A cellular transcription factor E4F1 interacts with an E1a-inducible enhancer and mediates constitutive enhancer function in vitro.

Abstract

Efficient transcription of the adenovirus Ela-inducible E4 gene is mediated by an Ela-dependent enhancer in vivo. In vitro, the enhancer functions constitutively in the absence of Ela, conferring high levels of transcription on the E4 and heterologous promoters. Binding of a cellular transcription factor, E4F1, to two sites within the E4 enhancer and to one other functionally important site located directly upstream of the E4 TATA box is required for transcriptional activity. The relationship between the enhancer and the TATA box proximal site is further demonstrated by the fact that the E4 enhancer can be functionally substituted by two copies of the TATA box proximal site. These and other results suggest that the E4 promoter may be comprised solely of multiple E4F1 binding sites and a TATA box. In addition to the E4 promoter, E4F1 interacts with other adenovirus early promoters and thus may be involved in the co-ordinate expression of Ela-inducible early viral genes.

Identification of factors that interact with the E1A-inducible adenovirus E3 promoter.

“…In these cases, it is possible that E1A-induced modification could affect some activity of the factor other than DNA binding. This may involve the physical relocation of factors within the nucleus, as has been suggested by Lee and Green (1987)who find that in vitro extracts from uninfected cells are as active in E4 transcription as infected whole cells. Alternatively, factor modification may alter interactions with other transcription factors and RNA polymerase II, so leading to the formation of stable initiation complexes.…”

“…Previous analysis of the E2A and E4 promoters indicated that similar factors might be interacting with specific regions of each promoter (Siva Raman et al 1986;Lee and Green 1987). Moreover, these same investigators also observed some slight competition with the E3 promoter, which we investigated further.…”

“…This suggests that E3.F2 and E2A.EF are the same factor. Lee and Green (1987)have described a factor, E4.F 1, that binds to at least three regions of the E4 promoter and is also competed by E2 promoter sequences. Subsequent competition assays strongly suggest that E3.F2 and E4.F1 are also the same factor (Lee et al 1987a).…”

The RNA Pol II sub-complex hsRpb4/7 is required for viability of multiple human cell lines

“…Secondary antibodies were anti-mouse or anti-rabbit HRP conjugated (Amersham NA931) and blots were developed using an ECL kit (Amersham NA931). Primer extension of hsRpb7 mRNA was performed as previously described (Lee and Green, 1987) using a 20nt 32 P-labeled primer (5'-CAGGATTTCGTGCTCTAGGG-3') complementary to a sequence near the 5' end (position 127-146) of hsRpb7mRNA.…”

Purification of DNA-binding transcription factors by their selective adsorption on the affinity latex particles

“…And they were examined for the ability to purify sequence-specific DNA binding factor, ATF or E4TF3, responsible for transcription of the adenovirus (Ad) early regions, E2, E3 and E4 (2)(3)(4)(5)(6)(7). This factor was quickly and efficiently purified from the extracts of HeLa cells by sequential batch-wise procedures with the affinity latex particles.…”