Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore, Singapore; Department of Biological Sciences, National University of Singapore, Singapore, Singapore.
Temasek Life Sciences Laboratory, 1 Research Link, National University of Singapore, Singapore, Singapore.
Cell Rep. 2022 May 31;39(9):110887. doi: 10.1016/j.celrep.2022.110887.
The evolutionarily conserved CLASPs (cytoplasmic linker-associated proteins) are microtubule-associated proteins that inhibit microtubule catastrophe and promote rescue. CLASPs can regulate axonal elongation and dendrite branching in growing neurons. However, their roles in microtubule orientation and neurite pruning in remodeling neurons remain unknown. Here, we identify the Drosophila CLASP homolog Orbit/MAST, which is required for dendrite pruning in ddaC sensory neurons during metamorphosis. Orbit is important for maintenance of the minus-end-out microtubule orientation in ddaC dendrites. Our structural analysis reveals that the microtubule lattice-binding TOG2 domain is required for Orbit to regulate dendritic microtubule orientation and dendrite pruning. In a genetic modifier screen, we further identify the conserved Par-1 kinase as a suppressor of Orbit in dendritic microtubule orientation. Moreover, elevated Par-1 function impairs dendritic microtubule orientation and dendrite pruning, phenocopying orbit mutants. Overall, our study demonstrates that Drosophila CLASP governs dendritic microtubule orientation and dendrite pruning at least partly via suppressing Par-1 kinase.
进化上保守的 CLASPs（细胞质连接蛋白相关蛋白）是微管相关蛋白，可抑制微管崩解并促进微管的恢复。CLASPs 可以调节生长神经元中的轴突延伸和树突分支。然而，它们在重塑神经元中的微管取向和神经突修剪中的作用仍然未知。在这里，我们鉴定了果蝇 CLASP 同源物 Orbit/MAST，它在变态期间 ddaC 感觉神经元的树突修剪中是必需的。Orbit 对于维持 ddaC 树突中的负端向外微管取向很重要。我们的结构分析表明，微管晶格结合的 TOG2 结构域对于 Orbit 调节树突微管取向和树突修剪是必需的。在遗传修饰筛中，我们进一步鉴定了保守的 Par-1 激酶作为 Orbit 在树突微管取向中的抑制因子。此外，升高的 Par-1 功能会损害树突微管取向和树突修剪，表现出 orbit 突变体的表型。总的来说，我们的研究表明，果蝇 CLASP 通过抑制 Par-1 激酶来控制树突微管取向和树突修剪。
