Department of Biology, Drexel University, Philadelphia, PA 19104, USA.
J Cell Biol. 2011 Jul 25;194(2):187-97. doi: 10.1083/jcb.201102076.
Establishment of epithelial polarity requires the reorganization of the microtubule (MT) cytoskeleton from a radial array into a network positioned along the apicobasal axis of the cell. Little is known about the mechanisms that spatially guide the remodeling of MTs during epithelial polarization. Septins are filamentous guanine triphosphatases (GTPases) that associate with MTs, but the function of septins in MT organization and dynamics is poorly understood. In this paper, we show that in polarizing epithelia, septins guide the directionality of MT plus end movement by suppressing MT catastrophe. By enabling persistent MT growth, two spatially distinct populations of septins, perinuclear and peripheral filaments, steer the growth and capture of MT plus ends. This navigation mechanism is essential for the maintenance of perinuclear MT bundles and for the orientation of peripheral MTs as well as for the apicobasal positioning of MTs. Our results suggest that septins provide the directional guidance cues necessary for polarizing the epithelial MT network.
上皮细胞极性的建立需要微管（MT）细胞骨架从放射状排列重新组织成沿着细胞顶底轴定位的网络。对于在上皮细胞极化过程中空间指导 MT 重塑的机制知之甚少。 凝缩蛋白是与 MT 相关的丝状鸟嘌呤三磷酸酶（GTPases），但凝缩蛋白在 MT 组织和动力学中的功能知之甚少。 在本文中，我们表明在极化上皮中，凝缩蛋白通过抑制 MT 崩溃来指导 MT 正极运动的方向性。 通过使 MT 持续生长，两种空间上不同的凝缩蛋白群体，核周和外周丝，引导 MT 正极的生长和捕获。 这种导航机制对于维持核周 MT 束以及外周 MT 的定向以及 MT 的顶底定位是必不可少的。 我们的结果表明，凝缩蛋白为极化上皮 MT 网络提供了必要的定向指导线索。
