PAR-2对自噬介导的心肌缺血/再灌注损伤的研究进展

心肌再灌注治疗是急性心肌梗死最重要的治疗方法之一,能够显著改善致死、致残率。但再灌注早期仍难以避免增加心肌损害,引起心肌缺血/再灌注(ischemia/reperfusion,I/R)损伤。心肌缺血阶段激活的自噬对心肌具有保护作用,而再灌注阶段激活的自噬对心肌具有损害作用,其机制可能与缺血阶段AMPK-mTOR信号通路,以及再灌注阶段Bcl-2-Beclin 1信号通路介导的自噬诱导I/R损伤的重要途径有关。蛋白酶激活受体2(protease activated receptor2,PAR-2)在缺血心肌细胞高度表达,是自噬的上游标记物之一,能够显著改善I/R损伤,具有心肌保护作用。在缺血阶段,PAR-2可能通过激活AMPK途径,抑制其下游mTOR表达,从而激活自噬,保护心肌;在再灌注阶段,通过Bcl-2下调激活Beclin 1表达,诱导自噬发生,并且能够上调Bcl-2mRNA表达水平。本文就PAR-2对自噬介导的I/R损伤的研究进展进行综述。     

黄芪甲苷对缺血再灌注诱导的大鼠心肌损伤及细胞自噬的调节作用

目的观察黄芪甲苷对缺血再灌注模型损伤大鼠心肌组织的保护作用及与心肌组织细胞自噬的关系。方法结扎大鼠左冠状动脉前降支建立心肌缺血再灌注损伤模型,采用细胞生物学及免疫组织化学法,观察心肌组织在缺血再灌注损伤模型及黄芪甲苷处理后的心肌组织损伤、细胞自噬的变化。结果缺血再灌注损伤使大鼠心肌组织中心肌灶性病变严重,兼有波浪改变及大片炎症细胞浸润,与假手术组相比损伤面积明显增多(P<0.05),而黄芪甲苷低、高剂量组均可使心肌灶性病变和炎症细胞浸润的面积明显减少(P<0.05)。Western blot结果显示,缺血再灌注损伤可激活心肌组织细胞中Beclin1的表达(P<0.05),而黄芪甲苷低、高剂量组均可降低缺血再灌注损伤诱导的心肌组织细胞Beclin1表达(P<0.05)。结论黄芪甲苷可在一定程度上减少缺血再灌注损伤的心肌面积,其机制可能是通过调节与自噬相关的Beclin1细胞信号转导通路而发挥作用。     

Beclin 1与mTOR对心肌缺血/再灌注损伤中自噬的交互调控机制

自噬是一个进化上高度保守的受损或功能障碍的蛋白质聚集体或细胞器降解的过程。在心肌缺血/再灌注(I/R)过程中,可以通过多种因素诱导细胞的自噬活动,而且越来越多的证据表明,自噬在心肌缺血/再灌注损伤(MIRI)中可能起“双刃剑”的作用,适度自噬可促进细胞存活;而不适当的激活自噬可能会加速细胞死亡。Beclin 1介导的自噬/凋亡互反馈信号通路和哺乳动物雷帕霉素靶蛋白(mTOR)介导的自噬与mTOR的互反馈信号通路,是两条经典的自噬激活信号途径,也可能是调控自噬“双刃剑”转向促进细胞存活的重要调控机制。本文将重点综述上述两条信号通路对自噬的交互式调控作用。速发挥作用。因此,Z盘部位实质上成为心肌细胞中的信号转导中心。     

cFLIP对心肌缺血再灌注损伤的调节作用

缺血心肌恢复血流灌注后,心肌细胞会因血流再灌注产生额外的损伤,称之为心肌缺血再灌注损伤。细胞程序性死亡是心肌缺血再灌注损伤的主要细胞归宿,减少细胞程序性死亡能改善患者的心功能和预后。细胞程序性死亡包括凋亡、自噬和程序性坏死,cFLIP可通过不同的方式分别调控凋亡、自噬与程序性坏死的发生,调节心肌缺血再灌注损伤。     

