Regulation of the muscle-specific expression and function of an ascidian T-box gene, As-T2.
Regulation of the muscle-specific expression and function of an ascidian T-box gene, As-T2.
复制标题
海鞘 T 盒基因 As-T2 的肌肉特异性表达和功能的调节。
作者：
Y. Mitani;H. Takahashi;N. Satoh
Tbx6 T-box基因在脊椎动物胚胎体节前体细胞中表达，对近轴中胚层的分化至关重要。然而，目前还不清楚基因表达的空间调控是如何控制的，以及基因如何发挥作用以促进肌肉分化。海鞘Halocynthia roretzi的Tbx6相关基因As-T2首先在32-约44-细胞阶段周围的内胚层细胞中非常短暂地表达，然后在肌肉前体细胞中明显且连续地表达，并且随后在位于伸长的尾巴的远端尖端区域的表皮细胞中表达。我们现在发现，通过将As-T2/En（R）显微注射到单细胞胚胎中来抑制As-T2介导的转录激活，导致肌肉特异性肌动蛋白基因（HrMA 4）和肌球蛋白重链基因（HrMHC）的表达受到抑制，但注射并不影响内胚层细胞或尾尖细胞的分化，提示As-T2的主要功能与肌细胞分化有关。As-T2的5 '侧翼区包含两个调控其特异性表达的启动子模块：负责其在尾部特异性表达的远端模块和其肌肉特异性表达所需的近端模块。在近端模块周围，存在两个推定的T蛋白结合基序（TTCACACTT）。将具有或不具有T结合基序的As-T2/lacZ构建体与As-T2 mRNA一起共注射表明，这些基序对于基因本身的自动调节激活至关重要。此外，我们发现HrMA4和HrMHC的最小启动子区含有T结合基序。将含有T结合基序的HrMA4/lacZ或HrMHC/lacZ与As-T2 mRNA共注射，表明As-T2蛋白与这些基序结合，上调基因活性。考虑到最近发现的母体分子的肌肉分化，我们提出了一个模型的遗传级联，其中包括作为调节器的海鞘胚胎中的肌肉细胞分化的T2。
The Tbx6 T-box genes are expressed in somite precursor cells of vertebrate embryos and are essential for the differentiation of paraxial mesoderm. However, it is unclear how spatial regulation of the gene expression is controlled and how the genes function to promote muscle differentiation. The Tbx6-related gene As-T2 of the ascidian Halocynthia roretzi is first expressed very transiently in endodermal cells around the 32- approximately 44-cell stage, is then expressed distinctly and continuously in muscle precursor cells, and later in epidermal cells situated in the distal tip region of the elongating tail. We now show that inhibition of As-T2-mediated transcriptional activation by microinjection of As-T2/En(R) into one-cell embryos resulted in suppression of the expression of the muscle-specific actin gene (HrMA4) and myosin heavy chain gene (HrMHC), but the injection did not affect the differentiation of endodermal cells or tail tip cells, suggesting that the primary function of As-T2 is associated with muscle cell differentiation. The 5' flanking region of As-T2 contains two promoter modules that regulate its specific expression: a distal module that responsible for its specific expression in the tail, and a proximal module required for its muscle-specific expression. Around the proximal module, there are two putative T protein-binding motifs (TTCACACTT). Co-injection of an As-T2/lacZ construct with or without the T-binding motifs together with As-T2 mRNA revealed that these motifs are essential for autoregulatory activation of the gene itself. In addition, we found that the minimal promoter regions of HrMA4 and HrMHC contain T-binding motifs. Co-injection of HrMA4/lacZ or HrMHC/lacZ containing the T-binding motifs along with As-T2 mRNA revealed that As-T2 protein binds to these motifs to upregulate the gene activity. Taking into account the recent finding of maternal molecules for muscle differentiation, we propose a model for a genetic cascade that includes As-T2 as a regulator of muscle cell differentiation in the ascidian embryo.
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影响因子：
2.7
作者：
Chapman, DL;Agulnik, I;Papaioannou, VE
通讯作者：
Papaioannou, VE
影响因子：
4.6
作者：
Jian Zhang;M. L. King
通讯作者：
Jian Zhang;M. L. King
海鞘胚胎细胞和位置命运的决定因素。
DOI：
10.1016/s0074-7696(01)03003-0
发表时间：
2001
期刊：
International review of cytology
影响因子：
--
作者：
Jeffery,WR
通讯作者：
Jeffery,WR
影响因子：
2.7
作者：
Hug, B;Walter, V;Grunwald, DJ
通讯作者：
Grunwald, DJ
影响因子：
3.5
作者：
Sinha, S;Abraham, S;Campbell, CE
通讯作者：
Campbell, CE