Increase in intracellular pH induces phosphorylation of axonemal proteins for activation of flagellar motility in starfish sperm
Increase in intracellular pH induces phosphorylation of axonemal proteins for activation of flagellar motility in starfish sperm
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DOI：
10.1242/jeb.01906
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发表时间：
2005-12-01
影响因子：
2.8
通讯作者：
Okuno, M
中科院分区：
文献类型：
--
作者：
Nakajima, A;Morita, M;Okuno, M
细胞内pH值升高（[pH](i)）激活海胆和哺乳动物精子中的动力蛋白，并诱导鞭毛运动的激活。人们认为，camp依赖性蛋白磷酸化通过增加[pH](i)与运动激活有关，但很少有人注意到[pH](i)升高也会诱导camp非依赖性磷酸化。本研究表明，海星精子中[pH](i)的增加诱导轴突蛋白的磷酸化和鞭毛运动的激活，而不依赖于cAMP。添加NH4Cl提高[pH](i)后，完整精子鞭毛运动被激活。组氨酸可以激活海星精子的运动能力，在运动能力激活过程中，组氨酸也提高了[pH](i)。此外，在没有cAMP的情况下，脱膜精子鞭毛的运动以ph依赖的方式被激活。这些结果表明，在海星精子中，[pH](i)的增加诱导了鞭毛运动的激活。此外，在脱膜精子的ph依赖性和camp非依赖性运动激活过程中，观察到轴索蛋白（分子量为25、32和45 kDa）的磷酸化。这表明[pH]的增加(i)通过与camp无关的轴突蛋白磷酸化调节鞭毛运动。
Increased intracellular pH ([pH](i)) activates dynein in sea urchin and mammalian sperm and induces activation of flagellar motility. It is thought that cAMP-dependent protein phosphorylation is associated with motility activation through increasing [pH](i), but little attention has been given to the cAMP-independent phosphorylation also induced by the [pH](i) increase. The present study demonstrates that the increase in [pH](i) in starfish sperm induces the phosphorylation of axonemal proteins and activation of flagellar motility independently of cAMP. Flagellar motility of intact sperm was activated when the [pH](i) was raised by addition of NH4Cl. Histidine, which is known to activate motility of starfish sperm, also raised the [pH](i) during the motility activation. In addition, motility of demembranated sperm flagella was activated in a pH-dependent manner without cAMP. These results indicate that in starfish sperm it is the increase in [pH](i) that induces activation of flagellar motility. Moreover, phosphorylation of axonemal proteins (of molecular mass 25, 32 and 45 kDa) was observed during the pH-dependent and cAMP-independent motility activation of demembranated sperm. This suggests that the increase in [pH](i) regulates flagellar motility via cAMP-independent phosphorylation of axonemal proteins.