Genetic loss of importin α4 causes abnormal sperm morphology and impacts on male fertility in mouse
Genetic loss of importin α4 causes abnormal sperm morphology and impacts on male fertility in mouse
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DOI：
10.1096/fj.202000768rr
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发表时间：
2020-10-15
期刊：
影响因子：
4.8
通讯作者：
Oka, Masahiro
中科院分区：
文献类型：
--
作者：
Miyamoto, Yoichi;Sasaki, Mitsuho;Oka, Masahiro
输入蛋白在从细胞质到细胞核的货物运输中起着核心作用。在这项研究中，我们观察到，输入由Kpna4基因（Kpna4(-/-)）编码的α 4基因敲除的雄性小鼠比野生型（WT）雄性小鼠生育能力低，产仔量小。相反，缺乏密切相关的α - 3输入蛋白（Kpna3(-/-)）的小鼠具有生育能力。体外受精和精子活力实验表明，来自kpna4（-/-）小鼠的精子质量和活力显著降低。此外，inKpna4（-/-）小鼠顶体反应也受到损害。透射电镜显示，kpna4（-/-）小鼠鞭毛存在显著缺陷，包括头部形态异常和多个轴突结构。与t小鼠相比，inKpna4（-/-）小鼠的异常频率增加了5倍，这表明输入α 4在正常精子发育中的功能重要性。此外，作为细胞核和细胞骨架复合物连接体的一个组成部分，nesprin2在kpna4（-/-）小鼠精子中的表达水平较低，并且定位于异常轴突，这表明在精子发生过程中核膜-细胞骨架结构的不正确形成。kpna4（-/-）睾丸的蛋白质组学分析显示，与精子形成相关的蛋白质表达显著改变，这证明了输入蛋白α 4的遗传缺失扰乱了染色质状态。总的来说，这些发现表明，输入蛋白α 4对于小鼠正常精子形态的建立至关重要，通过强调输入蛋白α 4对正常生育能力的要求，为男性生殖细胞发育提供了新的见解。
Importin alpha proteins play a central role in the transport of cargo from the cytoplasm to the nucleus. In this study, we observed that male knock-out mice for importin alpha 4, which is encoded by theKpna4gene (Kpna4(-/-)), were subfertile and yielded smaller litter sizes than those of wild-type (WT) males. In contrast, mice lacking the closely related importin alpha 3 (Kpna3(-/-)) were fertile. In vitro fertilization and sperm motility assays demonstrated that sperm fromKpna4(-/-)mice had significantly reduced quality and motility. In addition, acrosome reaction was also impaired inKpna4(-/-)mice. Transmission electron microscopy revealed striking defects, including abnormal head morphology and multiple axoneme structures in the flagella ofKpna4(-/-)mice. A five-fold increase in the frequency of abnormalities inKpna4(-/-)mice compared toWTmice indicates the functional importance of importin alpha 4 in normal sperm development. Moreover, Nesprin-2, which is a component of the linker of nucleus and cytoskeleton complex, was expressed at lower levels in sperm fromKpna4(-/-)mice and was localized with abnormal axonemes, suggesting incorrect formation of the nuclear membrane-cytoskeleton structure during spermiogenesis. Proteomics analysis ofKpna4(-/-)testis showed significantly altered expression of proteins related to sperm formation, which provided evidence that genetic loss of importin alpha 4 perturbed chromatin status. Collectively, these findings indicate that importin alpha 4 is critical for establishing normal sperm morphology in mice, providing new insights into male germ cell development by highlighting the requirement of importin alpha 4 for normal fertility.