Identification of a critical control element directing expression of the muscle-specific transcription factor MRF4 in the mouse embryo
Identification of a critical control element directing expression of the muscle-specific transcription factor MRF4 in the mouse embryo
复制标题
DOI：
10.1016/j.ydbio.2004.04.017
复制
发表时间：
2004-08-15
影响因子：
2.7
通讯作者：
Arnold, HH
中科院分区：
文献类型：
--
作者：
Fomin, M;Nomokonova, N;Arnold, HH
脊椎动物胚胎中骨骼肌的发育关键取决于生肌调节因子（MRF），包括 MRF4 和 Myf5。这两个基因在小鼠胚胎发生过程中表现出不同的表达模式，尽管它们与分散在共同基因座中的多个调控元件在遗传上密切相关。 MRF4 具有双相表达谱，首先在体节中，然后在胎儿骨骼肌中。在这里，我们通过转基因分析证明，MRF4 基因的 7.5 kb 启动子片段内的元件足以驱动胚胎表达波，与小鼠胚胎体节中的内源基因非常相似。相反，近端启动子的 3kb 片段无法支持肌节中的表达，表明必需的顺式作用元件位于 MRF4 上游 -7.5 和 -3 kb 之间。对该序列的进一步分析界定了 -6.6 和 -5.6 kb 之间的重要区域，该区域与 3-kb 启动子片段一起在适当的发育时期指导所有体节的外轴肌节中的转基因表达。这些数据证明体节中 MrA 和 Myf5 部分重叠的表达模式是由不同的调控元件控制的。我们还表明，MR-174上游的11.4 kb序列（包括本研究中鉴定的启动子和体节控制区）不足以引发针对强Myf5（-58/-48 kb）增强子的靶标特异性，这表明需要额外的尚未鉴定的元件来传递启动子选择性并保护MRF4基因免受该增强子的影响。 (C) 2004 Elsevier Inc. 保留所有权利。
Skeletal muscle development in the vertebrate embryo critically depends on the myogenic regulatory factors (MRFs) including MRF4 and Myf5. Both genes exhibit distinct expression patterns during mouse embryogenesis, although they are genetically closely linked with multiple regulatory elements dispersed throughout the common gene locus. MRF4 has a biphasic expression profile, first in somites and later in foetal skeletal muscles. Here, we demonstrate by transgenic analysis that elements within a 7.5-kb promoter fragment of the MRF4 gene are sufficient to drive the embryonic wave of expression very similar to the endogenous gene in somites of mouse embryos. In contrast, a 3kb fragment of the proximal promoter fails to support expression in the myotome, suggesting that essential cis-acting elements are located between -7.5 and -3 kb upstream of MRF4. Further analysis of this sequence delimits an essential region between -6.6 and -5.6 kb that together with the 3-kb promoter fragment directs transgene expression in the epaxial myotome of all somites during the appropriate developmental period. These data provide evidence that the partly overlapping expression patterns of MrA and Myf5 in somites are controlled by distinct regulatory elements. We also show that 11.4 kb sequence upstream of MR-174, including the promoter and the somitic control region identified in this study, is not sufficient to elicit target specificity towards the strong Myf5 (-58/-48 kb) enhancer, suggesting that additional yet unidentified elements are necessary to convey promoter selectivity and protect the MRF4 gene from this enhancer. (C) 2004 Elsevier Inc. All rights reserved.