Molecular and Cellular Mechanisms of Trabeculation

小梁形成的分子和细胞机制

• 批准号: 8315278
• 负责人: David Wells Staudt
• 金额: $ 3.72万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2015-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8315278
• 关键词: Actins; Affect; Apical; Behavior; Biological; Biological Models; Cardiac; Cardiac Myocytes; Cardiomyopathies; Cardiovascular system; Categories; Cell Shape; Cells; Complex; Congenital Abnormality; Coronary; Data; Decision Making; Development; Developmental Process; Endocardium; Epithelial; Exclusion; Failure; Gene Expression; Genetic; Heart; Heart Ventricle; Image; Immunofluorescence Immunologic; Individual; Knowledge; Lateral; Learning; Life; Ligands; Light; Molecular; Monitor; Muscle Cells; Myocardial; Myocardium; Myosin ATPase; Pathway interactions; Pattern; Physiology; Play; Prevalence; Process; Proteins; Research; Role; Shapes; Signal Pathway; Signal Transduction; Simple Epithelium; Staging; Structure; System; Testing; Time; Transgenic Organisms; Ventricular; Zebrafish; cardiogenesis; congenital heart disorder; constriction; heart function; innovation; insight; muscular structure; notch protein; prevent; promoter; three dimensional structure; time use; tool

DESCRIPTION (provided by applicant): Over the course of development, the heart transforms from an epithelial layer of myocytes to a complex, three-dimensional structure critical for its function. A number of morphogenetic processes contribute to this transformation, and one of these processes leads to the formation of the cardiac trabeculae, sheet-like muscular structures in the ventricular myocardial wall. Trabeculae play a critical role in increasing myocardial mass before the development of a coronary circulatory system, and serve as precursors for the ventricular conduction system. Additionally, failure to form trabeculae or failure of ventricular compaction can cause congenital cardiomyopathies. Despite the importance of these structures, there remain many open questions about how they are formed. In this proposal, we will use the powerful live imaging and transgenic approaches available with the zebrafish system to examine the cellular and molecular determinants of trabecular formation. How individual myocytes enter the trabecular layer is currently unknown. Our initial data suggest that trabeculae form via a process of delamination, but the precise cellular mechanisms remain unclear. We hypothesize that myocytes use the conserved developmental process of apical constriction to exit the compact layer and form trabecular sheets. To test this hypothesis, we will use mosaic expression of fluorescent proteins combined with live imaging to monitor the cell shape changes of individual cardiomyocytes within the zebrafish ventricle. Additionally, we will use a combination of live imaging and immunofluorescence to examine the behavior of actin and myosin during this process. Only some cells within the ventricular myocardium contribute to the trabecular layer, and how these cells are chosen is currently unknown. The Notch pathway plays many roles in development, and is known to regulate asymmetric cell fate decisions in a variety of contexts. Our initial data suggest that Notch signaling within myocytes is restricted to the compact layer. We hypothesize that activation of Notch signaling prevents cells from contributing to trabeculae. We propose to test this hypothesis by monitoring Notch activation over time using a transgenic zebrafish line expressing GFP under a notch-responsive promoter. Further, we will use mosaic expression of dominant activators and repressors of the Notch pathway to determine whether Notch activation is necessary and sufficient for preventing trabecular incorporation. By using the powerful imaging and genetic tools available in the zebrafish system, this proposal will shed light on the mechanisms controlling trabecular formation at a cellular level. PUBLIC HEALTH RELEVANCE: Cardiac trabeculae are sheet-like muscular structures within the ventricles of the heart that play a role in both contraction and electrical conduction within te ventricular chambers. Despite their functional importance, little is known about how cells physically enter the trabeculae, or what signals tell some, but not all, myocardial cells to form these trabeculae. This proposal seeks to understand how cells make the decision to enter the trabeculae, and, once they do, how they move and change shape to form these structures.

描述（由申请人提供）：在发育过程中，心脏从心肌细胞的上皮层转变为复杂的三维结构对其功能至关重要。许多形态发生的过程有助于这种转化，其中一个过程导致心脏心肌壁中心脏小梁，类似肌肉的肌肉结构的形成。小梁在发展冠状动脉循环系统之前在增加心肌质量方面起着关键作用，并作为心室传导系统的前体。另外，未能形成小梁或心室压实的失败会导致先天性心肌病。尽管这些结构很重要，但关于它们的形成方式仍然存在许多悬而未决的问题。在此提案中，我们将使用斑马鱼系统可用的功能强大的活成像和转基因方法来检查小梁形成的细胞和分子决定因素。当前未知的单个肌细胞进入小梁层。我们的初始数据表明，小梁通过分层过程形成，但精确的细胞机制尚不清楚。我们假设肌细胞使用顶端收缩的保守发展过程退出紧凑层并形成小梁片。为了检验这一假设，我们将 使用荧光蛋白与实时成像结合的镶嵌表达来监测斑马鱼心室中单个心肌细胞的细胞形状变化。此外，我们将使用实时成像和免疫荧光的组合来检查肌动蛋白和肌球蛋白在此过程中的行为。只有心室心肌内的某些细胞有助于小梁层，以及当前如何选择这些细胞。 Notch途径在发展中起着许多作用，并且已知可以在各种情况下调节不对称的细胞命运决策。我们的初始数据表明，肌细胞内的缺口信号仅限于 紧凑层。我们假设Notch信号的激活阻止细胞对小梁的贡献。我们建议使用在缺口响应启动子下表达GFP的转基因斑马线线来监测Notch的激活来检验该假设。此外，我们将使用Notch途径的主要激活因子和阻遏物的镶嵌表达来确定Notch激活是否是必需的，并且足以防止小梁掺入。通过使用斑马鱼系统中可用的强大成像和遗传工具，该建议将阐明控制小梁形成在细胞水平上的机制。 公共卫生相关性：心脏小梁是心脏心室内的类似薄片的肌肉结构，在te心室内部的收缩和电导传导中都起着作用。尽管它们的功能重要性，但对细胞如何物理进入小梁的知识知之甚少，或者信号告诉某些但不是全部的心肌细胞以形成这些小梁。该提案试图了解细胞如何决定进入小梁的决定，一旦它们做到了，它们如何移动和改变形状以形成这些结构。