DNA sequences required for efficient transcription of the estrogen regulated Xenopus laevis vitellogenin promoter

In liver cells of Xenopus laevis expression of the vitellogenin genes is tightly regulated by estrogen. Estrogen activates gene transcription by binding as estradiol-estrogen receptor complex to estrogen response elements (EREs) in the 5$\sp\prime$-flanking region of target genes. In order to identify the DNA sequences essential for estrogen-regulated and liver-specific vitellogenin gene expression, we employed site-specific mutagenesis to create a variety of deletions, mutations, and insertions in the 5$\sp\prime$-flanking region of the vitellogenin B1 promoter. The effects of these mutations on promoter activity were studied by using a homologous cotransfection system developed in our laboratory with cell lines derived from Xenopus hepatocytes and fibroblasts. The role of EREs and other cis-acting sequences in the B1 promoter has been characterized. Mutation of the CAAT box or deletion of a conserved nematode box or the entire region between -301 and -121 had no significant effect on vitellogenin promoter activity. An eight base DNA element with weak sequence homology to the NF1 element is essential for efficient transcription of the B1 promoter. Deletion or mutation of this vitellogenin activator (VA) element reduces promoter activity by at least an order of magnitude. Reinsertion of this sequence into the VA-deleted construct restores promoter activity in a position dependent manner. Gel mobility shift assays have been used to identify a protein in liver cell and oocyte extracts which binds to VA sequence with high affinity and specificity. Competition studies demonstrate that this factor is a member of an NF1-like protein family. The VA region linked to a TATA box can function as a more powerful independent transcription activator than the NF1 consensus sequence in a similar construct. These data indicate that the VA binding protein is related to, but probably not identical to NF1. (Abstract shortened with permission of author.)

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biology, Molecular

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2011

Author dc:creator

• Chang, Tsu-Chung

• Biology, Molecular
• Chemistry, Biochemistry

Statement dc:rights

• Copyright 1990 Chang, Tsu-Chung

Language dc:language

eng

Identifier

AAI9021659
(UMI)AAI9021659

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/23610