Raf-1 and B-Raf promote protein kinase C theta interaction with BAD.
PKCtheta regulates the proliferation, survival and differentiation of T-cells. Here we show that PKCtheta interacts with Raf-1 and B-Raf kinases. Raf-1 enhanced the kinase activity of associated PKCtheta, while PKCtheta reduced the catalytic activity of associated Raf-1. In contrast, B-Raf binding did not affect PKCtheta kinase activity, and PKCtheta did not change B-Raf activity. Coexpression of mutationally activated Raf-1 in cells enhanced the phosphorylation of T538 in the PKCtheta activation loop. PKCtheta and Raf cooperated in terms of binding to BAD, a pro-apoptotic Bcl-2 family protein that is inactivated by phosphorylation. While neither Raf-1 nor B-Raf could phosphorylate BAD, they enhanced the ability of PKCtheta to interact with BAD and to phosphorylate BAD in vitro and in vivo, suggesting a new role for Raf proteins in T-cells by targeting PKCtheta to interact with and phosphorylate BAD.
Hindley
Alison
A
Signalling and Proteomics Laboratory, The Beatson Institute for Cancer Research, Garscube Estate, Switchback Road, Glasgow G61 1BD, UK.
Kolch
Walter
W
D000818:Animals; D019556:COS Cells; D045744:Cell Line, Tumor; D002522:Chlorocebus aethiops; D006801:Humans; D019169:Jurkat Cells; D011493:Protein Kinase C / Q000378:metabolism*; D048493:Proto-Oncogene Proteins B-raf / Q000378:metabolism*; D019908:Proto-Oncogene Proteins c-raf / Q000378:metabolism*; D018411:Spodoptera / Q000166:cytology / Q000378:metabolism; D051025:bcl-Associated Death Protein / Q000235:genetics / Q000378:metabolism*
D051025:bcl-Associated Death Protein; C482119:BRAF protein, human; D048493:Proto-Oncogene Proteins B-raf; D019908:Proto-Oncogene Proteins c-raf; D011493:Protein Kinase C