Molecular mechanism of pH sensitivity of muscle contraction : investigation using site-directed mutagenesis

肌肉收缩 pH 敏感性的分子机制：利用定点突变进行研究

• 批准号: 08680891
• 负责人: MORIMOTO Sachio
• 金额: $ 0.13万
• 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: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1998
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08680891/
• 关键词: site-directed mutagenesis; pH; muscle contraction; calcium; troponin; PH; トロボニン

The Ca^<2+> sensitivity of contraction in vertebrate striated muscles is modified by a variety of agents such as protons, inorganic phosphate and caffeine. Proton, which is believed to contribute to the inhibited contractility during skeletal muscle fatigue and myocardial ischemia, has a profound depressant effect on the Ca^<2+> sensitivity of the skinned fibres prepared from vertebrate striated muscles, depending on the muscle types in the order of cardiac > fast skeletal > slow skeletal. In this project, we have examined the contributions of the isoforms of troponin subunits to the differential pH dependence of Ca^<2+> sensitivity in striated muscles, by exchanging endogenous TnI and TnC in cardiac skinned fibres with all possible combinations of the corresponding isoforms prepared from fast and s1ow skeletal and cardiac muscles. The results demonstrated that, unlike the findings of early studies by other investigators, the difference in the pH sensitivities of the fast skeletal and cardiac muscles solely depends on the TnC isoforms and also demonstrated that the highest resistibility to the acidic pH of slow skeletal muscle is a manifestation of the unique properties of slow skeletal TnI isoform. Further studies to clarify the site(s) or region(s) in troponin subunit molecules that determines these pH sensitivity are now in progress using site-direct mutagenesis.

脊椎动物横纹肌收缩对Ca ^2+的敏感性可被质子、无机磷酸盐和咖啡因等多种物质改变。质子被认为在骨骼肌疲劳和心肌缺血时对收缩力有抑制作用，它对从脊椎动物横纹肌制备的皮肤纤维的Ca ^2+敏感性有显著的抑制作用，这取决于心肌>快骨骼肌>慢骨骼肌的顺序。在这个项目中，我们通过将心肌皮肤纤维中的内源性TnI和TnC与从快、慢骨骼肌和心肌中制备的相应亚型的所有可能组合进行交换，研究了肌钙蛋白亚基亚型对横纹肌Ca ^2+敏感性的不同pH依赖性的贡献。结果表明，与其他研究人员的早期研究结果不同，快速骨骼肌和心肌的pH敏感性差异仅取决于TnC亚型，并且还表明，对慢速骨骼肌酸性pH的最高可吸收性是慢速骨骼肌TnI亚型独特性质的表现。目前正在使用定点诱变进行进一步研究，以阐明肌钙蛋白亚基分子中决定这些pH敏感性的位点或区域。

项目成果

Mizukami Y,Yoshioka K,Morimoto S,Yoshida K: "A novel mechanism of JNK1 activation. Nuclear translocation and activation of JNK1 during ischemia and reperfusion." J.Biol.Chem.272 (26). 16657-16662 (1997)

Mizukami Y、Yoshioka K、Morimoto S、Yoshida K：“JNK1 激活的新机制。缺血和再灌注期间 JNK1 的核转位和激活。”

Morimoto S,Yanaga F,Minakami R,and Ohtsuki I: "Ca^<2+>-sensitizing effects of the mutations at Ile-79 and Arg-92 of troponin T in hypertrophic cardiomyopathy." Am.J.Physiol.275 (Cell Physiol.44). C200-207 (1998)

Morimoto S、Yanaga F、Minakami R 和 Ohtsuki I：“肥厚型心肌病中肌钙蛋白 T Ile-79 和 Arg-92 突变的 Ca^2-敏化作用”。

F.Yanaga: "Ca^<22>-sensitization and patertiation of the maximum kuel of myofibnlkn ATpase actirity caused by mutations of traponin T found in familial hypertrans cardiomyotathy" J.Biol.Chem. in pross. (1999)

F.Yanaga：“家族性超反式心肌病中发现的由陷波蛋白T突变引起的肌纤维蛋白ATp酶活性最大抑制的Ca ^ 22 -敏化和帕特化”J.Biol.Chem。

森 本 幸 生: "骨格筋収縮・施緩のCa_+制御" 蛋白質・核酸・酵素. 43(12). 1744-1752 (1998)

Yukio Morimoto：“骨骼肌收缩和松弛的 Ca_+ 调节”蛋白质、核酸和酶 43(12) (1998)。

Sochio Morimoto: "Reduced Positive Feedback Regulation between Mycsin Crssbridge and Cardiac TroponinC in Fost Skeletal Myofibrils" J.Biochem. 119. 737-742 (1996)

Sochio Morimoto：“减少 Fost 骨骼肌原纤维中 Mycsin Crssbridge 和心肌肌钙蛋白 C 之间的正反馈调节”J.Biochem。