Adenovirus E1A coding sequences that enable ras and pmt oncogenes to transform cultured primary cells.

Abstract

Plasmids expressing partial adenovirus early region 1A (ElA) coding sequences were tested for activities which facilitate in vitro establishment (immortalization) of primary baby rat kidney cells and which enable the T24 Harvey ras-related oncogene and the polyomavirus middle T antigen (pmt) gene to transform primary baby rat kidney cells. ElA cDNAs expressing the 289-and 243-amino acid proteins expressed both ElA transforming functions. Mutant hrA, which encodes a 140-amino acid protein derived from the amino-terminal domain shared by the 289-and 243-amino acid proteins, enabled ras (but not pmt) to transform and facilitated in vitro establishment to a low, but detectable, extent. These studies suggest that ElA functions which collaborate with ras oncogenes and those which facilitate establishment are linked. Furthermore, ElA transforming functions are not associated with activities of the 289-amino acid ElA proteins required for efficient transcriptional activation of viral early region promoters.

Different functional domains of the adenovirus E1A gene are involved in regulation of host cell cycle products.

“…This was similar to our finding that the 13S but not the 12S ElA product stimulated rapid trans activation of the cellular TS gene in primary BRK cells. Early activation of TS may be part of the virus's usurpation of the host DNA replication machinery but does not appear to be required for induction of cell proliferation during 12S virus infection; examination of BRK cell lines established by either 12S or 13S plasmid transfection (73) showed similar levels of TS nuclear RNA expression in both cell lines (data not shown).…”

“…As the 12S and 13S products are both able to establish primary BRK cells (73) and induce cellular DNA synthesis (29,60), these activities appear to be independent of the facilitated trans activation activity for viral and certain cellular genes that is conferred by the presence of the 13S unique region (domain 3) in the ElA products. Thus, there appear to be different regulatory domains in the ElA gene with the ability to activate different sets of target genes.…”

“…1). The presence of conserved domain 3 in the ElA products appears to correlate strongly with the ability of the ElA gene products to trans activate the other virus genes efficiently, while various transformation-related activities of the ElA region appear to be independent of this domain (8,15,21,23,26,42,43,50,63,73).…”

Neoplastic transformation by Notch is independent of transcriptional activation by RBP-J signalling

“…This biological activity of the ANK domain was speci®c for Notch-IC since other ankyrin repeat containing proteins like IkappaB could not substitute for Notch-IC in this assay (data not shown). All results were con®rmed by testing MTE1A cells, which express E1A under the control of the metal- Transformation by Notch is independent of RBP-J signalling E Dumont et al lothionin promoter (Zerler et al, 1986). In order to exclude speci®c contributions of the cellular background of the RK3E cells, the Notch-IC, the RAMANK and the ANK fragments were tested for RBP-J dependent transcription in these cells ( Figure 4b).…”

Mapping of adenovirus 5 E1A domains responsible for suppression of neu-mediated transformation via transcriptional repression of neu

“…The E1A CR2 domain is known to bind with the RB family of proteins, leading to immortalization of the primary culture cells and in cooperation with ras or E1B oncogenes, E1A can lead to transformation (Whyte et al, 1989;Corbeil and Branton, 1994). Deletion of the CR2 domain or even a site mutation to knock out the RB-binding site on E1A is su cient to abolish the immortalization function of E1A (Lillie et al, 1986;Moran et al, 1986;Zerler et al, , 1987Schneider et al, 1987;Kuppuswamy and Chinnadurai, 1987;Smith and Zi , 1988;Jelsma et al, 1989;Whyte et al, 1989). Thus, the deletion of the CR2 and CR3 domains in the mini-E1A would abolish the potential risk of immortalization and consequent transformation caused by wild type E1A.…”