Walston Timothy D, Hardin Jeff
Laboratory of Genetics, University of Wisconsin, Madison, 53706, USA.
Semin Cell Dev Biol. 2006 Apr;17(2):204-13. doi: 10.1016/j.semcdb.2006.04.005. Epub 2006 May 2.
Correct orientation of the mitotic spindle is crucial for the proper segregation of localized determinants and the correct spatial organization of cells in early embryos. The cues dividing cells use to orient their mitotic spindles are currently the subject of intensive investigation in a number of model systems. One of the cues that cells use during spindle orientation is provided by components of the Wnt signaling pathway. Because of its stereotypical cleavage divisions, the availability of Wnt pathway mutants and the ability to perform RNAi, and because cell-cell interactions can be studied in vitro, the C. elegans embryo continues to be a useful system for identifying specific cell-cell interactions in which Wnt-dependent signals polarize the mitotic spindle. This review discusses the evidence for involvement of Wnt signaling during spindle orientation in several contexts in the early C. elegans embryo, a process that involves upstream Wnt effectors but does not involve downstream nuclear effectors of Wnt signaling, and places this Wnt spindle orientation pathway in the larger context of other known modulators of spindle orientation in animal embryos.
有丝分裂纺锤体的正确定向对于早期胚胎中局部决定因素的正确分离以及细胞的正确空间组织至关重要。目前，在许多模型系统中，正在深入研究分裂细胞用于定向其有丝分裂纺锤体的线索。细胞在纺锤体定向过程中使用的线索之一由Wnt信号通路的成分提供。由于其典型的卵裂分裂、Wnt通路突变体的可用性以及进行RNA干扰的能力，并且由于可以在体外研究细胞间相互作用，秀丽隐杆线虫胚胎仍然是用于鉴定特定细胞间相互作用的有用系统，在这些相互作用中，Wnt依赖信号使有丝分裂纺锤体极化。本综述讨论了秀丽隐杆线虫早期胚胎在几种情况下纺锤体定向过程中Wnt信号参与的证据，这一过程涉及上游Wnt效应器，但不涉及Wnt信号的下游核效应器，并将这种Wnt纺锤体定向途径置于动物胚胎中其他已知纺锤体定向调节因子的更大背景下。
