title: Overexpression of acyl-CoA synthetase-1 increases lipid deposition in hepatic (HepG2) cells and rodent liver in vivo.
abstract: Accumulation of intracellular lipid in obesity is associated with metabolic disease in many tissues including liver. Storage of fatty acid as triglyceride (TG) requires the activation of fatty acids to long-chain acyl-CoAs (LC-CoA) by the enzyme acyl-CoA synthetase (ACSL). There are five known isoforms of ACSL (ACSL1, -3, -4, -5, -6), which vary in their tissue specificity and affinity for fatty acid substrates. To investigate the role of ACSL1 in the regulation of lipid metabolism, we used adenoviral-mediated gene transfer to overexpress ACSL1 in the human hepatoma cell-line HepG2 and in liver of rodents. Infection of HepG2 cells with the adenoviral construct AdACSL1 increased ACSL activity >10-fold compared with controls after 24 h. HepG2 cells overexpressing ACSL1 had a 40% higher triglyceride (TG) content (93 +/- 3 vs. 67 +/- 2 nmol/mg protein in controls, P < 0.05) after 24-h exposure to 1 mM oleate. Furthermore, ACSL1 overexpression produced a 60% increase in cellular LCA-CoA content (160 +/- 6 vs. 100 +/- 6 nmol/g protein in controls, P < 0.05) and increased [(14)C]oleate incorporation into TG without significantly altering fatty acid oxidation. In mice, AdACSL1 administration increased ACSL1 mRNA and protein more than fivefold over controls at 4 days postinfection. ACSL1 overexpression caused a twofold increase in TG content in mouse liver (39 +/- 4 vs. 20 +/- 2 mumol/g wet wt in controls, P < 0.05), and overexpression in rat liver increased [1-(14)C]palmitate clearance into liver TG. These in vitro and in vivo results suggest a pivotal role for ACSL1 in regulating TG synthesis in liver.
authors.affiliation: Diabetes and Obesity Research Program, Garvan Institute of Medical Research, 384 Victoria St. Darlinghurst, New South Wales, 2010, Australia.
authors.forename: Heidi A
authors.initials: HA
authors.lastname: Parkes
authors.forename: Elaine
authors.initials: E
authors.lastname: Preston
authors.forename: Donna
authors.initials: D
authors.lastname: Wilks
authors.forename: Mercedes
authors.initials: M
authors.lastname: Ballesteros
authors.forename: Lee
authors.initials: L
authors.lastname: Carpenter
authors.forename: Leonie
authors.initials: L
authors.lastname: Wood
authors.forename: Edward W
authors.initials: EW
authors.lastname: Kraegen
authors.forename: Stuart M
authors.initials: SM
authors.lastname: Furler
authors.forename: Gregory J
authors.initials: GJ
authors.lastname: Cooney
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D045744:Cell Line, Tumor; D003066:Coenzyme A Ligases / Q000096:biosynthesis* / Q000097:blood / Q000235:genetics / Q000378:metabolism; D004435:Eating; D005230:Fatty Acids, Nonesterified / Q000097:blood / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000096:biosynthesis / Q000235:genetics; D015151:Immunoblotting; D050356:Lipid Metabolism / Q000502:physiology*; D008099:Liver / Q000033:anatomy & histology / Q000201:enzymology / Q000378:metabolism*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009765:Obesity / Q000201:enzymology / Q000378:metabolism*; D019301:Oleic Acid / Q000235:genetics / Q000378:metabolism; D009929:Organ Size; D012313:RNA / Q000737:chemistry / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014280:Triglycerides / Q000097:blood
chemical_list: D005230:Fatty Acids, Nonesterified; D014280:Triglycerides; D049452:Green Fluorescent Proteins; D019301:Oleic Acid; D012313:RNA; D003066:Coenzyme A Ligases; C561832:Acsl1 protein, rat