Wnt/beta-cantenin signaling and cardiac ion channels

Wnt/β-cantenin 信号传导和心脏离子通道

• 批准号: 8883315
• 负责人: Haodong Xu
• 金额: $ 38.5万
• 依托单位: UNIVERSITY OF CALIFORNIA LOS ANGELES
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-01 至 2020-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8883315
• 关键词: Action Potentials; Arrhythmia; Binding; Binding Sites; Biological Assay; Cardiac; Cardiac Myocytes; Cell membrane; Complex; Computer Simulation; Cre-LoxP; Deceleration; Development; Gene Expression; Gene Targeting; Genes; Genetic Transcription; Genetically Engineered Mouse; Health; Heart; Heart Diseases; Histology; Human; In Vitro; Ion Channel; Link; Lithium Chloride; Mediating; Modeling; Molecular; Mus; Muscle Cells; Myocardial Ischemia; Myocardium; Oxidative Stress; Pathway interactions; Phosphorylation; Play; Rattus; Recruitment Activity; Regulation; Risk; Role; Signal Pathway; Signal Transduction; Site; Sodium Channel; TCF7L2 gene; Tamoxifen; Technology; Testing; Therapeutic Agents; Transcriptional Regulation; Vascular blood supply; Ventricular; Ventricular Fibrillation; Ventricular Tachycardia; base; beta catenin; chromatin immunoprecipitation; heart cell; heart electrical activity; histone modification; inhibitor/antagonist; mouse model; mutant; new therapeutic target; novel; novel therapeutics; overexpression; promoter; public health relevance; transcription factor

 DESCRIPTION (provided by applicant): Alterations of ion channel activity play important roles in the development of cardiac arrhythmias. NaV1.5, encoded by the SCN5a gene, is a subunit of the cardiac Na+ channel, the activity of which determines cardiac excitability and electrical conduction. Decreased Na+ channel activity is linked to cardiac arrhythmias in different types of cardiac diseases, but it is largely unknown how this channel is transcriptionally regulated. FoxO1 mediates the inhibition of SCN5a promoter activity by oxidative stress, and oxidative stress promotes ß-catenin and FoxO interaction to enhance the expression of the target genes. Canonical Wnt/ß-catenin signaling is quiescent in the normal hearts. However, in the diseased hearts, this signaling pathway is activated while NaV1.5 expression and Na+ channel are inhibited, suggesting that this signaling pathway may involve the Na+ channel regulation. Activation of the Wnt/ß-catenin pathway decreases ß-catenin phosphorylation by CK- 1ß and GSK-3ß and promotes its interaction with transcriptional factors such as TCF4 and FoxO1 to regulate the target genes' expression. Our preliminary results showed that treatment with the GSK-3ß inhibitors, lithium chloride and BIO or overexpression of activated ß-catenin led to decreased NaV1.5 expression. We also found that expression of constitutively active GSK-3ßS9A decreased ß-catenin and increased NaV1.5 expression in HL-1 cardiomyocytes. We hypothesize that activation of Wnt/ß-catenin signaling suppresses NaV1.5 expression by its interaction with TCF4 and FoxO1, leading to a decrease of Na+ channel activity, cardiac depolarization and cardiac conduction. We will test this hypothesis in the 3 specific aims as follows: AIM 1: To define the role of ß-catenin in the regulation of NaV1.5 expression in mouse hearts; AIM 2: To determine the molecular mechanisms of ß-catenin suppressing NaV1.5 expression in mouse hearts; AIM 3: To determine if ß-catenin-mediated inhibition of NaV1.5 expression in cardiomyocytes requires both FoxO1 and TCF4 for cardiac conduction regulation. In order to achieve these 3 specific AIMs, we will particularly use cardiac specific Cre-Lox technology and delete key Wnt signaling components such TCF4, ß- catenin, and APC, and FoxO1 transcriptional factor in mouse hearts. We will identify the alterations of NaV1.5 expression and Na+ channel activity and cardiac electrical remodeling in these genetically engineered mice. Our main anticipated finding is that ß-catenin, TCF4 and FoxO1 form a complex to suppress NaV1.5 expression by inhibiting the SCN5a promoter activity, leading to slowed cardiac depolarization and cardiac conduction. The proposed studies will identify a potential and novel therapeutic target for treatment of cardiac arrhythmias.

 描述(由申请人提供)：离子通道活性的改变在心律失常的发展中起着重要作用。NaV1.5由SCN5A基因编码，是心脏Na+通道的一个亚基，其活性决定心脏的兴奋性和电传导。在不同类型的心脏疾病中，Na+通道活性降低与心律失常有关，但该通道如何转录调控在很大程度上尚不清楚。Foxo1介导氧化应激对SCN5A启动子活性的抑制，氧化应激促进？-catenin和FoxO的相互作用，促进靶基因的表达。在正常心脏中，典型的Wnt/？catenin信号是静止的。然而，在患病的心脏中，该信号通路被激活，而NaV1.5的表达和Na+通道被抑制，提示该信号通路可能参与了Na+通道的调节。Wnt/？-catenin通路的激活降低了Ck-1？和GSK-3？的？？连接蛋白的磷酸化，并促进其与转录因子如TCF4和FoxO1的相互作用，从而调节靶基因的表达。我们的初步结果表明，用GSK-3？抑制剂、氯化锂和生物或过度表达活化的？连环蛋白处理会导致NaV1.5的表达降低。我们还发现，在HL-1心肌细胞中，具有结构性活性的GSK-3？S9A的表达降低了？连环蛋白，增加了NaV1.5的表达。我们推测，Wnt/？catenin信号的激活通过与TCF4和FoxO1的相互作用抑制NaV1.5的表达，导致Na+通道活性降低、心脏去极化和心脏传导。我们将在以下三个具体目标中验证这一假说：目的1：确定？连环蛋白在调节小鼠心脏NaV1.5表达中的作用；目的2：确定？连环蛋白抑制小鼠心脏NaV1.5表达的分子机制；目的3：确定？连环蛋白介导的抑制心肌细胞NaV1.5表达的作用是否需要FoxO1和TCF4来调节心脏传导。为了达到这三个特定的目的，我们将特别使用心脏特异的Cre-Lox技术，并删除小鼠心脏中关键的Wnt信号成分，如TCF4、ç-catenin、APC和FoxO1转录因子。我们将确定这些基因工程小鼠的NaV1.5表达、Na+通道活性和心脏电重构的变化。我们的主要预期发现是，ç-catenin、TCF4和FoxO1形成一个复合体，通过抑制SCN5A启动子的活性来抑制NaV1.5的表达，导致心脏去极化和心脏传导减慢。拟议的研究将确定治疗心律失常的潜在和新的治疗靶点。