COLLABORATIVE RESEARCH: Establishing the microtubule-actin crosstalk in the preprophase band by the rice kinesin OsKCH2

该项目研究调节水稻植株细胞分裂和生长的基本机制，预计将产生广泛的社会影响。首先，该项目的发现将影响未来的水稻育种，水稻养活了世界一半的人口。其次，俄勒冈州立大学和加州大学戴维斯分校的科学家将通过参与以发现为导向的研究，接受多学科领域的培训。第三，该项目包含基于光学显微镜的短期课程和为贫困学生提供的动手培训机会，这将激发他们对STEM学科的兴趣。此外，为了提高公众对前沿研究项目的认识，将在高中和社区大学科学教师的高级光学显微镜研讨会中将植物马达蛋白作为活生生的例子。具体地说，该项目旨在研究水稻植物特有的激动素OsKCH2如何使皮层分裂部位的微管(MT)和丝状肌动蛋白(F-Actin)之间的串扰以及它如何调节细胞分裂。动蛋白是一种马达蛋白，它利用ATP水解产生的能量来驱动许多重要的细胞过程，如沿MTS运输货物和组织/重塑具有重要生理意义的MT阵列。OsKCH2属于高等植物中具有钙调素同源结构域(KCHs)的动蛋白家族。已知KCHs在体外能使MTS和F-肌动蛋白发生交联，但它们在植物生长发育中的作用尚不清楚。该项目基于几个关键的初步发现，包括：(1)OsKCH2的突变导致了矮化表型；(2)OsKCH2在有丝分裂的早期阶段与PPB特异相关；(3)OsKCH2在体外直接与微管上的F-肌动蛋白结合并运输；(4)OsKCH2是第一个以单二聚体的形式展示前进运动的负端导向的Kinesin-14。本项目将使用多学科方法来解决两个目标：(1)利用体外单分子成像技术剖析OsKCH2前进运动的调控机制，以及(2)通过检测与kch2缺失突变相关的表型来探讨OsKCH2在细胞分裂和植物生长中的作用。

This project studies the fundamental mechanisms that regulate cell division and growth of the rice plant and is expected to have a broad spectrum of societal impacts. First, findings from this project will impact future breeding of rice, which feeds half of the world's population. Second, scientists at both Oregon State University and University of California in Davis will be trained in multi-disciplinary areas by participating in the discovery-oriented research. Third, this project contains light microscopy-based short courses and hands-on training opportunities for underserved students, which will stimulate their interests in STEM disciplines. In addition, to increase public awareness of cutting-edge research programs, plant motor proteins will be included as living examples in advanced light microscopy workshops for high school and community college science teachers.Specifically, this project is aimed at investigating how OsKCH2, a plant-specific kinesin in the rice plant Oryza sativa, enables the crosstalk between microtubules (MTs) and filamentous actins (F-actins) at the cortical division site and how it regulates cell division. Kinesins are motor proteins that use the energy from ATP hydrolysis to power numerous essential cellular processes such as transporting cargos along MTs and organizing/remodeling physiologically important MT-based arrays. OsKCH2 belongs to the group of Kinesins with a Calponin Homology domain (KCHs) in high plants. KCHs are known to crosslink MTs and F-actin in vitro, but their functions in plant growth and development remain poorly understood. The project is based on several critical preliminary findings including: (1) mutations in OsKCH2 caused a dwarfism phenotype, (2) OsKCH2 is specifically associated with the PPB during early stages of mitosis, (3) OsKCH2 directly binds to and transports F-actin on microtubules in vitro, and (4) OsKCH2 is the first minus end-directed Kinesin-14 to demonstrate processive motility as a single dimer. This project will use a multi-disciplinary approach to address two objectives: (1) dissecting the regulatory mechanism underlying the processive motility of OsKCH2 using in vitro single-molecule imaging, and (2) interrogating the in vivo functions of OsKCH2 in cell division and plant growth by examining phenotypes linked to a null kch2 mutation.