title: Mitochondrial uncoupling protein-2 deficiency protects steatotic mouse hepatocytes from hypoxia/reoxygenation.
abstract: Steatotic livers are sensitive to ischemic events and associated ATP depletion. Hepatocellular necrosis following these events may result from mitochondrial uncoupling protein-2 (UCP2) expression. To test this hypothesis, we developed a model of in vitro steatosis using primary hepatocytes from wild-type (WT) and UCP2 knockout (KO) mice and subjected them to hypoxia/reoxygenation (H/R). Using cultured hepatocytes treated with emulsified fatty acids for 24 h, generating a steatotic phenotype (i.e., microvesicular and broad-spectrum fatty acid accumulation), we found that the phenotype of the WT and UCP2 KO were the same; however, cellular viability was increased in the steatotic KO hepatocytes following 4 h of hypoxia and 24 h of reoxygenation; Hepatocellular ATP levels decreased during hypoxia and recovered after reoxygenation in the control and UCP2 KO steatotic hepatocytes but not in the WT steatotic hepatocytes; mitochondrial membrane potential in WT and UCP2 KO steatotic groups was less than control groups but higher than UCP2 KO hepatocytes. Following reoxygenation, lipid peroxidation, as measured by thiobarbituric acid reactive substances, increased in all groups but to a greater extent in the steatotic hepatocytes, regardless of UCP2 expression. These results demonstrate that UCP2 sensitizes steatotic hepatocytes to H/R through mitochondrial depolarization and ATP depletion but not lipid peroxidation.
authors.affiliation: Department of Microbiology and Immunology, Medical University of South Carolina, Charleston, South Carolina, USA.
authors.forename: Zachary P
authors.initials: ZP
authors.lastname: Evans
authors.forename: Arun P
authors.initials: AP
authors.lastname: Palanisamy
authors.forename: Alton G
authors.initials: AG
authors.lastname: Sutter
authors.forename: Justin D
authors.initials: JD
authors.lastname: Ellett
authors.forename: Venkat K
authors.initials: VK
authors.lastname: Ramshesh
authors.forename: Hubert
authors.initials: H
authors.lastname: Attaway
authors.forename: Michael G
authors.initials: MG
authors.lastname: Schmidt
authors.forename: Rick G
authors.initials: RG
authors.lastname: Schnellmann
authors.forename: Kenneth D
authors.initials: KD
authors.lastname: Chavin
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D015687:Cell Hypoxia / Q000502:physiology*; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D004655:Emulsions / Q000494:pharmacology; D005227:Fatty Acids / Q000378:metabolism; D005234:Fatty Liver; D022781:Hepatocytes / Q000187:drug effects / Q000378:metabolism / Q000473:pathology*; D007473:Ion Channels / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects; D051379:Mice; D008815:Mice, Inbred Strains; D018345:Mice, Knockout; D008820:Mice, Obese; D024101:Mitochondrial Proteins / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D010100:Oxygen / Q000494:pharmacology*; D010743:Phospholipids / Q000494:pharmacology; D013024:Soybean Oil / Q000494:pharmacology; D000071246:Uncoupling Protein 2
chemical_list: D004655:Emulsions; D005227:Fatty Acids; D007473:Ion Channels; D024101:Mitochondrial Proteins; D010743:Phospholipids; C000604390:Ucp2 protein, mouse; D000071246:Uncoupling Protein 2; C545823:soybean oil, phospholipid emulsion; D013024:Soybean Oil; D000255:Adenosine Triphosphate; D010100:Oxygen
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