Tandemly repeated hexamer sequences within the beta interferon promoter can function as an inducible regulatory element in activation by the adenovirus E1B 19-kilodalton protein

Adenovirus EIA encodes two major proteins of 289 and 243 amino acids (289R and 243R), which both have transcription regulatory properties. EIA-289R is a transactivator whereas E1A-243R primarily functions as a repressor of transcription. Here we show that ElA repression is not restricted to RNA polymerase II genes but also includes the adenovirus virus-associated (VA) RNA genes. These genes are transcribed by RNA polymerase HI and have previously been suggested to be the target of an ElA-289R-mediated transactivation. Surprisingly, we found that during transient transfection both ElA proteins repressed VA RNA transcription. EIA repression of VA RNA transcription required both conserved regions 1 and 2 and therefore differed from the ElA-mediated inhibition of simian virus 40 enhancer activity which primarily required conserved region 1. The repression was counteracted by the ElB-19K protein, which also, in the absence of ElA, enhanced the accumulation of VA RNA. Importantly, we show that efficient VA RNA transcription requires expression of both EIA and the ElB-19K protein during virus infection.

Section: Discussionsupporting

confidence: 92%

Repression of RNA polymerase III transcription by adenovirus E1A

Sollerbrant

Akusjärvi

Svensson

1993

“…gested that the 19K protein may act directly or indirectly to repress ElA-dependent early gene transcription. However, in plasmid transfection experiments, it was concluded that the ElB-19K protein stimulates expression from Ad and certain cellular promoters (26,45,54,73,91). The activation may be due, at least in part, to a relief from ElA-mediated enhancer repression (91).…”

Section: Fig 2 An Adenovirus Early Protein Protects Hel-299 Cellsmentioning

confidence: 99%

“…Increased gene expression by the ElB-19K protein has also been detected in ElA-negative Ads (26, 73, 85). However, a later report suggested that the increased transcription by the ElB-19K protein of transfected plasmids was indirect and resulted from stabilization by the ElB-19K protein of the transfected plasmid DNA (27), although this was not observed with the Adl2 ElB-19K protein (54). Therefore, the role of the ElB-19K protein in gene regulation is unclear at present.…”

Section: Fig 2 An Adenovirus Early Protein Protects Hel-299 Cellsmentioning

confidence: 99%

The E1B 19,000-molecular-weight protein of group C adenoviruses prevents tumor necrosis factor cytolysis of human cells but not of mouse cells

Gooding

Aquino

Duerksen-Hughes

et al. 1991

125

Tumor necrosis factor (TNF) is a multifunctional immunoregulatory protein that is secreted by activated macrophages and is believed to have antiviral activities. We reported earlier that when mouse C3HA fibroblasts are infected with human adenoviruses, the 289R and 243R proteins encoded by region ElA render the cells susceptible to lysis by TNF, and a 14,700-molecular-weight protein (14.7K protein) encoded by region E3 protects the cells against lysis by TNF. We now report that the 19,000-molecular-weight (19K) (176R) protein encoded by the E1B transcription unit can protect human HEL-299 fibroblasts and human ME-180 cervical carcinoma cells against lysis by TNF. This was determined by infecting cells with adenovirus double mutants that lack region E3 and do or do not express the ElB-19K protein and by measuring cytolysis by using a short-term (18-h)-5Cr-release assay. Under these assay conditions, the-5Cr release was specific to TNF and was not a consequence of the cyt phenotype associated with ElB-19K protein-negative mutants. Also, by using virus double mutants that lack E3 in combination with other early regions, we found that ElA, the ElB-55K protein-encoding gene, E3, and E4 are not required to protect HEL-299 cells against TNF cytolysis. Three additional human cancer cell lines (HeLa, HCT8, and RC29) and a simian virus 40-transformed W138 cell line (VA-13) also required E1B for protection against TNF cytolysis, indicating that the ElB-19K protein is required to protect many if not all human cell types against lysis by TNF when infected by adenovirus. The ElB-19K protein was not able to protect six different adenovirus-infected mouse cell lines against TNF lysis, even though the protein was shown to be efficiently expressed in one of the cell lines. HEL-299 or ME-180 cells infected by a mutant that lacks the ElB-19K protein but retains region E3 were not lysed by TNF, indicating that one or more of the E3 proteins can protect these cells against TNF lysis in the absence of the ElB-19K protein. Thus, the E3-14.7K but not the EIB-19K protein can protect adenovirus-infected mouse cells against TNF cytolysis, whereas the ElB-19K protein as well as one or more of the E3 proteins can protect adenovirus-infected human cells against TNF cytolysis.

“…3Y1 cells were transfected with each of pNeol2ElA, pNeo3E(12S) EMA, pNeo13SE1A, pNeoPv2ElA, pNeoRsa2ElA, pNeo SE1A, pNeo5-12E1A, pNeol2-5E1A, and pNeoElB. 3Y1 cells were also cotransfected with pSV2Neo and pMT-1 (SV40 T), SRp53, pRmyc27, pFBJ-2 (v-fos), and pMK-fos DNAs by the calcium phosphate technique described previously (32,33). At 40 h after transfection, the cells were trypsinized and replated at a 1:3 dilution.…”

Section: Rsv3y1-k-mix)mentioning

confidence: 99%

“…Assay for CAT activity. The assay for chloramphenicol acetyltransferase (CAT) activity was carried out as described previously (4,32,34). At 48 h after transfection with 0.1, 0.03, and 0.01, ,ug of LTR-CAT DNA, the cells (4-cm plate) were scraped off for the CAT assay.…”

Section: Rsv3y1-k-mix)mentioning

confidence: 99%

Highly efficient focus formation by Rous sarcoma virus on adenovirus type 12 E1A-transformed rat 3Y1 cells

Shiroki

Hamaguchi

Kawai

1992

Self Cite

When rat 3Y1 cells were infected with Rous sarcoma virus (RSV) variant SR-RSV-D(H), many 3Y1 cells acquired a stable provirus but only few of them formed transformed foci. In contrast, 12E1AY cells (3Y1 cells expressing the adenovirus type 12 [Adl2] ElA protein) formed transformed foci upon RSV infection with the same high frequency as did chicken embryo fibroblast cells. This enhancement of focus-forming efficiency was specifically observed in 3Y1 cells expressing Adl2 ElA protein but was not observed in 3Y1 cells expressing simian virus 40 T, c-myc, p53, c-fos, or v-fos protein. This enhancement was not evident in 5E1AY cells (3Y1 cells expressing the Ad5 ElA protein). Judging from the experiment using Adl2-Ad5 hybrid EIA DNAs, the N-terminal half of the Adl2 ElA protein was responsible for this enhancement. The promoter activity of the RSV long terminal repeat measured by pLTR-CAT did not correlate to the efficiency of focus formation by RSV in these 3Y1 cells. Moreover, RSV containing the neo gene instead of the src gene produced G418-resistant cells equally efficiently among 3Y1, ElAY, and chicken embryo fibroblast cells. These results suggest that the enhancement of focus formation by RSV is not due to the increased expression of the src gene by the ElA protein. src mRNA and src protein were lower in RSV-transformed ElAY (RSVElAY) cells than in RSV-transformed 3Y1 (RSV3Y1) cells. The phosphotyrosine-containing proteins were also less abundant in RSVElAY cells than in RSV3Y1 cells, suggesting that ElAY cells require a lower threshold dose of p60vs-C for transformation than do 3Y1 cells. ElAY cells were found to be more sensitive to lysis by detergents. The results suggest that the enhancement is due to changes in membrane structures of ElAY cells.