Stowers Institute, Kansas City, MO, USA.
University of Chicago, Chicago, IL, USA.
Nat Commun. 2021 Nov 18;12(1):6706. doi: 10.1038/s41467-021-26986-2.
Hox genes are highly conserved transcription factors renowned for their roles in the segmental patterning of the embryonic anterior-posterior (A/P) axis. We report functions for Hox genes in A/P tissue segmentation and transverse fission behavior underlying asexual reproduction in adult planarian flatworms, Schmidtea mediterranea. Silencing of each of the Hox family members identifies 5 Hox genes required for asexual reproduction. Among these, silencing of hox3 genes results in supernumerary fission segments, while silencing of post2b eliminates segmentation altogether. The opposing roles of hox3 and post2b in segmentation are paralleled in their respective regulation of fission behavior. Silencing of hox3 increases the frequency of fission behavior initiation while silencing of post2b eliminates fission behavior entirely. Furthermore, we identify a network of downstream effector genes mediating Hox gene functions, providing insight into their respective mechanisms of action. In particular, we resolve roles for post2b and effector genes in the functions of the marginal adhesive organ in fission behavior regulation. Collectively, our study establishes adult stage roles for Hox genes in the regulation of tissue segmentation and behavior associated with asexual reproduction.
Hox 基因是高度保守的转录因子，以其在胚胎前后（A/P）轴的节段模式形成中的作用而闻名。我们报告了 Hox 基因在 A/P 组织分段和无性生殖中横向分裂行为中的作用，这是成年扁形动物 Schmidtea mediterranea 的无性生殖的基础。沉默每个 Hox 家族成员都鉴定出 5 个 Hox 基因是无性生殖所必需的。在这些基因中，hox3 基因的沉默导致额外的分裂节段，而 post2b 的沉默则完全消除了分段。hox3 和 post2b 在分段中的相反作用与其在分裂行为中的各自调节是平行的。沉默 hox3 增加了分裂行为开始的频率，而沉默 post2b 则完全消除了分裂行为。此外，我们鉴定出一个下游效应基因网络，介导 Hox 基因的功能，深入了解它们各自的作用机制。特别是，我们确定了 post2b 和效应基因在分裂行为调节中边缘粘附器官功能中的作用。总的来说，我们的研究确立了 Hox 基因在调节与无性生殖相关的组织分段和行为中的成年阶段作用。
