Saturno Dominique M, Castanzo Dominic T, Williams Margaret, Parikh Devayu A, Jaeger Eva C, Lyczak Rebecca
Ursinus College, Department of Biology, Collegeville, PA 19426, United States.
Dev Biol. 2017 Feb 15;422(2):135-145. doi: 10.1016/j.ydbio.2016.12.025. Epub 2017 Jan 6.
In C. elegans, the anterior-posterior axis is established at the one-cell stage when the embryo polarizes along its long axis. One model suggests that a cue from the centrosome triggers symmetry breaking and is then dispensable for further steps in the process. In the absence of the initial centrosome cue, a redundant mechanism, reliant on the centrosome's microtubules, can polarize the cell. Despite this model, data from multiple sources suggest that direct centrosome-contact with the cortex may play a role in ensuring robust polarization. Some of this past work includes analysis of pam-1 mutants, which lack a functional puromycin-sensitive aminopeptidase and have aberrant centrosome positioning and variable polarization defects. To better understand the role of centrosome dynamics in polarization, we looked in detail at centrosome behavior in relation to key polarity landmarks in pam-1 mutants as well as those lacking cortical flows. We provide evidence for a model in which sustained direct contact between the centrosome and the cortex acts to reinforce both the actomyosin and the microtubule-dependent pathways. This contact is necessary for polarization when flows are inhibited.
在秀丽隐杆线虫中，前后轴在胚胎沿其长轴极化的单细胞阶段就已确立。一种模型认为，来自中心体的信号触发对称性破缺，然后在该过程的后续步骤中不再需要。在没有初始中心体信号的情况下，一种依赖于中心体微管的冗余机制可以使细胞极化。尽管有这个模型，但来自多个来源的数据表明，中心体与皮层的直接接触可能在确保稳健极化方面发挥作用。过去的一些工作包括对pam-1突变体的分析，这些突变体缺乏功能性嘌呤霉素敏感氨肽酶，具有异常的中心体定位和可变的极化缺陷。为了更好地理解中心体动力学在极化中的作用，我们详细研究了pam-1突变体以及缺乏皮层流动的突变体中与关键极性标志物相关的中心体行为。我们为一个模型提供了证据，在该模型中，中心体与皮层之间持续的直接接触起到增强肌动球蛋白和微管依赖途径的作用。当流动受到抑制时，这种接触对于极化是必要的。
