Nucleic Acids Research, 2001, Vol. 29, No. 11 2284-2291
© 2001 Oxford University Press
Identification of a novel activation domain in the Notch-responsive transcription factor CSL
Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia, PA 19104-6145, USA
CSL is the primary target of the Notch signaling pathway in mammalian cells. It is a DNA binding protein that generally represses transcription in the absence of Notch signaling and activates transcription upon formation of a ternary complex with NICD, the protease-generated intracellular domain of Notch. Previous mapping experiments identified the central third of CSL as both necessary and sufficient for DNA binding and activation by Notch. Here we show that CSL promotes transcription in 293T cells in the absence of added NICD and that this activity requires both the central domain plus the C-terminal third of the protein. Evidence is presented that argues against a contribution of endogenous NICD and instead supports the possibility that distinct coactivators may directly stimulate the activity of CSL in a cell type-specific manner. This conclusion supports a recent finding that Drosophila CSL (Suppressor of Hairless) can also mediate transcriptional activation in the absence of Notch.
* To whom correspondence should be addressed. Tel: +1 215 898 1047; Fax: +1 215 898 9750; Email: kadesch{at}mail.med.upenn.edu Present address:Zhenyu Tang, Department of Cancer Biology, Dana Farber Cancer Institute, 44 Binney Street, Boston, MA 02115, USA