TOPAZ1在精子发生减数分裂I中期纺锤体形成中的作用和机制

中期纺锤体形成是细胞完成分裂、实现染色体正确分离的基础，而中心体作为微管组织中心则是体细胞纺锤体形成所必需的。然而，精子发生减数分裂纺锤体形成中中心体的作用和机制尚不清楚。我们发现小鼠生殖细胞特异表达蛋白TOPAZ1与中心体蛋白γ-Tubulin共定位，其缺失不影响减数分裂I前期进程和交叉重组形成，但导致染色体不能正确排列在赤道板上。进一步研究发现Topaz1突变小鼠中，85%中期精母细胞呈现单极纺锤体。由此我们推测TOPAZ1可能通过调节中心体复制/分离或微管聚合能力等来促进双极纺锤体的形成，从而确保减数分裂的正常进行。本项目将进一步明确Topaz1突变对中心体行为和纺锤体形成的影响，并从寻找TOPAZ1结合蛋白入手，通过一系列筛选和功能验证，发现参与调控纺锤体组装的新因子，以期揭示精母细胞减数分裂双极纺锤体形成的特殊调控机制，为相关精子发生障碍所致不育症的诊治和遗传咨询提供理论基础。

Metaphase spindle formation is the fundament for the completion of cell division and correct segregation of chromosomes, while the centrosome as the microtubule-organizing center is required for the spindle formation in somatic cells. However, the role and mechanism of the centrosome in the formation of a meiotic spindle during spermatogenesis are unclear. We found that germ cell-specific protein TOPAZ1 was colocalized with centrosomal protein γ-Tubulin in mouse spermatocytes and its mutation did not affect the meiotic prophase I progression and crossover formation but resulted in the chromosomes not being correctly aligned on the equatorial plate. Further study showed that 85% of metaphase I spermatocytes of Topaz1 mutant mice displayed monopolar spindles. Therefore, we speculate that TOPAZ1 may promote the formation of bipolar spindles by regulating either the replication and separation of the centrosome or the ability of microtubule polymerization to ensure normal meiotic progression. This project will further clarify the effect of the Topaz1 mutation on centrosome behavior and spindle formation and start with the search for TOPAZ1 binding proteins, and then through a series of screening and functional verification, to find out new factors involved in the regulation of spindle assembly, not only to reveal the special regulatory mechanism of the formation of the meiotic bipolar spindle in spermatocytes but also to provide a theoretical basis for the diagnosis and therapeutic of infertility caused by related spermatogenesis disorders and genetic counseling.