Mango Susan E
Department of Oncological Sciences, Huntsman Cancer Institute, University of Utah, Salt Lake City, UT 84112, USA.
WormBook. 2007 Jan 22:1-26. doi: 10.1895/wormbook.1.129.1.
The C. elegans foregut (pharynx) has emerged as a powerful system to study organ formation during embryogenesis. Here I review recent advances regarding cell-fate specification and epithelial morphogenesis during pharynx development. Maternally-supplied gene products function prior to gastrulation to establish pluripotent blastomeres. As gastrulation gets under way, pharyngeal precursors become committed to pharyngeal fate in a process that requires PHA-4/FoxA and the Tbox transcription factors TBX-2, TBX-35, TBX-37 and TBX-38. Subsequent waves of gene expression depend on the affinity of PHA-4 for its target promoters, coupled with combinatorial strategies such as feed-forward and positive-feedback loops. During later embryogenesis, pharyngeal precursors undergo reorganization and a mesenchymal-to-epithelial transition to form the linear gut tube. Surprisingly, epithelium formation does not depend on cadherins, catenins or integrins. Rather, the kinesin ZEN-4/MKLP1 and CYK-4/RhoGAP are critical to establish the apical domain during epithelial polarization. Finally, I discuss similarities and differences between the nematode pharynx and the vertebrate heart.
秀丽隐杆线虫的前肠（咽）已成为研究胚胎发育过程中器官形成的强大系统。在此，我综述了咽发育过程中细胞命运特化和上皮形态发生的最新进展。母源提供的基因产物在原肠胚形成之前发挥作用，以建立多能性卵裂球。随着原肠胚形成的开始，咽前体在一个需要PHA-4/FoxA和T盒转录因子TBX-2、TBX-35、TBX-37和TBX-38的过程中确定为咽命运。随后的基因表达波取决于PHA-4与其靶启动子的亲和力，以及诸如前馈和正反馈环等组合策略。在胚胎发育后期，咽前体经历重组和间充质到上皮的转变，以形成线性肠管。令人惊讶的是，上皮形成并不依赖于钙黏蛋白、连环蛋白或整合素。相反，驱动蛋白ZEN-4/MKLP1和CYK-4/RhoGAP对于上皮极化过程中顶端结构域的建立至关重要。最后，我讨论了线虫咽与脊椎动物心脏之间的异同。
