Department of Cell and Developmental Biology, Feinberg School of Medicine, Northwestern University, Chicago, United States.
Cell Biology and Physiology Center, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, United States.
Elife. 2020 Feb 14;9:e54216. doi: 10.7554/eLife.54216.
Local accumulation of ) mRNA in the oocyte determines the posterior pole of the future embryo. Two major cytoskeletal components, microtubules and actin filaments, together with a microtubule motor, kinesin-1, and an actin motor, myosin-V, are essential for mRNA posterior localization. In this study, we use Staufen, an RNA-binding protein that colocalizes with mRNA, as a proxy for mRNA. We demonstrate that posterior localization of /Staufen is determined by competition between kinesin-1 and myosin-V. While kinesin-1 removes /Staufen from the cortex along microtubules, myosin-V anchors /Staufen at the cortex. Myosin-V wins over kinesin-1 at the posterior pole due to low microtubule density at this site, while kinesin-1 wins at anterior and lateral positions because they have high density of cortically-anchored microtubules. As a result, posterior determinants are removed from the anterior and lateral cortex but retained at the posterior pole. Thus, posterior determination of oocytes is defined by kinesin-myosin competition, whose outcome is primarily determined by cortical microtubule density.
mRNA 在卵母细胞中的局部积累决定了未来胚胎的后极。两种主要的细胞骨架成分，微管和肌动蛋白丝，以及微管马达 kinesin-1 和肌球蛋白马达 myosin-V，对于 mRNA 后极定位是必不可少的。在这项研究中，我们使用与 mRNA 共定位的 RNA 结合蛋白 Staufen 作为 mRNA 的替代物。我们证明了 /Staufen 的后极定位是由 kinesin-1 和 myosin-V 之间的竞争决定的。虽然 kinesin-1 沿着微管将 /Staufen 从皮层中移除，但 myosin-V 将 /Staufen 锚定在皮层上。由于该部位微管密度低，myosin-V 在后部极战胜了 kinesin-1，而 kinesin-1 在前后和侧面位置取胜，因为它们具有高密度的皮层锚定微管。因此，后部决定因素从前部和侧面皮层中去除，但保留在后极。因此，卵母细胞的后极决定是由 kinesin-myosin 竞争决定的，其结果主要取决于皮层微管密度。
