Exploring calcium signaling in the heart

探索心脏中的钙信号传导

• 批准号: RGPIN-2022-04756
• 负责人: Collins, Michelle
• 金额: $ 2.7万
• 依托单位: University of Saskatchewan
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=743472
• 关键词: Exploring; calcium; signaling; heart

Background: To efficiently pump blood throughout the body, the heart must beat rhythmically. Each heartbeat is triggered by an electrical impulse that travels through the heart muscle, causing the atrial and ventricular chambers to contract in synchrony. Cardiomyocytes, the cells that make up the cardiac muscle, function by coupling electrical activation to muscle contraction. One of the key ions involved in the coupling process is Ca2+. Intracellular Ca2+ levels directly activate the myofilaments, causing the heart muscle to contract. Ca2+ must then be rapidly removed from the cytoplasm to allow the heart to relax and fill with blood. Any imbalance between Ca2+ entry and exit can lead to changes in heart rate, heart rhythm, and cardiac output, thus having profound consequences on cell homeostasis and heart function. Deciphering how Ca2+ dynamics are regulated and how Ca2+ microdomains function within the cardiomyocyte is the long-term goal of my NSERC research program. Rationale/Hypothesis: While the sarcoplasmic reticulum is the major Ca2+ store in cardiomyocytes, recent data indicate that acidic organelles, including the endosomes and lysosomes, may act as additional Ca2+ stores that are regulated by cation permeable TRPML channels. Endolysosomes play remarkably diverse roles supporting cell biology, including cell signaling and energy metabolism. However, whether these organelles contribute to Ca2+ dynamics in cardiomyocytes is unknown. This proposal builds upon my preliminary work and tests the hypothesis that TRPML channels regulate Ca2+ dynamics and function to maintain Ca2+ homeostasis in cardiomyocytes. Specific Short-Term Aims/Methods: In Aim 1, we will characterize acidic Ca2+ stores by defining TRPML gene expression in developing vertebrate embryos and analyzing Ca2+ dynamics by high-speed imaging of beating zebrafish hearts. Functional roles for each TRPML channel will be tested in Aim 2 using genetic loss-of-function models. Aim 3 will take a two-pronged approach to dissect the factors that regulate endolysosomal Ca2+ by analyzing an upstream transcriptional regulator (TFEB) and by performing a chemical screen using a novel biosensor that reports Ca2+ dynamics from the endolysosomes.   Impact:Defining the function of acidic Ca2+ stores, identifying the channels that regulate their function, and exploring how Ca2+ can be mobilized from these stores will describe a novel paradigm for studying Ca2+ homeostasis in cardiac muscle. Addressing this gap in knowledge will allow us to comprehensively understand how the heart functions.  HQP: Within this proposal, I will train 15 HQP over five years. HQP will use genetic tools, molecular techniques, advanced live imaging, and cell and developmental studies to generate fundamental knowledge on mechanisms of Ca2+ homeostasis. My training program will allow HQP to develop technical expertise in these areas, as well as hone their expertise in communication, critical thinking, and teaching.

背景：为了有效地将血液泵送到全身，心脏必须有节奏地跳动。每次心跳都是由穿过心肌的电脉冲触发，导致心房和心室同步收缩。心肌细胞是构成心肌的细胞，通过将电激活与肌肉收缩耦合起来发挥作用。耦合过程中涉及的关键离子之一是 Ca2+。细胞内 Ca2+ 水平直接激活肌丝，导致心肌收缩。然后，Ca2+ 必须迅速从细胞质中去除，以使心脏放松并充满血液。 Ca2+ 进入和排出之间的任何不平衡都会导致心率、心律和心输出量的变化，从而对细胞稳态和心脏功能产生深远的影响。破译 Ca2+ 动力学如何调节以及 Ca2+ 微区如何在心肌细胞内发挥作用是我的 NSERC 研究项目的长期目标。 基本原理/假设：虽然肌浆网是心肌细胞中主要的 Ca2+ 储存，但最近的数据表明，酸性细胞器（包括内体和溶酶体）可能充当额外的 Ca2+ 储存，并受阳离子渗透性 TRPML 通道调节。内溶酶体在支持细胞生物学方面发挥着非常多样化的作用，包括细胞信号传导和能量代谢。然而，这些细胞器是否有助于心肌细胞中的 Ca2+ 动态尚不清楚。该提议建立在我的初步工作的基础上，并测试了 TRPML 通道调节 Ca2+ 动力学和功能以维持心肌细胞中 Ca2+ 稳态的假设。具体的短期目标/方法：在目标 1 中，我们将通过定义发育中的脊椎动物胚胎中的 TRPML 基因表达来表征酸性 Ca2+ 储存，并通过跳动的斑马鱼心脏的高速成像来分析 Ca2+ 动态。每个 TRPML 通道的功能作用将在目标 2 中使用遗传功能丧失模型进行测试。目标 3 将采取双管齐下的方法，通过分析上游转录调节因子 (TFEB) 和使用报告内溶酶体 Ca2+ 动态的新型生物传感器进行化学筛选，剖析调节内溶酶体 Ca2+ 的因素。   影响：定义酸性 Ca2+ 储存的功能，确定调节其功能的通道，并探索如何从这些储存中调动 Ca2+，将为研究心肌中 Ca2+ 稳态提供一个新的范例。解决这一知识空白将使我们能够全面了解心脏的功能。  HQP：在本提案中，我将在五年内培训 15 名 HQP。 HQP 将使用遗传工具、分子技术、先进的实时成像以及细胞和发育研究来生成有关 Ca2+ 稳态机制的基础知识。我的培训计划将使 HQP 能够发展这些领域的技术专业知识，并磨练他们在沟通、批判性思维和教学方面的专业知识。