Domains of the adenovirus E1A protein required for oncogenic activity are also required for dissociation of E2F transcription factor complexes.

Abstract

Recent experiments have shown that the cellular E2F transcription factor is found in complexes with cellular proteins and that one such complex contains the cyclin-A protein. Isolation of a cellular activity, which we term E2F-BF, can reconstitute the E2F-cyclin-A complex and has permitted a more detailed analysis of the mechanism of E1A dissociation. Through the analysis of a series of EIA mutants, we find that sequences in conserved region 1 (CR1) and conserved region 2 (CR2) are important for dissociation of the E2F complex, whereas amino-terminal sequences are not required. In contrast to the requirements for dissociation, only the CR1 sequences are required to block formation of the complex if E1A is added when the components are combined. We have also identified an activity, termed E2F-I, that inhibits E2F binding to DNA, again apparently through the formation of a complex with E2F. This inhibitory activity is also blocked by E1A, dependent on the same elements of the E1A protein that disrupt the interaction with E2F-BF. Because the E1A sequences that are important for releasing E2F from these interactions are also sequences necessary for oncogenesis, we suggest that this activity may be a critical component of the transforming activity of E1A.

Smad-dependent stimulation of type I collagen gene expression in human skin fibroblasts by TGF-β involves functional cooperation with p300/CBP transcriptional coactivators

“…CBP 1891 ± 2175 (from R Janknecht) contains amino acids 1891 ± 2175 of CBP (Janknecht et al, 1998). E1A12S contains the E1A structural gene in pBC12/CMV (Raychaudhuri et al, 1991). In E1AD2-36, amino acids 2 ± 36 of the p300-interacting domain of E1A have been deleted (Raychaudhuri et al, 1991).…”

“…E1A12S contains the E1A structural gene in pBC12/CMV (Raychaudhuri et al, 1991). In E1AD2-36, amino acids 2 ± 36 of the p300-interacting domain of E1A have been deleted (Raychaudhuri et al, 1991). pEGFP-N-FLAG-Smad3 (from H Lodish) contains N-terminal FLAG-tagged Smad3 (Liu et al, 1997b).…”

Inhibition of p53-mediated transactivation and cell cycle arrest by E1A through its p300/CBP-interacting regionSelfcloseTable

“…For cellular transformation both the Rb-and p300/CBP-interacting domains of E1A are required, while either domain is su cient for induction of DNA synthesis (Howe et al, 1990;Wang et al, 1991Wang et al, , 1993. The mechanism by which the Rb-binding region of E1A permits unscheduled DNA synthesis involves binding to Rb family members thereby releasing the E2F family of transcription factors (Bagchi et al, 1990;Raychaudhuri et al, 1991;Helin et al, 1992;Kaelin et al, 1992). However the role of the p300/CBP-binding region of E1A in either cell cycle deregulation or cellular transformation is much less clear.…”

Interactions of the p107 and Rb proteins with E2F during the cell proliferation response.

“…The DNA binding properties of this E2F-E4 heteromeric complex are quite different from that of the uncomplexed E2F molecule. E2F binding to the E2 promoter results in the formation of an unstable DNA-protein complex, whereas the E2F-E4 interaction is cooperative and generates a very stable DNA-protein complex Huang and Hearing, 1989;Neill et al, 1990;Raychaudhuri et al, 1991). Although the majority of E2F in a HeLa cell is in a form that allows interaction with the E4 protein, analysis of E2F in extracts of a variety of other cell types revealed the existence of E2F-containing complexes that prevented the interaction of E4 with E2F (Bagchi et al, 1990).…”