Motility initiation in herring sperm is regulated by reverse sodium-calcium exchange
Motility initiation in herring sperm is regulated by reverse sodium-calcium exchange
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DOI：
10.1073/pnas.042700899
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发表时间：
2002-02
影响因子：
11.1
通讯作者：
C. Vines;Kaoru Yoshida;F. Griffin;M. Pillai;M. Morisawa;R. Yanagimachi;G. Cherr
中科院分区：
文献类型：
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作者：
C. Vines;Kaoru Yoshida;F. Griffin;M. Pillai;M. Morisawa;R. Yanagimachi;G. Cherr
太平洋鲱鱼的精子是独一无二的，因为它们在环境中产卵时是不活动的。鲱鱼精子已经进化到在产卵后几天内保持不动，但仍然能够使卵子受精。一种被称为“精子运动启动因子”(SMIF)的卵绒毛膜配体诱导鲱鱼精子运动，这是受精所必需的。在这项研究中，我们证明SMIF诱导鲱鱼精子钙内流、钠外流和膜去极化。SMIF对精子活力的启动依赖于细胞外钠的降低(<；350 mM)，在极低钠海水中，SMIF不存在也能诱导精子运动。运动的启动依赖于≥1 mM胞外钙离子。SMIF引起的钙内流既涉及电压门控性钙通道的开放，也涉及钠钙(Na+/Ca~(2+))的反向交换。膜去极化被钙通道阻滞剂轻度抑制，被Na+/Ca~(2+)交换阻滞剂显著抑制。当同时使用细胞外和细胞内钠探针时，观察到由SMIF启动的运动引起的钠外流。用犬Na+/Ca~(2+)交换器的抗体证明，Na~+/Ca~(2+)交换抗原存在于精子表面，主要在精子的中段。该抗体识别与犬心肌细胞Na+/Ca~(2+)交换器共迁移的120 kDa蛋白。太平洋鲱鱼的精子现在被证明使用反向Na+/Ca~(2+)交换来启动运动。这种运动启动的调节机制可能是为了维持产卵后的静止以及配体诱导的运动启动而进化的。
Sperm of the Pacific herring, Clupea pallasi, are unique in that they are immotile upon spawning in the environment. Herring sperm have evolved to remain motionless for up to several days after spawning, yet are still capable of fertilizing eggs. An egg chorion ligand termed “sperm motility initiation factor” (SMIF) induces motility in herring sperm and is required for fertilization. In this study, we show that SMIF induces calcium influx, sodium efflux, and a membrane depolarization in herring sperm. Sperm motility initiation by SMIF depended on decreased extracellular sodium (<350 mM) and could be induced in the absence of SMIF in very low sodium seawater. Motility initiation depended on ≥ 1 mM extracellular calcium. Calcium influx caused by SMIF involved both the opening of voltage-gated calcium channels and reverse sodium–calcium (Na+/Ca2+) exchange. Membrane depolarization was slightly inhibited by a calcium channel blocker and markedly inhibited by a Na+/Ca2+ exchange inhibitor. Sodium efflux caused by SMIF-initiated motility was observed when using both extracellular and intracellular sodium probes. A Na+/Ca2+ exchange antigen was shown to be present on the surface of the sperm, primarily over the midpiece, by using an antibody to the canine Na+/Ca2+ exchanger. This antibody recognized a 120-kDa protein that comigrated with the canine myocyte Na+/Ca2+ exchanger. Sperm of Pacific herring are now shown to use reverse Na+/Ca2+ exchange in motility initiation. This mechanism of regulation of motility initiation may have evolved for both maintenance of immotility after spawning as well as ligand-induced motility initiation.