Deciphering the role of lysosomal membrane permeabilization in Diabetic Cardiac Injury

项目概要/摘要 糖尿病心肌病和心力衰竭是糖尿病患者死亡的主要原因。然而，有效 仍然缺乏预防和管理这种致命疾病的方法。我研究的长期目标 目的是确定介导糖尿病心脏损伤的细胞和分子机制。溶酶体发挥重要作用 在细胞质质量控制和细胞稳态中的作用。最近的研究表明存在关联 糖尿病心脏损伤和溶酶体通路紊乱之间的关系。溶酶体功能障碍的一个显着特征 溶酶体膜透化（LMP）增加，引发蛋白酶渗漏和细胞死亡。我们的 初步结果表明，糖尿病小鼠的心脏损伤伴随着 组织蛋白酶 D (CTSD)，一种主要的溶酶体蛋白酶。高糖诱导培养心肌细胞的 LMP， 导致 CTSD 表达和分布的改变。重要的是，CTSD 过度表达加剧了高 葡萄糖诱导的心肌细胞死亡，同时敲低 CTSD 或抑制 CTSD 活性减弱高 葡萄糖毒性。我们的假设是 LMP 增加以及随之而来的 CTSD 泄漏和异常 累积介导糖尿病心脏损伤；从而加强溶酶体质量控制并最大限度地减少 CTSD的异位效应将保护糖尿病心脏。我们将追求两个具体目标来检验这一假设。 目标 1 将确定 LMP 和随后的 CTSD 渗漏是否会导致高血糖 心肌细胞死亡。目标 2 将利用 LMP 来研究糖尿病性心脏损伤中 LMP 的病理意义 糖尿病小鼠模型。将使用药理学和遗传学方法来增强溶酶体 修复并操纵 CTSD 的表达和成熟。糖尿病引起的溶酶体损伤 使用新型 LMP 报告小鼠系进行评估。改变 CTSD 对高血糖心脏毒性的影响 糖尿病心肌病将通过多种方法确定。本项目顺利完成 将为介导糖尿病心脏损伤的机制提供新的见解，促进药物设计 预防或治疗糖尿病引起的心肌病和心力衰竭。

PROJECT SUMMARY/ABSTRACT Diabetic cardiomyopathy and heart failure are a leading cause of death in diabetic patients. However, effective approaches to preventing and managing this deadly disease are still lacking. The long-term goal of my research is to identify cellular and molecular mechanisms that mediate diabetic cardiac injury. Lysosomes play important roles in cytoplasmic quality control and cellular homeostasis. Recent studies have demonstrated an association between diabetic cardiac injury and a disturbed lysosome pathway. A prominent feature of lysosomal dysfunction is increased lysosomal membrane permeabilization (LMP) which triggers protease leakage and cell death. Our preliminary results showed that cardiac damage in diabetic mice was accompanied by elevated expression of cathepsin D (CTSD), a major lysosomal protease. High glucose induced LMP in cultured cardiomyocytes, leading to altered expression and distribution of CTSD. Importantly, CTSD overexpression exacerbated high glucose-induced cardiomyocyte death, while knocking down CTSD or inhibiting CTSD activity attenuated high glucose toxicity. Our hypothesis is that the increased LMP and the ensuing CTSD leakage and aberrant accumulation mediate diabetic cardiac injury; thus enhancing lysosomal quality control and minimizing the ectopic effects of CTSD will protect the diabetic heart. We will pursue two specific aims to test this hypothesis. Aim 1 will determine whether LMP and the ensuing CTSD leakage contributes to hyperglycemia-induced cardiomyocyte death. Aim 2 will investigate the pathological significance of LMP in diabetic heart injury using mouse models of diabetes. Pharmacological and genetic approaches will be used to enhance the lysosomal repair and to manipulate the expression and maturation of CTSD. Diabetes-induced lysosomal injury will be assessed with a novel LMP reporter mouse line. The effects of altered CTSD on hyperglycemic cardiotoxicity and diabetic cardiomyopathy will be determined with multiple approaches. Successful completion of this project will provide novel insight into the mechanisms that mediate diabetic cardiac injury, facilitating drug design for preventing or treating cardiomyopathy and heart failure in diabetes.