Hunter C P, Harris J M, Maloof J N, Kenyon C
Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143-0554, USA.
Development. 1999 Feb;126(4):805-14. doi: 10.1242/dev.126.4.805.
In Caenorhabditis elegans males, a row of epidermal precursor cells called seam cells generates a pattern of cuticular alae in anterior body regions and neural sensilla called rays in the posterior. The Hox gene mab-5 is required for two posterior seam cells, V5 and V6, to generate rays. In mab-5 mutant males, V5 and V6 do not generate sensory ray lineages but instead generate lineages that lead to alae. Here we show that two independent regulatory pathways can activate mab-5 expression in the V cells. First, the caudal homolog pal-1 turns on mab-5 in V6 during embryogenesis. Second, a Wnt signaling pathway is capable of activating mab-5 in the V cells during postembryonic development; however, during normal development Wnt signaling is inhibited by signals from neighboring V cells. The inhibition of this Wnt signaling pathway by lateral signals between the V cells limits the number of rays in the animal and also determines the position of the boundary between alae and rays.
在秀丽隐杆线虫雄性个体中，一排称为体壁细胞的表皮前体细胞在前体区域产生角质层翼膜的模式，在后部产生称为射线的神经感器。Hox基因mab-5是两个后部体壁细胞V5和V6产生射线所必需的。在mab-5突变体雄性个体中，V5和V6不产生感觉射线谱系，而是产生导致翼膜的谱系。在这里，我们表明两条独立的调控途径可以激活V细胞中mab-5的表达。首先，尾部同源物pal-在胚胎发育过程中开启V6中的mab-5。其次，Wnt信号通路能够在胚胎后发育过程中激活V细胞中的mab-5；然而，在正常发育过程中，Wnt信号受到相邻V细胞信号的抑制。V细胞之间的侧向信号对这种Wnt信号通路的抑制限制了动物体内射线的数量，也决定了翼膜和射线之间边界的位置。
