Role of the Na, K-ATPase Alpha4 Isoform in Sperm Motility

Na, K-ATP 酶 Alpha4 同工型在精子活力中的作用

• 批准号: 7073064
• 负责人: PAUL F JAMES
• 金额: $ 21.3万
• 依托单位: MIAMI UNIVERSITY OXFORD
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-15 至 2010-05-14
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7073064
• 关键词: acidity /alkalinity; adenosinetriphosphatase; calcium ion; enzyme activity; human tissue; immunoprecipitation; intracellular transport; ion transport; potassium ion; protein isoforms; protein structure function; sodium ion; sperm analysis; sperm motility

DESCRIPTION (provided by applicant): Project Summary: The Na,K-ATPase alpha4 isoform has been found only in the membrane of male germ cells of rats and is most abundant in mature sperm. Specific pharmacological inhibition of this Na,K-ATPase isoform using the cardiac glycoside ouabain has been shown to completely inhibit the motility of rat sperm. The mechanism underlying the loss of motility of Na,K-ATPase alpha4 inhibited sperm is unclear, however indirect evidence suggests that an increase in intracellular [H+] is responsible. The Na,K-ATPase does not transport H+ itself therefore, the increase in intracellular [H+] associated with inhibition of the Na,K-ATPase alpha4 isoform is likely due to secondary inhibition of one of the Na+/H+ exchanger (NHE) isoforms found in sperm. The NHEs use the Na+ gradient established by the Na,K-ATPase to extrude H+ from the cell in exchange for extracellular Na+. Using rats and mice as models we w II asses the changes in intracellular ion concentrations in Na,K-ATPase inhibited sperm and examine the role that isoforms of the NHE and other Na,K-ATPase isoforms play in maintaining sperm motility. We will also characterize the Na,K-ATPase alpha4 isoform from humans with respect to its tissue distribution and its identity as a functional Na,K- ATPase alpha isoform. These studies will not only be important for defining the role that isoforms of the Na,K-ATPase and the NHE play in sperm motility but also may have medically relevant implications: If the human Na,K-ATPase alpha4 isoform plays the same role in human sperm as the rat isoform does in rat sperm it is likely that 1) a subset of infertile men are infertile due to inactivating mutations in the Na,K- ATPase alpha4 gene and 2) specific inhibitors of the Na,K-ATPase alpha4 isoform could be developed as male contraceptive agents. Relevance: Understanding the interactions between these proteins will further our understanding of the basic biology of sperm and will impact human reproductive biology. These studies could lead to understanding the underlying reasons for some forms of male infertility as well as to identifying male-specific contraceptives.

项目简介：Na， k - atp酶α 4亚型仅在大鼠雄性生殖细胞膜中发现，在成熟精子中含量最多。使用心脏糖苷乌阿巴因对这种Na， k - atp酶异构体的特异性药理抑制已被证明可以完全抑制大鼠精子的运动能力。Na - k - atp酶α 4抑制精子运动能力丧失的机制尚不清楚，但间接证据表明细胞内[H+]的增加是原因。Na， k - atp酶本身不运输H+，因此，细胞内[H+]的增加与Na， k - atp酶α 4亚型的抑制有关，可能是由于精子中发现的Na+/H+交换（NHE）亚型之一的继发抑制。NHEs利用由Na， k - atp酶建立的Na+梯度从细胞中挤出H+以换取细胞外Na+。以大鼠和小鼠为模型，我们将评估Na， k - atp酶抑制精子细胞内离子浓度的变化，并检查NHE和其他Na， k - atp酶同工型在维持精子活力中的作用。我们还将对人类Na，K- atp酶α 4亚型的组织分布及其作为功能性Na，K- atp酶α亚型的身份进行表征。这些研究不仅对确定Na， k - atp酶和NHE在精子运动中的作用很重要，而且可能具有医学意义：如果人类Na，K- atp酶α 4亚型在人类精子中的作用与在大鼠精子中的作用相同，那么很可能：(1)一部分不育男性是由于Na，K- atp酶α 4基因失活突变造成的；(2)Na，K- atp酶α 4亚型的特异性抑制剂可能被开发为男性避孕药。相关性：了解这些蛋白质之间的相互作用将进一步加深我们对精子基本生物学的理解，并将影响人类生殖生物学。这些研究可以帮助我们了解某些男性不育症的潜在原因，并确定男性专用避孕药。