Activation of YRP kinase by v-Src and protein kinase C-mediated signal transduction pathways.

Abstract

We have previously reported that a serine(threonine) protein kinase that phosphorylates histone Hi in vitro is activated by tyrosine phosphorylation in v-Srctransformed rat 3Y1 fibroblasts. We now refer to this kinase as YRP kinase, for tyrosine-regulated protein kinase. Since YRP kinase may play a role in mediating the growthstimulatory and morphology-altering effects of v-Src, we have further examined the signal transduction involved in the activation of YRP kinase. Although YRP kinase is constitutively activated in fibroblasts transformed by v-Src, activation of protein kinase C was also found to lead to activation ofYRP kinase. Activation of YRP kinase by protein kinase C was found to be potentiated by vanadate treatment or overexpression of c-Src. The activation of YRP kinase by v-Src, however, does not appear to be mediated by protein kinase C, suggesting that YRP kinase can be activated by two separate signal transduction pathways. Transformation of fibroblasts by vRas or v-Mil did not result in activation of YRP kinase, indicating that the MAP kinase pathway does not mediate the activation of YRP kinase by v-Src or protein kinase C.

Transcriptional Down Regulation of the nov Proto-Oncogene in Fibroblasts Transformed by p60v-src

“…CEFs were prepared from 11-day-old embryos, and secondary cultures were infected with virus as described previously (19). The viruses used in this study (Schmidt-Ruppin D strain of Rous sarcoma virus, tsNY-72, NY5H [c-Src], NYMet295 (kinase-inactive v-Src), NY315 (nonmyristylated v-Src), avian erythroleukemia virus, v-Ras, INC29, and CT10 have been described previously (7,15,19,28,32,42). CEFs were made quiescent by maintaining cultures in medium supplemented with 0.5% serum for 48 h.…”