权益分类	功能权益	普通用户	{{item.name}}会员
{{category.name}}	{{benefitItem.name}}

Creation of a transgenic animal model of hypertrophic cardiomyopathy caused by cardiac troponin T mutation.

心肌肌钙蛋白T突变引起的肥厚型心肌病转基因动物模型的创建。

基本信息

批准号：
10557073
负责人：
OKA Naoki
金额：
$ 3.46万
依托单位：
Kurume University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
1998
资助国家：
日本
起止时间：
1998 至 1999
项目状态：
已结题

项目摘要

[Purpose] Previous finding suggest that myocardial hypertrophy seen in patients with hypertrophic cardiomyopathy (HCM) caused by β-myosin heavy chain mutation is a compensatory mechanism for depressed myocyte contraction. Although the patients with HCM caused by the cardiac TnT (TnT) mutations are typically associated with an incomplete disease penetrance and mild to moderate cardiac hypertrophy, their prognosis is though to poor. It remains unknown whether a mode of pathogenesis for TnT mutation is similar to that for myosin heavy chain mutation. To clarify this question, two truncated cardiac TnTs produced by a splice donor site mutation in intron 15 and three missense mutations (Phe110lle, Glu244Asp and Arg278Cys) were constructed. [methods] Human cardiac TnT cDNA was cloned by RT-PCR, then above mutations were inserted into this cDNA using PCR based procedure. Those mutants were expressed in E. coli and partially (50%-55%) exchanged into rabbit permeabilized cardiac muscle fibers. [Results] The muscle fibers exchanged with the splice donor site mutations conferred a lower cooperativity, while the fibers exchanged with missense mutations did not affects the cooperativity, compared to wild type TnT. Glu244Asp mutation augmented both a CaィイD12+ィエD1 sensitivity and a maximum force-generating capability, whereas Arg278Cys mutation showed the higher CaィイD12+ィエD1 sensitivity without any effects on the maximum force. In contrast, Phe110lle showed marked increase in CaィイD12+ィエD1 -activated maximum force without CaィイD12+ィエD1 sensitizing effect. [Conclusions] There results indicate that a hypercontractility may be a common feature of the cardiac muscle expressing mutant troponin T. Moreover, it is also suggest that cardiac hypertrophy in patients with hypertrophic cardiomyopathy caused by troponin T mutation is not a consequence of depressed cardiac function.

【目的】既往研究提示肥厚性心肌病（HCM）患者β-肌球蛋白重链突变引起的心肌肥大是心肌细胞收缩抑制的代偿机制。虽然由心脏TnT （TnT）突变引起的HCM患者通常伴有不完全疾病外显率和轻至中度心脏肥厚，但其预后较差。TnT突变的发病模式是否与肌球蛋白重链突变相似尚不清楚。为了澄清这个问题，我们构建了两个由内含子15剪接供体位点突变和三个错义突变（Phe110lle， Glu244Asp和Arg278Cys）产生的截断的心脏TnTs。【方法】采用RT-PCR方法克隆人心脏TnT cDNA，并采用PCR方法将上述突变插入该cDNA。这些突变体在大肠杆菌中表达，部分（50%-55%）交换到兔渗透心肌纤维中。[结果]与野生型TnT相比，与剪接供体位点突变交换的肌纤维具有较低的协同性，而与错义突变交换的肌纤维不影响协同性。突变体Glu244Asp增强了Ca的敏感性和最大发力能力，而突变体Arg278Cys增强了Ca的敏感性，但对最大发力没有影响。相比之下，Phe110lle对Ca的最大激活力明显增加，但无Ca的致敏作用。结论：肌钙蛋白T突变引起的肥厚性心肌病患者心肌肥大可能是肌钙蛋白T突变心肌的共同特征，并不是心功能下降的结果。