Role of Phosphatidic Acid in the Sperm Acrosome Reaction

磷脂酸在精子顶体反应中的作用

• 批准号: 7072440
• 负责人: BRADLEY J STITH
• 金额: $ 21.45万
• 依托单位: UNIVERSITY OF COLORADO DENVER/HSC DENVER
• 依托单位国家: 美国
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-05-01 至 2008-05-12
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7072440
• 关键词: Xenopus; Xenopus oocyte; acrosome; calcium flux; confocal scanning microscopy; enzyme activity; exocytosis; fertility; fertilization; glycoproteins; high performance liquid chromatography; light scattering; lipid metabolism; membrane proteins; phosphatidate; phosphatidylinositols; phospholipase D; phospholipid inhibitor; sperm; vitelline membrane

DESCRIPTION (provided by applicant): The acrosome reaction (AR) is found in all vertebrate sperm and is required for the success of subsequent fertilization. AR is the exocytosis of the very large acrosome that is located at the forward edge of the head of the sperm. This exocytosis releases crucial enzymes that cut through the coats surround eggs to allow the approach of the sperm. The exocytosis also moves crucial sperm membrane proteins to the sperm surface to allow for sperm and egg (or egg surface) binding. Thus, the AR is a crucial step to fertilization. However, the mechanism of the AR is not well described. The series of experiments outlined here will examine the role of a lipid, phosphatidic acid (PA) in the induction of the AR. As the mass of the lipid PA increased during agonist (both artificial or with the natural inducer found in egg coats) induction of the AR, there is preliminary evidence supporting our hypothesis. These results utilize our new lipid analysis methodology (HPLC with evaporative light scattering mass detection). In further support, the numerous reports that exocytosis involves the lipid PA are summarized. However, the increase in PA associated with the AR may be a result not a causative event. Thus, experiments will test whether lowering of the sperm PA levels with a proven method will inhibit the acrosome reaction. Furthermore, the percent of sperm undergoing the AR will be determined after addition of exogenous PA. Once again, all methods (use of confocal to detect the Xenopus AR, procedures for the addition of appropriate levels of commercially available PA, lipid analysis, etc) have been worked out. Twenty years of experience with Xenopus laevis (a species that has been designated by the NIH as an animal model organism), the fact that Xenopus sperm do not have to be capacitated (a complication and variable to the study of the AR), that all methodology has been worked out, the reduced human ethical issues make our selection of experimental model appropriate. Although future studies will involve human sperm if our model for the AR is supported, the studies outlined here will increase our knowledge of the male gamete and may lead to improvements of in vitro fertilization or human fertility. Artificial induction of the AR may enable some infertile males to conceive.

描述（由申请人提供）：顶体反应（AR）存在于所有脊椎动物精子中，并且是后续受精成功所必需的。 AR 是位于精子头部前缘的巨大顶体的胞吐作用。这种胞吐作用释放出关键的酶，这些酶可以穿透卵子周围的外壳，从而允许精子接近。胞吐作用还将重要的精子膜蛋白移动到精子表面，以允许精子和卵子（或卵子表面）结合。因此，AR是受精的关键步骤。然而，AR 的机制还没有得到很好的描述。这里概述的一系列实验将检查脂质、磷脂酸 (PA) 在诱导 AR 中的作用。随着激动剂（人工的或蛋壳中发现的天然诱导剂）诱导 AR 期间脂质 PA 的质量增加，有初步证据支持我们的假设。这些结果利用了我们新的脂质分析方法（具有蒸发光散射质量检测的 HPLC）。为了进一步支持，总结了胞吐作用涉及脂质 PA 的大量报道。然而，与 AR 相关的 PA 增加可能是结果而不是因果事件。因此，实验将测试用经过验证的方法降低精子 PA 水平是否会抑制顶体反应。此外，将在添加外源 PA 后确定接受 AR 的精子百分比。再次，所有方法（使用共聚焦检测非洲爪蟾 AR、添加适当水平的市售 PA 的程序、脂质分析等）均已制定完成。非洲爪蟾（一种被 NIH 指定为动物模型生物的物种）二十年的经验，非洲爪蟾精子不必具有获能的事实（AR 研究的一个复杂因素和变量），所有方法论已经制定出来，人类伦理问题的减少使得我们选择实验模型是合适的。虽然如果我们的 AR 模型得到支持，未来的研究将涉及人类精子，但这里概述的研究将增加我们对雄配子的了解，并可能导致体外受精或人类生育能力的改善。 AR 的人工诱导可能使一些不育男性能够怀孕。