title: Chronic leptin treatment stimulates lipid oxidation in immortalized and primary mouse skeletal muscle cells.
abstract: Leptin administration enhances lipid oxidation in skeletal muscle. Nevertheless, direct and chronic effect of leptin has not been well characterized. Here, we measured the effect of leptin on skeletal muscles and their signaling pathways using differentiated C(2)C(12) myotubes and primary myotube cultures. Differentiated myotubes expressed both the short and long forms of leptin receptors. Leptin increased lipid oxidation in myotubes in a concentration- and time-dependent manner, with significant induction of lipid oxidation occurring after 6 h. Actinomycin D completely blocked leptin-induced lipid oxidation. Leptin significantly increased phosphorylation of JAK2 and STAT3 in myotubes, and leptin-induced lipid oxidation was abolished by treatment with a JAK2 inhibitor or STAT3 siRNA. We then used mouse myotubes to measure these effects under physiological conditions. Leptin increased lipid oxidation, which again was blocked by a JAK2 inhibitor and STAT3 siRNA. These results suggest that the JAK2/STAT3 signaling pathway may underlie the chronic effects of leptin on lipid oxidation in skeletal muscles.
authors.affiliation: Discovery Research Laboratories, Kyorin Pharmaceutical Co., Ltd., 2399-1 Nogi-machi, Shimotsuga-gun, Tochigi 329-0114, Japan.
authors.forename: Yunike
authors.initials: Y
authors.lastname: Akasaka
authors.forename: Masaki
authors.initials: M
authors.lastname: Tsunoda
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Ide
authors.forename: Koji
authors.initials: K
authors.lastname: Murakami
mesh_terms: D000818:Animals; D015153:Blotting, Western; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D007473:Ion Channels / Q000235:genetics / Q000378:metabolism; D053614:Janus Kinase 2 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D020738:Leptin / Q000494:pharmacology*; D015227:Lipid Peroxidation / Q000187:drug effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D010084:Oxidation-Reduction; D010766:Phosphorylation / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000494:pharmacology; D050796:STAT3 Transcription Factor / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D000071246:Uncoupling Protein 2
chemical_list: D015820:Cadherins; D007473:Ion Channels; D020738:Leptin; D024101:Mitochondrial Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D000071246:Uncoupling Protein 2; C070896:M-cadherin; C507926:Jak2 protein, mouse; D053614:Janus Kinase 2