Expression of six protein kinase C isotypes in endothelial cells

Abstract

Protein kinase C (PKC) family is an important regulatory element in signal transduction, cellular regulation and tumor promotion. The classical PKC isotypes (α, β and γ) are Ca 2+-dependent and can be activated by diacylglyserol. The novel isotypes, PKCδ, PKCϵ, PKCη(L) and PKCθ, are Ca 2+-independent, whereas the two atypical PKCs (ζ and λ) lack the Ca 2+-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 PKCγ or δ were detected in endothelial cells. On the contrary the classical PKCs (α and β), the novel PKCϵ, as well as the atypical PKCζ are present at the mRNA level in human endothelial cells and the corresponding proteins are also detected by immunoblotting.