Labat-de-Hoz Leticia, Rubio-Ramos Armando, Casares-Arias Javier, Bernabé-Rubio Miguel, Correas Isabel, Alonso Miguel A
Centro de Biología Molecular "Severo Ochoa", Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Madrid, Spain.
Department of Molecular Biology, Universidad Autónoma de Madrid, Madrid, Spain.
Front Cell Dev Biol. 2021 Jan 7;8:622918. doi: 10.3389/fcell.2020.622918. eCollection 2020.
Primary cilia are solitary, microtubule-based protrusions surrounded by a ciliary membrane equipped with selected receptors that orchestrate important signaling pathways that control cell growth, differentiation, development and homeostasis. Depending on the cell type, primary cilium assembly takes place intracellularly or at the cell surface. The intracellular route has been the focus of research on primary cilium biogenesis, whereas the route that occurs at the cell surface, which we call the "alternative" route, has been much less thoroughly characterized. In this review, based on recent experimental evidence, we present a model of primary ciliogenesis by the alternative route in which the remnant of the midbody generated upon cytokinesis acquires compact membranes, that are involved in compartmentalization of biological membranes. The midbody remnant delivers part of those membranes to the centrosome in order to assemble the ciliary membrane, thereby licensing primary cilium formation. The midbody remnant's involvement in primary cilium formation, the regulation of its inheritance by the ESCRT machinery, and the assembly of the ciliary membrane from the membranes originally associated with the remnant are discussed in the context of the literature concerning the ciliary membrane, the emerging roles of the midbody remnant, the regulation of cytokinesis, and the role of membrane compartmentalization. We also present a model of cilium emergence during evolution, and summarize the directions for future research.
初级纤毛是基于微管的单个突出物，被配备有特定受体的纤毛膜所包围，这些受体协调控制细胞生长、分化、发育和内稳态的重要信号通路。根据细胞类型的不同，初级纤毛组装在细胞内或细胞表面发生。细胞内途径一直是初级纤毛生物发生研究的重点，而在细胞表面发生的途径，我们称之为“替代”途径，其特征尚未得到充分研究。在本综述中，基于最近的实验证据，我们提出了一种通过替代途径进行初级纤毛发生的模型，其中胞质分裂时产生的中体残余物获得紧密的膜，这些膜参与生物膜的区室化。中体残余物将这些膜的一部分输送到中心体以组装纤毛膜，从而许可初级纤毛的形成。在有关纤毛膜、中体残余物的新作用、胞质分裂的调节以及膜区室化的作用的文献背景下，讨论了中体残余物在初级纤毛形成中的参与、其由ESCRT机制对其遗传的调节以及从最初与残余物相关的膜组装纤毛膜的过程。我们还提出了进化过程中纤毛出现的模型，并总结了未来研究的方向。
