Regulation of Metal Ion Homeostasis by Channel Kinases

描述（由申请人提供）：本项目的目标是通过研究通道激酶的结构和功能，揭示脊椎动物中金属离子稳态，特别是镁稳态的调节机制。通道激酶，也称为“chanzymes”（通道加酶）是最近发现的双功能分子，其由融合到蛋白激酶的离子通道组成。最近的证据表明，通道激酶TRPM 6和TRPM 7在调节脊椎动物的金属离子稳态中起着关键作用。具体地，通道激酶具有几个主要功能：1）作为镁通道，它们代表镁稳态的关键调节剂，并且可以提供哺乳动物细胞中的主要镁摄取机制; 2）作为痕量金属离子通道，通道激酶可以提供用于痕量金属离子（例如锰和锌）进入细胞的主要离子通道机制。在项目1（Andrea Fleig，PI）中，我们将对TRPM 7和TRPM 6离子通道进行生物物理，分子和功能分析。我们将研究提供二价金属离子选择性的通道渗透的分子决定因素。在项目2（Alexey Ryazanov，4PI）中，我们将研究TRPM 7和TRPM 6激酶的生理功能和激活机制。我们将确定这些激酶识别的序列基序，并确定其生理底物。在项目3（Andrew Scharenberg，PI）中，我们将研究TRPM 7在镁稳态调节中的作用。我们将确定TRPM 7介导细胞和生物体生长的镁依赖性调节的信号通路。在项目4（John Stokes，PI）中，我们将使用基因敲除小鼠模型分析TRPM 6和TRPM 7在镁稳态调节中的作用。我们将确定镁平衡如何影响TRPM 6或TRPM 7缺陷小鼠的肾功能。我们还将开发TRPM 6和TRPM 7的条件性和器官特异性敲除小鼠。这些项目将由管理核心（核心A）和动物和分析核心（核心B）支持。考虑到通道激酶可能在缺血和中风等疾病中发挥作用，并且由于通道激酶的突变导致与金属离子失衡相关的疾病，因此这项工作具有高度的医学相关性。

DESCRIPTION (provided by applicant): The goal of this program is to uncover the mechanism of the regulation of metal ion homeostasis, particularly magnesium homeostasis in vertebrates through the investigation of the structure and function of channel kinases. Channel kinases, also know as "chanzymes" (channels plus enzymes) are recently discovered bifunctional molecules that consist of an ion channel fused to a protein kinase. Recent evidence suggests that channel kinases TRPM6 and TRPM7 play a key role in the regulation of metal ion homeostasis in vertebrates. Specifically, channel kinases have several major functions: 1) As magnesium channels they represent key regulators of magnesium homeostasis and may provide the major magnesium uptake mechanism in mammalian cells; 2) As trace metal ion channels, channel kinases may provide a major ion channel mechanism for cellular entry of trace metal ions such as manganese and zinc. In Project 1 (Andrea Fleig, PI), we will perform biophysical, molecular, and functional analysis of the TRPM7 and TRPM6 ion channels. We will investigate molecular determinants of channel permeation that provide selectivity for divalent metal ions. In Project 2 (Alexey Ryazanov, 4PI), we will investigate the physiological function and mechanism of activation of TRPM7 and TRPM6 kinases. We will determine sequence motifs recognized by these kinases and identify their physiological substrates. In Project 3 (Andrew Scharenberg, PI) we will investigate the role of TRPM7 in the regulation of magnesium homeostasis. We will identify signaling pathways through which TRPM7 mediates magnesium-dependent regulation of cell and organism growth. In Project 4 (John Stokes, PI), we will analyze the role of TRPM6 and TRPM7 in the regulation of magnesium homeostasis using knockout mouse models. We will determine how magnesium balance affects kidney function in mice deficient in TRPM6 or TRPM7. We will also develop mice with conditional and organ-specific knockouts of TRPM6 and TRPM7. These projects will be supported by an Administrative Core (Core A), and an Animal and Analytical Core (Core B). This work has a high degree of medical relevance considering that channel kinases are likely to play a role in such conditions as ischemia and stroke, and since mutations in channel kinases are causing diseases associated with metal ion imbalance.