Thyroid hormone regulation of cardiomyocyte T-tubule structureand function

项目摘要/摘要 包括心力衰竭(HF)在内的慢性疾病通常伴有甲状腺功能障碍。来自动物的证据 人类对心力衰竭的研究提供了强有力的证据表明，低甲状腺激素(TH)会导致贫穷 预后和治疗改善心功能的措施。心脏的实验研究 因缺血和高血压引起的疾病，或糖尿病心肌病，都会导致心脏组织T3降低 我们提出的(生物活性TH)浓度是心肌细胞功能障碍的主要原因。T3调节 许多细胞过程，包括调节钙和收缩能力的心脏基因的转录，细胞 存活、生长、肾上腺素能和离子通道活动。我们假设T3调节T小管(TT)。 结构，而受损的T3信号导致不利的TT重塑和 收缩功能障碍。这一概念得到了最近的研究的支持，这些研究表明， 在从结构不成熟的新生儿到 成年心肌细胞。超分辨率成像的进步证实了逆性重塑 TT的发生在心衰患者和动物模型的心肌细胞中，导致兴奋受损。 收缩(EC)-耦合。我们的初步数据显示，心肌细胞的TT周期显著 减少心肌梗死引起的心力衰竭和TH缺乏的动物模型，导致钙动力学和 伸缩性。这项工作的首要目标是提供严格的科学证据来支持 对心力衰竭患者TH功能正常化的疗效。为了实现这一目标， 我们建议研究甲状腺功能障碍的两种疾病模型：(1)心肌梗死所致的心力衰竭 心肌梗死(MI)，以及(2)TH缺乏是由于化学物质(PTU)抑制TH的产生。在高频中 模型，心肌梗死后立即开始口服替代剂量T3，并持续16天 几周。从分离的心室肌细胞中记录钙瞬变和收缩能力，以及T3效应 在TT重构方面，将通过共聚焦显微镜进行评估。我们将使用多波长超分辨率 单分子成像是目前量化T3诱导的潜在变化的最佳方法 钙离子调节蛋白(Ryanodine受体、L类钙通道、桥联整合子-1、 Junctophlin-2)。在TH缺乏模型中，单独短期T3治疗对TT周期的影响， 钙蛋白的聚集性和收缩功能也将得到类似的评估。分子的审问 T3对TT重塑反应的潜在机制将涉及培养的成人心室肌细胞， 以及表达基因研究，包括RNAseq方法。这项研究的结果有可能 血清TH水平较低的心衰患者的高级治疗方案。支持这项建议 通过REAP将促进NYIT的研究环境，并为我们的学生提供机会 参与可能改变患者护理进程的临床相关研究。

Project summary/abstract Chronic diseases including heart failure (HF) often present with thyroid dysfunction. Evidence from animal and human studies of HF provide strong evidence that low thyroid hormones (TH) contribute to poor prognosis and that TH treatment improves measures of cardiac function. Experimental studies of heart diseases due to ischemia and hypertension, or diabetic cardiomyopathy, all induce low cardiac tissue T3 (bioactive TH) concentrations that we propose is the primary cause of myocyte dysfunction. T3 regulates many cellular processes including transcription of cardiac genes regulating calcium and contractility, cell survival, growth, adrenergic and ion channel activities. We hypothesize that T3 regulates T-tubule (TT) structures in cardiomyocytes, and that impaired T3 signaling leads to adverse TT remodeling and contractile dysfunction. This concept is supported by recent studies indicating an essential requirement of THs in the development of a functioning TT network in the transition from structurally immature neonatal to adult cardiomyocytes. Advancements in super-resolution imaging have confirmed that adverse remodeling of TT occurs in cardiomyocytes from patients and animal models of HF leading to impaired excitation- contraction (EC)-coupling. Our preliminary data show that cardiomyocyte TT periodicity is significantly reduced in MI-induced heart failure and TH-deficient animal models, causing slower calcium kinetics and contractility. The overarching goal of this work is to provide rigorous scientific evidence to support a therapeutic benefit in normalizing TH function in patients with heart failure. To accomplish this goal, we propose to study two disease models of thyroid dysfunction: (1) heart failure induced by myocardial infarction (MI), and (2) TH-deficiency produced by chemical (PTU) inhibition of TH production. In the HF model, oral treatment with replacement-dose T3 will be initiated immediately after MI and continued for 16 weeks. Ca2+ transients and contractility will be recorded from isolated ventricular myocytes, and T3 effects on TT remodeling will be assessed by confocal microscopy. We will use multi-wavelength super-resolution single-molecule imaging that is currently the best approach to quantify potential T3-induced changes in distribution of Ca2+ handling proteins (Ryanodine receptors, L-type Ca2+ channels, Bridging Integrator-1, Junctophilin-2). In the TH-deficient model, effects of short-term T3 treatment alone on TT periodicity, clustering of Ca2+ proteins and contractile function will be similarly assessed. Interrogation of the molecular mechanisms underlying the TT remodeling responses to T3 will involve cultured adult ventricular myocytes, and expressed gene studies including RNAseq approaches. Results from this study have the potential to advance treatment options for the patient with HF presenting with low serum THs. Support of this proposal by REAP will promote the research environment at NYIT, and provide opportunities for our students to participate in clinically relevant research that may change the course of patient care.