Laboratory of Genetics, University of Wisconsin-Madison, Madison, WI 53706, USA.
Curr Biol. 2012 May 22;22(10):843-51. doi: 10.1016/j.cub.2012.03.058. Epub 2012 Apr 26.
The centrosome has a well-established role as a microtubule organizer during mitosis and cytokinesis. In addition, it facilitates the union of parental haploid genomes following fertilization by nucleating a microtubule aster along which the female pronucleus migrates toward the male pronucleus. Stable associations between the sperm aster and the pronuclei are essential during this directed movement.
Our studies reveal that the zebrafish gene futile cycle (fue) is required in the zygote for male pronucleus-centrosome attachment and female pronuclear migration. We show that fue encodes a novel, maternally-provided long form of lymphoid-restricted membrane protein (lrmp), a vertebrate-specific gene of unknown function. Both maternal lrmp messenger RNA (mRNA) and protein are highly localized in the zygote, in a largely overlapping pattern at nuclear membranes, centrosomes, and spindles. Truncated Lrmp-EGFP fusion proteins identified subcellular targeting signals in the C terminus of Lrmp; however, endogenous mRNA localization is likely important to ensure strict spatial expression of the protein. Localization of both Lrmp protein and lrmp RNA is defective in fue mutant embryos, indicating that correct targeting of lrmp gene products is dependent on Lrmp function.
Lrmp is a conserved vertebrate gene whose maternally inherited products are essential for nucleus-centrosome attachment and pronuclear congression during fertilization. Precise subcellular localization of lrmp products also suggests a requirement for strict spatiotemporal regulation of their function in the early embryo.
中心体在有丝分裂和胞质分裂期间作为微管组织中心的作用已得到充分证实。此外，它通过在沿着该微管星状体的核母体基因组的融合来促进受精后双亲单倍体基因组的融合，其中雌性原核向雄性原核迁移。在这种定向运动中，精子星状体与原核之间的稳定关联是必不可少的。
我们的研究表明，斑马鱼基因无效循环（fue）在合子中对于雄性原核-中心体附着和雌性原核迁移是必需的。我们表明，fue 编码一种新的、母体提供的淋巴限制膜蛋白（lrmp）的长形式，lrmp 是一种具有未知功能的脊椎动物特异性基因。母体 lrmp 信使 RNA（mRNA）和蛋白都在合子中高度定位，在核膜、中心体和纺锤体上呈现出很大程度上重叠的模式。截断的 Lrmp-EGFP 融合蛋白鉴定了 Lrmp C 末端的亚细胞靶向信号；然而，内源性 mRNA 定位可能对确保蛋白质的严格空间表达很重要。在 fue 突变体胚胎中，Lrmp 蛋白和 lrmp RNA 的定位都存在缺陷，表明 lrmp 基因产物的正确靶向依赖于 Lrmp 功能。
Lrmp 是一种保守的脊椎动物基因，其母体遗传产物对于受精期间核-中心体附着和原核聚集是必需的。lrmp 产物的精确亚细胞定位也表明其在早期胚胎中的功能需要严格的时空调节。
