EXPRESSION OF 6 PROTEIN-KINASE-C ISOTYPES IN ENDOTHELIAL-CELLS

Protein kinase C (PKC) family is an important regulatory element in signal transduction, cellular regulation and tumor promotion. The classical PKC isotypes (alpha, beta and gamma) are Ca2+-dependent and can be activated by diacylglyserol. The novel isotypes, PKC delta, PKC epsilon, PKC eta(L) and PKC theta, are Ca2+-independent, whereas the two atypical PKCs (zeta and lambda) lack the Ca2+ binding region and are not activated by diacylglyserol. Here we show that cultured human endothelial cell line EA.hy926 as well as freshly isolated human umbilical vein endothelial cells express members of all PKC subfamilies. No traces of PKC gamma or delta were detected in endothelial cells. On the contrary the classical PKCs (alpha and beta), the novel PKC epsilon, as well as the atypical PKC zeta are present at the mRNA level in human endothelial cells and the corresponding proteins are also detected by immunoblotting.