Novel Therapeutic Strategy for Heart Failure : Molecular Mechanism underlying the Regulation of Ca^<2+> Signaling in the Heart

1) H_2O_2处理可激活大鼠新生心室肌细胞G_I/G_o。我们发现H_2O_2修饰了G_<αi>的Cys^<287>和Cys^<326>。血管紧张素II刺激产生ROS，诱导MAP激酶活化。通过共表达过氧化物氧化酶II来消除ROS，可以消除血管紧张素II诱导的JNK活化，而不影响ERK或p38 MAPK活性。这些结果表明，由受体刺激产生的ROS是连接受体刺激和MARK （JNK）激活的细胞内介质。2)为了阐明Ca^<2+>通道调节剂门控调制l型Ca^<2+>通道的分子机制，我们在l型Ca^<2+>通道a_<1C>亚基中寻找DHP结合位点。我们在IIIS5-S6成孔区鉴定了两个关键残基，Phe^<1112>和Ser^<1115>。双突变体Ca^<2+>通道（F1112A/S115A）对Ca^<2+>通道激动剂不敏感，并且被Ca^<2+>通道激动剂和拮抗剂微弱阻断。我们提出了一个新的模型，通过Ca^<2+>通道调制器在Ca^<2+>通道α_<1C>亚基的成孔区结合来调制Ca^<2+>通道门控。3)研究了l型Ca^<2+>通道与ryanodine受体间特权交叉通讯的生理作用。我们发现Ca^<2+>通道作为SR Ca^<2+>含量的传感器，在APs期间通过Ca^<2+>通道控制APD和总Ca^<2+>内流，通过Ca^<2+>近端诱导Ca^<2+>释放cicr依赖性CDI产生的Ca^<2+>通道的Ca^<2+>依赖失活，以确保cicr的有效性。4)为了说明Na^+-Ca^<2+>交换器（NCX）在心脏兴奋-收缩耦合中的生理作用。我们检测了NCX敲除杂合小鼠心脏中的Ca^<2+>信号。我们发现正向模式NCX活性在SR Ca^<2+>含量的调控中起着重要的生理作用。少

1) Treatment with H_2O_2 activates G_I/G_o in rat neonatal ventricular myocytes. We found that H_2O_2 modifies Cys^<287> and Cys^<326> of G_<αi>. Angiotensin II stimulation generated ROS and induced the activation of MAP kinase. The elimination of ROS by the co expression of peroxiredoxn II abolished JNK activation induced by angiotensin II without affecting ERK or p38 MAPK activities. These results indicate that ROS, produced by receptor stimulation, serves as an intracellular mediator linking the receptor stimulation and the activation of MARK (JNK).2) Aiming at elucidating the molecular mechanism underlying the gating modulation of L-type Ca^<2+> channels by Ca^<2+> channel modulators, we searched for the DHP binding sites in L-type Ca^<2+> channel a_<1C> subunit. We identified the two key residues, Phe^<1112> and Ser^<1115> in IIIS5-S6 pore-forming region. The double mutant Ca^<2+> channel (F1112A/S115A) was insensitive to Ca^<2+> channel agonists, and weakly blocked by both Ca^<2+ … More > channel agonists and antagonists. We proposed a novel model for the modulation of Ca^<2+> channel gating by the binding of Ca^<2+> channel modulators at the pore-forming region of Ca^<2+> channel α_<1C> subunit.3) We investigated the physiological role of the privileged cross-communication between L-type Ca^<2+> channels and ryanodine receptors. We found that Ca^<2+> channels function as a sensor to the SR Ca^<2+> content to manipulate APD and the total Ca^<2+> influx through Ca^<2+> channels during APs, via the Ca^<2+>-dependent inactivation of Ca^<2+> channels produced by proximal Ca^<2+>-induced Ca^<2+> release CICR-dependent CDI, to ensure the efficacy of CICR.4) In order to elucidate the physiological role of Na^+-Ca^<2+> exchanger (NCX) in cardiac excitation-contraction coupling, we examined the Ca^<2+> signaling in NCX knockout heterozygous mouse heart. We found that the forward mode NCX activity plays a physiologically important role in the regulation of the SR Ca^<2+> content. Less