Tissue-specific regulation of the number of cell division rounds by inductive cell interaction and transcription factors during ascidian embryogenesis
Tissue-specific regulation of the number of cell division rounds by inductive cell interaction and transcription factors during ascidian embryogenesis
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DOI：
10.1016/j.ydbio.2011.04.033
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发表时间：
2011-07-15
影响因子：
2.7
通讯作者：
Nishida, Hiroki
中科院分区：
文献类型：
--
作者：
Fujikawa, Tetsuya;Takatori, Naohito;Nishida, Hiroki
调节构成身体的细胞数量的机制在很大程度上仍然难以捉摸。我们在海鞘类（Halocynthia roretzi）中解决了这个问题，它发育成具有少量细胞的蝌蚪幼虫。从受精到孵化，胚胎细胞平均分裂11次。细胞分裂轮数因组织类型而异。例如，蝌蚪中的脊索细胞分裂 9 次并产生大的有丝分裂后细胞。来自64细胞阶段分离的组织前体卵裂球的部分胚胎中的细胞分裂轮数在组织之间也存在差异，并且在某种程度上与完整的整个胚胎中的对应部分一致，这表明细胞分裂的组织自主调节。通过抑制或异位激活诱导性 FGF 信号来操纵脊索、神经索、肌肉和间充质谱系细胞的细胞命运，根据改变的命运改变细胞分裂的数量。 Brachyury (Bra) 是一种 FGF 诱导的脊索分化的脊索特异性关键转录因子，其敲低和错误表达表明 Bra 还负责调节细胞分裂轮数，这表明 Bra 激活了一种假定的机制，使细胞分裂停止在特定阶段。 Bra 早熟表达的结果表明，该机制涉及一个假定的发育时钟，该时钟可能在除脊索之外的卵裂球中共享，并具有在 64 细胞阶段后三轮终止细胞分裂的功能。 Bra 的早熟表达对发育时钟本身的进展没有影响。 (C) 2011 Elsevier Inc. 保留所有权利。
Mechanisms that regulate the number of cells constituting the body have remained largely elusive. We approached this issue in the ascidian, Halocynthia roretzi, which develops into a tadpole larva with a small number of cells. The embryonic cells divide 11 times on average from fertilization to hatching. The number of cell division rounds varies among tissue types. For example, notochord cells divide 9 times and give rise to large postmitotic cells in the tadpole. The number of cell division rounds in partial embryos derived from tissue-precursor blastomeres isolated at the 64-cell stage also varied between tissues and coincided with their counterparts in the intact whole embryos to some extent, suggesting tissue-autonomous regulation of cell division. Manipulation of cell fates in notochord, nerve cord, muscle, and mesenchyme lineage cells by inhibition or ectopic activation of the inductive FGF signal changed the number of cell divisions according to the altered fate. Knockdown and missexpression of Brachyury (Bra), an FGF-induced notochord-specific key transcription factor for notochord differentiation, indicated that Bra is also responsible for regulation of the number of cell division rounds, suggesting that Bra activates a putative mechanism to halt cell division at a specific stage. The outcome of precocious expression of Bra suggests that the mechanism involves a putative developmental clock that is likely shared in blastomeres other than those of notochord and functions to terminate cell division at three rounds after the 64-cell stage. Precocious expression of Bra has no effect on progression of the developmental clock itself. (C) 2011 Elsevier Inc. All rights reserved.