Phorbol Ester Stimulates Expression of the Human Tryptophanyl-tRNA Synthetase Gene

The effect of the phorbol ester phorbol 12-myristate 13-acetate (PMA) on expression of the human interferon (IFN)-inducible tryptophanyl-tRNA synthetase (WRS) gene was studied. PMA caused an increase in the basal and IFNγ-induced WRS protein content in HeLa and HEK293 cultured cells. Besides, PMA upregulated WRS mRNA level in HeLa cells. Since PMA is known as a selective activator of protein kinase C (PKC) and is widely used to study the PKC-related pathways, these results show possible PKC involvement in regulation of the WRS gene expression. PKC inhibition by staurosporine (10 and 100 nM) had no effect on either basal or IFNγ-induced expression of WRS in either cell line. Consequently, PKC is not an indispensable element in WRS induction by IFNγ. Rather, PKC may activate WRS gene expression only by a distinct pathway.