Activation of cAMP‐dependent phosphorylation pathways is independent of ROS production during mouse sperm capacitation
Activation of cAMP‐dependent phosphorylation pathways is independent of ROS production during mouse sperm capacitation
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DOI：
10.1002/mrd.23524
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发表时间：
2021-07
影响因子：
2.5
通讯作者：
Gen L. Takei;Darya A. Tourzani;Bidur Paudel;P. Visconti
中科院分区：
文献类型：
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作者：
Gen L. Takei;Darya A. Tourzani;Bidur Paudel;P. Visconti
哺乳动物的精子必须经过获能才能使卵子受精。在分子水平上，获能涉及cAMP的合成，蛋白激酶A的激活，以及下游酪氨酸磷酸化的增加。此外，在获能过程中，哺乳动物精子会主动产生活性氧(ROS)。有人提出ROS调节磷酸化途径；然而，这些信号过程之间的串扰还没有被很好地理解。在这项研究中，我们使用功能丧失和功能获得的方法来评估ROS和磷酸化之间的相互联系。结果表明，获能培养液中的牛血清白蛋白和HCO3−是ROS产生所必需的，而不是钙离子。这些化合物的协同作用既不是通过HCO3−刺激cAMP合成介导的，也不是通过牛血清白蛋白诱导的胆固醇外流来实现的。在超氧化物歧化酶(SOD)、过氧化氢酶和载脂蛋白的存在下，获能诱导的ROS的产生被阻断。然而，这些化合物都不影响cAMP依赖或酪氨酸磷酸化。另一方面，在没有牛血清白蛋白和HCO3−的情况下，加入NADPH诱导精子产生ROS，而不上调cAMP依赖或酪氨酸磷酸化信号。最有趣的是，阻止体外受精的是过氧化氢酶，而不是超氧化物歧化酶，这表明过氧化氢在这一过程中发挥了作用。
Mammalian sperm have to undergo capacitation to fertilize the egg. At the molecular level, capacitation involves cAMP synthesis, protein kinase A activation, and downstream increase in tyrosine phosphorylation. In addition, during capacitation, mammalian sperm actively generate reactive oxygen species (ROS). It has been proposed that ROS modulate phosphorylation pathways; however, the crosstalk between these signaling processes is not well‐understood. In the present study, we used loss‐ and gain‐of‐function approaches to evaluate the interconnection between ROS and phosphorylation. We showed that BSA and HCO3−, but not Ca2+, in the capacitation media are required for ROS production. The synergic effect of these compounds was neither mediated by HCO3− stimulation of cAMP synthesis nor by BSA‐induced cholesterol efflux. The capacitation‐induced ROS generation was blocked in the presence of superoxide dismutase (SOD), catalase, and apocynin. However, none of these compounds affected cAMP‐dependent or tyrosine phosphorylation. On the other hand, the addition of NADPH to the media induced ROS generation in sperm incubated in the absence of BSA and HCO3− without upregulating cAMP‐dependent or tyrosine phosphorylation signaling. Most interestingly, catalase, but not SOD, blocked in vitro fertilization suggesting a role for H2O2 in this process.