RESUMO

Fibrotic disorders are characterized by an increase in extracellular matrix protein expression and deposition, Duchene Muscular Dystrophy being one of them. Among the factors that induce fibrosis are Transforming Growth Factor type ß (TGF-ß) and the matricellular protein Connective Tissue Growth Factor (CTGF/CCN2), the latter being a target of the TGF-ß/SMAD signaling pathway and is the responsible for the profibrotic effects of TGF-ß. Both CTGF and TGF are increased in tissues affected by fibrosis but little is known about the regulation of the expression of CTGF mediated by TGF-ß in muscle cells. By using luciferase reporter assays, site directed mutagenesis and specific inhibitors in C2C12 cells; we described a novel SMAD Binding Element (SBE) located in the 5' UTR region of the CTGF gene important for the TGF-ß-mediated expression of CTGF in myoblasts. In addition, our results suggest that additional transcription factor binding sites (TFBS) present in the 5' UTR of the CTGF gene are important for this expression and that SP1/SP3 factors are involved in TGF-ß-mediated CTGF expression.

Assuntos

Fator de Crescimento do Tecido Conjuntivo/genética , Fator de Crescimento do Tecido Conjuntivo/metabolismo , Mioblastos/efeitos dos fármacos , Fator de Transcrição Sp1/metabolismo , Fator de Crescimento Transformador beta/farmacologia , Regiões 5' não Traduzidas , Animais , Sítios de Ligação , Linhagem Celular , Fator de Crescimento do Tecido Conjuntivo/química , Regulação da Expressão Gênica , Camundongos , Mutagênese Sítio-Dirigida , Mioblastos/metabolismo , Mioblastos/fisiologia , Transdução de Sinais/efeitos dos fármacos , Proteína Smad3/metabolismo , Fator de Transcrição Sp3/metabolismo