植物微丝骨架和微管骨架通过高度复杂的动态变化在细胞生命活动中发挥作用，如细胞生长、细胞分裂。在植物细胞周期中，细胞骨架相关蛋白如微丝结合蛋白(ABPs)和微管结合蛋白(MAPs)通过调控微丝、微管的结构和动态变化与微丝、微管在细胞周期中协调发挥功能。因此，研究细胞骨架及其相关蛋白在细胞周期中的功能对于深入理解细胞分裂的分子机制具有重要的科学意义。 本研究以拟南芥悬浮细胞和烟草BY-2悬浮细胞为实验材料，探究了AtMAP96在植物细胞中的定位及其可能的功能。通过激光共聚焦显微镜观察发现：在细胞间期，AtMAP96存在周质分布、核周辐射分布以及核周和周质并存的三种分布情况；在分裂期，AtMAP96定位在早前期带、纺锤体和成膜体等有丝分裂器上。实验室前期的研究结果表明AtMAP96是一个微管结合蛋白，本研究通过进一步观察统计AtMAP96不同的截短蛋白在细胞周期中的定位情况得出结论，N-CC1(N端M1-S222)是AtMAP96与微管相互作用的功能结构域。 此外，本研究通过观察AtMAP96-GFP和RFP-MAP4共表达的细胞以及AtMAP96-GFP和mcherry-fABD2共表达的细胞发现，AtMAP96在细胞周期中与RFP-MAP4标记的微管和mcherry-fABD2标记的微丝均存在共定位。药理学实验结果表明AtMAP96在细胞周期中的定位既依赖于微管也依赖于微丝。因此，本研究进一步探究了AtMAP96对微管骨架和微丝骨架的调控作用。药理学实验结果表明，过表达AtMAP96可以增强细胞抵抗微管解聚药物的作用，说明AtMAP96可以稳定微管；同时，过表达AtMAP96能够使细胞内的微丝成束并且使成膜体微丝中线的宽度变小。以上结果表明，AtMAP96在体内以不同的方式调控微管骨架和微丝骨架。本研究通过观察AtMAP96对细胞周期进程的影响发现，过表达AtMAP96导致胞质分裂后期出现具有微丝、微管装置并且可以形成膜结构的“额外成膜体”；缺失AtMAP96导致胞质分裂后期出现片段化的成膜体，说明AtMAP96可以调控植物细胞胞质分裂后期成膜体的动态和组装。 综上所述， AtMAP96是一个可以调控微丝骨架的微管结合蛋白，通过调控细胞内微丝骨架和微管骨架的结构与动态变化在细胞周期进程中发挥重要的作用。

Microtubules and actin filaments play critical roles through their highly dynamic structures in many cellular processes, including cell growth and cell division. In cell cycle progression, cytoskeleton associated proteins, such as actin binding proteins (ABPs) and microtubule-associated proteins (MAPs), can coordinate their functions with actin filaments and microtubules, by regulating the structures and dynamics of actin filaments and microtubules. Therefore, it's of great significance to explore functions of the cytoskeleton and cytoskeleton associated proteins in cell cycle, providing a deeper insight into the molecular mechanism of cell division. In this research, suspension culture of Arabidopsis thaliana cell line and tobacco BY-2 cell line were chosen to investigate the localization and possible functions of AtMAP96. Through laser confocal microscopy, it was observed that the localization of AtMAP96 can be classified into the following three cases: cortical array, radial array or both of them during interphase; and localized on mitotic apparatus, such as preprophase band, spindle and phragmoplast during mitosis. Previous study in our laboratory showed that AtMAP96 was a microtubule-associated protein. In this study, we demonstrated that N-CC1 (N-terminal M1-S222) was the functional domain of AtMAP96 which could interact with microtubules, by exploring the localization of different truncated protein of AtMAP96 in cell cycle. In addition, in BY-2 cells that co-expressed AtMAP96-GFP fusion protein and RFP-MAP4 fusion protein, as well as cells that co-expressed AtMAP96-GFP fusion protein and mcherry-fABD2 fusion protein, we found that AtMAP96 could co-localize with RFP-MAP4 labeled microtubules and mcherry-fABD2 labeled actin filaments. What's more, pharmacological experiment implied that the subcellular localization of AtMAP96 relied on not only microtubules but also actin filaments. Next, we further explored the regulating effects of AtMAP96 on microtubules and actin filaments. The overexpression of AtMAP96 increased the resistance of microtubules disrupting drug-Oryzalin in BY-2 cells, indicating that AtMAP96 could stabilize microtubules. Meanwhile, overexpression of AtMAP96 induced the bundles of actin filaments, and narrowed the width of actin filaments’ midline on phragmoplast. These results implied that AtMAP96 regulated microtubules and actin filaments in different patterns. We also studied the influence of AtMAP96 on cell progression. Overexpression of AtMAP96 leaded to the “extra phragmoplasts”, which had microtubules and actin filaments apparatus, and could form cell plates eventually. However, there were only segmented phragmoplasts could be observed in atmap96atmap92 mutant cells. These findings suggested that AtMAP96 was able to regulate the organization and dynamics of phragmoplasts in the late stage of cytokinesis in plant cells. In summary, AtMAP96 is a microtubule-associated protein which can regulate actin filaments, and plays important roles in cell cycle progression through regulating structures and dynamics of microtubules and actin filaments.