Multiple upstream modules regulate zebrafish myf5 expression.
Multiple upstream modules regulate zebrafish myf5 expression.
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多个上游模块调节斑马鱼MyF5表达式。
DOI：
10.1186/1471-213x-7-1
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发表时间：
2007-01-03
影响因子：
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通讯作者：
Tsai, Huai-Jen
中科院分区：
文献类型：
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作者：
Chen, Yau-Hung;Wang, Yun-Hsin;Chang, Min-Yen;Lin, Cheng-Yung;Weng, Chih-Wei;Westerfield, Monte;Tsai, Huai-Jen
Myf5是基本螺旋-环-螺旋转录因子家族的成员之一，它是一种肌生成因子，对肌肉细胞的特化和分化具有重要作用。在胚胎发生过程中，myf5的表达通过微妙的调控而与体和阶段相关。然而，对myf5的这种复杂调控机制尚不清楚。我们分离了一个156-kb的细菌人工染色体克隆，其中包括一个上游80-kb区域和一个下游70-kb区域的斑马鱼myf5，并产生了一个转基因系，携带这个156-kb的片段融合到绿色荧光蛋白（GFP）报告基因。我们发现GFP在大多数吻侧体和体前中胚层中有很强的表达，类似于内源性myf5的表达。后来，GFP信号在尾芽附近的尾端体中持续存在，但在较老的吻侧体中被下调。在咽期，我们在胸鳍芽、背吻肌、下轴肌、下斜肌和上斜肌中检测到GFP信号，这种模式也与内源性myf5转录本相吻合。为了描述调控这种复杂和动态表达模式的特定上游顺式元件，我们还生成了几个在上游80 kb片段内具有不同长度的转基因系。我们发现(1)- 80kb /-9977片段包含鳍和颅肌元件和脊索抑制因子；(2) -9977/-6213片段包含一个不包括脊索特异性抑制因子的强抑制元件；(3) -6212/-2938段包含骨和脊髓的组织特异性元素；(4) -2937/-291段含有眼增强剂，-2937/-2457段是脊索和肌细胞表达所必需的；(5) -290/-1片段负责体母细胞和体前中胚层的基础转录。我们认为myf5的细胞谱系特异性表达是由远端上游区域的多个模块精心策划的。本研究为了解myf5的分子调控和斑马鱼肌生成提供了新的思路。
Myf5 is one member of the basic helix-loop-helix family of transcription factors, and it functions as a myogenic factor that is important for the specification and differentiation of muscle cells. The expression of myf5 is somite- and stage-dependent during embryogenesis through a delicate regulation. However, this complex regulatory mechanism of myf5 is not clearly understood. We isolated a 156-kb bacterial artificial chromosome clone that includes an upstream 80-kb region and a downstream 70-kb region of zebrafish myf5 and generated a transgenic line carrying this 156-kb segment fused to a green fluorescent protein (GFP) reporter gene. We find strong GFP expression in the most rostral somite and in the presomitic mesoderm during segmentation stages, similar to endogenous myf5 expression. Later, the GFP signals persist in caudal somites near the tail bud but are down-regulated in the older, rostral somites. During the pharyngula period, we detect GFP signals in pectoral fin buds, dorsal rostral myotomes, hypaxial myotomes, and inferior oblique and superior oblique muscles, a pattern that also corresponds well with endogenous myf5 transcripts. To characterize the specific upstream cis-elements that regulate this complex and dynamic expression pattern, we also generated several transgenic lines that harbor various lengths within the upstream 80-kb segment. We find that (1) the -80 kb/-9977 segment contains a fin and cranial muscle element and a notochord repressor; (2) the -9977/-6213 segment contains a strong repressive element that does not include the notochord-specific repressor; (3) the -6212/-2938 segment contains tissue-specific elements for bone and spinal cord; (4) the -2937/-291 segment contains an eye enhancer, and the -2937/-2457 segment is required for notochord and myocyte expression; and (5) the -290/-1 segment is responsible for basal transcription in somites and the presomitic mesoderm. We suggest that the cell lineage-specific expression of myf5 is delicately orchestrated by multiple modules within the distal upstream region. This study provides an insight to understand the molecular control of myf5 and myogenesis in the zebrafish.