Xu Zhijing, Zang Jingze, Zhang Xintong, Zheng Qiwei, Li Yifan, Field Nadine, Fiserova Jindriska, Hua Bing, Qu Xiaolu, Kriechbaumer Verena, Deeks Michael J, Hussey Patrick J, Wang Pengwei
National Key Laboratory for Germplasm Innovation and Utilization of Horticultural Crops, College of Horticulture and Forestry Sciences, Huazhong Agricultural University, Wuhan 430070, China.
Hubei Hongshan Laboratory, Wuhan 430070, China.
Proc Natl Acad Sci U S A. 2025 Feb 11;122(6):e2416927122. doi: 10.1073/pnas.2416927122. Epub 2025 Feb 6.
Plant cytokinesis requires coordination between the actin cytoskeleton, microtubules, and membranes to guide division plane formation and cell plate expansion; how these regulatory factors are coordinated remains unknown. The actin cytoskeleton assembly is controlled by several actin nucleation factors, such as the SCAR/WAVE complex, which regulates actin nucleation and branching through the activation of the ARP2/3 complex. The activity of these actin regulatory proteins is likely influenced by interactions with specific membranes; however, the molecular basis and the biological relevance of SCAR-membrane interactions are also unclear. In this study, we demonstrate that the ER-PM tethering protein VAP27-1 directly interacts with SCAR2 at the ER membrane and that they colocalize to guide cell plate orientation during cell division. In the root meristem, both VAP27-1 and SCAR2 exhibit polarized localization at the cell plates, where the interaction between ER and PM is abundant. VAP27-1 recruits SCAR2 to the cell division plane, where there is a high concentration of actin filaments. In the mutant, the densities of cortical ER, SCAR2, and consequently actin filaments are significantly reduced at the cell division plane, affecting cell plate orientation, cell division, and root development. A similar phenomenon is also observed in the mutant, suggesting that VAP27 and SCAR proteins regulate cell division through a similar pathway. In conclusion, our data reveal a plant-specific function of VAP27-regulated ER-PM interaction and advance our understanding of plant ER-PM contact site and its role in cell division.
植物胞质分裂需要肌动蛋白细胞骨架、微管和膜之间的协调,以引导分裂平面的形成和细胞板的扩展;这些调控因子如何协调尚不清楚。肌动蛋白细胞骨架的组装受几种肌动蛋白成核因子控制,如SCAR/WAVE复合体,它通过激活ARP2/3复合体来调节肌动蛋白的成核和分支。这些肌动蛋白调节蛋白的活性可能受与特定膜相互作用的影响;然而,SCAR与膜相互作用的分子基础和生物学相关性也不清楚。在本研究中,我们证明内质网-质膜锚定蛋白VAP27-1在内质网膜处直接与SCAR2相互作用,并且它们共定位以在细胞分裂期间引导细胞板定向。在根分生组织中,VAP27-1和SCAR2在细胞板处均表现出极化定位,内质网和质膜之间的相互作用在此处丰富。VAP27-1将SCAR2招募到细胞分裂平面,此处肌动蛋白丝浓度较高。在突变体中,细胞分裂平面处的皮质内质网、SCAR2以及相应的肌动蛋白丝密度显著降低,影响细胞板定向、细胞分裂和根发育。在突变体中也观察到类似现象,表明VAP27和SCAR蛋白通过相似途径调节细胞分裂。总之,我们的数据揭示了VAP27调节的内质网-质膜相互作用的植物特异性功能,并推进了我们对植物内质网-质膜接触位点及其在细胞分裂中作用的理解。