Regulation of cardiac patterning by the BAF complex subunit Smarcc1a

BAF 复合体亚基 Smarcc1a 对心脏模式的调节

• 批准号: 10661089
• 负责人: Ivy Fernandes
• 金额: $ 4.06万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN DIEGO
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10661089
• 关键词: Address; Candidate Disease Gene; Cardiac; Characteristics; Chromatin Remodeling Factor; Complex; Congenital Abnormality; Data; Defect; Embryonic Heart; Endocardium; Exhibits; Gene Expression; Gene Expression Profile; Genes; Genetic; Genetic Epistasis; Genetic Screening; Heart; Heart Atrium; Investigation; Laboratories; Modeling; Molecular; Morphogenesis; Morphology; Mutation; Myocardial; Myocardium; Pathway interactions; Pattern; Phenotype; Process; Regulation; Repression; Role; SMARCC1 gene; Structure; Testing; Tissues; Transgenic Organisms; Tube; Ventricular; Work; Zebrafish; causal variant; chromatin remodeling; congenital heart disorder; constriction; gain of function; loss of function; mutant; novel; overexpression; positional cloning; programs; trait; transcription factor; transcriptomics

PROJECT SUMMARY Cardiac patterning is an essential process that creates distinct regions with unique functions within the embryonic heart. As the heart develops, it transforms from a simple linear heart tube into a patterned structure with atrial and ventricular chambers and the atrioventricular canal (AVC) at their junction. The formation of these morphological distinctions is accompanied by dynamic changes in gene expression patterns: genes that were at first broadly expressed throughout the heart tube become restricted to either the chambers or the AVC. Despite the functional importance of AVC and chamber patterning, we do not fully understand the molecular mechanisms that promote the restriction of specific genes to either region. To address this open question, our laboratory has carried out genetic screens in zebrafish in search of mutations that disrupt the morphology of the AVC or the cardiac chambers. In a previous screen, we identified a mutant with severe defects in AVC and chamber morphogenesis, resulting in a relatively linear heart without a morphologically distinct AVC at the boundary between the atrium and the ventricle. In addition, the mutant heart fails to exhibit the appropriate refinement of gene expression to the AVC. Positional cloning revealed that the causative mutation disrupts the zebrafish smarcc1a gene, encoding a SWI/SNF-type ATP-dependent chromatin remodeling complex subunit homologous to mammalian BAF155. These results suggest a novel model in which chromatin remodeling by Smarcc1a-containing BAF complexes refines the gene expression patterns that promote the distinction between AVC and chamber identities. To test this model, I will first determine when and where Smarcc1a acts to restrict gene expression to the AVC. Specifically, I will examine the extent to which smarcc1a influences regional patterns of gene expression, determine when gene expression defects first emerge in smarcc1a mutants, and utilize transgenic strategies for tissue-specific rescue of smarcc1a mutants. Additionally, I will identify effector genes that act downstream of Smarcc1a to drive cardiac patterning. Using loss-of-function, gain-of-function, and epistasis analysis, I will test whether smarcc1a controls cardiac patterning through its influence on repression of tbx2b expression. I will also use transcriptomic approaches to identify a broader roster of candidate genes that are regulated by smarcc1a, and I will test whether top candidates are key effectors in executing cardiac patterning. Together, these studies are likely to reveal a novel role of smarcc1a in regulating the mechanisms that distinguish the traits of the AVC from the traits of the adjacent cardiac chambers. This role of smarcc1a would represent a previously unappreciated function for BAF chromatin remodeling complexes during cardiac patterning. Thus, this work has the potential to have a broader biomedical impact, as it may enhance our understanding of how mutations in genes encoding components of chromatin remodeling complexes could relate to the origins of congenital heart disease.

项目摘要 心脏图案是一个必不可少的过程，在胚胎中创建具有独特功能的不同区域 心。随着心脏的发展，它从简单的线性心管转变为带有房屋的图案结构 和心室腔室和室内通道（AVC）在交界处。这些形成 形态学的区别伴随着基因表达模式的动态变化： 首先在整个心管中广泛表达，仅限于腔室或AVC。尽管 AVC和腔室模式的功能重要性，我们不完全了解分子机制 这促进了特定基因对任何区域的限制。 为了解决这个开放的问题，我们的实验室已经在斑马鱼中进行了遗传筛选以寻找突变 破坏了AVC或心脏室的形态。在上一个屏幕中，我们确定了一个突变体 在AVC和腔室形态发生中存在严重缺陷，导致相对线性心脏没有 在中庭和心室之间的边界上的形态上不同的AVC。另外，突变心 未能表现出适当的基因表达对AVC的细化。位置克隆揭示了 致病突变破坏斑马鱼smarcc1a基因，编码SWI/SNF型ATP依赖性染色质 与哺乳动物BAF155的重塑复合物亚基同源。这些结果表明了一个新型模型，其中 通过含Smarcc1a的BAF复合物重塑染色质，完善了基因表达模式 促进AVC和腔室身份之间的区别。 为了测试该模型，我将首先确定smarcc1a在何时何地作用将基因表达限制为AVC。 具体而言，我将研究SMARCC1A影响基因表达的区域模式的程度， 确定基因表达何时在Smarcc1a突变体中首次出现，并利用转基因策略 组织特异性的SMARCC1A突变体。此外，我将确定在下游作用的效应基因 Smarcc1a驱动心脏模式。使用功能丧失，功能获得和上毒分析，我将测试 SMARCC1A是否通过对TBX2B表达的抑制作用来控制心脏模式。我也会 使用转录组方法来识别由Smarcc1a调节的更广泛的候选基因花名册， 我将测试顶级候选人是否是执行心脏模式的关键效应子。 总之，这些研究可能揭示了Smarcc1a在调节区分机制中的新作用 来自相邻心脏室特征的AVC的特征。 Smarcc1a的角色将代表 在心脏模式期间，BAF染色质重塑复合物的先前未批准的功能。因此，这个 工作有可能产生更广泛的生物医学影响，因为它可能会增强我们对如何的理解 编码染色质重塑复合物成分的基因突变可能与 先天性心脏病。