Mechanisms of Disease associated with mechanically-activated Piezo ion channels

Piezo 1和Piezo 2离子通道对于我们的触觉和本体感觉是必不可少的， 肺伸展和血管血流。到目前为止，8种不同的人类疾病与61种疾病有关。 Piezos中的单点突变，其中许多与其已知的生理 功能协调发展的虽然大多数突变对压电功能的影响是未知的，因此研究的少数突变 远明显地影响压电失活，这本身在机理上是不理解的。本申请的总体目标是对机械激活的压电离子通道中所有目前已知的人类疾病相关突变进行全面的功能表征，并解决失活机制。我们的基本原理是，通过确定每个点突变的功能效应和了解压电失活的机制，我们采取了理解这些疾病所必需的两个前步骤。我们的中心假设是，与人类疾病相关的Piezos单点突变影响膜表达，离子渗透或开放概率，并且Piezo失活由C-末端胞外结构域（CED）内的特定结构（残基/结构域）决定。该假设的科学前提是基于以下事实：i）诊断为结肠直肠息肉病、脱水性口细胞增多症、淋巴发育不良、溶血性贫血和远端关节弯曲症、马登-沃克综合征、戈登综合征、小眼畸形的人类患者分别与Piezo 1和Piezo 2的突变相关，ii）CED赋予失活，并且已知功能性免疫缺陷的主要靶点是Piezo 1和Piezo 2。 通过突变、配体和电压调节Piezos，以及iii）我们自己的研究表明， 改变失活动力学的疾病相关点突变深刻地改变了重复的 Piezos在机械振动期间可能遇到的机械刺激， 呼吸或心脏跳动时的脉动血流。我们的具体目标将检验以下假设： 目的1：确定61个单点突变对Piezo 1和Piezo 2功能的影响;目的2：鉴定 失活的结构和分子机制。这项研究是创新的，因为我们探索了61个人类Piezo 1和Piezo 2疾病相关单点突变的功能后果，几乎所有这些突变在功能水平上都没有特征，并且因为我们将确定失活机制及其结构相关性，这两者目前都是未知的。本研究的意义在于对与人类未知机制疾病相关的Piezo点突变的功能效应进行全面的生物物理分析，并对其靶点失活的机制和结构进行探索。这些知识将使我们深入了解这些疾病的潜在机制，并指导进一步的机制研究策略。 探索，有效的诊断和疾病治疗。

Piezo1 and Piezo2 ion channels are essential for our senses of touch and proprioception, and the detection of lung stretch and vascular blood flow. As of today, 8 distinct human diseases have been associated with 61 single-point mutations in Piezos, many of which are not obviously related to their known physiological functions. While for most mutations their effects on Piezo function are unknown, the few mutations studied thus far distinctly affect Piezo inactivation, which is itself not understood mechanistically. The overall objective of this application is a comprehensive functional characterization of all currently-known human disease-related mutations in mechanically-activated Piezo ion channels and solving the mechanism of inactivation. Our rationale is that by determining functional effects of each point-mutation and by knowing the mechanism of Piezo inactivation we take the two first steps necessary for understanding these diseases. Our central hypothesis is that single-point mutations in Piezos that have been associated with human diseases affect membrane expression, ion permeation, or open probability, and that Piezo inactivation is determined by specific structures (residues/domains) within the C-terminal-extracellular domain (CED). The scientific premise for this hypothesis is based on the facts, that i) human patients diagnosed with colorectal polyposis, dehydrated stomatocytosis, lymphatic dysplasia, hemolytic anemia, and distal arthrogryposis, Marden-Walker syndrome, Gordon syndrome, microphthalmia are associated with mutations in Piezo1 and Piezo2, respectively, that ii) inactivation is conferred by the CED and the known main target of functional modulation of Piezos by either mutations, ligands, and voltage, and iii) our own studies showing that human disease-related point-mutations that alter inactivation kinetics profoundly change transduction of repetitive mechanical stimuli, which Piezos likely encounter during mechanical vibrations, repetitive lung stretch during breathing, or pulsating blood flow upon heart beating. Our specific aims will test the following hypotheses: Aim1: Determine the effects of 61 single-point mutations on Piezo1 and Piezo2 function; Aim2: Identification of the structures and molecular mechanism of inactivation. The proposed research is innovative, because we explore the functional consequences of 61 human Piezo1 and Piezo2 disease-related single-point mutations, nearly all of which have remained uncharacterized on a functional level, and because we will identify the mechanism of inactivation and its structural correlates, both of which are currently unknown. The significance of this study is a comprehensive biophysical analysis of functional effects of Piezo point-mutations that have been associated with human diseases of unknown mechanisms, and the mechanistic and structural exploration of inactivation as their target. This knowledge will give deep insight into the mechanisms underlying these diseases and guide strategies for further mechanistic explorations, effective diagnosis and disease treatment.