Adenovirus E1a proteins repress expression from polyomavirus early and late promoters.
AUTOR(ES)
Velcich, A
RESUMO
We have examined the effects of the E1a products of adenovirus types 5 and 12 on the expression of polyomavirus early and late promoters. In cotransfection experiments in HeLa cells, plasmids expressing the E1a region of adenovirus type 5 or 12 repressed both the early and late promoters of polyomavirus, and deletion analysis indicates that the polyomavirus enhancers were the target of the E1a repression. With mutants lacking enhancer sequences, the polyomavirus early promoter but not the late promoter was trans-activated by E1a. Chimeric mutant plasmids with deletions in the regulatory region that contained either the A enhancer or the B enhancer were repressed to the same extent, indicating that E1a can repress both elements. Polyomavirus variant plasmids with rearrangements in the regulatory region conferring activity in embryonal carcinoma stem cells were repressed by E1a as was the wild type, suggesting that the repressor function is quite general. We discuss a model in which the influence of E1a on the transcriptional activity of a gene is the sum of positive and negative effects on promoter and enhancer elements and discuss possible mechanisms of negative regulation of enhancer function.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=367166Documentos Relacionados
- ICP22 homolog of equine herpesvirus 1: expression from early and late promoters.
- Complementary functions of E1a conserved region 1 cooperate with conserved region 3 to activate adenovirus serotype 5 early promoters.
- Upstream DNA sequences determine different autoregulatory responses of the adenovirus types 5 and 3 E1A promoters.
- Differentiation-specific expression from the bovine papillomavirus type 1 P2443 and late promoters.
- Vector expression of adenovirus type 5 E1a proteins: evidence for E1a autoregulation.