Localization, Interactions, And Functions of Synaptotagmins in the Pituitary

描述(申请人提供)：突触素1，一种发现于突触小泡上的蛋白质，在神经递质释放中作为钙感受器。这种蛋白质有16个同源物，虽然人们普遍认为这些其他蛋白质具有相关功能，但实际上，人们对它们的位置和功能一无所知。本申请中提供的初步数据显示，几种突触素亚型在后部和/或前部垂体腺中含量丰富，这些腺体释放多肽激素，基本上控制哺乳动物生理的所有关键方面。在这些新的初步结果之前，脑下垂体已被确定为一种易于定量的生物物理研究的制剂，该研究旨在研究含肽的囊泡如何与质膜融合以将其内容释放到循环中。因此，在垂体中发现新的突触素亚型为详细测试它们的功能和阐明它们在兴奋-分泌偶联中的确切作用提供了一个独特的机会。本项目将用互补的方法研究脑垂体突触素亚型，研究它们在体外的结合特性，以及它们在脑垂体中的定位和生理功能。功能研究采用了一种策略，使用转基因小鼠来去除特定突触素亚型的基因，并通过基因打靶来识别表达这些亚型的特定细胞群，以便进行电子记录。通过对识别的细胞和神经末梢进行电容记录，我们将确定syt亚型如何通过钙敏感性和融合毛孔来调节胞吐作用。这里提出的实验将测试突触素4、7、9、10、11和12在控制生长、新陈代谢、压力、液体平衡和生殖的激素释放中的功能。 公共卫生相关性：这些实验将阐明一类在神经、精神和内分泌功能中具有广泛作用的蛋白质的功能，从而有助于改善神经疾病和精神疾病的治疗。通过阐明催产素、加压素、生长激素、促肾上腺皮质激素、促甲状腺激素、卵泡刺激素、黄体生成素和催乳素的调控机制，这些研究将加深我们对生长缺陷、异常应激反应、代谢紊乱和生殖健康的理解。

DESCRIPTION (provided by applicant): Synaptotagmin 1, a protein found on synaptic vesicles, serves as a Ca2+ sensor in neurotransmitter release. This protein has 16 homologues, and while these other proteins are widely thought to serve related functions essentially nothing is known about where they are or what they do. Preliminary data presented in this application shows that several synaptotagmin isoforms are abundant in the posterior and/or anterior pituitary, glands that release peptide hormones that control essentially all vital aspects of mammalian physiology. Prior to these new preliminary results, the pituitary had been established as a preparation amenable to quantitative biophysical study of how peptide-containing vesicles fuse with the plasma membrane to release their content into the circulation. Thus, the finding of novel synaptotagmin isoforms in the pituitary offers a unique opportunity to test their function in detail and elucidate their precise roles in excitation-secretion coupling. This project will study the pituitary synaptotagmin isoforms with complementary approaches, investigating their binding properties in vitro, and their localization and physiological function in the pituitary. The functional studies employ a strategy of using transgenic mice for gene ablation of specific synaptotagmin isoforms, and gene targeting to identify specific cell populations that express those isoforms for electrical recording. By performing capacitance recording in identified cells and nerve terminals we will determine how syt isoforms regulate exocytosis in terms of Ca2+ sensitivity and fusion pores. The experiments proposed here will test the functions of synaptotagmins 4, 7, 9, 10, 11, and 12 in the release of hormones that control growth, metabolism, stress, fluid balance, and reproduction. PUBLIC HEALTH RELEVANCE: These experiments will shed light on the function of a class of proteins with broad roles in neurological, mental, and endocrine function and thus contribute to improving treatment of neurological disorders and mental illness. By illuminating the mechanisms of control of the pituitary hormones oxytocin, vasopressin, growth hormone, adrenocorticotropin, thyroid stimulating hormone, follicle stimulating hormone, luteinizing hormone, and prolactin, these studies will improve our understanding of growth defects, abnormal stress responses, metabolic disorders, and reproductive health.