YY1 Is a Positive Regulator of Transcription of the Col1a1 Gene

Franck B. Riquet, Lujian Tan, Bob K. Choy, Makoto Osaki, Gerard Karsenty, Timothy F. Osborne, Philip E. Auron, Mary B. Goldring

Research output: Contribution to journalArticlepeer-review

Abstract

Both cell-specific and ubiquitous transcription factors in fibroblasts have been identified as critical for expression of the Col1a1 gene, which encodes the α1 chain of type I collagen. Here, we report that Yin Yang 1 (YY1) binds to the Col1a1 promoter immediately upstream of the TATA box, and we examine the functional implications of YY1 binding for regulation of Col1a1 gene expression in BALBc/3T3 fibroblasts. The Col1a1 promoter region spanning base pairs (bp) -56 to -9 bound purified recombinant YY1 and the corresponding binding activity in nuclear extracts was supershifted using a YY1-specific antibody. Mutation of the TATA box to TgTA enhanced YY1 complex formation. Mutation analysis revealed two YY1 core binding sites at -40/-37 bp (YY1A) and, on the reverse strand, at -32/-29 bp (YY1B) immediately adjacent to the TATA box. In transfections using Col1a1-luciferase constructs, mutation of YY1A decreased activity completely (wild-type p350 (p350wt), -222/+113 bp) or partially (p130wt, -84 bp/+13 bp), whereas mutation of YY1B blocked the expression of both promoter constructs. Cotransfection with pCMV-YY1 increased p350wt and p130wt activities by as much as 10-fold, whereas antisense YY1 decreased constitutive expression and blocked the increased activity due to pCMV-YY1 overexpression. The mTgTA constructs were devoid of activity, arguing for a requirement for cognate binding of the TATA box-binding protein (TBP). Electrophoretic mobility shift assays performed under conditions permitting TBP binding showed that recombinant TBP/TFIID and YY1 could bind to the -56/-9 bp fragment and that YY1B was the preferred site for YY1 binding. Our results indicate that YY1 binds to the Col1a1 proximal promoter and functions as a positive regulator of constitutive activity in fibroblasts. Although YY1 is not sufficient for transcriptional initiation, it is a required component of the transcription machinery in this promoter.

Original languageEnglish (US)
Pages (from-to)38665-38672
Number of pages8
JournalJournal of Biological Chemistry
Volume276
Issue number42
DOIs
StatePublished - Oct 19 2001
Externally publishedYes

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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