Alpha4 enhances the phosphorylation of Bcl-xL induced by c-jun N-terminal kinase (JNK)
Kano Tanabe, Kazuki Takemoto, Akihiro Goto, Ryutaro Kajihara, Hideyuki Yamamoto, Seiji Inui
1Department of Immunology andHematology,Graduate School ofHealth Sciences, Faculty ofLife Sciences,Kumamoto
2Department ofCellModulation, Institute ofMolecularEmbryology andGenetics,KumamotoUniversity, (JAPAN)
3Department ofBiochemistry,Graduate School ofMedicine,University of theRyukyus, (JAPAN)
c-Jun N-terminal kinase (JNK) phosphorylates Ser62 of Bcl-xL to induce degradation by the ubiquitin proteasome pathway inWEHI-231 cells upon BCR crosslinking. To elucidate the mechanism underlying this regulation of Bcl-xL phosphorylation, we prepared a system in which JNK phosphorylated Bcl-xLinHEK293T cells. This phosphorylationwas Ser62-specific, because the phosphorylation of the Ser62Ala (S62A)mutant formof Bcl-xL was not observed with a pSer62-specific antibody. We found that a signal transductionmolecule,alpha4, enhanced the phosphorylation of Bcl-xL by JNK.Alpha4 associated both with JNK and Bcl-xL, and was mainly localized in cytoplasm. Therefore, alpha4 may regulate the activity of JNK toward Bcl-xLin cytoplasm.
Bcl-xL; JNK, alpha4; Apoptosis; Phosphorylation.