Stability of F-box Protein Atrogin-1 is Regulated by p38 Mitogen-activated Protein Kinase Pathway in Cardiac H9c2 Cells

摘要

Backgroud 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 iin vivo/i and iin vitro/i 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. Conclusion These findings may define a new mechanism for regulating the stability of atrogin-1 partially by p38 MAPK signaling.