Hirano M, Hirai S, Mizuno K, Osada S, Hosaka M, Ohno S
Department of Molecular Biology, Yokohama City University School of Medicine, Japan.
Biochem Biophys Res Commun. 1995 Jan 5;206(1):429-36. doi: 10.1006/bbrc.1995.1059.
In order to examine whether PKC is involved in the activation of NF-kappa B by TPA, we overexpressed a variety of PKC isozymes in rat 3Y1 fibroblasts and monitored the expression of the co-transfected reporter NF-kappa B gene. In contrast to TPA response element (TRE), where overexpression of a variety of PKC isozymes results in enhanced activation by TPA, activation of NF-kappa B by TPA is not enhanced by overexpression of PKC isozymes such as cPKC alpha, nPKC delta, or nPKC theta. However, the overexpression of nPKC epsilon does result in enhancement. A kinase-negative point mutant of nPKC epsilon, where Lys at the ATP binding site is altered to Arg, does not cause this enhancement of NF-kappa B activation. Further, the kinase-negative nPKC epsilon partially suppresses endogenous NF-kappa B activity. These results suggest that nPKC epsilon is specifically involved in the activation of NF-kappa B when cells are treated with TPA.
为了研究蛋白激酶C（PKC）是否参与佛波酯（TPA）对核因子-κB（NF-κB）的激活过程，我们在大鼠3Y1成纤维细胞中过表达了多种PKC同工酶，并监测共转染的报告基因NF-κB的表达情况。与佛波酯反应元件（TRE）不同，在TRE中过表达多种PKC同工酶会导致佛波酯激活增强，但佛波酯对NF-κB的激活并不会因过表达如经典PKCα、新型PKCδ或新型PKCθ等PKC同工酶而增强。然而，过表达新型PKCε确实会导致激活增强。新型PKCε的激酶失活点突变体（其中ATP结合位点的赖氨酸被改变为精氨酸）不会引起NF-κB激活的这种增强。此外，激酶失活的新型PKCε会部分抑制内源性NF-κB活性。这些结果表明，当细胞用佛波酯处理时，新型PKCε特异性参与NF-κB的激活。
