title: Cigarette smoke-induced skeletal muscle atrophy is associated with up-regulation of USP-19 via p38 and ERK MAPKs.
abstract: Ubiquitin-specific proteases (USPs) deubiquitinate ubiquitin-protein conjugates in the ubiquitin-proteasome system. Previous research shows that ubiquitin-specific protease-19 (USP-19) is up-regulated in mammalian skeletal muscle in some degradative conditions, such as including fasting, diabetes, dexamethasone treatment, and cancer, and its function is associated with muscle atrophy. However, it is still unclear whether USP-19 is involved in muscle atrophy induced by chronic obstructive pulmonary disease. Rats exposed to chronic cigarette smoke and L6 myotubes incubated with cigarette smoke extract (CSE) were studied here. Using western blot analysis and quantitative real-time polymerase chain reaction (qPCR), we observed over-expression of USP-19 and down-regulation of myosin heavy chain (MHC) in both models. Moreover, CSE exposure inhibited myogenic differentiation and myotube formation in L6 myotubes. To explore the mechanism underlying these effects, we investigated the levels of phosphorylated mitogen-activated protein kinases (MAPKs) and total MAPKs. Exposing myotubes to CSE resulted in the general activation of MAPKs such as p38, JNK, and ERK1/2. The ERK inhibitor PD98059 and the p38 inhibitor SB203580 significantly blocked the increase in USP-19 gene expression induced by CSE. Our findings suggest that USP-19 is associated with muscle atrophy in response to cigarette smoke and is a potential therapeutic target. CSE promotes myotube wasting in culture partly by inhibiting myogenic differentiation and acts via p38 and ERK MAPK to stimulate expression of USP-19 in vitro.
authors.affiliation: Department of Respirology, College of Medicine, Xinhua Hospital, Shanghai Jiao Tong University, Shanghai, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Liu
authors.forename: Wei-Guo
authors.initials: WG
authors.lastname: Xu
authors.forename: Yong
authors.initials: Y
authors.lastname: Luo
authors.forename: Feng-Feng
authors.initials: FF
authors.lastname: Han
authors.forename: Xiao-Hong
authors.initials: XH
authors.lastname: Yao
authors.forename: Tian-Yun
authors.initials: TY
authors.lastname: Yang
authors.forename: Yue
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wei-Feng
authors.initials: WF
authors.lastname: Pi
authors.forename: Xue-Jun
authors.initials: XJ
authors.lastname: Guo
mesh_terms: D000818:Animals; D002460:Cell Line; D010450:Endopeptidases / Q000235:genetics / Q000378:metabolism*; D048049:Extracellular Signal-Regulated MAP Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015870:Gene Expression; D008297:Male; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000473:pathology / Q000648:ultrastructure; D009133:Muscular Atrophy / Q000209:etiology* / Q000378:metabolism; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D052097:Quadriceps Muscle / Q000378:metabolism / Q000473:pathology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012907:Smoking / Q000009:adverse effects*; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D047428:Protein Kinase Inhibitors; D048049:Extracellular Signal-Regulated MAP Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D010450:Endopeptidases; C559917:USP19 protein, human; D018995:Myosin Heavy Chains