| Autor: |
Ornatsky, Olga I., Andreucci, John J., McDermott, John C. |
| Zdroj: |
Journal of Biological Chemistry; December 1997, Vol. 272 Issue: 52 p33271-33278, 8p |
| Abstrakt: |
A biological role for MEF2 (myocyteenhancer factor 2) activity during mammalian myogenesis has been inferred but not directly proven because of its role in the transcriptional activation of many muscle-specific genes. Therefore, our purpose was to determine whether MEF2 activity is absolutely required for mammalian myogenesis. Using a dominant-negative approach to address this question, we constructed a mutated MEF2A protein comprised of the amino-terminal DNA binding/dimerization domain of MEF2A without its trans-activation domain as a bacterial fusion protein (GST-131) or in a eukaryotic expression vector (pcDNA-131). GST-131 and the protein encoded by pcDNA-131 bind specifically to the MEF2ciselement and abrogate trans-activation of a MEF2-responsive luciferase reporter gene by wild type MEF2A, thus serving a role as trans-dominant inhibitors of MEF2 function. In congruence with their ability to interfere with wild type MEF2 function, microinjection of GST-131 or pcDNA-131 into L6E9 or C2C12 myoblasts inhibited myotube formation. Immunofluorescence analysis showed that the expression of myogenin, myosin heavy chain, and MEF2A were inhibited in the GST-131 or pcDNA-131-injected cells compared with GST or pcDNA-injected controls. We also document that this trans-dominant MEF2 inhibitor impairs the myogenic conversion of C3H10T1/2 fibroblasts by MyoD. Thus, these data provide evidence that the trans-activation function of the MEF2 proteins during mammalian myogenesis is required for muscle-specific gene expression and differentiation. |
| Databáze: |
Supplemental Index |
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