Gomez-Ferreria Maria Ana, Rath Uttama, Buster Daniel W, Chanda Sumit K, Caldwell Jeremy S, Rines Daniel R, Sharp David J
Department of Physiology and Biophysics, Albert Einstein College of Medicine, New York, New York 10461, USA.
Curr Biol. 2007 Nov 20;17(22):1960-6. doi: 10.1016/j.cub.2007.10.019. Epub 2007 Nov 1.
As cells enter mitosis, centrosomes dramatically increase in size and ability to nucleate microtubules. This process, termed centrosome maturation, is driven by the accumulation and activation of gamma-tubulin and other proteins that form the pericentriolar material on centrosomes during G2/prophase. Here, we show that the human centrosomal protein, Cep192 (centrosomal protein of 192 kDa), is an essential component of the maturation machinery. Specifically, we have found that siRNA depletion of Cep192 results in a complete loss of functional centrosomes in mitotic but not interphase cells. In mitotic cells lacking Cep192, microtubules become organized around chromosomes but rarely acquire stable bipolar configurations. These cells contain normal numbers of centrioles but cannot assemble gamma-tubulin, pericentrin, or other pericentriolar proteins into an organized PCM. Alternatively, overexpression of Cep192 results in the formation of multiple, extracentriolar foci of gamma-tubulin and pericentrin. Together, our findings support the hypothesis that Cep192 stimulates the formation of the scaffolding upon which gamma-tubulin ring complexes and other proteins involved in microtubule nucleation and spindle assembly become functional during mitosis.
当细胞进入有丝分裂时，中心体的大小和微管成核能力会显著增加。这个过程被称为中心体成熟，是由γ-微管蛋白和其他蛋白质在G2期/前期积累并激活所驱动的，这些蛋白质在中心体上形成中心粒外周物质。在这里，我们表明人类中心体蛋白Cep192（192 kDa的中心体蛋白）是成熟机制的一个重要组成部分。具体而言，我们发现通过小干扰RNA（siRNA）耗尽Cep192会导致有丝分裂细胞而非间期细胞中功能性中心体完全丧失。在缺乏Cep192的有丝分裂细胞中，微管围绕染色体排列，但很少形成稳定的双极结构。这些细胞中的中心粒数量正常，但无法将γ-微管蛋白、中心体蛋白或其他中心粒外周蛋白组装成有组织的中心粒外周物质（PCM）。或者，Cep192的过表达会导致形成多个额外的γ-微管蛋白和中心体蛋白聚集点。总之，我们的研究结果支持这样一种假设，即Cep192刺激支架的形成，γ-微管蛋白环复合物和其他参与微管成核及纺锤体组装的蛋白质在有丝分裂期间在该支架上发挥功能。
