晚期糖基化终末化产物受体和beta1肾上腺素受体在心衰中的相互作用及其机制研究

Heart failure (HF) is the end stage of cardiovascular diseases. Now, it is recognized as the leading cause of mortality and morbility in the world. Cardiac injury induced by myocardial infarction is one of the most important reasons of HF. In the heart, beta-adrenergic receptor (beta-AR) stimulation by catecholamines serves as the most powerful regulatory mechanism to enhance myocardial contractility in response to stress or exercise, via activating the classic stimulatory G protein (Gs)-adenylyl cyclase-cAMP-PKA signaling pathway. However, increasing evidence indicates that prolonged beta1AR stimulation exerts a cardiotoxic effect, which often outweighs the short-term gain in cardiac contractile support. We and others have demonstrated that prolonged beta1AR stimulation leads to cardiac myocyte injury and death via a signaling pathway independent of cAMP/PKA but involving Ca2+ and Ca2+/calmodulin-dependent protein kinase II (CaMKII). .The receptor for advanced glycation end-products (RAGE), a pattern recognition receptor that interacts with multiple ligands and elicits innate immune responses, and its ligand high mobility group box 1 (HMGB1) have been implicated in ischemia/reperfusion-induced cardiac injury. It is also well established that activation of RAGE triggers robust cell necrotic death, and HMGB1 is released to cellular milieu as an endogenous "danger signal" under necrotic conditions. We hypothesize that RAGE-HMGB1 axis may be involved in the beta1-AR-elicited cardiomyocyte death, and that blockade of the RAGE axis protects cardiomyocytes against beta1AR-induced myocyte injury and death. The overall objective of our study is to determine whether RAGE and beta1AR interact with each other in mediating cardiac cell injury and cell death and, if so, to explore the underlying mechanism..Our previous studies have shown that enhanced beta1AR stimulation plays a central role in cardiomyocyte death via CaMKII activation. Recently, RAGE and its ligand HMGB1 have also been implicated in ischemia/reperfusion induced myocardial injury. We hypothesize that RAGE may be involved in the beta1AR-elicited cardiomyocyte death. To test the hypothesis, we selectively blocked beta1AR with CGP 20712A (CGP)/atenolol, or RAGE with its decoy soluble RAGE (sRAGE), respectively, and determined whether the blockade can attenuate cardiac cell death. We found that administration of sRAGE abolished beta1AR-induced cell death; and the HMGB1-induced cell death was completely eradicated by a beta1AR antagonist, CGP or atenolol, implying a functional cross-talk between these two receptors. Using co-immunoprecipitation, we also showed a physical interaction between beta1AR and RAGE in HEK293 cells expressing both receptors. These findings suggest a novel mechanism of cross-talk between beta1AR and RAGE. Blockage of both beta1AR and RAGE may therefore represent a novel therapeutic strategy for treating cardiovascular diseases.

心力衰竭是一种由于心脏结构或功能受损，造成心脏输出的血量无法满足机体需要的病生理状态，是多种心脏疾病最终的表现。beta肾上腺素受体阻断剂是目前治疗心力衰竭的最主要的一线用药之一。RAGE是免疫球蛋白家族的一员，是一种特异性相对较低对配体广谱识别的模式识别受体，目前成为炎症相关受体的研究热点之一。我们研究发现：1.阻碍了RAGE信号传递的sRAGE能够完全抑制beta1-AR激活引起的心肌细胞死亡；2.HMGB1引起的心肌细胞死亡也能够被beta1-AR选择性抑制剂有效地抑制；3.利用Co-IP方法发现RAGE与beta-AR存在相互作用。这些结果提示RAGE与beta1-AR之间存在一种新机制来相互影响。本课题拟以两条通路的相互作用为研究对象，探究心脏疾病发生中一个重要的新机制，更加深入了解RAGE和beta1-AR通路，联合抑制两通路可能是对抗心血管疾病的一种新策略。

一直以来大家都认为，β1肾上腺素受体(β1AR)和晚期糖化终产物受体(RAGE)两个通路是相互独立的病因，在受到心肌梗塞、缺血/再灌注损伤,或代谢刺激时互相独立的起作用。在这个研究中，我们发现这两个互相独立的治病通路在心肌损伤的导致的心肌病中是相互依赖的。抑制RAGE同时阻止了β1AR和RAGE两条通路，同时阻止β1AR也能够完全阻断RAGE和β1AR两条通路。进一步研究发现，这一现象的分子机制是β1AR和RAGE形成复合物，转而激活钙/钙调素依赖激酶II （CaMKII），导致心肌细胞的死亡和心肌重塑。β1AR-RAGE两通路不仅存在物理联系，并且功能上共同汇集在一个共同分子CaMKII上。而共同抑制β1AR和RAGE两通路可能是针对不同心肌损伤疾病的新作用机制。