours, Cedex, France. Electronic address: jean-francois.dumas@univ-tours.fr.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Dumas
authors.affiliation: Inserm UMR1069, Nutrition, Croissance et Cancer, Université François Rabelais de Tours, 10, bd Tonnellé, 37032 Tours, Cedex, France; CHRU de Tours, Département de Médecine Interne, 2, boulevard Tonnellé, 37044 Tours, Cedex 9, France. Electronic address: maillot@med.univ-tours.fr.
authors.forename: François
authors.initials: F
authors.lastname: Maillot
authors.affiliation: Department of Pharmacology and Therapeutics, Biochemistry and Medical Genetics, Faculty of Health Sciences, Center for Research and Treatment of Atherosclerosis, DREAM Children's Hospital Research Institute of Manitoba, University of Manitoba, 513-715 McDermot Avenue Winnipeg MB R3E 3P4, Manitoba, Canada. Electronic address: ghatch@chrim.ca.
authors.forename: Grant M
authors.initials: GM
authors.lastname: Hatch
authors.affiliation: Inserm UMR S-991, Foie, Métabolismes et Cancer, CHU Pontchaillou, 2 rue Henri Le Guilloux, 35033 Rennes, France; Université de Rennes 1, 2 rue du Thabor CS46510, 35065 Rennes, Cedex, France. Electronic address: pascal.loyer@univ-rennes1.fr.
authors.forename: Pascal
authors.initials: P
authors.lastname: Loyer
authors.affiliation: Inserm UMR1069, Nutrition, Croissance et Cancer, Université François Rabelais de Tours, 10, bd Tonnellé, 37032 Tours, Cedex, France. Electronic address: stephane.servais@univ-tours.fr.
authors.forename: Stephane
authors.initials: S
authors.lastname: Servais
mesh_terms: D000255:Adenosine Triphosphate / Q000096:biosynthesis*; D002308:Cardiolipins / Q000032:analysis*; D002478:Cells, Cultured; D004579:Electron Transport; D004734:Energy Metabolism; D022781:Hepatocytes / Q000378:metabolism*; D006801:Humans; D008928:Mitochondria / Q000378:metabolism
chemical_list: D002308:Cardiolipins; D000255:Adenosine Triphosphate
keywords: Cardiolipin synthase; Hepatocytes; Mitochondrial network; Oxidative phosphorylation; Supercomplexes