Note (General)AbstractWe examined the biological functions of the gene Cbl in erythropoietin (EPO) signaling using Cbl-deficient F-36P human erythroleukemia cells by the introduction of the Cbl siRNA expression vector. Knockdown of Cbl promoted EPO-dependent proliferation and survival of F-36P cells, especially at a low concentration of EPO (0.01 U/mL), similar to serum concentrations of EPO in healthy volunteers (0.005–0.04 U/mL). We found that Src was degraded mainly by the proteasomal pathway because the proteasome inhibitor MG-132 but not the lysosome inhibitor NH4Cl suppressed the EPO-induced degradation of Src in F-36P cells and that knockdown of Cbl inhibited EPO-induced ubiquitination and degradation of Src in F-36P cells. The experiments using the Src inhibitor PP1 and co-expression experiments further confirmed that Cbl and the kinase activity of Src are required for the EPO-induced ubiquitination of Src. In addition, the co-expression experiments and in vitro kinase assay demonstrated that the EPO-induced tyrosine phosphorylation and ubiquitination of Cbl were dependent on the kinase activity of Src but not Jak2. Thus, Cbl negatively regulates EPO signaling mainly through the proteasome-dependent degradation of Src, and the E3 ligase activity of Cbl and its tyrosine phosphorylation are regulated by Src but not Jak2.
DOIinfo:doi/10.1016/j.bcmd.2014.06.005
Collection (particular)国立国会図書館デジタルコレクション > デジタル化資料 > 博士論文
Date Accepted (W3CDTF)2016-12-01T22:39:34+09:00
Data Provider (Database)国立国会図書館 : 国立国会図書館デジタルコレクション