Savaid School of Medicine, University of Chinese Academy of Sciences, Beijing 100049, China.
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
Biochim Biophys Acta Mol Cell Res. 2017 Apr;1864(4):645-654. doi: 10.1016/j.bbamcr.2017.01.007. Epub 2017 Jan 13.
Centrosome cohesion, mostly regarded as a proteinaceous linker between parental centrioles, ensures the interphase centrosome(s) to function as a single microtubule-organizing center. Maintenance of centrosome cohesion counts on a number of centrosomal linker proteins because depletion of any of those leads to premature centrosome separation in interphase, termed centrosome splitting. However, the underlying mechanisms of the dependence are unknown. Here, we show that absence of Rootletin triggers the von Hippel-Lindau tumour suppressor protein (VHL)-mediated proteasomal degradation of Cep68 and, in turn, results in centrosome splitting. The VHL E3 ligase complex ubiquitinates Cep68 in vitro and in vivo. Co-silencing of Rootletin and VHL reverts Cep68 loss and centrosome splitting. Expression of a stable mutant of Cep68, either diminishing its polyubiquitylation or eliminating binding to β-domain of VHL, also suppresses centrosome splitting provoked by Rootletin depletion. We propose that the archetypal linker protein Rootletin maintains centrosome cohesion in part through inhibition of VHL-mediated Cep68 degradation.
中心体黏合，大多被认为是亲代中心粒之间的蛋白连接物，确保有丝分裂期中心体作为一个单一的微管组织中心发挥作用。中心体黏合的维持依赖于许多中心体连接蛋白，因为这些蛋白的缺失会导致有丝分裂期中心体过早分离，即中心体分裂。然而，这种依赖性的潜在机制尚不清楚。在这里，我们发现 Rootletin 的缺失会触发抑瘤蛋白（VHL）介导的 Cep68 蛋白酶体降解，进而导致中心体分裂。VHL E3 连接酶复合物在体外和体内泛素化 Cep68。Rootletin 和 VHL 的共沉默逆转了 Cep68 的缺失和中心体分裂。表达 Cep68 的稳定突变体，无论是减少其多泛素化还是消除与 VHL 的β结构域的结合，也能抑制由 Rootletin 缺失引起的中心体分裂。我们提出，典型的连接蛋白 Rootletin 通过抑制 VHL 介导的 Cep68 降解来维持中心体黏合。
