Metallothionein 2A interacts with the kinase domain of PKCmu in prostate cancer

Prostate cancer (PC) patients die from progression to androgen independence (AI) and chemoresistance (CR). Protein kinase Cmu (PKCmu) a novel member of the PKC family of signal transduction proteins is downregulated in AI PC. Studying PKCmu interactors in the yeast two-hybrid system identified metallothionein 2A (MT 2A) as an interactor of PKCmu kinase domain (KD) in PC, which was quantified by beta-gal assay, confirmed in PC cells by immunoprecipitation, and PKCmu-MT 2A co-localization in vivo by immunofluorescence studies. PKCmu domain interaction studies revealed that MT 2A interacted strongly with KD, relatively weakly with C1, and failed to interact with C2, PH or kinase mutant domains. Peptide library and in silico analysis strongly suggest that MT 2A is a novel substrate of PKCmu and our data indicate that the PKCmu-MT 2A interaction depends on PKCmu kinase activity. Because metallothioneins are associated with cell proliferation and CR, the PKCmu-MT 2A interaction may contribute to CR and/or AI in PC.