CHF1/Hey2 suppresses SM-MHC promoter activity through an interaction with GATA-6.
The bHLH transcription factor CHF1/Hey2 has been previously shown to regulate neointimal formation after vascular injury, but the mechanisms have not been fully elucidated. The zinc-finger protein GATA-6 has also been shown to regulate vascular smooth-muscle phenotype through regulation of smooth-muscle contractile protein gene expression. To address the potential mechanisms by which CHF1/Hey2 regulates vascular smooth-muscle phenotype switching, we investigated the effect of CHF1/Hey2 on GATA-6-dependent smooth-muscle myosin heavy chain promoter activity. When cotransfected into NIH3T3 cells, CHF1/Hey2 reduced GATA-6-dependent activation of the promoter by 90%. Exogenous p300 was not sufficient to overcome this repression effect, demonstrating that the inhibitor effect did not involve coactivation by p300. Coimmunoprecipitation studies demonstrated that CHF1/Hey2 interacts directly with GATA-6. Mutational analysis demonstrated that the bHLH domain is required for transcriptional repression. Our findings highlight an important transcriptional mechanism by which CHF1/Hey2 may affect smooth-muscle cell phenotype.
Shirvani
Shervin
S
Vascular Medicine Research, Brigham & Women's Hospital, Harvard Medical School, Cambridge, MA 02139, USA.
Xiang
Fan
F
Koibuchi
Nobutaka
N
Chin
Michael T
MT
D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D019281:Dimerization; D050993:GATA6 Transcription Factor / Q000378:metabolism*; D006801:Humans; D051379:Mice; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000235:genetics* / Q000378:metabolism; D041681:NIH 3T3 Cells; D011401:Promoter Regions, Genetic; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation; D050880:p300-CBP Transcription Factors / Q000378:metabolism
D051792:Basic Helix-Loop-Helix Proteins; D050993:GATA6 Transcription Factor; D018995:Myosin Heavy Chains; D012097:Repressor Proteins; D050880:p300-CBP Transcription Factors; C405693:HEY2 protein, human