Schlesinger A, Shelton C A, Maloof J N, Meneghini M, Bowerman B
Institute of Molecular Biology, University of Oregon, Eugene, Oregon 97403, USA.
Genes Dev. 1999 Aug 1;13(15):2028-38. doi: 10.1101/gad.13.15.2028.
In a four-cell-stage Caenorhabditis elegans embryo, Wnt signaling polarizes an endoderm precursor called EMS. The polarization of this cell orients its mitotic spindle in addition to inducing endodermal fate in one daughter cell. Reducing the function of Wnt pathway genes, including a newly identified GSK-3beta homolog called gsk-3, disrupts endoderm induction, whereas only a subset of these genes is required for proper EMS mitotic spindle orientation. Wnt pathway genes thought to act downstream of gsk-3 appear not to be required for spindle orientation, suggesting that gsk-3 represents a branch point in the control of endoderm induction and spindle orientation. Orientation of the mitotic spindle does not require gene transcription in EMS, suggesting that Wnt signaling may directly target the cytoskeleton in a responding cell.
在四细胞期的秀丽隐杆线虫胚胎中，Wnt信号通路使一种名为EMS的内胚层前体细胞发生极化。该细胞的极化除了在一个子细胞中诱导内胚层命运外，还会使其有丝分裂纺锤体定向。降低Wnt信号通路基因的功能，包括一种新鉴定出的名为gsk-3的GSK-3β同源物，会破坏内胚层诱导，而这些基因中只有一部分对于EMS有丝分裂纺锤体的正确定向是必需的。被认为在gsk-3下游起作用的Wnt信号通路基因似乎对于纺锤体定向不是必需的，这表明gsk-3代表了内胚层诱导和纺锤体定向控制中的一个分支点。有丝分裂纺锤体的定向在EMS中不需要基因转录，这表明Wnt信号可能直接作用于响应细胞中的细胞骨架。
