Colombié Nathalie, Vérollet Christel, Sampaio Paula, Moisand André, Sunkel Claudio, Bourbon Henri-Marc, Wright Michel, Raynaud-Messina Brigitte
Centre de Recherche en Pharmacologie-Santé, Unité Mixte de Recherche 2587, Centre National de la Recherche Scientifique-Pierre Fabre, Institut de Sciences et Technologies du Médicament de Toulouse, 31400 Toulouse, France.
Mol Biol Cell. 2006 Jan;17(1):272-82. doi: 10.1091/mbc.e05-08-0722. Epub 2005 Oct 19.
Gamma-tubulin, a protein critical for microtubule assembly, functions within multiprotein complexes. However, little is known about the respective role of gamma-tubulin partners in metazoans. For the first time in a multicellular organism, we have investigated the function of Dgrip84, the Drosophila orthologue of the Saccharomyces cerevisiae gamma-tubulin-associated protein Spc97p. Mutant analysis shows that Dgrip84 is essential for viability. Its depletion promotes a moderate increase in the mitotic index, correlated with the appearance of monopolar or unpolarized spindles, impairment of centrosome maturation, and increase of polyploid nuclei. This in vivo study is strengthened by an RNA interference approach in cultured S2 cells. Electron microscopy analysis suggests that monopolar spindles might result from a failure of centrosome separation and an unusual microtubule assembly pathway via centriolar triplets. Moreover, we point to an involvement of Dgrip84 in the spindle checkpoint regulation and in the maintenance of interphase microtubule dynamics. Dgrip84 also seems essential for male meiosis, ensuring spindle bipolarity and correct completion of cytokinesis. These data sustain that Dgrip84 is required in some aspects of microtubule dynamics and organization both in interphase and mitosis. The nature of a minimal gamma-tubulin complex necessary for proper microtubule organization in the metazoans is discussed.
γ-微管蛋白是一种对微管组装至关重要的蛋白质，在多蛋白复合物中发挥作用。然而，关于后生动物中γ-微管蛋白伴侣各自的作用，人们了解甚少。在多细胞生物中，我们首次研究了酿酒酵母γ-微管蛋白相关蛋白Spc97p的果蝇同源物Dgrip84的功能。突变分析表明，Dgrip84对生存能力至关重要。其缺失会使有丝分裂指数适度增加，这与单极或无极化纺锤体的出现、中心体成熟受损以及多倍体细胞核的增加相关。在培养的S2细胞中采用RNA干扰方法加强了这项体内研究。电子显微镜分析表明，单极纺锤体可能是由于中心体分离失败以及通过中心粒三联体的异常微管组装途径所致。此外，我们指出Dgrip84参与纺锤体检查点调节以及间期微管动力学的维持。Dgrip84对雄性减数分裂似乎也至关重要，可确保纺锤体双极性和胞质分裂的正确完成。这些数据表明，Dgrip84在间期和有丝分裂的微管动力学和组织的某些方面是必需的。本文还讨论了后生动物中适当微管组织所需的最小γ-微管蛋白复合物的性质。
