INTERACTION OF RETINOBLASTOMA GENE-PRODUCT WITH TRANSCRIPTION FACTORSATFA AND ATF2

Two highly related transcription factors, activating transcription fac tors a and 2 (ATFa and ATF2) are able to activate expression in CHO ce lls of a reporter gene driven by the human transforming growth factor P2 gene promoter. This action is dependent on the intact motif CGTCA w hich is found as part of the cAMP responsive element in a number of pr omoters and to which both factors can bind in vitro. The retinoblastom a gene product also weakly stimulates expression of this reporter gene but, in combination with the factors, it exhibits a differential acti on: additive or greater stimulatory effects with ATF2 but strong inhib ition of the actions of ATFa. Thus, although both of these two related factors are able to exert the same apparent effect on this promoter, coexpression of the retinoblastoma gene product reveals at least one s ignificant difference in their actions. (C) 1995 Academic Press, Inc.