Department of Cell Biology, Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional, Av. Instituto Politécnico Nacional 2508, San Pedro Zacatenco, Del. Gustavo A. Madero, México City 07360, Mexico.
Department of Health Sciences, Universidad Autónoma Metropolitana, División de Ciencias Biológicas y de la Salud, Unidad Iztapalapa, Av. San Rafael Atlixco No. 186, Colonia Vicentina, Alcaldía Iztapalapa, México City 09310, Mexico.
Int J Mol Sci. 2023 Feb 16;24(4):3980. doi: 10.3390/ijms24043980.
Capacitation is a series of physiological, biochemical, and metabolic changes experienced by mammalian spermatozoa. These changes enable them to fertilize eggs. The capacitation prepares the spermatozoa to undergo the acrosomal reaction and hyperactivated motility. Several mechanisms that regulate capacitation are known, although they have not been fully disclosed; among them, reactive oxygen species (ROS) play an essential role in the normal development of capacitation. NADPH oxidases (NOXs) are a family of enzymes responsible for ROS production. Although their presence in mammalian sperm is known, little is known about their participation in sperm physiology. This work aimed to identify the NOXs related to the production of ROS in guinea pig and mouse spermatozoa and define their participation in capacitation, acrosomal reaction, and motility. Additionally, a mechanism for NOXs' activation during capacitation was established. The results show that guinea pig and mouse spermatozoa express NOX2 and NOX4, which initiate ROS production during capacitation. NOXs inhibition by VAS2870 led to an early increase in the capacitation and intracellular concentration of Ca in such a way that the spermatozoa also presented an early acrosome reaction. In addition, the inhibition of NOX2 and NOX4 reduced progressive motility and hyperactive motility. NOX2 and NOX4 were found to interact with each other prior to capacitation. This interaction was interrupted during capacitation and correlated with the increase in ROS. Interestingly, the association between NOX2-NOX4 and their activation depends on calpain activation, since the inhibition of this Ca-dependent protease prevents NOX2-NOX4 from dissociating and ROS production. The results indicate that NOX2 and NOX4 could be the most important ROS producers during guinea pig and mouse sperm capacitation and that their activation depends on calpain.
获能是哺乳动物精子经历的一系列生理、生化和代谢变化。这些变化使它们能够受精卵子。获能使精子能够发生顶体反应和超激活运动。虽然已经知道有几种调节获能的机制，但它们尚未完全揭示；其中，活性氧物质 (ROS) 在正常的获能发育中起着至关重要的作用。NADPH 氧化酶 (NOXs) 是负责 ROS 产生的酶家族。尽管已经知道它们存在于哺乳动物精子中，但它们在精子生理学中的参与知之甚少。这项工作旨在鉴定与豚鼠和小鼠精子 ROS 产生相关的 NOXs，并定义它们在获能、顶体反应和运动中的参与。此外，还建立了 NOXs 在获能过程中激活的机制。结果表明，豚鼠和小鼠精子表达 NOX2 和 NOX4，它们在获能过程中启动 ROS 产生。通过 VAS2870 抑制 NOXs 导致获能和细胞内 Ca 浓度的早期增加，从而使精子也表现出早期顶体反应。此外，NOX2 和 NOX4 的抑制降低了渐进性运动和超活跃运动。发现 NOX2 和 NOX4 在获能前相互作用。这种相互作用在获能过程中中断，并与 ROS 的增加相关。有趣的是，NOX2-NOX4 的相互作用及其激活取决于钙蛋白酶的激活，因为这种 Ca 依赖性蛋白酶的抑制阻止了 NOX2-NOX4 的解离和 ROS 的产生。结果表明，NOX2 和 NOX4 可能是豚鼠和小鼠精子获能过程中最重要的 ROS 产生者，其激活取决于钙蛋白酶。
