BACKGROUND Cardiovascular diseases (CVDs), with highest mortality and morbidity rates, are the major cause of death in the world. Due to the limited information on heart tissue changes, mediated by hypercholesterolemia, we planned to investigate molecular mechanisms of endoplasmic reticulum (ER) stress and related cell death in high cholesterol fed rabbit model and possible beneficial effects of α-tocopherol. METHODS Molecular changes in rabbit heart tissue and cultured cardiomyocytes (H9c2 cells) were measured by western blotting, qRT-PCR, immunflouresence and flow cytometry experiments. Histological modifications were assessed by light and electron microscopes, while degradation of mitochondria was quantified through confocal microscope. RESULTS Feeding rabbits 2% cholesterol diet for 8 weeks and treatment of cultured cardiomyocytes with 10 μg/mL cholesterol for 3 h induced excessive autophagic activity via IRE1/JNK pathway. While no change in ER-associated degradation (ERAD) and apoptotic cell death were determined, electron and confocal microscopy analyses in cholesterol supplemented rabbits revealed significant parameters of autophagic cell death, including cytoplasmic autophagosomes, autolysosomes and organelle loss in juxtanuclear area as well as mitochondria engulfment by autophagosome. Either inhibition of ER stress or JNK in cultured cardiomyocytes or α-tocopherol supplementation in rabbits could counteract the effects of cholesterol. CONCLUSION Our findings underline the essential role of hypercholesterolemia in stimulating IRE1/JNK branch of ER stress response which then leads to autophagic cell death in heart tissue. Results also showed α-tocopherol as a promising regulator of autophagic cell death in cardiomyocytes.

中文翻译：

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经由IRE1 / JNK途径的胆固醇诱导的自噬促进了心脏组织中自噬细胞的死亡。

背景技术具有最高死亡率和发病率的心血管疾病（CVD）是世界上主要的死亡原因。由于高胆固醇血症介导的关于心脏组织变化的信息有限，我们计划研究高胆固醇喂养兔模型中内质网（ER）应激和相关细胞死亡的分子机制以及α-生育酚的可能有益作用。方法采用Western blotting，qRT-PCR，免疫荧光和流式细胞仪检测兔心脏组织和心肌细胞（H9c2细胞）的分子变化。通过光学和电子显微镜评估组织学改变，而通过共聚焦显微镜定量线粒体的降解。结果喂兔2％胆固醇饮食8周，用10μg/ mL胆固醇处理培养的心肌细胞3 h，会通过IRE1 / JNK途径诱导过度自噬活性。虽然未确定ER相关降解（ERAD）和凋亡细胞死亡的变化，但在补充胆固醇的兔子中进行电子和共聚焦显微镜分析显示自噬细胞死亡的重要参数，包括近核区的细胞质自噬体，自溶酶体和细胞器损失以及线粒体被自噬吞噬。在培养的心肌细胞中抑制ER应激或JNK或在兔体内补充α-生育酚均可抵消胆固醇的作用。结论我们的研究结果强调了高胆固醇血症在刺激ER应激反应的IRE1 / JNK分支中的重要作用，然后导致心脏组织中的自噬细胞死亡。结果还表明，α-生育酚是心肌细胞自噬细胞死亡的有希望的调节剂。