title: The microtubule-associated protein ASPM regulates spindle assembly and meiotic progression in mouse oocytes.
abstract: The microtubule-associated protein ASPM (abnormal spindle-like microcephaly-associated) plays an important role in spindle organization and cell division in mitosis and meiosis in lower animals, but its function in mouse oocyte meiosis has not been investigated. In this study, we characterized the localization and expression dynamics of ASPM during mouse oocyte meiotic maturation and analyzed the effects of the downregulation of ASPM expression on meiotic spindle assembly and meiotic progression. Immunofluorescence analysis showed that ASPM localized to the entire spindle at metaphase I (MI) and metaphase II (MII), colocalizing with the spindle microtubule protein acetylated tubulin (Ac-tubulin). In taxol-treated oocytes, ASPM colocalized with Ac-tubulin on the excessively polymerized microtubule fibers of enlarged spindles and the numerous asters in the cytoplasm. Nocodazole treatment induced the gradual disassembly of microtubule fibers, during which ASPM remained colocalized with the dynamic Ac-tubulin. The downregulation of ASPM expression by a gene-specific morpholino resulted in an abnormal meiotic spindle and inhibited meiotic progression; most of the treated oocytes were blocked in the MI stage with elongated meiotic spindles. Furthermore, coimmunoprecipitation combined with mass spectrometry and western blot analysis revealed that ASPM interacted with calmodulin in MI oocytes and that these proteins colocalized at the spindle. Our results provide strong evidence that ASPM plays a critical role in meiotic spindle assembly and meiotic progression in mouse oocytes.
authors.affiliation: Institute of Animal Husbandry and Veterinary Medicine, Beijing Municipal Academy of Agriculture and Forestry Sciences, Beijing, China.
authors.forename: Xiao-Ling
authors.initials: XL
authors.lastname: Xu
authors.forename: Wei
authors.initials: W
authors.lastname: Ma
authors.forename: Yu-Bo
authors.initials: YB
authors.lastname: Zhu
authors.forename: Chao
authors.initials: C
authors.lastname: Wang
authors.forename: Bing-Yuan
authors.initials: BY
authors.lastname: Wang
authors.forename: Na
authors.initials: N
authors.lastname: An
authors.forename: Lei
authors.initials: L
authors.lastname: An
authors.forename: Yan
authors.initials: Y
authors.lastname: Liu
authors.forename: Zhong-Hong
authors.initials: ZH
authors.lastname: Wu
authors.forename: Jian-Hui
authors.initials: JH
authors.lastname: Tian
mesh_terms: D000818:Animals; D002147:Calmodulin / Q000378:metabolism; D002148:Calmodulin-Binding Proteins; D015536:Down-Regulation / Q000187:drug effects; D004622:Embryo, Mammalian / Q000166:cytology; D005260:Female; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D047468:Immunoprecipitation; D008540:Meiosis / Q000187:drug effects; D051379:Mice; D008810:Mice, Inbred C57BL; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D060172:Morpholinos / Q000494:pharmacology; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D009865:Oocytes / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D008941:Spindle Apparatus / Q000187:drug effects / Q000378:metabolism*; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism
chemical_list: C512460:ASPM protein, mouse; D002147:Calmodulin; D002148:Calmodulin-Binding Proteins; D008869:Microtubule-Associated Proteins; D060172:Morpholinos; D009419:Nerve Tissue Proteins