ARP2/3-independent WAVE/SCAR pathway and class XI myosin control sperm nuclear migration in flowering plants
ARP2/3-independent WAVE/SCAR pathway and class XI myosin control sperm nuclear migration in flowering plants
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DOI：
10.1073/pnas.2015550117
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发表时间：
2020-12-22
影响因子：
11.1
通讯作者：
Kawashima, Tomokazu
中科院分区：
文献类型：
--
作者：
Ali, Mohammad Foteh;Fatema, Umma;Kawashima, Tomokazu
真核生物受精后，配子核迁移融合亲本基因组，以启动下一代的发育。在大多数动物中，微管控制受精卵中雌性和雄性原核的迁移。另一方面，有花植物已经进化出基于肌动蛋白丝（F-actin）的精子核迁移系统用于核配。有花植物还进化出一种独特的双受精过程：两个雌性配子体细胞，即卵细胞和中央细胞，每个细胞都被一个精细胞受精。开花植物如何利用和控制F-肌动蛋白的双受精事件的分子和细胞机制是未知的。使用共聚焦显微镜活细胞成像与药理学和遗传学方法相结合，我们确定了参与F-肌动蛋白动力学和精子核迁移在拟南芥（拟南芥）和烟草（烟草）的因素。我们证明，F-肌动蛋白调节，SCAR 2，而不是ARP 2/3蛋白复合物，控制协调的主动F-肌动蛋白运动。这些结果表明，ARP 2/3-独立的WAVE/SCAR信号通路调节F-actin在雌性配子体细胞受精的动力学。我们还确定，XI类肌球蛋白XI-G控制活跃的F-肌动蛋白运动在拟南芥中央细胞。XI-G不是一个简单的转运体，沿着F-肌动蛋白运送货物，而是可以产生控制F-肌动蛋白动态运动的力，以进行受精。我们的研究结果提供了深入了解的机制，控制配子核迁移，并揭示开花植物动态F-肌动蛋白运动的调控途径。
After eukaryotic fertilization, gamete nuclei migrate to fuse parental genomes in order to initiate development of the next generation. In most animals, microtubules control female and male pronuclear migration in the zygote. Flowering plants, on the other hand, have evolved actin filament (F-actin)-based sperm nuclear migration systems for karyogamy. Flowering plants have also evolved a unique double-fertilization process: two female gametophytic cells, the egg and central cells, are each fertilized by a sperm cell. The molecular and cellular mechanisms of how flowering plants utilize and control F-actin for double-fertilization events are largely unknown. Using confocal microscopy live-cell imaging with a combination of pharmacological and genetic approaches, we identified factors involved in F-actin dynamics and sperm nuclear migration in Arabidopsis thaliana (Arabidopsis) and Nicotiana tabacum (tobacco). We demonstrate that the F-actin regulator, SCAR2, but not the ARP2/3 protein complex, controls the coordinated active F-actin movement. These results imply that an ARP2/3-independent WAVE/SCAR-signaling pathway regulates F-actin dynamics in female gametophytic cells for fertilization. We also identify that the class XI myosin XI-G controls active F-actin movement in the Arabidopsis central cell. XI-G is not a simple transporter, moving cargos along F-actin, but can generate forces that control the dynamic movement of F-actin for fertilization. Our results provide insights into the mechanisms that control gamete nuclear migration and reveal regulatory pathways for dynamic F-actin movement in flowering plants.