Institute of Molecular Biology, University of Oregon, Eugene, OR 97403 Institute of Neuroscience, University of Oregon, Eugene, OR 97403 Department of Biochemistry and Molecular Biology, University of Calgary, Calgary, AB T2N 4N1, Canada.
Mol Biol Cell. 2014 Apr;25(8):1298-311. doi: 10.1091/mbc.E13-11-0687. Epub 2014 Feb 19.
In many animals, including vertebrates, oocyte meiotic spindles are bipolar but assemble in the absence of centrosomes. Although meiotic spindle positioning in oocytes has been investigated extensively, much less is known about their assembly. In Caenorhabditis elegans, three genes previously shown to contribute to oocyte meiotic spindle assembly are the calponin homology domain protein encoded by aspm-1, the katanin family member mei-1, and the kinesin-12 family member klp-18. We isolated temperature-sensitive alleles of all three and investigated their requirements using live-cell imaging to reveal previously undocumented requirements for aspm-1 and mei-1. Our results indicate that bipolar but abnormal oocyte meiotic spindles assemble in aspm-1(-) embryos, whereas klp-18(-) and mei-1(-) mutants assemble monopolar and apolar spindles, respectively. Furthermore, two MEI-1 functions--ASPM-1 recruitment to the spindle and microtubule severing--both contribute to monopolar spindle assembly in klp-18(-) mutants. We conclude that microtubule severing and ASPM-1 both promote meiotic spindle pole assembly in C. elegans oocytes, whereas the kinesin 12 family member KLP-18 promotes spindle bipolarity.
在许多动物中，包括脊椎动物，卵母细胞减数分裂纺锤体是双极的，但在没有中心体的情况下组装。尽管卵母细胞减数分裂纺锤体的定位已经被广泛研究，但对它们的组装知之甚少。在秀丽隐杆线虫中，以前有三个基因被证明有助于卵母细胞减数分裂纺锤体的组装，它们是由 aspm-1 编码的钙调蛋白同源结构域蛋白、 katanin 家族成员 mei-1 和 kinesin-12 家族成员 klp-18。我们分离了这三个基因的温度敏感等位基因，并使用活细胞成像技术研究了它们的需求，揭示了以前未记录的 aspm-1 和 mei-1 的需求。我们的结果表明，双极但异常的卵母细胞减数分裂纺锤体在 aspm-1(-)胚胎中组装，而 klp-18(-)和 mei-1(-)突变体分别组装单极和无极性纺锤体。此外，MEI-1 的两个功能——ASPM-1 向纺锤体的募集和微管的切割——都有助于 klp-18(-)突变体中单极纺锤体的组装。我们得出结论，微管切割和 ASPM-1 都促进了秀丽隐杆线虫卵母细胞减数分裂纺锤体极的组装，而 kinesin 12 家族成员 KLP-18 则促进了纺锤体的双极性。
