Protein kinase CKII (CKII), a heterotetramer composed of two catalytic (alpha or alpha') subunits and two regulatory (beta) subunits, plays a critical role in cell proliferation and anti-apoptosis. Recently, capsaicin was shown to trigger apoptosis. Therefore, we examined the effect of capsaicin on CKII activity. Although capsaicin induced apoptotic death in HeLa cells, CKII activity was increased in the cytosolic fraction of HeLa cells after treatment. Capsaicin did not change the expression of the CKIIalpha and CKIIbeta proteins. Capsaicin stimulated the catalytic activity of recombinant CKII tetramer, but not the CKIIalpha subunit. Moreover, capsaicin enhanced the autophosphorylation of CKIIalpha and CKIIbeta. Taken together, our data suggest that capsaicin stimulates the phosphotransferase activity of CKII holoenzyme by interacting with the CKIIbeta subunit.
Capsaicin Capsicum