Functional analyset of mutations in human cardiac troponin T that cause familial hypertrophic cardiomyopathy

导致家族性肥厚型心肌病的人心肌肌钙蛋白T突变的功能分析

• 批准号: 11670045
• 负责人: MORIMOTO Sachio
• 金额: $ 2.3万
• 依托单位: KYUSHU UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1999
• 资助国家: 日本
• 起止时间: 1999 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11670045/
• 关键词: Heart; muscle; hypertrophy; mutation; troponin; 肥大型心筋症; トロポニン; カルシウム; 筋肉; 張力; 突然変異; クローニング

Familial hypertrophic cardiomyopathy (HCM) is an autosomal dominant cardiac disease associated with a high incidence of sudden death. HCM is a genetically heterogeneous disease which has been shown to be caused by mutations in the genes for a variety of cardiac myofibrillar proteins, including β-myosin heavy chain (β-MHC), subunits of Ca^<2+>- receptor troponin (troponin T and troponin I), α-tropomyosin, myosin-binding protein C, and myosin light chains. HCM is also clinically variable and the mutations in cardiac troponin T (TnT) are known to be associated with a high risk of sudden death despite an incomplete disease penetrance with moderate hypertrophy, in contrast to the high penetrance with more severe hypertrophy of β-MHC mutations with a comparable poor prognosis.At least 13 different mutations in the TnT gene have been identified ; 11 missense mutations, a mutation involving a deleted codon and a splice donor site mutation. To explore mechanism (s) underlying the pathogenesis o … More f HCM, several mutants of human cardiac TnT associated with HCM [five missense mutants (Ile79Asn, Arg92Gln, Phe110Ile, Glu244Asp, Arg278Cys), one deletion mutant (ΔGlu160), and two truncated mutants produced by a splice donor site mutation] were expressed in E.Coli, exchanged into permeabilized rabbit cardiac muscle fibers, and Ca^<2+>-activated force was determined.The missense mutations Ile79Asn and Arg92Gln and the mutation involving a deleted codon ΔGlu160 had a Ca^<2+>- sensitizing effect on the contraction of the skinned cardiac muscle fibers without affecting the maximum force and the cooperativity. The missense mutations Glu244Asp and Arg278Cys and the splice donor site mutation also had a Ca^<2+>-sensitizing effect, but the Glu244Asp mutation was also found to increase the maximum force remarkably and the missense mutation Arg278Cys and the splice donor site mutation decreased the cooperativity significantly. The missense mutation Phe110Ile, the only TnT mutation which has ever been shown to be associated with a favorable prognosis, had no Ca^<2+>-sensitizing effect and did not change the cooperativity, but was found to increase the maximum force remarkably. The results indicate that these HCM-linked mutations in TnT can be classified into at least four groups according to their functional effects on the Ca^<2+>-activated contraction, which are Ca^<2+>-sensitization (Ile79Asn, Arg92Gln, ΔGlu160), potentiation of the maximum force (Phe110Ile), a mixture of Ca^<2+>-sensitization and potentiation of the maximum force (Glu244Asp), and a mixture of Ca^<2+>-sensitization and reduction in the cooperativity (Arg278Cys and splice donor site mutation).These results indicate that TnT plays a critical role in the thin filament regulatory mechanism involving the Ca^<2+> sensitivity, cooperativity and maximum force-generating capability of cardiac muscle contraction and that an increased Ca^<2+>-sensitivity might be responsible for the distinguishing feature of HCM caused by TnT mutations, i.e. incomplete disease penetrance and poor prognosis. Less

