Herman Michael A, Wu Mingfu
Program in Molecular, Cellular and Developmental Biology, Division of Biology, Kansas State University, Manhattan, KS 66506, USA.
Front Biosci. 2004 May 1;9:1530-9. doi: 10.2741/1306.
In the nematode Caenorhabditis elegans, a canonical Wnt signaling pathway controls a cell migration whereas noncanonical Wnt pathways control the polarities of individual cells. Despite the differences in the identities and interactions among canonical and noncanonical Wnt pathway components, as well as the processes they regulate, almost all C. elegans Wnt pathways involve the sole Tcf homolog, POP-1. Intriguingly, POP-1 is asymmetrically distributed between the daughters of an asymmetric cell division, with the anterior sister cell usually having a higher level of nuclear POP-1 than its posterior sister. At some divisions, asymmetric distribution of POP-1 is controlled by noncanonical Wnt signaling, but at others the asymmetry is generated independently. Recent experiments suggest that despite this elaborate anterior-posterior POP-1 asymmetry, the quantity of POP-1 protein may have less to do with the subsequent determination of fate than does the quality of the POP-1 protein in the cell. In this review, we will embark on a quest to understand Quality (1), at least from the standpoint of the effect POP/Tcf quality has on the control of cell polarity in C. elegans.
在线虫秀丽隐杆线虫中，经典Wnt信号通路控制细胞迁移，而非经典Wnt通路控制单个细胞的极性。尽管经典和非经典Wnt通路成分的特性和相互作用以及它们所调控的过程存在差异，但几乎所有秀丽隐杆线虫Wnt通路都涉及唯一的Tcf同源物POP-1。有趣的是，POP-1在不对称细胞分裂的子代细胞之间呈不对称分布，前姐妹细胞的核POP-1水平通常高于后姐妹细胞。在某些分裂过程中，POP-1的不对称分布由非经典Wnt信号控制，但在其他情况下，这种不对称是独立产生的。最近的实验表明，尽管存在这种精细的前后POP-1不对称现象，但与细胞中POP-1蛋白的质量相比，POP-1蛋白的数量可能与随后的命运决定关系较小。在这篇综述中，我们将着手探索质量（1），至少从POP/Tcf质量对秀丽隐杆线虫细胞极性控制的影响角度进行探索。