AMPK与心肌缺血-再灌注损伤

心肌缺血-再灌注损伤是急性心肌梗死后溶栓疗法、经皮冠状动脉介入治疗、冠状动脉旁路移植术后心肌损伤的重要机制之一。单磷酸腺苷激活的蛋白激酶(AMPK)不仅是细胞内能量代谢的重要调控因子,而且能通过抗氧化应激、内质网应激、抑制凋亡、调节自噬、抗炎、参与缺血预处理或缺血后处理等心肌保护效应减轻心肌缺血-再灌注损伤。因此,AMPK对防治心肌缺血-再灌注损伤有潜在的临床意义。     

自噬相关基因14在心脏缺血再灌注损伤中的作用及其机理研究进展

自噬被证明在多种疾病中发挥重要作用,急性心肌梗死时自噬活化可以帮助心肌细胞维持细胞内必需的生理活动。自噬相关基因14(autophagy related gene14,ATG14)是自噬过程中的关键分子,参与自噬体的形成同时调节自噬体与溶酶体的融合。ATG14在心脏缺血再灌注损伤中具有重要作用,在心肌缺血期,含有ATG14的复合物Ⅰ与自噬前体结构(pre-autophagosomal structure,PAS)结合,形成双层囊泡的自噬体结构;在再灌注期,ATG14参与形成的自噬体与损伤的线粒体融合,清除受损线粒体,维持心肌细胞内稳态。无论在缺血期还是再灌注期,ATG14功能缺失都会影响心肌细胞内自噬活性,最终影响心肌梗死面积和预后。本文综述ATG14在心肌梗死不同时期的功能,为临床上不同时期通过调节自噬活性来治疗心肌梗死提供新的理解。     

细胞自噬及相关因子在老年肝外伤中的表达及意义

目的研究细胞自噬及相关因子在老年肝外伤中的表达,探讨在老年肝脏缺血再灌注损伤中诱导老年肝细胞自噬的分子机制。方法选取不同鼠龄的大鼠,建立老年大鼠肝外伤缺血再灌注损伤的模型,通过采用电子显微镜、免疫印迹和荧光显微镜等方法观察细胞自噬与细胞凋亡,研究因子Bcl-2及Beclin 1在细胞自噬/细胞凋亡之间的调控关系。结果 Beclin 1在老年大鼠肝外伤再灌注期表达明显增多,而Bcl-2的表达下调(P0.01),Bcl-2和Beclin 1平衡状态失调,免疫印迹表明Beclin 1阳性细胞百分率(40.8±10.6)%与Bcl-2(17.6±5.2)%比较差异有统计学意义(P0.01),而在中晚期阶段(外伤后3~6月),Bcl-2表达下调的作用减缓,同时也激活Beclin1激活自噬,此时年轻大鼠与老年大鼠的肝功能检测及病理切片检查差异不大(P0.01)。结论 Bcl-2与Beclin 1在老年肝脏缺血再灌注损伤的分子机制中可能发挥着重要作用。     

自噬在肝脏缺血再灌注损伤中的作用及研究进展

肝脏缺血再灌注损伤是肝脏外科常见的一种并发症,是导致术后肝功能障碍的重要原因.肝脏缺血再灌注损伤的发生机制十分复杂,涉及多种因素.自噬是真核细胞内的一种溶酶体依赖的降解途径,具有维持细胞内环境稳定的作用.自噬在肝脏缺血再灌注损伤的发生发展过程中发挥重要的作用,是目前的研究热点之一,但是其具体作用及机制仍有较大争议.本文就自噬在肝脏缺血再灌注损伤中的作用及其机制作一详尽综述.     

自噬在预处理心肌保护中的作用研究进展

预处理可通过调节自噬发挥心肌保护作用。缺血预处理对自噬的调节可能与 Bcl-2结合的抗凋亡蛋白 BAG-1、自噬相关蛋白 Beclin-1相关。此外,多种药物预处理也可以通过诱发自噬,减轻缺血-再灌注引发的心肌损伤。该文介绍自噬在预处理心肌保护中的作用及机制。     

组织因子途径抑制物与无复流

缺血再灌注损伤在无复流病理生理中起核心作用。自噬在缺血再灌注损伤病理过程中起"双刃剑"作用。组织因子途径抑制物对组织因子介导的伴有炎症通路和凝血系统激活的无复流可能起到有效地预防及治疗作用。现就组织因子途径抑制物、心肌无复流与自噬的关系做一综述。     

Distinct roles of autophagy in the heart during ischemia and reperfusion: roles of AMP-activated protein kinase and Beclin 1 in mediating autophagy

