State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100101, China.
Acta Pharmacol Sin. 2011 Jun;32(6):721-4. doi: 10.1038/aps.2011.35. Epub 2011 May 9.
Upon ejaculation, mammalian sperm experience a natural osmotic decrease during male to female reproductive tract transition. This hypo-osmotic exposure not only activates sperm motility, but also poses potential harm to sperm structure and function by inducing unwanted cell swelling. In this physiological context, regulatory volume decrease (RVD) is the major mechanism that protects cells from detrimental swelling, and is essential to sperm survival and normal function. Aquaporins are selective water channels that enable rapid water transport across cell membranes. Aquaporins have been implicated in sperm osmoregulation. Recent discoveries show that Aquaporin-3 (AQP3), a water channel protein, is localized in sperm tail membranes and that AQP3 mutant sperm show defects in volume regulation and excessive cell swelling upon physiological hypotonic stress in the female reproductive tract, thereby highlighting the importance of AQP3 in the postcopulatory sperm RVD process. In this paper, we discuss current knowledge, remaining questions and hypotheses about the function and mechanismic basis of aquaporins for volume regulation in sperm and other cell types.
在射精时，哺乳动物精子在从雄性到雌性生殖道的转变过程中经历自然的渗透减少。这种低渗暴露不仅激活了精子的运动能力，而且通过诱导不必要的细胞肿胀对精子结构和功能造成潜在的伤害。在这种生理环境下，调节性体积减少（RVD）是保护细胞免受有害肿胀的主要机制，对精子的存活和正常功能至关重要。水通道蛋白是允许快速跨细胞膜水运输的选择性水通道。水通道蛋白已被牵连到精子渗透调节中。最近的发现表明，水通道蛋白 3（AQP3），一种水通道蛋白，定位于精子尾部膜上，并且 AQP3 突变精子在雌性生殖道的生理低渗应激下显示出体积调节缺陷和过度细胞肿胀，从而强调了 AQP3 在射精后精子 RVD 过程中的重要性。在本文中，我们讨论了关于水通道蛋白在精子和其他细胞类型的体积调节中的功能和机制基础的现有知识、遗留问题和假设。
