Jun-Jie Li1, Tian-Peng Zhang, Yan Meng, Jie Du, Hui-Hua Li. 1. 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.
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. CONCLUSION: These findings may define a new mechanism for regulating the stability of atrogin-1 partially by p38 MAPK signaling.
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. CONCLUSION: These findings may define a new mechanism for regulating the stability of atrogin-1 partially by p38 MAPK signaling.
Authors: Xiaofang Huo; Kerry B Dunbar; Xi Zhang; Qiuyang Zhang; Stuart Jon Spechler; Rhonda F Souza Journal: Am J Physiol Gastrointest Liver Physiol Date: 2020-01-27 Impact factor: 4.052