Autophagy is an intracellular bulk degradation process for proteins and organelles. In the heart, autophagy is stimulated by myocardial ischemia. However, the causative role of autophagy in the survival of cardiac myocytes and the underlying signaling mechanisms are poorly understood. Glucose deprivation (GD), which mimics myocardial ischemia, induces autophagy in cultured cardiac myocytes. Survival of cardiac myocytes was decreased by 3-methyladenine, an inhibitor of autophagy, suggesting that autophagy is protective against GD in cardiac myocytes. GD-induced autophagy coincided with activation of AMP-activated protein kinase (AMPK) and inactivation of mTOR (mammalian target of rapamycin). Inhibition of AMPK by adenine 9-beta-d-arabinofuranoside or dominant negative AMPK significantly reduced GD-induced autophagy, whereas stimulation of autophagy by rapamycin failed to cause an additive effect on GD-induced autophagy, suggesting that activation of AMPK and inhibition of mTOR mediate GD-induced autophagy. Autophagy was also induced by ischemia and further enhanced by reperfusion in the mouse heart, in vivo. Autophagy resulting from ischemia was accompanied by activation of AMPK and was inhibited by dominant negative AMPK. In contrast, autophagy during reperfusion was accompanied by upregulation of Beclin 1 but not by activation of AMPK. Induction of autophagy and cardiac injury during the reperfusion phase was significantly attenuated in beclin 1(+/-) mice. These results suggest that, in the heart, ischemia stimulates autophagy through an AMPK-dependent mechanism, whereas ischemia/reperfusion stimulates autophagy through a Beclin 1-dependent but AMPK-independent mechanism. Furthermore, autophagy plays distinct roles during ischemia and reperfusion: autophagy may be protective during ischemia, whereas it may be detrimental during reperfusion.     

微小RNA对缺血再灌注损伤心肌线粒体作用的研究进展

心肌缺血再灌注损伤是造成心肌结构损伤、功能障碍的一种病理生理过程,进一步发展会导致级联的多器官功能障碍。线粒体是一种结构功能复杂且对外界环境反应敏感的细胞器,其稳态的维持依赖于正常形态、功能及数量的相对稳定状态。线粒体质量与代谢异常和心血管疾病尤其是心肌缺血再灌注损伤的发生密切相关。微小RNA是近年来研究较多的在缺血再灌注损伤心肌线粒体保护中具有重要作用的调控因子。本文通过微小RNA对心肌缺血再灌注损伤时线粒体形态、功能、线粒体自噬和线粒体DNA几个方面的调控机制与相关前沿进展进行综述,为微小RNA参与缺血再灌注心肌线粒体损伤的后续研究提供一定的理论依据。     

自噬在常见心血管疾病中的作用

自噬是细胞利用细胞内溶酶体清除过量或受损的长半衰期蛋白质及细胞器的现象。自噬可通过营养剥夺适应,清除细胞内蛋白质及微细胞器等生理及病理学作用和再利用细胞废物,以维持内环境稳定、参与生长发育和疾病的发生及发展。研究发现,自噬参与了心肌肥厚、心室重构、心肌缺血/再灌注损伤等多种心血管疾病病的理生理过程。本文主要阐述自噬在正常心脏及各种常见心脏疾病中作用的研究进展,并初步探讨可能的治疗新靶点。     

Recycle or die: the role of autophagy in cardioprotection

Autophagy is a highly conserved cellular process responsible for the degradation of long-lived proteins and organelles. Autophagy occurs at low levels under normal conditions, but is upregulated in response to stress such as nutrient deprivation, hypoxia, mitochondrial dysfunction, and infection. Upregulation of autophagy may be beneficial to the cell by recycling of proteins to generate free amino acids and fatty acids needed to maintain energy production, by removing damaged organelles, and by preventing accumulation of protein aggregates. In contrast, there is evidence that enhanced autophagy can contribute to cell death, possibly through excessive self-digestion. In the heart, autophagy has an essential role for maintaining cellular homeostasis under normal conditions and increased autophagy can be seen in conditions of starvation, ischemia/reperfusion, and heart failure. However, the functional significance of autophagy in heart disease is unclear and controversial. Here, we review the literature and discuss the evidence that autophagy can have both beneficial and detrimental roles in the myocardium depending on the level of autophagy, and discuss potential mechanisms by which autophagy provides protection in cells.     

