title: Free fatty acids increase PGC-1alpha expression in isolated rat islets.
abstract: PGC-1alpha mRNA and protein are elevated in islets from multiple animal models of diabetes. Overexpression of PGC-1alpha impairs glucose-stimulated insulin secretion (GSIS). However, it is not well known which metabolic events lead to upregulation of PGC-1alpha in the beta-cells under pathophysiological condition. In present study, we have investigated effects of chronic hyperlipidemia and hyperglycemia on PGC-1alpha mRNA expression in isolated rat islets. Isolated rat islets are chronically incubated with 0, 0.2 and 0.4 mM oleic acid/palmitic acid (free fatty acids, FFA) or 5.5 and 25 mM glucose for 72 h. FFA dose-dependently increases PGC-1alpha mRNA expression level in isolated islets. FFA also increases PGC-1alpha expression in mouse beta-cell-derived beta TC3 cell line. In contrast, 25 mM glucose decreases expression level of PGC-1alpha. Inhibition of PGC-1alpha by siRNA improves FFA-induced impairment of GSIS in islets. These data suggest that hyperlipidemia and hyperglycemia regulate PGC-1alpha expression in islets differently, and elevated PGC-1alpha by FFA plays an important role in chronic hyperlipidemia-induced beta-cell dysfunction.
authors.affiliation: Institute of Mecular Medicine and State Key Laboratory of Pharmaceutical Biotechnology, School of Life Sciences, Nanjing University, 22 Hankou Road, Nanjing, Jiangsu 210093, PR China.
authors.forename: Peixiang
authors.initials: P
authors.lastname: Zhang
authors.forename: Chang
authors.initials: C
authors.lastname: Liu
authors.forename: Chunni
authors.initials: C
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhang
authors.forename: Pingping
authors.initials: P
authors.lastname: Shen
authors.forename: Junfeng
authors.initials: J
authors.lastname: Zhang
authors.forename: Chen-Yu
authors.initials: CY
authors.lastname: Zhang
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D005230:Fatty Acids, Nonesterified / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects*; D005934:Glucagon / Q000494:pharmacology; D052216:Glucagon-Like Peptide 1; D005947:Glucose / Q000494:pharmacology; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism*; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008297:Male; D051379:Mice; D010446:Peptide Fragments / Q000494:pharmacology; D011498:Protein Precursors / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D014157:Transcription Factors / Q000235:genetics*
chemical_list: D005230:Fatty Acids, Nonesterified; D010446:Peptide Fragments; D011498:Protein Precursors; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D014157:Transcription Factors; C111264:peroxisome-proliferator-activated receptor-gamma coactivator-1; D005576:Colforsin; D052216:Glucagon-Like Peptide 1; D005934:Glucagon; D005947:Glucose