FUNCTIONAL DIVERGENCE OF PROTEIN-KINASE-C (PKC) FAMILY MEMBERS - PKC-GAMMA DIFFERS FROM PKC-ALPHA AND PKC-BETA-II AND NPKC-EPSILON IN ITS COMPETENCE TO MEDIATE-12-O-TETRADECANOYL PHORBOL 13-ACETATE (TPA)-RESPONSIVE TRANSCRIPTIONAL ACTIVATION THROUGH A TPA-RESPONSE ELEMENT
A. Hata et al., FUNCTIONAL DIVERGENCE OF PROTEIN-KINASE-C (PKC) FAMILY MEMBERS - PKC-GAMMA DIFFERS FROM PKC-ALPHA AND PKC-BETA-II AND NPKC-EPSILON IN ITS COMPETENCE TO MEDIATE-12-O-TETRADECANOYL PHORBOL 13-ACETATE (TPA)-RESPONSIVE TRANSCRIPTIONAL ACTIVATION THROUGH A TPA-RESPONSE ELEMENT, The Journal of biological chemistry, 268(12), 1993, pp. 9122-9129
We have established an assay system where overexpression of a specific
protein kinase C (PKC) type caused by introduction of the respective
cDNA results in the enhancement of a cell response: the transcriptiona
l activation of a set of genes in response to PKC activators such as 1
2-O-tetradecanoylphorbol 13-acetate (TPA). When monitored by the expre
ssion of a reporter gene containing the chloramphenicol acetyltransfer
ase gene fused downstream of a synthetic TPA response element (TRE) or
a serum response element (SRE), the overexpression of cPKCalpha and b
etaII or nPKCepsilon all resulted in the enhancement of transcriptiona
l activation through both TRE and SRE. On the other hand, PKCgamma act
ivates TRE only very weakly, although it activates SRE in a similar ma
nner to the other PKC members examined. The overexpression of cPKCalph
a and -betaII or nPKCepsilon, but not cPKCgamma, resulted in the enhan
ced expression of the endogenous c-jun gene, which contains TRE in the
5'-upstream, promoter region. The gel mobility shift assay showed tha
t the activation of PKCgamma, as well as PKCalpha and -betaII and nPKC
epsilon, causes the increase in TRE-binding proteins, suggesting that
transcriptional activation through TRE requires an additional step, wh
ich is not activated by PKCgamma, such as a qualitative change in TRE-
binding or in TRE-associating proteins. This finding provides not only
a rationale to explain the presence of multiple PKC family members, b
ut also permits the dissection of the complex cellular signaling casca
de involving PKC family members.