Biology Department, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States of America.
Department of Biology, Knox College, Galesburg, Illinois, United States of America.
PLoS Genet. 2023 Mar 28;19(3):e1010319. doi: 10.1371/journal.pgen.1010319. eCollection 2023 Mar.
One of the most common cell shape changes driving morphogenesis in diverse animals is the constriction of the apical cell surface. Apical constriction depends on contraction of an actomyosin network in the apical cell cortex, but such actomyosin networks have been shown to undergo continual, conveyor belt-like contractions before the shrinking of an apical surface begins. This finding suggests that apical constriction is not necessarily triggered by the contraction of actomyosin networks, but rather can be triggered by unidentified, temporally-regulated mechanical links between actomyosin and junctions. Here, we used C. elegans gastrulation as a model to seek genes that contribute to such dynamic linkage. We found that α-catenin and β-catenin initially failed to move centripetally with contracting cortical actomyosin networks, suggesting that linkage is regulated between intact cadherin-catenin complexes and actomyosin. We used proteomic and transcriptomic approaches to identify new players, including the candidate linkers AFD-1/afadin and ZYX-1/zyxin, as contributing to C. elegans gastrulation. We found that ZYX-1/zyxin is among a family of LIM domain proteins that have transcripts that become enriched in multiple cells just before they undergo apical constriction. We developed a semi-automated image analysis tool and used it to find that ZYX-1/zyxin contributes to cell-cell junctions' centripetal movement in concert with contracting actomyosin networks. These results identify several new genes that contribute to C. elegans gastrulation, and they identify zyxin as a key protein important for actomyosin networks to effectively pull cell-cell junctions inward during apical constriction. The transcriptional upregulation of ZYX-1/zyxin in specific cells in C. elegans points to one way that developmental patterning spatiotemporally regulates cell biological mechanisms in vivo. Because zyxin and related proteins contribute to membrane-cytoskeleton linkage in other systems, we anticipate that its roles in regulating apical constriction in this manner may be conserved.
在不同动物中驱动形态发生的最常见的细胞形状变化之一是顶端细胞表面的收缩。顶端收缩依赖于顶端细胞皮层中肌动球蛋白网络的收缩，但在顶端表面开始收缩之前，已经显示这种肌动球蛋白网络会经历连续的、输送带样的收缩。这一发现表明，顶端收缩不一定是由肌动球蛋白网络的收缩触发的，而是可以由肌动球蛋白和连接点之间未被识别的、时间调节的机械连接触发。在这里，我们使用线虫胚层形成作为模型来寻找有助于这种动态连接的基因。我们发现α-连环蛋白和β-连环蛋白最初没有随着收缩的皮质肌动球蛋白网络向中心移动，这表明在完整的钙粘蛋白-连环蛋白复合物和肌动球蛋白之间存在调节的连接。我们使用蛋白质组学和转录组学方法来鉴定新的参与者，包括候选连接蛋白 AFD-1/afadin 和 ZYX-1/zyxin，它们有助于线虫胚层形成。我们发现 ZYX-1/zyxin 是 LIM 结构域蛋白家族的一员，其转录本在多个细胞即将进行顶端收缩之前富集。我们开发了一种半自动图像分析工具，并使用它发现 ZYX-1/zyxin 与收缩的肌动球蛋白网络一起有助于细胞-细胞连接向中心移动。这些结果鉴定了几个有助于线虫胚层形成的新基因，并鉴定出 zyxin 是肌动球蛋白网络在顶端收缩过程中有效向内拉动细胞-细胞连接的关键蛋白。在 C. elegans 中特定细胞中 ZYX-1/zyxin 的转录上调表明了一种方式，即发育模式在体内时空调节细胞生物学机制。由于 zyxin 和相关蛋白在其他系统中有助于膜-细胞骨架连接，我们预计它以这种方式调节顶端收缩的作用可能是保守的。
