Allele-specific Effects-Single Amino Acid Exchanges/cTnT

等位基因特异性效应-单氨基酸交换/cTnT

• 批准号: 6830791
• 负责人: Jil C Tardiff
• 金额: $ 29.95万
• 依托单位: ALBERT EINSTEIN COLLEGE OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-12-01 至 2007-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6830791
• 关键词: alleles; aminoacid metabolism; cardiovascular disorder epidemiology; cardiovascular function; cardiovascular stress test; confocal scanning microscopy; congenital heart disorder; electron microscopy; gene mutation; gene targeting; genetic disorder; genetic markers; genetically modified animals; heart contraction; heart dimension /size; hypertrophic myocardiopathy; laboratory mouse; microfilaments; myocardium; myofibrils; protein protein interaction; protein structure function; sarcomeres; tropomyosin; troponin

DESCRIPTION (provided by applicant): The regulatory function of the cardiac sarcomere resides in the thin filament. It is a complex macromolecular structure comprised of multiple protein subunits, which interact and modulate contractile function in response to both chronic and acute physiologic stress. The binding of Ca2+ to Troponin C initiates a cascade of allosteric changes in the interactions of the proteins within the troponin (cTnC, cTnl and cTnT) and tropomyosin-actin complexes, facilitating the formation of the actinomyosin complex and the power stroke of muscle contraction. While normal hearts retain the ability to alter these complex interactions, for example, via contractile protein isoform shifts and post-translational modifications, many naturally-occurring thin filament mutations are poorly tolerated. In fact, mutations in cardiac Troponin T (cTnT) result in a particularly severe form of Familial Hypertrophic Cardiomyopathy (FHC) characterized by a high frequency of early sudden cardiac death in the absence of overt ventricular hypertrophy. The direct link between the gene mutation and the complex clinical phenotype remains unknown. Troponin T is a highly elongated protein that interacts with all other components of the thin filament and has been described as the "glue" of the regulatory system. The full ternary structure is unknown and thus the details of these complex protein-protein interactions remain unclear. The hypothesis for this application is that individual cTnT mutations disrupt discrete aspects of these protein-protein interactions causing specific changes in thin filament function and leading to distinct cardiovascular phenotypes. To address this hypothesis we have developed three independent transgenic mouse models based solely on amino acid substitutions at Codon 92 (Arg92GIn, Arg92Trp and Arg92Leu), a known mutational hotspot in human cTnT. Initial characterization has revealed allele-specific changes in cardiac mass, contractility and hypertrophic signaling pathways. In these initial studies we have selected specific aspects of the observed phenotypes to serve as physiologic "indicators" of the differences in thin filament function caused by each mutation. Establishing the mechanistic link between the specific cTnT mutant allele and it's cellular phenotype will both provide new insights into the fundamental biology of thin filament function and further our understanding of the pathogenic pathways involved in thin filament related cardiomyopathies.

描述（由申请人提供）：心脏肉瘤的调节功能位于细丝中。它是一种复杂的大分子结构，由多个蛋白质亚基组成，它们响应慢性和急性生理应力而相互作用并调节收缩功能。 Ca2+与肌钙蛋白C的结合启动了肌动蛋白（CTNC，CTNL和CTNT）和肌动蛋白 - 肌动蛋白复合物中蛋白质相互作用的变构变化，从而促进了放线肌素复合物的形成以及肌肉相互作用的动力。尽管正常的心脏保留改变这些复杂相互作用的能力，例如，通过收缩蛋白质同工型转移和翻译后修饰的能力，许多天然出现的薄丝丝突变的耐受性不佳。实际上，心脏肌钙蛋白T（CTNT）的突变导致一种特别严重的家族性肥厚性心肌病（FHC），其特征是在没有明显的心室肥大的情况下高发生早期心脏死亡的频率。基因突变与复杂临床表型之间的直接联系仍然未知。肌钙蛋白T是一种高度伸长的蛋白质，与薄丝所有其他成分相互作用，已被描述为调节系统的“胶水”。完整的三元结构尚不清楚，因此这些复杂的蛋白质蛋白质相互作用的细节尚不清楚。该应用的假设是单个CTNT突变破坏了这些蛋白质 - 蛋白质相互作用的离散方面，从而导致薄丝功能的特定变化并导致独特的心血管表型。为了解决这一假设，我们仅基于密码子92（ARG92GIN，ARG92TRP和ARG92LEU）的三个独立的转基因小鼠模型，这是人类CTNT中已知的突变热点。最初的表征揭示了等位基因特异性的心脏质量，收缩力和肥厚信号通路的变化。在这些最初的研究中，我们选择了观察到的表型的特定方面，以作为每个突变引起的薄丝功能差异的生理“指标”。建立特定的CTNT突变等位基因与它的细胞表型之间的机械联系都将为薄丝功能的基本生物学提供新的见解，并进一步了解我们对与瘦细丝相关心肌病的致病途径的理解。