MODELING CALCIUM WAVES IN MATURE XENOPUS LAEVIS OOCYTES

成熟爪蟾卵细胞中钙波的建模

• 批准号: 2685816
• 负责人: JOEL E KEIZER
• 金额: $ 18.01万
• 依托单位: UNIVERSITY OF CALIFORNIA AT DAVIS
• 依托单位国家: 美国
• 财政年份: 1996
• 资助国家: 美国
• 起止时间: 1996-03-01 至 2001-03-02
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2685816
• 关键词: Xenopus oocyte; alternatives to animals in research; biological signal transduction; calcium channel; calcium flux; calcium indicator; calcium transporting ATPase; cell membrane; chemical kinetics; chemical models; computer simulation; confocal scanning microscopy; diffusion; electrodes; endoplasmic reticulum; fertilization; inositol phosphates; mathematical model; mitochondria; model design /development; phospholipase C; receptor expression; second messengers

Propogating waves of Ca2+ have been observed by physiologists in a wide variety of cellular systems, ranging from secretory cells in the pancreas to neurons. These waves appear to function as part of the second messenger role of Ca2+ in transmitting signals from hormone receptors and other molecular detectors in the plasma membrane. In mature oocytes Ca2+ waves are initiated by the egg-sperm fusion event and have been observed in every species studied. In the mature Xenopus laevis oocyte, as in mammalian species, the inositol phospholipid cascade has been demonstrated to be the major signal transduction pathway involved in these waves. The proposed research investigates the mechanism of initiation, propogation, and termination of the fertilization wave in the mature Xenopus laevis oocyte by developing computer-based models of the primary Ca2+ handling mechanisms in this cell. Development and analysis of these kinetic mechanisms will be modular, i.e., individual steps in the overall mechanism will be fine-tuned to experimental measurements before being combined into a 3-dimensional model. The 3-dimensional model, necessitated by the large size of the oocyte (1.2mm), will include diffusion of Ca2+ in the presence of exogenous and endogenous buffers, diffusion of inositol 1,4,5-trisphosphate (IP3), and Ca2+ handling by the endoplasmic reticulum, mitochondria, and plasma membrane. To insure that model parameters are chosen correctly and to test predictions of the model, experiments that establish the rate of Ca2+ handling will be performed in the stratified mature Xenopus laevis oocyte, a novel preparation that permits separation of cellular organelles in vivo. Simulations will be carried out to help test hypotheses regarding possible mechanisms of initiation, propogation and termination of the fertilization wave. Additional calculations will be performed to help interpret on-going experiments with the unstratified egg. Because IP3-induced Ca2+ release from the endoplasmic reticulum is the major process involved in the fertilization wave in mammalian eggs, the African frog, Xenopus laevis, is a good biological model for fertilization in mammals. After dormancy for many years, fertilization stimulates events that activate the metabolism and development of an egg cell. This research will help clarify the role that the Ca2+ wave plays in these important physiological processes.

生理学家已经观察到Ca2+的传播波 各种细胞系统，范围从胰腺中的分泌细胞 致神经元。这些波似乎是第二波的一部分 Ca2+在从激素受体传输信号和 质膜中的其他分子探测器。在成熟的卵母细胞Ca2+中 波浪是由蛋式融合事件引发的，并且已经观察到 在每个研究的物种中。在成熟的Xenopus laevis卵母细胞中，如 哺乳动物物种，肌醇磷脂级联反应是 证明是涉及的主要信号转导途径 这些波。拟议的研究调查了 受精波的启动，兴趣和终止 通过开发基于计算机的模型的成熟Xenopus laevis卵母细胞 该细胞中的主要CA2+处理机制。开发和分析 这些动力学机制将是模块化的，即单个步骤 总体机制将进行微调进行实验测量 在组合成三维模型之前。三维 大尺寸的卵母细胞（1.2mm）所需的型号将包括 在存在外源和内源缓冲区的情况下，Ca2+的扩散， 肌醇1,4,5-三磷酸（IP3）和Ca2+处理的扩散 内质网，线粒体和质膜。确保这一点 正确选择模型参数并测试 模型，建立CA2+处理速率的实验将是 在分层成熟的Xenopus laevis卵母细胞中进行的小说 允许在体内分离细胞细胞器的制备。 将进行模拟以帮助测试有关的假设 启动，促进和终止的可能机制 受精波。将进行其他计算以帮助 用未分层的鸡蛋解释正在进行的实验。 因为IP3引起的Ca2+从内质网释放是 哺乳动物卵受精波涉及的主要过程， 非洲青蛙，Xenopus laevis是一个很好的生物学模型 哺乳动物的受精。休眠多年后，受精 刺激激活卵新陈代谢和发展的事件 细胞。这项研究将有助于阐明Ca2+ Wave发挥的作用 在这些重要的生理过程中。