Lytic and transforming functions of individual products of the adenovirus E1A gene

Abstract

To distinguish the individual roles of the 13S, 12S, and 9S adenovirus ElA gene products, we isolated the corresponding cDNA clones and recombined them into both plasmids and viruses. Only the expected ElA mRNA products were made from the corresponding 12S and 13S viruses. The 9S mRNA was detected when the 9S virus was coinfected with the 13S virus but not when either virus was infected alone. The 13S virus formed plaques equally well in 293 cells, HeLa cells, and A549 cells, a human lung oat cell carcinoma line. Plaque titers of the 12S virus were much reduced in HeLa and A549 cells compared with 293 cells, although the 12S virus is multiplicity-dependent leaky in both HeLa and A549 cells. A549 cells were significantly more permissive than HeLa cells for growth of the 12S virus. In A549 cells even at low multiplicities of infection the final yield of 12S virus eventually approached the maximum yield from 293 cells. Expression from the adenovirus early region 2 and early region 3 promoters in HeLa cells was activated in the presence of a 13S cDNA ElA region but not in the presence of a 12S ElA cDNA region. Although defective for lytic growth in HeLa cells, the 12S virus immortalized BRK cells at very high efficiency, whereas infection of these cells with 13S virus, as with wild-type ElA virus, resulted mainly in cell death. The 13S product does have an immortalization function, however, revealed in the absence of adenovirus lytic functions when a plasmid containing the ElA 13S cDNA region was transfected into BRK cells. The 9S virus failed to immortalize infected BRK cells or to interfere with focus formation when coinfected with the 12S virus.

BS69, a novel adenovirus E1A-associated protein that inhibits E1A transactivation.

“…Similarly, the pRb-related p107 can bind to the transactivation domain of E2F-4 and of c-Myc, in each case causing a dramatic decrease in transactivation (Beijersbergen et al, 1994a,b), and MDM-2 which can suppress p53 transactivation (Oliner et al, 1993). CR3 of 289R ElA is not strictly required for transformation by ElA (Moran et al, 1986). It is therefore unlikely that BS69, like pRb and p107, is a protein with growth inhibitory activity.…”

“…It is likely that ElA can also activate the expression of several cellular genes by competing with pRb, p107 or p130 from inactive E2F complexes (Bagchi et al, 1990). This activity requires conserved regions 1 and 2 of ElA and is independent of the activation domain that is specified by CR3 (Moran et al, 1986). Secondly, ElA can be recruited to promoters through direct binding to sequence-specific DNA binding proteins.…”

Suppression of adenovirus type 5 E1A‐mediated transformation and expression of the transformed phenotype by caffeic acid phenethyl ester (CAPE)

“…CREF cells expressing the 289-or 243-aa Ad5 E1A protein were constructed by cotransfection of CREF cells with 20 p g Ad5 135 E1A cDNA [9,10] or Ad5 125 E1A cDNA [9,10] (both kindly supplied by Drs. 6.…”

Adenovirus E1A 12S protein induces DNA synthesis and proliferation in primary epithelial cells in both the presence and absence of serum

“…The 13S protein is capable of transactivating viral early genes. The 12S protein expressed from an intact viral genome does not transactivate other adenoviral genes (17,35,37). Whether the 12S protein possesses any transactivating activity remains controversial and may depend upon the experimental system used.…”

“…A virus that carries an adenovirus 2 (Ad2) ElA 12S cDNA in place of the normal ElA region is defective for transcriptional activation of viral early genes and thus replicates inefficiently in permissive human Hela cells (37). Because the ElA 12S cDNA virus can be used to efficiently infect all of the cells in a culture and because it is not cytotoxic, we used it to study the early effects of the 12S gene product on primary baby rat kidney (BRK) cells.…”