Ikegami Richard, Zheng Hong, Ong Siew-Hwa, Culotti Joseph
Samuel Lunenfeld Research Institute, Mt. Sinai Hospital, 600 University Avenue, Toronto M5G 1X5, Canada.
Dev Cell. 2004 Mar;6(3):383-95. doi: 10.1016/s1534-5807(04)00057-7.
Semaphorins and ephrins are axon guidance cues. In C. elegans, semaphorin-2a/mab-20 and ephrin-4/efn-4/mab-26 also regulate cell sorting to form distinct rays in the male tail. Several erf (enhancer of ray fusion) mutations were identified in a mab-20 enhancer screen. Mutants of plexin-2 (plx-2) and unc-129, which encodes an axon guiding TGF-beta, were also found to be erfs. Genetic analyses show that plx-2 and mab-20 function in the same pathway, as expected if PLX-2 is a receptor for MAB-20. Surprisingly, MAB-20 also signals in a parallel pathway that requires efn-4. This signal utilizes a non-plexin receptor. The expression of plx-2, efn-4, and unc-129 in subsets of 3-cell sensory ray clusters likely mediates the ray-specific cell sorting functions of the ubiquitously expressed mab-20. We present a model for the integrated control of TGF-beta, semaphorin, and ephrin signaling in the sorting of cell clusters into distinct rays in the developing male tail.
信号素和 Ephrin 是轴突导向因子。在秀丽隐杆线虫中，信号素 -2a/mab -20 和 Ephrin -4/efn -4/mab -26 也调节细胞分选，以在雄性尾部形成不同的射线。在 mab -20 增强子筛选中鉴定出了几个 erf（射线融合增强子）突变。还发现丛状蛋白 -2（plx -2）和 unc -129（编码一种轴突导向转化生长因子 -β）的突变体是 erf。遗传分析表明，plx -2 和 mab -20 在同一途径中起作用，这与 PLX -2 是 MAB -20 的受体的预期一致。令人惊讶的是，MAB -20 也在需要 efn -4 的平行途径中发出信号。该信号利用一种非丛状蛋白受体。plx -2、efn -4 和 unc -129 在 3 细胞感觉射线簇的子集中的表达可能介导了普遍表达的 mab -20 的射线特异性细胞分选功能。我们提出了一个模型，用于在发育中的雄性尾部将细胞簇分选成不同射线的过程中对转化生长因子 -β、信号素和 Ephrin 信号进行综合控制。
