Signal transduction mechanisms for the regulation of sperm motility

独特的是，禽类精子表现出可逆的、温度依赖的运动抑制现象：在体外简单盐溶液中，它们在禽类体温为40-41ºC时不运动，但在温度降至30ºC时恢复运动。然而，参与运动调节的细胞内分子级联仍有待确定。细胞内游离Ca^<2+>似乎是维持精子活力所必需的，因为在40ºC时，完整精子的活力可以通过添加Ca^<2+>来恢复。此外，在30 C时，携带细胞内Ca^<2+>螯合剂BAPTA/AM的完整精子的活力可以忽略不计，但可以通过随后添加Ca^<2+>立即恢复。然而,即使在Ca ^ < 2 + >,添加钙调素拮抗剂如若和三氟啦嗪抑制精子的运动性30゚C和40゚CThe激活蛋白磷酸酶1型(PP1),出现在家禽精子基因丝,可能涉及到我 ... 更多n家禽的抑制精子的运动性40゚C,因为,除了calyculin和冈田酸,PP1的特定抑制剂,抑制剂1和2,也刺激demembranated精子的运动性40゚C。此外，肌球蛋白轻链激酶（MLCK）或MLCK样蛋白的参与已被提出作为Ca^<2+>/钙调素依赖性蛋白激酶的候选蛋白，因为在30 C下，完整和脱膜的鸡精子的运动性在添加MLCK的特异性抑制剂ML-9后显著降低，但在添加特异性抑制剂H-8或camp依赖性蛋白激酶（PKA）后没有明显下降。在30kda蛋白中观察到磷酸化的显著差异。在加入PKA底物肽Kemptide以及对照样品后，该蛋白被强烈磷酸化，但在肌球蛋白轻链激酶（MLCK）底物肽存在时仅轻微磷酸化。这些结果表明，Ca^<2+>/钙调素依赖性蛋白激酶的磷酸化，而不是PKA，可能是维持家禽精子活力的一个调节步骤，并且MLCK或MLCK样蛋白对30kda蛋白的磷酸化可能参与了30c下鞭毛运动的调节。少

Uniquely, fowl spermatozoa display the phenomenon of reversible, temperature-dependent motility inhibition : in simple salt solutions in vitro, they are immotile at the avian body temperature of 40-41ﾟC,but regain motility on reduction of the temperature to 30ﾟC.However, the intracellular molecular cascades involved in the regulation of motility remain to be determined.Intracellular free Ca^<2+> seems to be essential for the maintenance of motility, since the motility of intact spermatozoa at 40ﾟC can be restored by the addition of Ca^<2+>. Furthermore, the motility of intact spermatozoa loaded with an intracellular Ca^<2+> chelator, BAPTA/AM is negligible at 30ﾟC,but can be instantly restored by the subsequent addition of Ca^<2+>. However, even in the presence of Ca^<2+>, the addition of calmodulin antagonists such as W-7 and trifluoperazine inhibited sperm motility at 30ﾟC and 40ﾟCThe activation of protein phosphatase type 1 (PP1), present in the fowl sperm axoneme, may be involved i … More n the inhibition of fowl sperm motility at 40ﾟC,since, in addition to calyculin A and okadaic acid, specific inhibitors of PP1, inhibitors 1 and 2, also stimulated the motility of demembranated spermatozoa at 40ﾟC.Furthermore, the involvement of myosin light chain kinase (MLCK), or a MLCK-like protein, has been proposed to be a candidate of Ca^<2+>/calmodulin dependent protein kinase, since the motility of both intact and demembranated fowl spermatozoa at 30ﾟC decreased markedly following the addition of ML-9, a specific inhibitor of MLCK,but not following the addition of H-8, a specific inhibitor or cAMP-dependent protein kinase (PKA). A marked difference in phosphorylation was observed in a 30 kDa protein. This protein was strongly phosphorylated after the addition of Kemptide, a PKA substrate peptide as well as control samples but only slightly phosphorylated in the presence of a myosin light chain kinase (MLCK) substrate peptide.These results suggest that phosphorylation by Ca^<2+>/calmodulin-dependent protein kinases, rather tha PKA,is likely to be a regulatory step in the maintenance of fowl sperm motility, and that phosphorylation of a 30 kDa protein by MLCK or a MLCK-like proteinis may be involved in the regulation of flagellar movement at 30ﾟC. Less