A switch from hBrm to Brg1 at IFNγ-activated sequences mediates the activation of human genes.
Cell Res
; 20(12): 1345-60, 2010 Dec.
Article
em En
| MEDLINE
| ID: mdl-21079652
ABSTRACT
The SWI/SNF chromatin-remodeling complexes utilize energy from ATP hydrolysis to reposition nucleosomes and regulate the expression of human genes. Here, we studied the roles of human Brahma (hBrm) and Brahma-related gene 1 (Brg1), the ATPase subunits of the SWI/SNF complexes, in regulating human genes. Our results indicate that both hBrm and Brg1 interact with Signal transducer and activator of transcription (Stat) 1 in vitro. However, Stat1 in its native form only recruits hBrm to IFNγ-activated sequences (GAS) of individual genes; by contrast, in a stress-induced phosphorylated form, Stat1 mainly binds to Brg1. Under basal conditions, hBrm is recruited by native Stat1 to the GAS and exists in a mSin3/HDAC co-repressor complex on the hsp90α gene, which shows a compact chromatin structure. Upon heat-shock, hBrm is acetylated by p300 and dissociates from the co-repressor complex, which the phosphorylated Stat1 is increased, and binds and recruits Brg1 to the GAS, leading to elevated induction of the gene. This hBrm/Brg1 switch also occurs at the GAS of all of the three examined immune genes in heat-shocked cells; however, this switch only occurs in specific cell types upon exposure to IFNγ. Regardless of the stimulus, the hBrm/Brg1 switch at the GAS elicits an increase in gene activity. Our data are consistent with the hypothesis that the hBrm/Brg1 switch is an indicator of the responsiveness of a gene to heat-shock or IFNγ stimulation and may represent an "on-off switch" of gene expression in vivo.
Texto completo:
1
Bases de dados:
MEDLINE
Assunto principal:
Fatores de Transcrição
/
Proteínas Nucleares
/
Ativação Transcricional
/
Interferon gama
/
DNA Helicases
Tipo de estudo:
Prognostic_studies
Limite:
Humans
Idioma:
En
Revista:
Cell Res
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
China