Paired MyoD-binding sites regulate myosin light chain gene expression.
Paired MyoD-binding sites regulate myosin light chain gene expression.
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DOI：
10.1073/pnas.88.4.1242
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发表时间：
1991-02
影响因子：
11.1
通讯作者：
B. Wentworth;M. Donoghue;J. Engert;E. B. Berglund;N. Rosenthal
中科院分区：
文献类型：
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作者：
B. Wentworth;M. Donoghue;J. Engert;E. B. Berglund;N. Rosenthal
位于编码MLC 1和MLC 3的肌球蛋白轻链（MLC）基因座下游的肌肉特异性增强子元件含有生肌决定因子MyoD的三个结合位点（A、B和C）。MLC基因增强子的173个碱基对区域，包括这三个位点，在转染到肌肉细胞中时保留了完整的增强子功能。然而，上游MyoD结合位点（A或B）的突变对肌肉特异性增强子活性具有轻微影响，第三个MyoD结合位点（C）的突变显著削弱了增强子，无论是在肌肉细胞还是在用MyoD、肌细胞生成素或myf 5表达载体共转染的非肌肉细胞中。位点C是必需的，但不充分，因为两个MyoD结合位点（A加B）的双重突变消除了增强子活性。因此，位点C需要位点A或B来实现增强子功能。这项研究显示了MLC增强子中三个MyoD结合位点之间的功能层次。我们提出，蛋白质-DNA复合物与这些位点中的至少两个（A和C或B和C）形成，以在肌生成期间激活编码MLC 1/3的位点。
The muscle-specific enhancer element located downstream of the myosin light chain (MLC) locus encoding MLC1 and MLC3 contains three binding sites (A, B, and C) for the myogenic determination factor MyoD. A 173-base-pair region of the MLC gene enhancer, including these three sites, retains full enhancer function when transfected into muscle cells. Whereas mutation of either upstream MyoD binding site (A or B) has a mild effect on muscle-specific enhancer activity, mutation of the third MyoD binding site (C) substantially weakens the enhancer, both in muscle cells or in nonmuscle cells cotransfected with a MyoD, myogenin, or myf5 expression vector. Site C is necessary but insufficient, since double mutation of two MyoD binding sites (A plus B) abrogates enhancer activity. Thus, site C requires either site A or B for enhancer function. This study shows a hierarchy of function among the three MyoD binding sites in the MLC enhancer. We propose that a protein-DNA complex is formed with at least two of these sites (A and C or B and C) to effect activation of the locus encoding MLC1/3 during myogenesis.