Cell Surface Receptor Recognition and Membrane Fusion in Mammalian Fertilization

项目摘要/摘要 受精是一个基本的生物过程，涉及细胞表面识别、黏附、 以及单倍体精子和卵子的融合，形成一个新的、在遗传上截然不同的二倍体有机体。令人惊讶的是 人们对质膜如何相互作用和融合知之甚少，这主要是由于可获得性有限 哺乳动物配子和捕捉瞬时细胞外相互作用的技术挑战。 虽然配子膜融合机制仍然难以捉摸，但已知人类 免疫球蛋白超家族蛋白Izumo1定位于精子的赤道段， 在配子融合发生之前，它与卵母细胞配体Juno相互作用。到目前为止，出云1- Juno是在该途径中发现的唯一重要的受体-配体对。最新的遗传学研究 小鼠已经鉴定出对男性生育能力至关重要的其他精子表面蛋白，但它们之间的相互作用 而监管还没有被定义。 为了缩小这些重大差距，我围绕中心假说设计了一个研究计划 配子表面蛋白协调它们的结构重排和膜重塑， 导致配子融合。我将通过(1)确定分子机制来检验我的假设 人类Izumo1自组装，(2)人类Izumo家族蛋白在 膜的黏附和融合，以及(3)识别其他必需的受体-配体相互作用 用于配子融合和哺乳动物受精。我的多学科方法充分利用了 解析结构分析以询问已知基本配子的功能组织 表面蛋白，并利用高通量正向遗传筛选来探索相互作用 其他新兴分子的网络。至关重要的是，了解这些相互作用将有助于阐明 细胞-细胞识别和膜融合的机制，并揭示维持 人类生育和生殖健康。 从研究生院开始，我接受过广泛的遗传学、细胞生物学和细胞膜方面的培训。 生物化学。在我早期的博士后工作中，我磨练了我在细胞表面结构生物学方面的技能 病毒膜融合机的受体和蛋白质工程。我会利用优秀的 在我的导师Peter Kim博士和我的同事Chaitan博士的实验室里的研究环境 科斯拉和斯坦福大学。在我杰出的科学顾问的指导下 委员会，我将获得掌握酶学、生殖细胞生物学和功能的必要培训 基因组学。这些研究和职业发展机会将使我能够建立一个 独立实验室研究哺乳动物精子-卵子受精的基本问题 在细胞生物学、机械生物化学和结构生物学水平上的过程。

Project Summary/Abstract Fertilization is an essential biological process that involves cell surface recognition, adhesion, and fusion of haploid sperm and egg to form a new, genetically distinct diploid organism. Surprisingly little is known about how plasma membranes interact and fuse, largely due to the limited availability of mammalian gametes and the technical challenges of capturing transient extracellular interactions. While the gamete membrane fusion machinery remains elusive, it is known that a human immunoglobulin superfamily protein, Izumo1, localizes to the equatorial segment of spermatozoon, where it interacts with an oocyte ligand, Juno, before gamete fusion takes place. To date, Izumo1- Juno is the only essential receptor-ligand pair identified in the pathway. Recent genetic studies in mice have identified additional sperm surface proteins essential for male fertility, but their interactions and regulation have not been defined. To close these major gaps, I have designed a research program around the central hypothesis that gamete surface proteins orchestrate their structural rearrangements and membrane remodeling, leading to gamete fusion. I will test my hypothesis by (1) determining the molecular mechanisms of human Izumo1 self-assembly, (2) characterizing the roles of human Izumo family proteins in membrane adhesion and fusion, and (3) identifying additional receptor-ligand interactions essential for gamete fusion and mammalian fertilization. My multidisciplinary approach leverages high- resolution structural analyses to interrogate the functional organization of known essential gamete surface proteins, and harnesses high-throughput forward genetic screens to explore the interacting networks of additional emerging molecules. Crucially, understanding these interactions will elucidate mechanisms of cell-cell recognition and membrane fusion and reveal essential factors that maintain human fertility and reproductive health. From graduate school, I have extensive training in genetics, cell biology, and membrane biochemistry. During my early postdoctoral work, I honed my skills in structural biology of cell surface receptors and protein engineering of viral membrane fusion machines. I will exploit the excellent research environments in the laboratories of my mentor Dr. Peter Kim and my co-mentor Dr. Chaitan Khosla and at Stanford University. Under the guidance of my outstanding scientific advisory committee, I will obtain training essential to mastering enzymology, germ cell biology, and functional genomics. These research and career-development opportunities will empower me to establish an independent laboratory to study fundamental questions in the mammalian sperm-egg fertilization process at the levels of cell biology, mechanistic biochemistry, and structural biology.