Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan.
Department of Zoology, Graduate School of Science, Kyoto University, Sakyo, Kyoto 606-8502, Japan
Development. 2019 Feb 4;146(3):dev173104. doi: 10.1242/dev.173104.
Striated muscle cells in the tail of ascidian tadpole larvae differentiate cell-autonomously. Although several key regulatory factors have been identified, the genetic regulatory pathway is not fully understood; comprehensive understanding of the regulatory pathway is essential for accurate modeling in order to deduce principles for gene regulatory network dynamics, and for comparative analysis on how ascidians have evolved the cell-autonomous gene regulatory mechanism. Here, we reveal regulatory interactions among three key regulatory factors, Zic-r.b, Tbx6-r.b and Mrf, and elucidate the mechanism by which these factors activate muscle structural genes. We reveal a cross-regulatory circuit among these regulatory factors, which maintains the expression of and during gastrulation. Although these two factors combinatorially activate muscle structural genes in late-stage embryos, muscle structural genes are activated mainly by Tbx6-r.b before gastrulation. Time points when expression of muscle structural genes become first detectable are strongly correlated with the degree of Tbx6-r.b occupancy. Thus, the genetic pathway, starting with and , which are activated by maternal factors, and ending with expression of muscle structural genes, has been revealed.
海鞘幼体尾部的横纹肌细胞能自主分化。尽管已经鉴定出了几个关键的调控因子，但遗传调控途径还不完全清楚；全面了解调控途径对于准确建模至关重要，以便推导出基因调控网络动态的原则，并进行比较分析，了解海鞘是如何进化出自主的基因调控机制的。在这里，我们揭示了三个关键调控因子 Zic-r.b、Tbx6-r.b 和 Mrf 之间的调控相互作用，并阐明了这些因子激活肌肉结构基因的机制。我们揭示了这些调控因子之间的一个交叉调控回路，该回路在原肠胚形成过程中维持 和 的表达。虽然这两个因子在晚期胚胎中组合激活肌肉结构基因，但在原肠胚形成之前，肌肉结构基因主要由 Tbx6-r.b 激活。肌肉结构基因开始表达的时间点与 Tbx6-r.b 占据的程度密切相关。因此，已经揭示了从母源性因子激活的 和 开始，到肌肉结构基因表达结束的遗传途径。
