Di Lisi Raffaella, Picard Anne, Ausoni Simonetta, Schiaffino Stefano
Department of Biomedical Sciences, University of Padova, Padova, Italy.
BMC Mol Biol. 2007 Sep 17;8:78. doi: 10.1186/1471-2199-8-78.
We reported previously that the cardiac troponin I (cTnI) promoter drives cardiac-specific expression of reporter genes in cardiac muscle cells and in transgenic mice, and that disruption of GATA elements inactivates the cTnI promoter in cultured cardiomyocytes. We have now examined the role of cTnI promoter GATA elements in skeletal muscle cells.
Mutation or deletion of GATA elements induces a strong transcriptional activation of the cTnI promoter in regenerating skeletal muscle and in cultured skeletal muscle cells. Electrophoretic mobility shift assays show that proteins present in nuclear extracts of C2C12 muscle cells bind the GATA motifs present in the cTnI promoter. However, GATA protein complex formation is neither reduced nor supershifted by antibodies specific for GATA-2, -3 and -4, the only GATA transcripts present in muscle cells.
These findings indicate that the cTnI gene promoter is repressed in skeletal muscle cells by GATA-like factors and open the way to further studies aimed at identifying these factors.
我们之前报道过，心肌肌钙蛋白I（cTnI）启动子可驱动报告基因在心肌细胞和转基因小鼠中进行心脏特异性表达，并且在培养的心肌细胞中，GATA元件的破坏会使cTnI启动子失活。我们现在研究了cTnI启动子GATA元件在骨骼肌细胞中的作用。
GATA元件的突变或缺失会在再生骨骼肌和培养的骨骼肌细胞中诱导cTnI启动子强烈的转录激活。电泳迁移率变动分析表明，C2C12肌肉细胞核提取物中的蛋白质与cTnI启动子中存在的GATA基序结合。然而，GATA蛋白复合物的形成既没有被肌肉细胞中仅有的GATA-2、-3和-4特异性抗体减少，也没有被其超迁移。
这些发现表明，cTnI基因启动子在骨骼肌细胞中被类GATA因子抑制，并为进一步研究旨在鉴定这些因子开辟了道路。
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