Development of molecular therapy correcting abnormal intracellular Ca^<2+> regulation in chronic heart failure

肌浆网对细胞内Ca^<2+>的异常调节已被证明参与了心力衰竭收缩和舒张功能障碍的潜在机制。我们研究了在慢性心力衰竭中通过兰尼碱受体（RyR）或通过SR钙ATP酶（SERCA）/受磷蛋白（PLN）复合物纠正异常钙调节的分子靶向策略。在RyR中，我们发现在致心律失常性右心室发育不良患者中观察到的单个氨基酸突变可触发氨基末端和中央肽结构域之间的异常结构域相互作用，导致异常SR钙渗漏和随后的胎儿心律失常。在衰竭的心脏中观察到相同的构象变化，提示类似的致心律失常机制。此外，这种钙泄漏也是由衰竭心脏中活性氧（ROS）的产生增加引发的。因此，减少活性氧可能是一种新的应激反应。 关于我们 此外，我们还发现，治疗恶性高热的经典药物丹曲林可以干扰RyR的这些异常构象变化，从而潜在地纠正衰竭心脏中受损的钙循环。另一方面，在衰竭心脏中，通过SERCA泵和受磷蛋白网络SR中的钙摄取功能也受损。这部分归因于Ser 16的pholpholamban磷酸化水平降低，可能是由衰竭心脏中蛋白磷酸酶1（PP 1）活性增加引起的。我们试图纠正这种PP 1活性的异常增加。利用体内高效基因传递技术，我们将内源性组成型PP 1抑制剂Inhibitor-2导入心肌病仓鼠心脏。Inhibitor-2基因的导入不仅可以挽救心衰患者的心功能，而且可以改善BNP的表达，减轻心肌纤维化，延长患者的生存时间，因此，RyR或SERCA/PLN复合物及其相关的PP 1的分子靶向治疗策略可能成为心衰治疗的良好靶点。少

An abnormal regulation of intracellular Ca^<2+> by sarcoplasmic reticulum has been shown to be involved in the mechanism underlying contractile and relaxation dysfunction in heart failure. We investigated molecular targeting strategies of correcting the abnormal calcium regulation either via the ryanodine receptor (RyR) or via the SR calcium ATPase (SERCA) /phospholamban (PLN) complex in chronic heart failure. In RyR, we have found that a single amino acid mutation seen in the patient with arrhythmogenic right ventricular dysplasia can trigger abnormal domain interaction between amino-terminal and central peptide domain, leading to abnormal SR calcium leak and subsequent fetal arrhythmia. The same conformational change was observed in the failing heart, suggesting the similar arrhythmogenic mechanism. In addition, this kind of calcium leak is also triggered by the increased production of reactive oxygen species (ROS) in the failing heart. Therfore, reduction of ROS could be a novel str … More ategy to prevent fetal arrhythmia in heart failure Furthermore we also found that a classical medicine for malignant hyperthermia, dantrolene, can interfere with these abnormal conformational changes in RyR, thereby potentially correcting impaired calcium cycling in the failing heart.On the other hand, calcium uptake function via SERCA pump and phospholamban in the network SR is also impaired in the failing heart. This has in part been attributed to the decreased levels of pholpholamban phosphorylation at Ser 16, possibly caused by the increased protein phosphatase 1 (PP1) activity in the failing heart. We have attempted to correct this abnormal increase in PP1 activity. Using in vivo high efficiency gene delivery technique, we have introduced an endogenous constitutive PP1 inhibitor, inhibitor-2, into the cardiomyopathic hamster heart. Inhibitor-2 gene delivery not only rescued the cardiac finction but also ameliorated BNP expression, cardiac fibrosis and extended the consequent survival time.In summary, molecular targeting strategy in RyR or SERCA/PLN complex and associated PP1 could be a good therapeutic target for heart failure. Less