The origin and compartmentalization of core somatic histones and GSTO2 in sperm and their role in fertilization

受精是发育的基石，精子和卵子这两个分化的细胞为胚胎形成奠定了基础，而配子的能力对胚胎形成至关重要。然而，对于导致受精卵发育的精卵相互作用所涉及的分子和机制，人们只有初步的了解。我们的长期目标是了解这些机制。我们的方法是分子解剖精子室，如顶体和核膜周围，这涉及到受精过程。这些蛋白质的特性为它们的重要性提供了线索，并导致设计特定的探针和实验来测试它们预测的受精功能。这一策略是成功的，因为我们已经发现了新的精子蛋白质，这些蛋白质与受精过程中卵子的渗透及其激活有关，从而导致了用于检测和治疗不孕症的生物标志物和合成分子的发展。了解卵子第一次受精时发生的事件，有助于应用我们如何影响这些事件，并提高牲畜和人类的繁殖能力。*******利用这种蛋白质组学方法，我的实验室提出，核周膜（PT），精子细胞核周围的蛋白质帽，分为两个功能区域：顶体下部分，包含参与顶体组装的蛋白质，顶体后部分，包含参与受精过程中精子/卵子相互作用的蛋白质。本提案的主要目标是确定我们已经确定的几个关键精子PT蛋白的重要性：即一组核心体细胞组蛋白（H3, H2B， H2A和H4），它们在精子头部顶体后区域的细胞质中前所未有的位置表明在受精过程中雄性原核的染色质重塑中起作用；谷胱甘肽- s -转移酶-欧米茄2 (GSTO2)，其相似的位置表明在调节共价连接分子的氧化和还原状态，特别是在受精过程中精子核的分解过程中起作用。通过这些蛋白的功能失活，我们将测试它们在受精过程中的作用机制，并确定它们是否为合子发育所必需。*******要检验的四个具体假设是：1。PT中Core组蛋白和GSTO2的存在是正常精子的常见特征。2. 核心组蛋白和GSTO2在精子发生过程中重新合成，并通过微管manchette作为PT的一部分组装。3. PT核心组蛋白在受精过程中溶解在卵浆中，并通过稳定去致密精子核的DNA为原核形成做准备。4. PT锚定的GSTO2在受精过程中溶解在卵浆中，并利用谷胱甘肽减少蛋白之间的S-S键来降低精子核的密度

Fertilization is the cornerstone of development where the two differentiated cells, sperm and egg, set the stage for embryogenesis, for which competency of the gametes is essential. Yet only rudimentary knowledge is available on the molecules and mechanisms involved in sperm-egg interactions leading to zygotic development. Our long term goal is to gain an understanding of these mechanisms. Our approach is to molecularly dissect sperm compartments, such as the acrosome and perinuclear theca, that are implicated in the fertilization process. The identities of these proteins provide clues to their significance and lead to the design of specific probes and experiments to test their predicted fertilization functions. This strategy has been successful as we have discovered novel sperm proteins that are implicated in the penetration of the egg and its activation during fertilization, leading to the development of biomarkers and synthetic molecules for the detection and treatment of infertility. Understanding the events that occur when an egg is first fertilized leads to application of how we can influence those events and improve reproduction in livestock and humans.*******Utilizing this proteomic approach has led my lab to propose that the perinuclear theca (PT), a proteinaceous cap surrounding the sperm nucleus, is divided into two functional regions: the subacrosomal part, containing proteins involved in acrosomal assembly and the postacrosomal part, containing proteins involved in sperm/egg interactions during fertilization. The major goal of this proposal is to determine the significance of several key sperm PT proteins we have identified: namely, a group of core somatic histones (H3, H2B, H2A and H4), whose unprecedented cytosolic location in the postacrosomal region of the sperm head suggests a role in chromatin remodeling of the male pronucleus during fertilization and Glutathione-S-Transferase Omega 2 (GSTO2), whose similar location suggests a role in regulating the oxidative and reductive state of covalently-linked molecules, especially during the disassembly of the sperm nucleus during fertilization. By functional deactivation of these proteins we will test their proposed mechanisms of action during fertilization and determine if they are required for zygotic development.*******The four specific hypotheses to be tested are: 1. The presence of Core histones and GSTO2 in the PT is a common eutherian sperm feature. 2. Core histones and GSTO2 are synthesized de novo during spermiogenesis and assembled as part of the PT by the microtubular manchette. 3. PT core histones dissolve in the ooplasm during fertilization and contribute by stabilizing the DNA of the decondensing sperm nucleus in preparation for pronuclear formation. 4. PT anchored GSTO2 dissolves in the ooplasm during fertilization and utilizes glutathione in the reduction of S-S bonds between protamines to decondense the sperm nucleus.***