YY1 is a positive regulator of transcription of the Col1a1 gene.
J Biol Chem
; 276(42): 38665-72, 2001 Oct 19.
Article
de En
| MEDLINE
| ID: mdl-11514536
ABSTRACT
Both cell-specific and ubiquitous transcription factors in fibroblasts have been identified as critical for expression of the Col1a1 gene, which encodes the alpha1 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.
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Collection:
01-internacional
Base de données:
MEDLINE
Sujet principal:
Facteurs de transcription
/
Transcription génétique
/
Régulation de l'expression des gènes
/
Collagène
/
Collagène de type I
/
Protéines de liaison à l'ADN
Type d'étude:
Prognostic_studies
Limites:
Animals
Langue:
En
Journal:
J Biol Chem
Année:
2001
Type de document:
Article
Pays d'affiliation:
États-Unis d'Amérique