The adenovirus E1A domains required for induction of DNA rereplication in G(2)/M arrested cells coincide with those required for apoptosis

Induction of apoptosis by adenovirus E1A in rodent cells is stimulated by w ild type (wt) p53 but completely suppressed by mutated p53, The suppression is overcome by coexpression with Id proteins (Ids), The cells expressing E 1A and Ids undergo apoptosis after accumulation in S phase, suggesting that S phase events are perturbed by E1A and Ids. The E1A domains required for induction of apoptosis, analysed by transfection with expression vectors fo r E1A, Ids and their mutants, followed by flow cytometry, reside in N-termi nal (positions 17-38), CR1 and CR2 regions. Interaction of E1A with Ids req uires the N-terminal and CR1 regions. The cyclin D1 promoter activity in S phase was reduced severely by E1A and this reduction is caused through CR1 and CR2 regions required for interaction with pRB. Analysis of DNA synthesi s in G(2)/M arrested cells indicated that E1A is capable of inducing >4N ce lls and this E1A-mediated DNA rereplication is enhanced by coexpression wit h Id-1H, The E1A domains required for induction of DNA rereplication coinci de with those required for apoptosis.