Hox code in segmentation and patterning Hox genes encode conserved transcription factors that are best known for their role in governing anterior-posterior body patterning in diverse bilaterian animals. He et al. used a combination of CRISPR mutagenesis and short hairpin RNA–based gene knockdowns to interrogate Hox gene function in a cnidarian, the sea anemone Nematostella vectensis (see the Perspective by Arendt). Four homeobox-containing genes constitute a molecular network that coordinately controls the morphogenesis of radial endodermal segments and the patterning of tentacles. Thus, an ancient Hox code may have evolved to regulate both tissue segmentation and body patterning in the bilaterian-cnidarian common ancestor. Science, this issue p. 1377; see also p. 1310 Genetic analysis of Hox gene function in a developing cnidarian reveals ancestral roles in tissue segmentation and axial patterning. Hox genes encode conserved developmental transcription factors that govern anterior-posterior (A-P) pattering in diverse bilaterian animals, which display bilateral symmetry. Although Hox genes are also present within Cnidaria, these simple animals lack a definitive A-P axis, leaving it unclear how and when a functionally integrated Hox code arose during evolution. We used short hairpin RNA (shRNA)–mediated knockdown and CRISPR-Cas9 mutagenesis to demonstrate that a Hox-Gbx network controls radial segmentation of the larval endoderm during development of the sea anemone Nematostella vectensis. Loss of Hox-Gbx activity also elicits marked defects in tentacle patterning along the directive (orthogonal) axis of primary polyps. On the basis of our results, we propose that an axial Hox code may have controlled body patterning and tissue segmentation before the evolution of the bilaterian A-P axis.

中文翻译：

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轴向 Hox 代码控制 Nematostella vectensis 的组织分割和身体模式

分割和图案化中的 Hox 代码 Hox 基因编码保守的转录因子，这些转录因子以其在控制不同双侧动物的前后体图案化中的作用而闻名。他等人。使用 CRISPR 诱变和基于短发夹 RNA 的基因敲低的组合来询问刺胞动物海葵 Nematostella vectensis 的 Hox 基因功能（参见 Arendt 的观点）。四个含有同源框的基因构成了一个分子网络，可协调控制径向内胚层的形态发生和触手的图案。因此，一个古老的 Hox 密码可能已经演变为调节双边-刺胞动物共同祖先的组织分割和身体模式。科学，这个问题 p。第1377章 另见第。1310 发育中的刺胞动物中 Hox 基因功能的遗传分析揭示了祖先在组织分割和轴向模式中的作用。Hox 基因编码保守的发育转录因子，这些因子控制着不同双边动物的前后 (​​AP) 模式，它们显示出双侧对称性。尽管 Hox 基因也存在于刺胞动物中，但这些简单的动物缺乏明确的 AP 轴，因此尚不清楚在进化过程中功能整合的 Hox 代码是如何以及何时出现的。我们使用短发夹 RNA (shRNA) 介导的敲低和 CRISPR-Cas9 诱变来证明 Hox-Gbx 网络在海葵 Nematostella vectensis 发育过程中控制幼虫内胚层的径向分割。Hox-Gbx 活性的丧失还会引起沿原发息肉的定向（正交）轴的触手图案的明显缺陷。根据我们的结果，我们提出轴向 Hox 代码可能在双边 AP 轴进化之前控制了身体模式和组织分割。