REGULATION OF LIVER FUNCTION BY MAPK/MKP-1

这个项目的广泛目标是了解控制健康肝功能的分子机制 和疾病具体地说，本项目的目的是了解局部细胞核和细胞质钙离子是如何 信号与丝裂原活化蛋白激酶（MARK）信号转导通路整合， 控制肝脏生长、再生和代谢。MAPKs受一个家族的负调控， 这些酶被称为MARK磷酸酶（MKP）。该实验室最近的工作表明， 核定位的MKP家族成员MKP-1对于MAPKs的负调控是必需的。这些 我们发现缺乏MKP-1表达的小鼠表现出 肝脏中MAPK活化增强，这与肝脏脂质代谢增强相关， 对脂肪肝的抵抗力。我们目前的初步数据，以支持一个新的信号 细胞质和核钙信号差异调节MKP-1转录的范例， 分别以积极和消极的方式。钙离子对细胞核中MKP-1的这种离散调节 控制MAPK介导的基因表达。我们假设局部钙信号调节MKP-1 表达，其用于限制MAPK介导的基因的大小和时空动力学 肝脏生长、再生和代谢稳态所需的活性。我们将测试这个假设， 三个具体目标。目的1将确定核和胞质的差异效应的分子基础 钙离子通过破坏这些亚细胞中的钙信号传导对MKP-1基因转录的调节 使用先前开发的靶向钙结合蛋白的隔室。目标2将定义 MKP-1核定位对于其在肝脏中的生理功能的重要性。为了验证这一点，一本小说 MKP-1中将其靶向细胞质的基因突变将使用可诱导的 CreLoxP方法。目的3将确定MKP-1在肝脏生长、再生和应激中的作用 使用MKP 1“敲除”小鼠进行管理。连同内桑森和埃利希的项目，提出的分子， 生物化学和遗传学的方法将建立一个新的信号模式之间的地方 钙信号，MKP-1和MAPK介导的基因表达在控制肝功能。

The broad goal of this project is to understand the molecular mechanisms that control liver function in health and disease. Specifically, the aim of this project is to understand how local nuclear and cytosolic calcium signals integrate with the mitogen-activated protein kinase (MARK) signal transduction pathway in the control of liver growth, regeneration, and metabolism. The MAPKs are negatively regulated by a family of enzymes known as the MARK phosphatases (MKPs). Recent work from this laboratory has shown that the nuclear localized MKP family member, MKP-1, is essential for the negative regulation of the MAPKs. These observations are supported in vivo where we have discovered that mice lacking expression of MKP-1 exhibit enhanced MAPK activation in the liver which correlates with enhanced hepatic lipid metabolism and resistance to the acquisition of a fatty liver. We present preliminary data to support a new signaling paradigm in which cytosolic and nuclear calcium signals differentially regulate the transcription of MKP-1 in a positive and negative manner, respectively. This discrete regulation of MKP-1 in the nucleus by calcium controls MAPK-mediated gene expression. We hypothesize that local calcium signals regulates MKP-1 expression which serves to limit the magnitude and spatio-temporal kinetics of MAPK-mediated gene activity required for liver growth, regeneration, and metabolic homeostasis. We will test this hypothesis in three specific aims. Aim 1 will define the molecular basis for the differential effects of nuclear and cytosolic calcium on the regulation of MKP-1 gene transcription by disrupting calcium signaling in these sub-cellular compartments using previously developed targeted calcium-binding proteins. Aim 2 will define the importance of MKP-1 nuclear localization for its physiological function in the liver. To test this, a novel genetic mutation in MKP-1 that targets it to the cytosol will be "knocked-in" to mice using an inducible CreLoxP approach. Aim 3 will determine the role of MKP-1 on liver growth, regeneration, and stress management using MKP 1 "knock-out" mice. Together with projects by Nathanson and Ehrlich, the proposed molecular, biochemical and genetic approaches in this project will establish a new signaling paradigm between local calcium signals, MKP-1 and MAPK-mediated gene expression in the control of liver function.