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其ATPase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治疗心肌病的新型药物极具吸引力。只有在横纹肌中，人们才能发现肌钙蛋白与肌球蛋白结合并调节肌动蛋白与肌球蛋白的相互作用。这是因为，与其他平滑肌或非肌肉细胞不同，横纹肌型肌球蛋白始终处于活跃状态。也就是说，在横纹肌中，肌钙蛋白/原肌球蛋白直接调节肌动肌球蛋白的相互作用，而在平滑或非肌肉细胞中，各种蛋白质起中介作用。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较强的组织选择性。从链霉菌(Streptomyces sp.)中分离得到硫代曲霉素。肌球蛋白B的促进超沉淀是肌肉收缩的一个模型反应，这一结果表明硫代曲霉素促进了肌球蛋白的相互作用。我们进一步发现，硫代曲霉素通过直接影响肌动蛋白而抑制肌动球蛋白ATPase的活性。然而，在肌钙蛋白/原肌球蛋白存在的情况下，硫代曲霉素不显示任何抑制作用。激活超沉淀的机理尚不清楚，该化合物作为相互作用激活剂具有很大的应用价值。我们还发现，从甲藻中分离出的刚碘甲素可以促进肌球蛋白B的超沉淀。另一方面，刚碘甲素A以浓度依赖的方式抑制钙诱导的皮肤纤维收缩。虽然肌钙蛋白/原肌球蛋白浓度过高可减弱肌动球蛋白ATPase活性，但肌球蛋白A对肌动蛋白ATPase活性也有促进作用。我们发现两面针内酯B也能促进肌动球蛋白ATPase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.