Age Related Change in Mitochondrial Angiotensin System and Mitochondrial Decline

描述（由申请人提供）：衰老和线粒体功能下降密切相关。线粒体功能障碍的关键标志包括活性氧的产生增加，每消耗O2产生的ATP分子减少，以及细胞凋亡增加。ATP的减少转化为细胞维持过程的能量降低，包括有丝分裂和周转。我们最近报道了一种功能性线粒体血管紧张素系统（MAS）的鉴定，发现衰老影响线粒体中关键的血管紧张素1型和2型受体（AT 1 R和AT 2 R）的比例，AT 1 R阻断剂可能部分逆转这些变化并改善线粒体功能。重要的是，AT 1 R-/-小鼠的寿命延长了25%，部分原因是线粒体数量增加。衰老对线粒体（mt）AT 1 R和mtAT 2 R表达的影响及其对线粒体功能障碍中年龄相关变化的贡献以前尚未研究。新的初步证据表明，在老年小鼠中阻断AT 1 R可以通过改变p53诱导蛋白（MIEAP）表达来恢复与年龄相关的线粒体能量产生下降并改善线粒体自噬效率。我们推测，年龄相关的增加mtAT 1 R/AT 2 R比例介导的线粒体能量代谢下降，通过增加活性氧（ROS）的生产和受损的线粒体消除受损。为了验证这一假设，我们提出了一个全面的研究mtAT 1 R和mtAT 2 R，在对照和氯沙坦（AT 1 R阻滞剂）治疗，年轻和老年（38个月大）C57 BL/6，AT 1-/-和AT 2-/-小鼠。将使用与年龄相关的心肌生物能量学衰竭作为模型来研究mtAT 1 R和mtAT 2 R变化的影响，以下提出的具体目标：1。采用Q-PCR、Western blot、共聚焦显微镜和电子显微镜技术，确定外周血管紧张素系统（PAS）和MAS的年龄相关变化及其对活性氮/氧自由基ROS/RNS产生的影响。ROS/RNS的产生将使用特异性荧光探针在来自我们所有动物组的分离的心肌细胞和线粒体中定量。2.通过磁共振波谱分析和成像，明确基线和安慰剂或氯沙坦治疗4周后活体动物心脏组织中PAS和MAS年龄相关变化对生物能量功能障碍的贡献。MAS对生物能量学变化的贡献将在来自所有动物组的分离的心脏线粒体中进行研究。3.目的研究PAS和MAS在线粒体生物合成、修复和消除中的作用。方法利用心肌细胞系H9 C2，通过P53活性报告基因检测过表达AT 1 R和/或AT 2 R对MIEAP、氧化应激、线粒体DNA损伤和线粒体自噬的影响。还将在对照和LOS处理的、年轻和老年（38月龄）C57 BL/6、AT 1-/-和AT 2-/-小鼠之间比较类似的结果。

DESCRIPTION (provided by applicant): Aging and decline in mitochondrial function are closely linked. Key signs of mitochondrial dysfunction include increased generation of reactive oxygen species, fewer ATP molecules produced per O2 consumed, and increased apoptosis. The reduction in ATP translates to lower energy for cellular maintenance processes including mitobiogenesis and turnover. We recently reported the identification of a functional Mitochondrial Angiotensin System (MAS), and found that aging impacts the ratio of key angiotensin type 1 and type 2 receptors in mitochondria (AT1R and AT2R), that AT1R blocking agents may partially reverse these changes and improve mitochondrial function. Importantly, AT1R-/- mice have an enhanced life span by 25%, in part through an increase in mitochondrial numbers. The effects of aging on the expression of mitochondrial (mt) AT1R and mtAT2R and their contribution to age-related changes in mitochondrial dysfunction have not been previously studied. New preliminary evidence suggests that AT1R blockade in old mice may restore the age- related decline in mitochondrial energy production and improve mitophagy efficiency via alterations in p53- inducible protein (MIEAP) expression. We hypothesize that an age-related increase in mtAT1R/AT2R ratio mediates declines in mitochondrial energy metabolism via increased reactive oxygen species (ROS) production and impaired elimination of damaged mitochondria. In order to test this hypothesis we propose a comprehensive study of mtAT1R and mtAT2R, in control and losartan (AT1R blocker) treated, young and aged (38-month old) C57BL/6, AT1-/- and AT2-/- mice. Will use age related cardiac muscle bioenergetics failure as a model to study the impact of changes in mtAT1R and mtAT2R following proposed specific aims: 1. To identify age-related changes in peripheral angiotensin system (PAS) and MAS and their contribution to altered reactive nitrogen/oxygen species ROS/RNS generation, using Q-PCR, western blot, confocal and electron microscopy. Generation of ROS/RNS will be quantified in isolated cardiomyocytes and mitochondria from all our animal groups using specific fluorescent probes. 2. To specify the contribution of age-related changes in PAS and MAS to bioenergetic dysfunction by magnetic resonance spectroscopy and imaging in the cardiac tissue of living animals at baseline and after four weeks of placebo or losartan treatment. MAS contributions to the changes in bioenergetics will studied in isolated cardiac mitochondria from all animal groups. 3. To investigate the role of the PAS and MAS on mitochondrial biogenesis, repair, and elimination by utilizing a cardiac cell line (H9C2) instrumented with a P53 activity reporter to measure the effects of over-expressing AT1R and/or AT2R on MIEAP, oxidative stress, mtDNA damage and mitophagy. Similar outcomes will also be compared between control and LOS treated, young and aged (38-month old) C57BL/6, AT1-/- and AT2-/- mice.