Study of Meiotic Kinetochore Regulation

我们之前的研究表明，MEIKIN在分裂酵母中维持着丝粒凝聚力是必需的，就像分裂酵母中的MOA1一样。我们已经证明，着丝粒粘附素的保护者Shugoshin-2(Sgo2)在小鼠减数分裂中的着丝粒定位减少，这可能解释了MEIKIN KO(基因敲除)后期I的早熟姐妹染色单体分离。为了探讨SGO2在Meikin-/-精母细胞中定位下降的原因，我们研究了已知的调节SGO2定位的Bub1。由于Plk1在减数分裂中的动粒丰富在很大程度上依赖于MEIKIN，这些结果提出了Plk1活性可能是小鼠减数分裂中Bub1定位所必需的。在用BI 2536处理Plk1抑制的野生型精母细胞中，着丝粒的Bub1信号在中期I减弱，这与MEIKIN KO一致，而在终变过程中没有明显的影响。接下来，我们研究了Mps1对野生型精母细胞中Bub1定位的调节。事实上，Mps1在终变期特异性地调节Bub1，在中期I表现出比Plk1抑制更温和的影响。最后，同时抑制Plk1和Mps1不仅减少了终变期Bub1的额外水平，而且还减少了中期I的Bub1水平。我们得出结论，MEIKIN依赖的Plk1可能会将Bub1招募到减数分裂I的动粒上，从而调节着丝粒上SGO2的定位。此外，Plk1和Mps1在减数分裂I中冗余地调节Bub1。

Our previous study suggests that MEIKIN is required for maintenance of centromeric cohesion in anaphase I like moa1 in fission yeast. We have shown that centromeric localization of Shugoshin-2 (Sgo2), the protector of centromeric cohesin in mouse meiosis, is diminished and it may explain precocious sister chromatids separation during anaphase I in MEIKIN KO (knockout). To investigate the cause of SGO2 localization decrease in Meikin-/- spermatocytes, we examined Bub1 which are known to regulate SGO2 localization.Since kinetochore enrichment of Plk1 largely depends on MEIKIN in meiosis, these results raised the possibility that Plk1 activity might be required for Bub1 localization at kinetochore in mouse meiosis. In Plk1 inhibited wild-type spermatocytes by BI 2536 treatment, centromeric Bub1 signals are diminished in metaphase I which coincide with MEIKIN KO whereas no significant effects could be seen in diakinesis.Next we examined that Mps1 regulation for Bub1 localization in wild-type spermatocytes which are treated with the Mps1 inhibitor Reversine. Indeed, Mps1 specifically regulated Bub1 in diakinesis and showed milder effect in metaphase I than Plk1 inhibition. Finally, simultaneous inhibition of both Plk1 and Mps1 reduced additional levels of Bub1 not only in diakinesis but also metaphase I. We conclude that MEIKIN dependent Plk1 may recruit Bub1 to the kinetochore in meiosis I that regulates SGO2 localization on centromere. Furthermore, Plk1 and Mps1 redundantly regulate Bub1 in meiosis I.