GM130, a cis-Golgi protein, regulates meiotic spindle assembly and asymmetric division in mouse oocyte

GM130, a cis-Golgi protein, plays key roles in various mitotic events, but its function in mammalian oocyte meiosis remains unknown. In this study, we found that GM130 was localized to the spindle poles at both metaphase I and metaphase II stages and associated with the midbody at telophase I stage. The association of GM130 with spindle poles was further confirmed by its colocalization with the centrosome-associated proteins, MEK1/2. By nocodazole treatment, we clarified that GM130 localization was consistently dependent on spindle assembly. Then we investigated the possible function of GM130 by specific morpholino microinjection. This treatment caused abnormal spindle formation, and decreased first polar body extrusion. Our results showed that knockdown of GM130 impaired the localization of MTOCs proteins γ-tubulin and Plk1. Using live cell imaging we observed that depletion of GM130 affected spindle migration and resulted in elongated spindle and large polar body extrusion. We further found that depletion of GM130 blocked p-MEK1/2 accumulation at the spindle poles. And, it was shown that GM130 detached from the spindle poles in oocytes treated with MEK specific inhibitor U0126. Taken together, our results suggested that GM130 regulates microtubule organization and might cooperate with the MAPK pathway to play roles in spindle organization, migration and asymmetric division during mouse oocyte maturation.