Serum response factor neutralizes Pur alpha- and Pur beta-mediated repression of the fetal vascular smooth muscle alpha-actin gene in stressed adult cardiomyocytes.
Am J Physiol Cell Physiol
; 294(3): C702-14, 2008 Mar.
Article
em En
| MEDLINE
| ID: mdl-18344281
ABSTRACT
Mouse hearts subjected to repeated transplant surgery and ischemia-reperfusion injury develop substantial interstitial and perivascular fibrosis that was spatially associated with dysfunctional activation of fetal smooth muscle alpha-actin (SM alpha A) gene expression in graft ventricular cardiomyocytes. Compared with cardiac fibroblasts in which nuclear levels of the Sp1 and Smad 2/3 transcriptional-activating proteins increased markedly after transplant injury, the most abundant SM alpha A gene-activating protein in cardiomyocyte nuclei was serum response factor (SRF). Additionally, cardiac intercalated discs in heart grafts contained substantial deposits of Pur alpha, an mRNA-binding protein and known negative modulator of SRF-activated SM alpha A gene transcription. Activation of fetal SM alpha A gene expression in perfusion-isolated adult cardiomyocytes was linked to elevated binding of a novel protein complex consisting of SRF and Pur alpha to a purine-rich DNA element in the SM alpha A promoter called SPUR, previously shown to be required for induction of SM alpha A gene transcription in injury-activated myofibroblasts. Increased SRF binding to SPUR DNA plus one of two nearby CArG box consensus elements was observed in SM alpha A-positive cardiomyocytes in parallel with enhanced Pur alphaSPUR proteinprotein interaction. The data suggest that de novo activation of the normally silent SM alpha A gene in reprogrammed adult cardiomyocytes is linked to elevated interaction of SRF with fetal-specific CArG and injury-activated SPUR elements in the SM alpha A promoter as well as the appearance of novel Pur alpha protein complexes in both the nuclear and cytosolic compartments of these cells.
Texto completo:
1
Coleções:
01-internacional
Temas:
Geral
Base de dados:
MEDLINE
Assunto principal:
Proteínas Repressoras
/
Estresse Fisiológico
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Regulação da Expressão Gênica
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Actinas
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Fator de Resposta Sérica
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Miócitos Cardíacos
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Proteínas de Ligação a DNA
Tipo de estudo:
Prognostic_studies
Idioma:
En
Revista:
Am J Physiol Cell Physiol
Assunto da revista:
FISIOLOGIA
Ano de publicação:
2008
Tipo de documento:
Article
País de afiliação:
Estados Unidos