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Transcription by RNA polymerase II in DNA-PK deficient scid mouse cells
1Department of Biochemistry, University of California, 92521, Riverside, CA, USA.
Abstract:
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.
Insights
DNA-dependent protein kinase (DNA-PK) enhances transcription by RNA polymerase II. While not directly affecting p53 binding or activity, DNA-PK is crucial for efficient p53-dependent transcription in vivo.
Area of Science:
- Molecular Biology
- Genetics
- Biochemistry
Background:
- DNA-dependent protein kinase (DNA-PK) is primarily known for its role in DNA repair pathways.
- Emerging evidence suggests potential involvement of DNA-PK in the regulation of gene transcription.
- The precise mechanisms and scope of DNA-PK's transcriptional regulatory functions remain to be fully elucidated.
Purpose of the Study:
- To investigate the role of DNA-PK in transcriptional regulation.
- To determine if DNA-PK influences transcription mediated by specific activators, such as p53.
- To assess the general role of DNA-PK in RNA polymerase II-driven transcription.
Main Methods:
- Utilized DNA-PK negative (SCVA2) and DNA-PK positive (SC(8)-10) cell lines for comparative studies.
- Performed in vivo and in vitro experiments to assess transcription.
- Investigated the effect of DNA-PK on p53 DNA binding and transcriptional activity.
- Examined the influence of DNA-PK on the efficiency of various transcription activators.
Main Results:
- Efficient p53-dependent transcription, both in vivo and in vitro, requires the presence of DNA-PK.
- DNA-PK phosphorylation of p53 did not alter p53's DNA-binding ability or in vitro transcriptional activity.
- In vivo, several transcription activators demonstrated enhanced function in the presence of DNA-PK.
- DNA-PK does not exhibit a specific effect on p53-dependent transcription.
Conclusions:
- DNA-PK plays a general role in regulating transcription mediated by RNA polymerase II.
- The requirement for DNA-PK in p53-dependent transcription appears to be indirect, not through direct modulation of p53 activity.
- These findings highlight a broader function for DNA-PK beyond DNA repair, extending into transcriptional regulation.