Breen GA, Jordan EM. Upstream stimulatory factor 2 stimulates transcription through an initiator element in the mouse cytochrome c oxidase subunit Vb promoter.
BIOCHIMICA ET BIOPHYSICA ACTA 2000;
1517:119-27. [PMID:
11118624 DOI:
10.1016/s0167-4781(00)00269-4]
[Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Upstream stimulatory factor (USF) is a basic helix-loop-helix-leucine zipper transcription factor that plays an important role in transcriptional activation and cell proliferation. In this article, we demonstrate that the mouse cytochrome c oxidase subunit Vb gene (Cox5b) can be transactivated by ectopic expression of USF2 through an initiator (Inr) element in the core promoter. Importantly, using a dominant-negative mutant of USF2, we demonstrate the role of endogenous USF2 proteins in the transcriptional activation of the Cox5b Inr. Domains of USF2 encoded by exon 4, exon 5 and the USF-specific region are important for maximum activation of the Cox5b Inr. Using the adenovirus E1A oncoprotein, we show that p300/CBP acts as a coactivator in the USF2-dependent activation of the Cox5b Inr. We also demonstrate that although expression of multifunctional regulatory factor, Yin Yang 1 (YY1), can stimulate transcription of the Cox5b Inr to a modest extent, expression of YY1 together with USF2 greatly reduces the level of activation of the Cox5b Inr. Furthermore, we show that the transcription factor, Sp1, represses both the YY1- and the USF2-dependent activation of the Cox5b Inr, indicating competition among Sp1, YY1, and USF2.
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