BRCA1 is required for meiotic spindle assembly and spindle assembly checkpoint activation in mouse oocytes
BRCA1 is required for meiotic spindle assembly and spindle assembly checkpoint activation in mouse oocytes
复制标题
BRCA1 是小鼠卵母细胞减数分裂纺锤体组装和纺锤体组装检查点激活所必需的。
DOI：
10.1095/biolreprod.108.069641
复制
发表时间：
2008-10-01
影响因子：
3.6
通讯作者：
Sun, Qing-Yuan
中科院分区：
文献类型：
--
作者：
Xiong, Bo;Li, Sen;Sun, Qing-Yuan
BRCA1作为一种肿瘤抑制因子，在有丝分裂中的作用已被广泛研究，但其在减数分裂中的作用尚不清楚。在本研究中，我们检测了BRCA1在小鼠卵母细胞减数分裂成熟过程中的表达、定位和功能。我们发现，BRCA1的表达水平从生发泡到中期I期逐渐增加，然后保持稳定，直到中期II期。免疫荧光分析表明，BRCA1在中期I和中期II定位于纺锤体极，与中心体蛋白γ-微管蛋白共定位。紫杉醇处理导致BRCA1出现在纺锤体微管纤维上，而诺康唑处理则诱导BRCA1定位在染色体上。通过抗体注射和siRNA注射耗尽BRCA1会导致纺锤体严重受损和染色体错位。此外，BRCA1耗竭的卵母细胞在低剂量诺康唑存在的情况下不能在中期I停止，这表明纺锤体检查点是有缺陷的。此外，在BRCA1缺失的卵母细胞中，伽马微管蛋白从纺锤体极解离，MAD2L1在中期I期接触诺可达唑时不能与动点重新结合。总之，这些数据表明，BRCA1不仅调节减数分裂纺锤体组装，而且还调节纺锤体组装检查点，这意味着BRCA1缺陷与非整倍体胚胎之间存在联系。
BRCA1 as a tumor suppressor has been widely investigated in mitosis, but its functions in meiosis are unclear. In the present study, we examined the expression, localization, and function of BRCA1 during mouse oocyte meiotic maturation. We found that expression level of BRCA1 was increased progressively from germinal vesicle to metaphase I stage, and then remained stable until metaphase II stage. Immunofluorescent analysis showed that BRCA1 was localized to the spindle poles at metaphase I and metaphase II stages, colocalizing with centrosomal protein gamma-tubulin. Taxol treatment resulted in the presence of BRCA1 onto the spindle microtubule fibers, whereas nocodazole treatment induced the localization of BRCA1 onto the chromosomes. Depletion of BRCA1 by both antibody injection and siRNA injection caused severely impaired spindles and misaligned chromosomes. Furthermore, BRCA1-depleted oocytes could not arrest at the metaphase I in the presence of low-dose nocodazole, suggesting that the spindle checkpoint is defective. Also, in BRCA1-depleted oocytes, gamma-tubulin dissociated from spindle poles and MAD2L1 failed to rebind to the kinetochores when exposed to nocodazole at metaphase I stage. Collectively, these data indicate that BRCA1 regulates not only meiotic spindle assembly, but also spindle assembly checkpoint, implying a link between BRCA1 deficiency and aneuploid embryos.