c-Abl tyrosine kinase regulates c-fos gene expression via phosphorylating RNA polymerase II.

c-Abl tyrosine kinase, predominantly distributed in nucleus, has been implicated in many important cellular processes including the regulation of gene transcription. In this study, we showed that c-Abl promoted the transcription of c-fos gene, both exogenously and endogenously. The nuclear localization and tyrosine kinase activity of c-Abl were required for the activation of c-fos gene. c-Abl was associated with RNA polymerase II (RNAP II) in vivo and augmented the tyrosine phosphorylation of the largest subunit of RNAP II. In addition, c-Abl and RNAP II could be recruited to the region of c-fos promoter. The combined results suggest that c-Abl plays an important role in the transcriptional regulation of c-fos gene and the tyrosine phosphorylation of the largest subunit of RNAP II by c-Abl is involved in the regulating process.