Sp1- and Sp3-mediated transcriptional regulation of the fibroblast growth factor receptor 1 gene in chicken skeletal muscle cells
Sp1- and Sp3-mediated transcriptional regulation of the fibroblast growth factor receptor 1 gene in chicken skeletal muscle cells
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DOI：
10.1074/jbc.m108411200
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发表时间：
2002-03-15
影响因子：
4.8
通讯作者：
DiMario, JX
中科院分区：
文献类型：
--
作者：
Parakati, R;DiMario, JX
骨骼肌中成纤维细胞生长因子受体I（FGFR 1）基因的表达在增殖的成肌细胞中受到正向调节，并在分化过程中下降。我们的特点是顺式调控元件的近端区域的FGFR 1启动子，使积极的转录活性。-69和-14之间的多个元件激活FGFR 1启动子。成肌细胞转染揭示了潜在的Sp转录因子结合位点是启动子活性所必需的。电迁移率变化分析表明，成肌细胞核蛋白特异性结合这些顺式元件和分化的肌管核提取物不形成这些相同的复合物。此外，Southwestern印迹分析检测到最接近的Sp基序的Sp1样蛋白存在于成肌细胞核提取物，但不是在肌管的结合。在确证，Sp1和Sp3蛋白只在成肌细胞中检测到，而不是在分化的肌管。最后，果蝇SL 2细胞的转染表明，Sp1是FGFR 1启动子活性的正调控因子，Sp3是通过近端Sp结合位点的共激活因子。这些研究表明，FGFR 1启动子在增殖的成肌细胞中被Sp转录因子激活，并证明了FGFR 1基因表达在分化的肌纤维中下调的至少部分机制。
Expression of the fibroblast growth factor receptor I (FGFR1) gene in skeletal muscle is positively regulated in proliferating myoblasts and declines during differentiation. We have characterized the cis-regulatory elements in the proximal region of the FGFR1 promoter which render positive transcriptional activity. Multiple elements between -69 and -14 activate the FGFR1 promoter. Myoblast transfections revealed that potential Sp transcription factor binding sites are required for promoter activity. Electromobility shift assays indicated that myoblast nuclear proteins specifically bind to these cis-elements and that differentiated myotube nuclear extracts do not form these same complexes. In addition, Southwestern blot analysis detected binding of the most proximal Sp motif to a Sp1-like protein present in myoblast nuclear extracts but not in myotubes. In corroboration, Sp1 and Sp3 proteins were detected only in myoblasts and not in differentiated myotubes. Finally, transfection of Drosophila SL2 cells showed that Sp1 is a positive regulator of FGFR1 promoter activity and that Sp3 is a coactivator via the proximal Sp binding sites. These studies demonstrate that the FGFR1 promoter is activated by Sp transcription factors in proliferating myoblasts and demonstrate at least part of the mechanism by which FGFR1 gene expression is downregulated in differentiated muscle fibers.