Non-centrosomal microtubule-organizing centres (ncMTOCs) have a variety of roles that are presumed to serve the diverse functions of the range of cell types in which they are found. ncMTOCs are diverse in their composition, subcellular localization and function. Here we report a perinuclear MTOC in Drosophila fat body cells that is anchored by the Nesprin homologue Msp300 at the cytoplasmic surface of the nucleus. Msp300 recruits the microtubule minus-end protein Patronin, a calmodulin-regulated spectrin-associated protein (CAMSAP) homologue, which functions redundantly with Ninein to further recruit the microtubule polymerase Msps-a member of the XMAP215 family-to assemble non-centrosomal microtubules and does so independently of the widespread microtubule nucleation factor γ-Tubulin. Functionally, the fat body ncMTOC and the radial microtubule arrays that it organizes are essential for nuclear positioning and for secretion of basement membrane components via retrograde dynein-dependent endosomal trafficking that restricts plasma membrane growth. Together, this study identifies a perinuclear ncMTOC with unique architecture that regulates microtubules, serving vital functions.

中文翻译：

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核周微管组织中心控制核的定位和基底膜的分泌。

非中心体微管组织中心（ncMTOC）具有多种作用，据推测可发挥其所处细胞类型范围的多种功能。ncMTOC的组成，亚细胞定位和功能各不相同。在这里，我们报告果蝇脂肪体细胞中的核周MTOC，其被Nesprin同系物Msp300锚定在细胞核的细胞质表面。Msp300募集微管负端蛋白Patronin，钙调蛋白调节的血影蛋白相关蛋白（CAMSAP）同源物，与Ninein重复发挥功能，进一步募集微管聚合酶Msps（XMAP215家族的成员）以组装非中心体微管和这样做与广泛的微管成核因子γ-微管蛋白无关。在功能上 脂肪组织ncMTOC及其组织的放射状微管阵列对于核定位和通过逆行依赖动力蛋白的内体运输（限制质膜生长）分泌基膜成分至关重要。总之，这项研究确定了具有独特结构的微核ncMTOC，该结构调节微管，发挥重要功能。