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

1)H_2O_2可激活新生大鼠心室肌细胞G_i/G_o。我们发现H_2O_2对G&lt；αI&gt；的Cys^和Cys^&lt；326&gt；血管紧张素II刺激产生ROS，并诱导MAP激酶激活。通过共表达Peroxiredoxn II来消除ROS，可在不影响ERK或p38MAPK活性的情况下，阻断血管紧张素II诱导的JNK活化。这些结果表明，由受体刺激产生的ROS是连接受体刺激和MARK激活的细胞内介质。2)为了阐明钙通道调节剂对L型钙通道门控调节的分子机制，我们在L型钙通道a、1C和gt；亚单位中寻找DHP结合位点。我们在IIIS5-S6成孔区确定了两个关键残基，Phe^&lt；1112&gt；和Ser^&lt；1115&gt；。双突变钙通道(F1112A/S115A)对钙通道激动剂不敏感，并被两种钙通道激动剂…弱阻断更多的通道激动剂和拮抗剂。我们提出了一个新的模型，通过在钙通道α；1C；1C；亚单位的成孔区结合钙通道调节剂来调节钙通道门控。3)我们研究了L型钙通道与兰诺定受体之间特权交叉通讯的生理作用。我们发现，在AP过程中，钙离子通道作为肌浆网钙离子浓度的感应器，通过近端钙离子通道产生的钙离子通道失活钙离子通道，从而调控动作电位和通过钙离子通道的总钙离子内流，以阐明钠离子通道的生理作用。2+&gt；交换器(NCX)在心脏兴奋-收缩偶联中的作用，我们研究了NCX基因敲除杂合子小鼠心脏中的钙信号转导。我们发现，正向模式NCX活性在调节肌浆网钙离子含量中起着重要的生理作用。较少

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