The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
The Mina and Everard Goodman Faculty of Life Sciences, Bar-Ilan University, Ramat-Gan, 5290002, Israel.
Theriogenology. 2022 Oct 15;192:38-44. doi: 10.1016/j.theriogenology.2022.08.018. Epub 2022 Aug 24.
In order to fertilize the egg, spermatozoa must undergo a series of biochemical processes in the female reproductive tract collectively called capacitation. Only capacitated sperm can interact with the egg resulting in the acrosome reaction (AR), allowing egg penetration and fertilization. Sperm can undergo spontaneous AR (sAR) before reaching the egg, preventing successful fertilization. Here we investigated the metabolic pathways involved in sperm capacitation and sAR. Inhibition of glycolysis or oxidative phosphorylation did not affect capacitation or sAR levels; however, when both systems were inhibited, no capacitation occurred, and there was a significant increase in sAR. Under such ATP-starvation, the increase in sAR is triggered by Ca influx into the sperm via the CatSper cation channel. Protein kinase A (PKA) is an essential key enzyme in sperm capacitation; there was no change in its activity when a single metabolic system was inhibited, while complete inhibition of was observed when the two systems were inhibited. Protein tyrosine phosphorylation (PTP), also known to occur in sperm capacitation, was partially reduced by inhibition of one metabolic system, and completely blocked when the two metabolic systems were inhibited. We conclude that ATP, PKA and PTP are involved in the mechanisms protecting sperm from sAR.
为了使卵子受精，精子必须在女性生殖道中经历一系列称为获能的生化过程。只有获能的精子才能与卵子相互作用，导致顶体反应（AR），从而允许卵子穿透和受精。精子在到达卵子之前可能会发生自发的 AR（sAR），从而阻止受精成功。在这里，我们研究了参与精子获能和 sAR 的代谢途径。糖酵解或氧化磷酸化的抑制均不会影响获能或 sAR 水平；但是，当两种系统都被抑制时，不会发生获能，并且 sAR 会显著增加。在这种 ATP 饥饿的情况下，通过 CatSper 阳离子通道进入精子的 Ca2+内流触发 sAR 的增加。蛋白激酶 A（PKA）是精子获能的关键酶；当抑制单个代谢系统时，其活性没有变化，而当抑制两个系统时，则会观察到完全抑制。也已知在精子获能过程中发生蛋白酪氨酸磷酸化（PTP），当抑制一个代谢系统时，其部分减少，当抑制两个代谢系统时，其完全阻断。我们得出结论，ATP、PKA 和 PTP 参与了保护精子免受 sAR 的机制。
