Strikingly, epithelial morphogenesis remains incomplete at the end of C. elegans embryonic development; newly hatched larvae undergo extensive remodelling of their ventral epidermis during the first larval stage (L1), when newly-born epidermal cells move ventrally to complete the epidermal syncytium. Prior to this remodelling, undivided lateral seam cells produce anterior adherens junction processes that are inherited by the anterior daughter cells following an asymmetric division during L1. These adherens junction processes provide the ventral migratory route for these anterior daughters. Here, we show that these processes are perturbed in pal-1/caudal mutant animals, resulting in their inheritance by posterior, seam-fated daughters. This causes aberrant migration of seam daughter cells, disrupting the ventral epidermis. Using 4D-lineaging, we demonstrate that this larval epidermal morphogenesis defect in pal-1 mutants can be traced directly back to an initial cell positioning defect in the embryo. pal-1 expression, driven by a single intronic enhancer, is required to correctly position the seam cells in embryos such that the appropriate cell junctions support the correct migratory paths of seam daughters later in development, irrespective of their fate. Thus, during ventral epithelial remodelling in C. elegans, we show that the position of migrating cells, specified by pal-1/caudal, appears to be more important than their fate in driving morphogenesis.

中文翻译：

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尾依赖细胞定位指导线虫腹侧表皮的形态发生。

令人惊讶的是，在秀丽隐杆线虫胚胎发育结束时，上皮形态发生仍不完全。当刚出生的表皮细胞通过腹侧移动完成表皮合胞体时，刚孵出的幼虫在其幼虫的第一个阶段（L1）对其腹表皮进行广泛的重塑。在此重塑之前，未分裂的侧缝细胞会产生前粘连连接过程，该过程由L1期间的不对称分裂后的前子细胞继承。这些黏附连接过程为这些前代女儿提供了腹侧迁移途径。在这里，我们显示这些过程在pal-1 /尾状突变动物中受到干扰，从而导致它们由后接缝的后代继承。这会导致接缝子细胞异常迁移，破坏腹侧表皮。使用4D谱系 我们证明在pal-1突变体中这种幼虫表皮形态发生缺陷可以直接追溯到胚胎中最初的细胞定位缺陷。需要由单个内含子增强子驱动的pal-1表达来正确定位接缝细胞在胚胎中的位置，以使适当的细胞接合处支持接缝女儿后期发育的正确迁移路径，而不论其命运如何。因此，在秀丽隐杆线虫的腹上皮重塑过程中，我们显示由pal-1 /尾部指定的迁移细胞的位置在驱动形态发生中比其命运似乎更为重要。需要将接缝细胞正确定位在胚胎中，以便适当的细胞连接支持接缝女儿在发育后期的正确迁移路径，而不管其命运如何。因此，在秀丽隐杆线虫的腹上皮重塑过程中，我们显示由pal-1 /尾部指定的迁移细胞的位置在驱动形态发生中比其命运似乎更为重要。需要将接缝细胞正确定位在胚胎中，以便适当的细胞连接支持接缝女儿在发育后期的正确迁移路径，而不管其命运如何。因此，在秀丽隐杆线虫的腹上皮重塑过程中，我们显示由pal-1 /尾部指定的迁移细胞的位置在驱动形态发生中比其命运似乎更为重要。