A cell-specific activator in the Xenopus A2 vitellogenin gene: promoter elements functioning with rat liver nuclear extracts.

Abstract

Transfection experiments using Xenopus vitellogenin A2 gene constructs allowed us to identify an activator which increases the activity of the thymidine kinase promoter. The activator is located between −121 and −87 of the A2 vitellogenin gene and is separated by a stretch of curved DNA from the estrogen‐responsive DNA element at −331. The activator functions in a cell‐specific manner, as it is active in human breast cancer cells (MCF‐7) as well as hepatoma cells but not in fibroblasts or HeLa cells. The activator is composed of at least three elements: elements 1 and 2 which form a partial palindrome, function independently, but act synergistically when combined. Element 3 is not active on its own, but supports elements 1 and 2. A TATA box region derived from the Xenopus albumin gene is sufficient for the function of the activator. In vitro transcription experiments using rat liver nuclear extracts demonstrate that the activator interacts with transcription factors. These factors are distinct from those recognizing HP1, a regulatory element common to several genes specifically expressed in hepatocytes.

Mutational studies reveal a complex set of positive and negative control elements within the chicken vitellogenin II promoter.

“…The fact that three of the four factor-binding sites identified in the present study correspond to sites that were previously shown to be footprinted in vivo in response to estrogen (31) indicates that our results are very probably relevant to the normal regulation of this gene. A comparison of these results with data recently reported for the frog vitellogenin gene promoters (11,13) suggests that vitellogenin promoters have evolved much more than might have been predicted on the basis of sequence comparisons alone.…”

Intrinsic Bent DNA Sites in the Developmentally AmplifiedC3-22Gene Promoter ofRhynchosciara americana(Diptera: Sciaridae)

“…Several TATA-box-containing promoters have a bent DNA structure upstream of the TATAbox. 12,36,48) The helix trajectories of 504 vertebrate promoters indicate that all regions containing a TATAbox (either canonical or non-canonical) form curved DNA structures, 49) suggesting that intrinsic DNA curvature is important in the recognition of the TATA-box by TATA-box binding protein, TBP.…”

Identification of a Transactivation Function in the Progesterone Receptor That Interacts with the TAFII110 Subunit of the TFIID Complex

“…In Vitro Transcription-In vitro transcription reactions contained 6 l of rat liver nuclear extract (6.3 g/l) prepared as described by Döbbeling et al (32). E. coli mock extract, recombinant MH 6 -hPR(DBD), and recombinant MH 6 -hPR0 added to some of the reactions were expressed in E. coli or Sf21 cells infected with recombinant baculovirus, respectively, and purified as described above.…”