Transcription by RNA polymerase II in DNA-PK deficient scid mouse cells.

DNA-dependent protein kinase (DNA-PK) is involved in DNA repair but there is some evidence to suggest that it is also involved in regulating transcription. We used a pair of cell lines, SCVA2 and SC(8)-10, which are DNA-PK negative and positive respectively, in order to examine the effect of DNA-PK upon transcription. Initial experiments were performed using p53 as an activator of transcription because DNA-PK has been proposed as a candidate upstream activator of p53. It was found both in vivo and in vitro that efficient p53-dependent transcription required the presence of DNA-PK. However, phosphorylation of p53 by DNA-PK did not affect the DNA-binding ability of p53 nor its transcriptional activity when tested in vitro. Subsequent in vivo experiments suggested that a number of transcription activators functioned more efficiently in the presence of DNA-PK. Therefore DNA-PK may play a general role in regulation of transcription driven by RNA polymerase II. In addition, DNA-PK is shown to have no specific effect on p53-dependent transcription.