Applicatory study using actomyosin ATPase affecting compound for therapy of family hypertrophic cardiomyopathy

肥厚型心肌病与心肌肌球蛋白、原肌球蛋白或肌钙蛋白突变有关。突变的肌球蛋白失去了对肌动蛋白激活ATP酶活性的敏感性。因此，直接作用于心肌特异性收缩蛋白的化合物对开发新型心肌病药物极具吸引力。只有在横纹肌中，才能发现肌钙蛋白与肌动蛋白和肌球蛋白结合并调节它们的相互作用。这是因为，不同于其他平滑肌或非肌细胞，横纹肌型肌球蛋白总是处于活跃状态。也就是说，在横纹肌中，肌钙蛋白/原肌球蛋白直接调节肌动球蛋白的相互作用，而各种蛋白质介导调节平滑肌或非肌肉细胞中的相互作用。因此，直接作用于横纹肌肌球蛋白或肌钙蛋白的化合物具有很强的组织选择性。我们发现从链霉菌中分离的硫代替曲霉素促进了肌球蛋白B的超沉淀。超沉淀是肌肉收缩的模型反应，这一结果表明硫代替曲霉素促进了肌动球蛋白的相互作用。我们进一步发现硫替曲霉素通过直接作用于肌动蛋白而抑制肌动球蛋白ATP酶活性。然而，在存在肌钙蛋白/原肌球蛋白的情况下，硫替曲霉素未显示任何溶血作用。该化合物的超沉淀激活机理尚不清楚，但作为相互作用激活剂是非常有意义的。我们还发现，goniodomin A从腰鞭毛虫分离，促进超沉淀的肌球蛋白B。另一方面，goniodomin A抑制钙诱导的收缩在皮肤纤维的浓度依赖性方式。角蛋白A还显示对肌动球蛋白ATP酶活性的促进作用，尽管这种作用被过度浓度的肌钙蛋白/原肌球蛋白减弱。我们发现，两性蛋白酶B也可以促进肌动球蛋白ATP酶的活性。

Hypertrophic cardiomyopathy is relating to mutation in myosin, tropomyosin or troponin in cardiac muscle. The mutant myosin looses its susceptibility to actin activation of its ATPase activity. Therefore, the compounds that directly affect on cardiac muscle specific contractile proteins are extremely attractive to develop new type of medicinal for cardiomyopathy. Only in striated muscle, one may find that troponin bind to and regulating interaction of actin with myosin. This is because, differing from other smooth muscle or non-muscle cells, the myosin of striated muscle type is always in active state. Namely, in striated muscle, troponin/tropomyosin directly regulating the interaction of actomyosin, whereas various proteins are intermediating to regulate the interaction in smooth or non-muscle cells. Therefore, the compounds that directly affecting on striated muscle myosin or troponin can possess strong tissue selectivity. We found that thiotetromycin, isolated from Streptomyces sp. facilitated superprecipitation of myosin B.Superprecipitation is a model reaction of muscle contraction, this result suggesting that thiotetromycin facilitating the interaction of actomyosin. We further found that thiotetromycin inhibits actomyosin ATPase activity by directly affecting on actin. However, in the presence of troponin/tropomyosin, thiotetromycin do not show any inhibitoly effect. The mechanism of activating superprecipitation is still not clear, this compound is extremely interesting as interaction activator. We also found that goniodomin A isolated from dinoflagera, facilitates superprecipitation of myosin B.On the other hand, goniodomin A inhibited Ca-induced contraction in skinned fiber in concentration dependent manner. Goniodomin A also revealed facilitating effect on actomyosin ATPase activity although this effect attenuated by excessive concentration of troponin/tropomyosin. We found that amphidinolide B can also facilitate the activity of actomyosin ATPase.