Mechanistic framework for cell-intrinsic re-establishment of PIN2 polarity after cell division

First author: Matouš Glanc; Affiliations: IST Austria (奥地利科技学院): Klosterneuburg, Austria

Corresponding author: Jiří Friml 

Cell polarity, manifested by the localization of proteins to distinct polar plasma membrane (质膜) domains, is a key prerequisite (前提) of multicellular life. In plants, PIN auxin transporters are prominent (著名的) polarity markers crucial for a plethora of (繁多的) developmental processes. Cell polarity mechanisms in plants are distinct from other eukaryotes and still largely elusive. In particular, how the cell polarities are propagated and maintained following cell division remains unknown. Plant cytokinesis (胞质分裂) is orchestrated by the cell plate—a transient centrifugally (离心地) growing endomembrane (内膜) compartment (隔间) ultimately forming the cross wall (隔墙). Trafficking of polar membrane proteins is typically redirected to the cell plate, and these will consequently have opposite polarity in at least one of the daughter cells. Here, we provide mechanistic insights into post-cytokinetic re-establishment of cell polarity as manifested by the apical, polar localization of PIN2. We show that the apical domain is defined in a cell-intrinsic manner and that re-establishment of PIN2 localization to this domain requires de novo protein secretion and endocytosis (内吞作用), but not basal-to-apical transcytosis (胞转作用). Furthermore, we identify a PINOID-related kinase WAG1, which phosphorylates PIN2 in vitro and is transcriptionally upregulated specifically in dividing cells, as a crucial regulator of post-cytokinetic PIN2 polarity re-establishment.

细胞极性，通常由蛋白的定位区分极性质膜结构域，是多个细胞生活的前提。在植物中，PIN生长素转运体是著名的极性标记，对于各种植物体内的生物学过程非常重要。植物中细胞极性机制与其他的真核生物不一样，并且大部分还不清楚。尤其是细胞极性是如何在细胞分裂时是传递并维持下去的还需要更多的研究。植物的胞质分裂由细胞板精细调控，而细胞板是一种短暂出现的离心生长的内膜隔间，并最终形成两个细胞间的间隔细胞壁。极性膜蛋白的运输会重新定向到细胞板，并会导致至少一个子细胞中建立起完全相反的极性。本文的研究揭示了细胞胞质分裂后细胞极性的重新建立机制，由PIN2蛋白的顶端、极性定位所显示。作者的研究显示顶端结构域是细胞内在的固有特性，而PIN2蛋白定位于该结构域需要从头蛋白分泌和内吞作用，而不是基顶向的胞转作用。此外，作者还鉴定了一个PINOID相关蛋白WAG1，该蛋白会在体外磷酸化PIN2并且在分裂的细胞中特异性地被转录上调，是胞质分裂后PIN2极性重新建立的关键调控因子。

通讯：Jiří Friml (https://ist.ac.at/research/research-groups/friml-group/)

个人简介：1995年，马萨里克大学，化学学士；1997年，马萨里克大学，生物化学学士；2000年，科隆大学，生物学博士；2002年，马萨里克大学，生物化学博士。

研究方向：生长素的极性运输；细胞极性；细胞内吞与再循环；信号转导的非转录机制。

doi: https://doi.org/10.1038/s41477-018-0318-3

Journal: Nature Plants

Published date: 03 December, 2018