Molecular mechanisms underlying abnormal functions in RyR2 complex in cardiac hypertrophy/heart failure

2型Ryanodine受体(RyR2)是心肌肌浆网(SR)中的一种钙释放通道，在细胞内钙离子浓度的调节中起着关键作用。RyR2与几种影响RyR2活性的相关蛋白形成多蛋白复合体。在本研究中，我们利用动物模型研究了心肌肥厚(CH)/心力衰竭(HF)时RyR2复合体的异常。从CH/HF模型Dahl大鼠分离的心肌细胞的钙瞬变明显小于对照组。这是由于SR中的Ca^&lt；2&gt；含量减少。在Ryanodine结合实验和单通道记录中，Dahl大鼠RyR2的通道活性高于对照RyR2。为了解释活性增加的潜在机制，用双向电泳法测定了分离的SR的蛋白质表达谱。与对照组相比，Dahl大鼠SR中的许多蛋白质减少或增加。目前，我们正在通过RNA干扰实验检测几种候选蛋白质的功能。综上所述，这些发现表明，蛋白质表达的改变可能导致CH/HF中RyR2活性的增加，从而导致存储的Ca^&lt；2&gt；减少，并减少Ca^&lt；2&gt；瞬变。

Type 2 ryanodine receptor (RyR2) is a Ca^<2+> release channel in the sarcoplasmic reticulum (SR) in the cardiac muscle and plays a pivotal role in regulation of intracellular Ca^<2+> concentration. RyR2 forms a multi-protein complex with several associated proteins which affect the activity of RyR2. In this study, we examined the abnormality in the RyR2 complex in cardiac hypertrophy (CH)/heart failure (HF) by using animal model. Ca^<2+> transients of the myocytes isolated from the Dahl rats, a model for CH/HF, were significantly smaller than those from the control rats. This was due to a reduced Ca^<2+> content in the SR. The channel activity of Dahl rat RyR2 was higher than the control RyR2 in ryanodine binding assay and single channel recordings. To address the underlying mechanisms of the increased activity, protein expression profiles of the isolated SR were determined by 2D electrophoresis. Many proteins were decreased or increased in the Dahl rat SR in compared with control rat SR. We are currently examining the function of several candidate proteins by RNA interference assay. Taken together, these findings suggest that alterations in the protein expression may cause the increased activity of RyR2 in the CH/HF, which leads to reduction in the stored Ca^<2+> and decreased Ca^<2+> transients.