REGULATION OF INSP3 RECEPTOR FUNCTION BY MAPK

该项目将重点研究生长因子和MARK通路的激活如何控制细胞内 这将为细胞核和胞浆中钙离子的特定作用提供分子基础 这些影响的信号和调节对肝细胞生长和功能的重要性。 目前已鉴定出InsPSR的三种亚型。每种受体亚型的细胞定位可能是 与其功能特性相关。在肝细胞中，InsPSR 1型亚型(lnsP3R-1)是胞浆的 而2型亚型(lnsP3R-2)在整个细胞中都存在，但主要存在于细胞核中 和小管区。我们假设，在肝细胞中，MKP-1以不同的方式调节功能 和InsPSR的分布。在这个项目中，InsPSR和MAP激酶之间的相互作用将是 在单个InsPSR通道的活性测试中，分离的细胞产生瞬时变化的能力 细胞内钙离子浓度和InsPSR分布的动态变化。对这些复杂相互作用的理解 来解释钙信号转导的分子机制，从而解释肝脏的再生。 需要检验的假设包括：1)MAPK的激活是否改变了InsPSR的功能 细胞内钙信号转导？2)MKP-1失活MAPK是否改变InsPSR的功能 细胞内钙信号？3)MAPK磷酸化是否调节InsPSR异构体的分布 在牢房里？ 本文的初步结果首次表明，肝细胞的InsPSR受到调节。 通过MAPK途径，本项目中概述的实验将研究这一功能 在单信道级别对InsPSR进行调节，并将信道属性与小区和 器官功能。将获得的结果将确定决定异构体特异性的调控因素。 钙信号反应，细胞如何调节通道异构体以优化细胞反应，以及 在肝脏退化和再生等病理生理情况下，这种调节是如何出错的。 一个长期目标将是利用在这些研究中获得的分子信息来提出有用的 对肝病患者的治疗。

This project will focus on how growth factors and the activation of the MARK pathway control intracellular Ca2+ in intact cells and will suggest a molecular basis for the specific roles for nuclear and cytosolic Ca2+ signaling and the importance of the regulation of these effects on the growth and function of hepatocytes. Three isoforms of the InsPSR have been identified. The cellular localization of each receptor isoform may be correlated with its functional properties. In hepatocytes the InsPSR type 1 isoform (lnsP3R-1) is cytosolic whereas the type 2 isoform (lnsP3R-2) is found throughout the cell, but is predominantly found in the nucleus and the canalicular region. We hypothesize that in hepatocytes MKP-1 differentially regulates the function and distribution of the InsPSR. In this project the interplay between the InsPSR and MAP kinases will be tested on the activity of single InsPSR channels, the ability of isolated cells to generate transient changes in intracellular Ca2+, and the dynamics of InsPSR distribution. An understanding of these complex interactions is necessary to explain the molecular mechanisms of Ca2+ signaling and thus the regeneraton of liver. The hypotheses to be tested include 1) Does activation of MAPK alter the function of the InsPSR and intracellular Ca2+ signaling? 2) Does MKP-1 inactivation of MAPK alter the function of the InsPSR and intracellular Ca2+ signaling? and 3) Does MAPK phosphorylation modulate the InsPSR isoform distribution within the cell? The preliminary results presented here show for the first time that the InsPSR of hepatocytes are regulated by the MAPK pathway The experiments outlined in this project will investigate the functional of this regulation of the InsPSR at the single channel level and will correlate the channel properties with cell and organ function. The results to be obtained will identify regulatory factors that determine isoform-specific Ca2+ signaling responses, how the cell regulates the channel isoforms to optimize cellular responses, and how this regulation goes awry in pathophysiological situations, such as liver degeneration and regeneration. A long term goal will be to use the molecular information obtained in these studies to suggest useful treatments for individuals affected with liver disease.