Project description:Disruption of peripheral circadian rhyme pathways dominantly leads to metabolic disorders. Studies on circadian rhythm proteins in the heart indicated a role for Clock or Per2 in cardiac metabolism. In fact, Per2-/- mice have larger infarct sizes with a deficient lactate production during myocardial ischemia. To test the hypothesis that cardiac Per2 represents an important regulator of cardiac metabolism during myocardial ischemia, we performed lactate measurements during reperfusion in Per1-/-, Per2-/- or wildtype mice followed by gene array studies using various ischemia-reperfusion protocols comparing wildtype and Per2-/- mice. Lactate measurements in whole blood confirmed a dominant role of Per2 for lactate production during myocardial ischemia. Surprisingly, high-throughput gene array analysis of eight different conditions on one 24-microarray plate revealed dominantly lipid metabolism as differentially regulated pathway in wildtype mice when compared to Per2-/-. In all treatment groups, the enzyme enoyl-CoA hydratase, which is essential in fatty acid beta-oxidation, was regulated in wildtype animals only. Studies using nuclear magnet resonance imaging (NMRI) confirmed altered fatty acid populations with higher mono-unsaturated fatty acid levels in hearts from Per2-/- mice. Unexpectedly, studies on gene regulation during reperfusion revealed solely pro inflammatory genes as differentially regulated 'Per2-genes'. Subsequent studies on inflammatory markers showed increasing IL6 or TNFa levels during reperfusion in Per2-/- mice. In summary, these studies reveal a novel role of cardiac Per2 for fatty acid metabolism or inflammation during myocardial ischemia and reperfusion. We pursued studies on Per2 dependent gene expression during myocardial ischemia or reperfusion to understand its impact on cardiac metabolism. We designed different ischemia and reperfusion protocols and performed a high-throughput expression profiling of 24 samples at a time using an industry-standard whole mouse gene array (Affymetrix, Mouse Gene 2.1 ST 24-Array). To understand differential gene regulation during different conditions we performed 1) 30 minutes of ischemia without reperfusion, 2) ischemic preconditioning (IP, 4 x 5 minutes ischemia and reperfusion), as known cardioprotective mechanism, and 3) 30 minutes of ischemia followed by 60 minutes of reperfusion. Based on three arrays per condition the total number of arrays was 24, which we analyzed at the same time on a multi plate array to avoid inter-array variations. Quality analysis using Partek Genomics Suite 6.6 revealed high confidence in the quality of the microarray data and all samples met 'