title: Stability of F-box protein atrogin-1 is regulated by p38 mitogen-activated protein kinase pathway in cardiac H9c2 cells.
abstract: BACKGROUND
  Atrogin-1/MAFbx is a major atrophy-related E3 ubiquitin ligase that functions as a negative regulator of cardiac hypertrophy. The mRNA expression of atrogin-1 is induced by oxidative stress via p38 mitogen-activated protein kinase (p38 MAPK). However, the molecular mechanisms that regulate the stability of atrogin-1 protein remain unclear.
  
  
  METHODS
  293T and cardiac H9c2 cells were transfected with plasmids as indicated. The in vivo and in vitro ubiquitination assay and pulse-chase analysis were performed to detect the ubiquitination and stability of atrogin-1. The protein levels were measured by Western blot analysis.
  
  
  RESULTS
  We found that atrogin-1 underwent ubiquitin-mediated degradation by proteasome. The F-box motif of atrogin-1 and Skp1-Cul1-Roc1-F-box (SCF) complex are required for ubiquitination and degradation of atrogin-1. Furthermore, p38 MAPK signaling plays critical roles in regulating the ubiquitination and degradation of atrogin-1 as well as serum starvation-induced expression of atrogin-1 and reduction of H9c2 cell size.
  
  
  CONCLUSIONS
  These findings may define a new mechanism for regulating the stability of atrogin-1 partially by p38 MAPK signaling.
authors.affiliation: Department of Pathology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences and Peking Union Medical College, No.10 Xitoutiao, You An Men, Beijing, China.
authors.forename: Jun-Jie
authors.initials: JJ
authors.lastname: Li
authors.forename: Tian-Peng
authors.initials: TP
authors.lastname: Zhang
authors.forename: Yan
authors.initials: Y
authors.lastname: Meng
authors.forename: Jie
authors.initials: J
authors.lastname: Du
authors.forename: Hui-Hua
authors.initials: HH
authors.lastname: Li
mesh_terms: D000818:Animals; D015153:Blotting, Western; D006332:Cardiomegaly / Q000235:genetics / Q000378:metabolism*; D048429:Cell Size; D002478:Cells, Cultured; D044782:F-Box Motifs; D006801:Humans; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism*; D010957:Plasmids; D011485:Protein Binding; D051381:Rats; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism*; D044843:SKP Cullin F-Box Protein Ligases / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014162:Transfection; D025801:Ubiquitin / Q000378:metabolism*; D054875:Ubiquitination; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*
chemical_list: D009124:Muscle Proteins; D011994:Recombinant Proteins; D025801:Ubiquitin; C440907:FBXO32 protein, human; D044843:SKP Cullin F-Box Protein Ligases; D048051:p38 Mitogen-Activated Protein Kinases