The function and assembly of the lamin-B spindle sheath

描述（由申请人提供）：本提案旨在研究围绕纺锤体微管的有丝分裂膜网络如何调节纺锤体形态发生和纺锤体方向。有丝分裂纺锤体形态的组装和维持需要平衡基于微管的运动蛋白（如动力蛋白和动力蛋白Eg5）产生的力，并适当调节微管动力学。我们对含有层粘连蛋白b的有丝分裂膜网络的研究，我们称之为层粘连蛋白b纺锤体鞘，已经表明这种纺锤体相关结构调节纺锤体形态和纺锤体方向。由于纤层蛋白b与动力蛋白调节因子NudEL和微管解聚合酶MCAK相互作用，我们假设围绕纺锤体微管体的纤层蛋白b纺锤体鞘通过MCAK和/或NudEL在纺锤体边界内作为限制微管生长的屏障。此外，我们提出围绕纺锤极的层状蛋白- b纺锤体鞘调节星状微管，以确保正确搜索和捕获皮层纺锤体方向线索。我们将在Aim 1和Aim 2中使用我们生成的一些分析和工具来测试这些想法。我们之前已经证明，RanGTP、微管和动力蛋白都是lamin-B纺锤鞘组装所必需的。最近，我们发现核纤层蛋白b在有丝分裂中与几种核孔蛋白结合。在目的3中，我们将测试纤层蛋白- b和核孔蛋白之间的相互作用是纺锤体鞘组装所必需的假设。这些研究将对理解非微管细胞结构如何调节纺锤体在有丝分裂中的组装和取向作出重大贡献。

DESCRIPTION (provided by applicant): This proposal aims to study how the mitotic membrane network that surrounds the spindle microtubules regulates spindle morphogenesis and spindle orientation. The assembly and maintenance of mitotic spindle morphology requires balancing of forces generated by microtubule-based motor proteins such as dynein and the kinesin Eg5, and proper regulation of microtubule dynamics. Our studies of the lamin-B-containing mitotic membrane network, which we refer to as the lamin-B spindle sheath, have shown that this spindle-associated structure regulates spindle morphology and spindle orientation. Since lamin-B interacts with the dynein regulator NudEL and the microtubule depolymerase MCAK, we hypothesize that the lamin-B spindle sheath that surrounds the body of the spindle microtubules functions as a barrier to limit microtubule growth within the spindle boundary through MCAK and/or NudEL. Moreover, we propose that the lamin-B spindle sheath surrounding the spindle poles regulates the astral microtubules to ensure proper search and capture of the cortical spindle orientation cues. We will test these ideas in Aim 1 and Aim 2 using a number of assays and tools we have generated. We have shown previously that RanGTP, microtubules, and dynein are all required for the lamin-B spindle sheath assembly. More recently, we have found that lamin-B binds to several nucleoporins in mitosis. In Aim 3, we will test the hypothesis that the interactions between lamin-B and nucleoporins are required for the assembly of the spindle sheath. These studies will make a significant contribution toward understanding how non-microtubule cellular structures regulate spindle assembly and orientation in mitosis.