A family of transcriptional adaptor proteins targeted by the E1A oncoprotein

Abstract

THE cellular protein p300 is a target of the adenoviral El A oncoprotein and is thought to participate in preventing the GO/G1 transition in the cell cycle, activating certain enhancers and stimulating differentiation pathways1. CBP is a protein that is associated with and coactivates the transcription factor CREB, mediating the induction by cyclic AMP of certain responsive promoters2–4. The sequences of p300 and CBP are highly related4,5. We show here that p300, like CBP2, can stimulate transcription. This activity is directly and specifically inhibited by E1A. We also find that CBP exists in a DNA-bound complex containing a member of the CREB family and that El A and CBP interact with one another in vivo. In keeping with the idea that El A functionally targets CBP, cAMP-dependent transcription is repressed by El A. Thus, p300 and CBP define a family of transcriptional adaptor proteins that are specifically targeted by the El A oncoprotein.