Mitophagy: A novel target to improve liver function after ischemia/reperfusion in

线粒体自噬：改善缺血/再灌注后肝功能的新靶点

• 批准号: 8438454
• 负责人: Jae-Sung Kim
• 金额: $ 30.75万
• 依托单位: UNIVERSITY OF FLORIDA
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-04-01 至 2016-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8438454
• 关键词: Abdomen; Age; Apoptosis; Attention; Attenuated; Autophagocytosis; Autophagosome; Bioenergetics; Blood flow; Calpain; Carbamazepine; Cardiovascular Surgical Procedures; Cell Death; Cell physiology; Communities; Compartment syndromes; Complement; Data; Defect; Enzymes; Excision; Experimental Models; Extracorporeal Circulation; Failure; Genes; Genetic; Goals; Hemorrhagic Shock; Hepatic; Hepatocyte; Impairment; In Vitro; Injury to Liver; Intervention; Ischemia; Life Expectancy; Liver; Liver Dysfunction; Liver Failure; Liver diseases; Mediating; Microscopy; Mitochondria; Monitor; Morbidity - disease rate; Mus; Operative Surgical Procedures; Pathway interactions; Patients; Permeability; Recovery; Recycling; Reperfusion Injury; Reperfusion Therapy; Reporter; Research; Resolution; Role; Sirolimus; Testing; Therapeutic; Tissues; Transplantation; Warm Ischemia; age related; aged; hepatic necrosis; improved; in vivo; in vivo Model; innovation; insight; liver function; liver injury; liver ischemia; mitochondrial autophagy; mitochondrial dysfunction; mortality; novel; novel therapeutic intervention; older patient; operation; overexpression; research study; restoration; translational study

DESCRIPTION (provided by applicant): An increase in life expectancy has been accompanied by a larger number of patients with liver diseases that require surgical resection. The aged liver has significantly less reparative capacity following ischemia/ reperfusion (I/R) injury associated with this operation. Innovative approaches are urgently needed to reduce the age-dependent reperfusion injury and improve liver function of elderly patients following surgery. Mitochondrial dysfunction is the major mechanism precipitating lethal I/R injury to liver. Mitochondrial autophagy (mitophagy) is the cellular process that selectively removes abnormal mitochondria. The contribution of mitophagy to the age-dependent liver injury after warm ischemia is unknown. The goal of this study is to elucidate the mechanisms underlying the age-mediated lethal I/R injury to liver and to develop therapeutic strategies to improve liver function in the elderly patients after I/R. Our preliminary data demonstrate that the increased sensitivity of liver to I/R injury with age is strongly associated with its decreased mitophagic responsiveness. Preliminary results show that calpain-2-mediated loss of Atg4B, a key enzyme catalyzing the formation and recycling of autophagosomes, contributes to the age-dependent sensitivity of liver to I/R injury and mitochondrial dysfunction. In addition, we demonstrate that overexpression of Atg4B in both in vitro and in vivo models of I/R mitigates Atg4B loss, mitochondrial dysfunction and cell death. Thus, we propose that restoration or enhancement of mitophagy in aged liver will promote the clearance of dysfunctional mitochondria and consequently ameliorate liver dysfunction and bioenergetic failure after reperfusion. Our principal hypothesis is that defective or insufficient mitophagy is responsible for the increased sensitivity of old liver to lethal I/R injury. Two experimental models will be explored in this application using three different ages of mice. First, isolated hepatocytes will be utilized to determine the mechanisms of age-dependent mitophagic defects after I/R. Second, anesthetized mice will be employed to confirm and extend our I/R findings from an in vitro to an in vivo model. Finally, we will test the potential for mitophagy enhancing agents as therapeutic strategies to improve liver function after I/R in vivo. These studies provide critical mechanistic insights into the age-dependent I/R injury to liver, and will establish novel therapeutic approaches for improving I/R-mediated liver failure in the elderly patients.

描述（由申请人提供）：预期寿命的增加伴随着大量需要手术切除的肝病患者。与此操作相关的缺血/再灌注（I/ R）损伤后，老年肝脏的修复能力明显降低。迫切需要创新的方法来减少依赖年龄的再灌注损伤并改善手术后老年患者的肝功能。线粒体功能障碍是导致肝脏致命I/R损伤的主要机制。线粒体自噬（线粒体）是选择性去除异常线粒体的细胞过程。线粒体对温暖缺血后年龄依赖性肝损伤的贡献尚不清楚。这项研究的目的是阐明年龄介导的致命I/R损伤的机制，并制定治疗策略以改善肝脏功能 在I/R之后的老年患者中。我们的初步数据表明，随着年龄的增长，肝脏对I/R损伤的敏感性提高与其线性反应性降低密切相关。初步结果表明，CALPAIN-2介导的ATG4B损失是一种催化自噬体的形成和回收的关键酶，有助于肝脏对I/R损伤和线粒体功能障碍的年龄依赖性敏感性。此外，我们证明了ATG4B在体外和体内模型中的过表达，I/r减轻ATG4B损失，线粒体功能障碍和细胞死亡。因此，我们建议在老年肝脏中线粒体的恢复或增强将促进线粒体功能失调的清除，从而改善肝功能障碍和再灌注后的生物能衰竭。我们的主要假设是，有缺陷或不足的线粒体是导致旧肝脏对致命I/R损伤的敏感性提高的原因。在本应用程序中将使用三种不同年龄的小鼠探索两个实验模型。首先，将利用分离的肝细胞来确定I/R之后年龄依赖性线性缺陷的机制。其次，将使用麻醉小鼠来确认并将我们的I/R发现从体外变为体内模型。最后，我们将测试线粒体增强剂作为治疗策略，以改善体内I/R的肝功能。这些研究提供了对肝脏年龄依赖性I/R损伤的关键机理见解，并将建立新的治疗方法，以改善老年患者的I/R介导的肝衰竭。