Activation of a DNA Damage Checkpoint Response in a TAF1-Defective Cell Line

Abstract

Although the link between transcription and DNA repair is well established, defects in the core transcriptional complex itself have not been shown to elicit a DNA damage response. Here we show that a cell line with a temperature-sensitive defect in TBP-associated factor 1 (TAF1), a component of the TFIID general transcription complex, exhibits hallmarks of an ATR-mediated DNA damage response. Upon inactivation of TAF1, ATR rapidly localized to subnuclear foci and contributed to the phosphorylation of several downstream targets, including p53 and Chk1, resulting in cell cycle arrest. The increase in p53 expression and the G₁ phase arrest could be blocked by caffeine, an inhibitor of ATR. In addition, dominant negative forms of ATR but not ATM were able to override the arrest in G₁. These results suggest that a defect in TAF1 can elicit a DNA damage response.

We thank Julie Sullivan and Ping Hua for excellent technical assistance and members of the DeCaprio laboratory for advice and support. We gratefully acknowledge the gifts of cells, plasmids, and antibodies from Peter Howley, Michael Kastan, Patrick Concannon, and Stephen Elledge.

A.M.B. was supported by NIH training grant 2T32CA09361 and NRSA fellowship F32CA81745. J.R.S. is supported by an NSF Graduate Research Fellowship. J.A.D. is a Scholar of the Leukemia and Lymphoma Society. This work was supported in part by Public Health Service grants RO1-CA63113 and PO1-CA50661.