Mice deficient in CHRNA7, a subunit of the nicotinic acetylcholine receptor, produce sperm with impaired motility
Mice deficient in CHRNA7, a subunit of the nicotinic acetylcholine receptor, produce sperm with impaired motility
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DOI：
10.1095/biolreprod.105.042184
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发表时间：
2005-10-01
影响因子：
3.6
通讯作者：
Meizel, S
中科院分区：
文献类型：
--
作者：
Bray, C;Son, JH;Meizel, S
在这项研究中，我们研究了烟碱乙酰胆碱受体的CHRNA7亚基（也称为alpha7亚基）在小鼠精子功能中的作用。我们通过逆转录-聚合酶链反应证实了Chrna7 mRNA在成年小鼠睾丸中的表达，并通过免疫印迹证实了该亚基在小鼠精子中的存在。甲虫毒素结合一系列烟碱乙酰胆碱受体亚基，包括CHRNA7亚基。利用荧光-班加罗毒素-四甲基罗丹明偶联物进行定位研究，发现小鼠精子中部有特异性结合位点，鞭毛其余部分有较弱的班加罗毒素结合位点。双零破坏Chrna7基因的小鼠只在中间显示微弱的荧光，这表明Chrna7贡献了大部分观察到的α -班加罗毒素结合位点。α -班加罗毒素结合的位置提示烟碱乙酰胆碱受体可能在精子运动中起离子化作用。与Chma7（+/+）小鼠相比，来自Chrna7（-/-）小鼠的精子在数量、形态、活力和自发顶体反应率方面没有差异。使用计算机辅助精子分析的研究表明，Chrna7（-/-）精子的活力明显受损。与Chrna7（+/+）精子相比，Chrna7（-/-）精子的游泳速度明显降低，不能保持有力的游泳，并且过度激活的游泳模式水平较低。这是第一个证明精子烟碱乙酰胆碱受体对维持正常精子活力很重要的遗传证据。
In this study we investigate the role of the CHRNA7 subunit (also known as the alpha7 subunit) of the nicotinic acetylcholine receptor in mouse sperm function. We confirm by reverse-transcription-polyme rase chain reaction the expression in adult mouse testis of Chrna7 mRNA and demonstrate the subunit's presence in mouse sperm by immunoblot. Alpha-bungarotoxin binds a range of nicotinic acetylcholine receptor subunits, including the CHRNA7 subunit. Localization studies using a fluorescent alpha-bungarotoxin-tetramethyl-rhodamine conjugate revealed specific binding sites on the midpiece of mouse sperm with fainter alpha-bungarotoxin binding on the remainder of the flagellum. Mice engineered with a double-null disruption of the Chrna7 gene displayed only faint fluorescence on the midpiece, suggesting that the CHRNA7 contributed the majority of the observed alpha-bungarotoxin binding sites. The location of alpha-bungarotoxin binding suggested that nicotinic acetylcholine receptors may play an ionotropic role in sperm motility. Sperm from Chrna7(-/-) mice display no difference in number, morphology, viability or spontaneous acrosome reaction rate compared with Chma7(+/+) sperm. Studies using computer-assisted sperm analysis indicate the motility of Chrna7(-/-) sperm is significantly impaired. This impairment is characterized by significantly reduced swimming velocities, failure to maintain vigorous swimming, and lower levels of hyperactivated swimming patterns in Chrna7(-/-) sperm compared with Chrna7(+/+) sperm. This is the first genetic evidence that sperm nicotinic acetylcholine receptors are important for maintenance of normal sperm motility.