CDKL激酶参与调控纤毛的分子功能和调控机制

Cilia are present in the human bodies during development and in adults. They are involved in development, physiology and metabolism by mediating cell motility and signal transduction. Defects in cilia have been found to be associated with a cohort of diseases and developmental disorders such as polycystic kidney disease. Cilia are tightly linked with the cell cycle. They are assembled through mother centrioles after cytokinesis, disassembled prior to the next cell cycle and regulate the cell cycle progression. In contrast to intensive studies related to cilia assembly and cilia-based signaling, the study on cilia disassembly is an emerging new area and how cilia disassembly regulates cell cycle progression is still elusive. In the current proposal, we have found that a CDKL （CrFLS2） participates in cilia disassembly in the model organism Chlamydomonas. We propose to study its function and regulation during ciliary disassembly with a combination of approaches, including Physiology, Biochemistry, Cell biology, Molecular biology and Genetics. We also aim to explore its function during cell cycle progression. In addition, we plan to examine possible role of mammalian CDKLs in ciliogenesis.

纤毛在人体的发育过程和成体中都广泛存在，参与细胞的运动和多种信号转导，从而调控个体的发育，生理过程和代谢等。纤毛的缺陷和多种疾病密切相关，如肾囊肿等。纤毛的形态发生和细胞周期密切相关。细胞分裂完成后，纤毛通过母中心粒组装；而在下次细胞分裂之前，纤毛解聚缩短，参与调控细胞周期的进程。相对于有关纤毛组装和信号转导的大量研究，关于纤毛的解聚缩短机制的研究处在一个新兴起的阶段，纤毛解聚缩短的机制尚需深入的了解；此外，纤毛解聚调控细胞周期的机制不详。我们利用模式生物衣藻发现一个CDKL(CDK-like)激酶（CrFLS2）参与了纤毛的解聚缩短；我们欲通过生理生化，细胞生物学, 分子生物学和遗传手段研究该激酶调控纤毛解聚的分子功能和调控机制，以及对细胞周期的调控。另外,我们初步研究动物细胞的CDKL是否具有纤毛方面的功能

纤毛或鞭毛参与细胞的运动和信号传导，纤毛的缺陷可导致人类疾病。虽然纤毛的组装对于细胞行使正常功能是必需的，纤毛在不同生理条件下会发生解聚，纤毛的解聚和细胞分裂密切相关；此外，纤毛解聚的研究也可以揭示纤毛组装的重要机制。另外, “鞭毛内运输”本项目研究了CDKL激酶FLS2参与纤毛解聚的分子机制。衣藻FLS2的缺陷导致纤毛解聚缓慢，并且细胞分裂提前发生。在纤毛解聚时，FLS2发生去磷酸化和激酶活性下降，并且运输到纤毛中。FLS2的激酶活性不影响FLS2到纤毛的运输，但是影响其调控纤毛解聚。FLS2进入到纤毛中调控了Crkinesin13的磷酸化，是影响纤毛解聚的重要机制之一。FLS2与IFT70结合，通过“鞭毛内运输”（intraflagellar transport, IFT）而运输到纤毛中。缺失与IFT70互作的结构域抑制FLS2进入纤毛，抑制纤毛解聚。本工作揭示了CDKL激酶对于纤毛的正常解聚是必要的，而且首次直接证明了IFT主动参与了纤毛解聚的过程。