Conduit Paul T, Richens Jennifer H, Wainman Alan, Holder James, Vicente Catarina C, Pratt Metta B, Dix Carly I, Novak Zsofia A, Dobbie Ian M, Schermelleh Lothar, Raff Jordan W
Sir William Dunn School of Pathology, University of Oxford, Oxford, United Kingdom.
Medical Research Council Laboratory of Molecular Biology, Cambridge, United Kingdom.
Elife. 2014 Aug 22;3:e03399. doi: 10.7554/eLife.03399.
Centrosomes comprise a pair of centrioles surrounded by pericentriolar material (PCM). The PCM expands dramatically as cells enter mitosis, but it is unclear how this occurs. In this study, we show that the centriole protein Asl initiates the recruitment of DSpd-2 and Cnn to mother centrioles; both proteins then assemble into co-dependent scaffold-like structures that spread outwards from the mother centriole and recruit most, if not all, other PCM components. In the absence of either DSpd-2 or Cnn, mitotic PCM assembly is diminished; in the absence of both proteins, it appears to be abolished. We show that DSpd-2 helps incorporate Cnn into the PCM and that Cnn then helps maintain DSpd-2 within the PCM, creating a positive feedback loop that promotes robust PCM expansion around the mother centriole during mitosis. These observations suggest a surprisingly simple mechanism of mitotic PCM assembly in flies.
中心体由一对被中心粒周围物质（PCM）环绕的中心粒组成。当细胞进入有丝分裂时，PCM会急剧扩张，但目前尚不清楚其发生机制。在本研究中，我们发现中心粒蛋白Asl启动了DSpd-2和Cnn向母中心粒的募集；这两种蛋白随后组装成相互依赖的支架样结构，从母中心粒向外扩展并募集了大部分（如果不是全部）其他PCM成分。在缺乏DSpd-2或Cnn的情况下，有丝分裂期PCM的组装会减少；在两种蛋白都缺乏的情况下，PCM组装似乎被完全消除。我们发现DSpd-2有助于将Cnn整合到PCM中，而Cnn随后有助于将DSpd-2维持在PCM内，从而形成一个正反馈回路，促进有丝分裂期间母中心粒周围PCM的强劲扩张。这些观察结果揭示了果蝇中有丝分裂期PCM组装的一个惊人简单的机制。