家族性肥厚型心肌病（HCM）是一种常染色体显性遗传的心脏病，与猝死的发生率高。HCM是一种遗传异质性疾病，已显示其由多种心肌肌原纤维蛋白基因突变引起，包括β-肌球蛋白重链（β-MHC）、Ca^2+受体肌钙蛋白亚基（肌钙蛋白T和肌钙蛋白I）、α-原肌球蛋白、肌球蛋白结合蛋白C和肌球蛋白轻链。HCM的临床表现也是多变的，已知心肌肌钙蛋白T（TnT）突变与猝死的高风险相关，尽管不完全的疾病转移伴中度肥大，而β-MHC突变的高转移伴更严重的肥大，预后相当差。11个错义突变，涉及密码子缺失的突变和剪接供体位点突变。目的：探讨原发性高血压的发病机制。 ...更多信息 f HCM，与HCM相关的人心脏TnT的几种突变体[五种错义突变体（Ile 79 Asn，Arg 92 Gln，Phe 110 Ile，Glu 244 Asp，Arg 278 Cys），一个缺失突变体（Δ Glu 160）和两个由剪接供体位点突变产生的截短突变体]在大肠杆菌中表达，交换到透化的兔心肌纤维中，错义突变Ile 79 Asn和Arg 92 Gln以及缺失密码子Δ Glu 160的突变对去皮心肌纤维的收缩有Ca^2+敏感作用，但不影响最大力和协同性。错义突变Glu 244 Asp和Arg 278 Cys以及剪接供体位点突变也具有Ca^2+增敏效应，但Glu 244 Asp突变也显著增加最大作用力，而错义突变Arg 278 Cys和剪接供体位点突变显著降低协同效应。错义突变Phe 110 Ile是唯一一个被证明与良好预后相关的TnT突变，它没有Ca^2+增敏效应，也没有改变协同性，但发现它能显著增加最大作用力。结果表明，根据对Ca^2+激活的收缩的功能影响，这些TnT中的HCM连锁突变至少可以分为四类，即Ca^2+敏感化（Ile 79 Asn，Arg 92 Gln，Δ Glu 160），最大力增强（Phe 110 Ile），一种Ca^2+敏化和最大力增强的混合物（Glu244Asp），以及Ca^2+敏化和协同性降低的混合物这些结果表明TnT在涉及Ca^2+敏感性的细丝调节机制中起关键作用，协同性和心肌收缩的最大力产生能力，以及Ca^2+敏感性的增加可能是TnT突变引起的HCM的显著特征，即发病不完全，预后差。少

项目成果

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森本幸雄：“临床神经科学：肌肉收缩和松弛的分子生物学”中外医学社 5 (1999)。

Morimoto, S., Nakaura, H., Yanaga, F, and Ohtsuki, I.: "(1999) Functional consequences of a carboxyl terminal missense mutation Arg278Cys in human cardiac troponin T."Blochem.Biophys.Res.Commun.. 261. 79-82 (2000)

Morimoto, S.、Nakaura, H.、Yanaga, F 和 Ohtsuki, I.：“(1999) 人类心肌肌钙蛋白 T 中羧基末端错义突变 Arg278Cys 的功能后果。”Blochem.Biophys.Res.Commun.. 261

Morimoto, S., Sato, O., and Ogawa, Y.: "Effect of vanadate on force and myosin light chain phosphorylation in skinned aortic smooth muscle."J.Biochem.. 126 (1). 146-152 (1999)

Morimoto, S.、Sato, O. 和 Okawa, Y.：“钒酸盐对带皮主动脉平滑肌中力和肌球蛋白轻链磷酸化的影响。”J.Biochem.. 126 (1)。

Sachio Morimoto: "Functional Consequences of a Carboxyl Terminal Missense Mutation Arg 278 Cys in Human cardiac Troponin T"Biochem, Biophys. Res. Commun. 261(1). 79-82 (1999)

Sachio Morimoto：“人心脏肌钙蛋白 T 中羧基末端错义突变 Arg 278 Cys 的功能后果”Biochem、Biophys。

Nakaura, H., Yanaga, F., Ohtsuki, I., and Morimoto, S.: "Effects of missense mutations Phe110Ile and Glu244Asp in human cardiac troponin T on force generation in skinned cardiac muscle fibers."J.Biochem. 126. 457-460 (1999)

Nakaura, H.、Yanaga, F.、Ohtsuki, I. 和 Morimoto, S.：“人心肌肌钙蛋白 T 中错义突变 Phe110Ile 和 Glu244Asp 对带皮心肌纤维产生力的影响。”J.Biochem。