How does the heart (not) die? The role of autophagy in cardiomyocyte homeostasis and cell death

Autophagy plays a critical and seemingly dual-purposed role in cardiomyocytes, being implicated as a mechanism of both cellular survival, for example, during ischemia/reperfusion injury and a mechanism of cell death at stages in which progressive myocyte alterations are beyond repair. This review aims to highlight the current literature as it relates to autophagy in cardiomyocytes. It provides background into the mechanisms of cell death, discusses the details that are known about the ubiquitin proteasome system and autophagy, delves into the pathways that are known to initiate and inhibit autophagy, and comments on the role of autophagy in cardiomyocyte homeostasis and cell death.     

Cardioprotection requires taking out the trash

Autophagy is a critical cellular housekeeping process that is essential for removal of damaged or unwanted organelles and protein aggregates. Under conditions of starvation, it is also a mechanism to break down proteins to generate amino acids for synthesis of new and more urgently needed proteins. In the heart, autophagy is upregulated by starvation, reactive oxygen species, hypoxia, exercise, and ischemic preconditioning, the latter a well-known potent cardioprotective phenomenon. The observation that upregulation of autophagy confers protection against ischemia/reperfusion injury and inhibition of autophagy is associated with a loss of cardioprotection conferred by pharmacological conditioning suggests that the pathway plays a key role in enhancing the heart’s tolerance to ischemia. While many of the antecedent signaling pathways of preconditioning are well-defined, the mechanisms by which preconditioning and autophagy converge to protect the heart are unknown. In this review we discuss mechanisms that potentially underlie the linkage between cardioprotection and autophagy in the heart.     

Too much or not enough of a good thing — The Janus faces of autophagy in cardiac fuel and protein homeostasis

Cells respond to changes in their environment and in their intracellular milieu by altering specific pathways of protein synthesis and degradation. Autophagy is a highly conserved catabolic process involved in the degradation of long-lived proteins, damaged organelles, and subcellular structures. The process is orchestrated by the autophagy related protein (Atg) to form the double-membrane structure autophagosomes, which then fuse with lysosomes to generate autophagolysosomes where subcellular contents are degraded for a variety of cellular processes. Alterations in autophagy play an important role in diseases including cancer, neurodegenerative diseases, aging, metabolic diseases, inflammation and cardiovascular diseases. In the latter, dysregulated autophagy is speculated to contribute to the onset and development of atherosclerosis, ischemia/reperfusion injury, cardiomyopathy, diabetes mellitus, and hypertension. Autophagy may be both adaptive and beneficial for cell survival, or maladaptive and detrimental for the cell. Basal autophagy plays an essential role in the maintenance of cellular homeostasis whereas excessive autophagy may lead to autophagic cell death. The point and counterpoint discussion highlights adaptive vs. maladaptive autophagy. In this review, we discuss the molecular control of autophagy, focusing particularly on the regulation of physiologic vs. defective autophagy.     

自噬在心血管疾病中的作用

自噬是一种维持细胞稳态的重要通路。在特定环境下,细胞中的多余蛋白质和受损细胞器通过自噬这一途径被降解。自噬在多种心血管疾病中的作用正逐渐被阐明,例如缺血/再灌注损伤、动脉粥样硬化、心律失常、高血压和心力衰竭等。本文介绍了影响自噬基本过程的主要分子和调控自噬活性的机制,讨论了自噬与多种心血管疾病之间的关系。     

Urocortin inhibits Beclin1-mediated autophagic cell death in cardiac myocytes exposed to ischaemia/reperfusion injury

Autophagy is known to be a feature of cardiomyopathies and chronic ischaemia. Here we demonstrate that autophagy is also induced by a single cycle of ischaemia/reperfusion (I/R in neonatal and adult rat cardiac myocytes). Consistent with the critical role for Beclin1 in autophagocytosis, reduction of Beclin1 expression in cardiac myocytes by RNAi reduces I/R-induced autophagy and this is associated with enhanced cell survival. Autophagy is also reduced by urocortin, an endogenous cardiac peptide which we have previously shown to reduce other forms of myocyte cell death induced by I/R. The inhibition of autophagy by urocortin is mediated in part by inhibition of Beclin1 expression, an effect which is mediated by activation of the PI3 kinase/Akt pathway but which does not involve activation of p42/p44 MAPK.