REGULATION OF INSP3 RECEPTOR FUNCTION BY MAPK

本项目将重点关注生长因子和MARK通路的激活如何控制细胞内 完整细胞中的Ca 2+，并将为核和胞浆Ca 2+的特定作用提供分子基础 信号传导以及调节这些效应对肝细胞生长和功能的重要性。 已鉴定出InsPSR的三种亚型。每种受体同种型的细胞定位可以是 与其功能特性相关。在肝细胞中，InsPSR 1型同种型（InsP 3R-1）是胞浆型 而2型同种型（InsP 3R-2）在整个细胞中发现，但主要在细胞核中发现 和泪小管区我们推测，在肝细胞中，MKP-1差异性地调节了 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通道的活性上测试，分离的细胞产生瞬时变化的能力， 胞内Ca ~（2+）的变化以及InsPSR分布的动态变化。了解这些复杂的相互作用 对解释Ca ~（2+）信号传导的分子机制和肝再生的机制是必要的。 待检验的假设包括：1）MAPK的激活是否改变InsPSR的功能， 细胞内Ca 2+信号转导2)MAPK的MKP-1失活是否改变了InsPSR的功能， 细胞内Ca 2+信号转导MAPK磷酸化是否调节InsPSR亚型的分布 在细胞？ 本文提供的初步结果首次表明，肝细胞的InsPSR受到调控， 在这个项目中概述的实验将研究这种蛋白的功能。 在单通道水平上调节InsPSR，并将通道特性与细胞和 器官功能所获得的结果将鉴定决定异构体特异性的调节因子。 Ca 2+信号传导反应，细胞如何调节通道亚型以优化细胞反应，以及 这种调节在病理生理学情况下是如何出错的，如肝脏变性和再生。 一个长期的目标将是利用这些研究中获得的分子信息， 治疗受肝病影响的个人。

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.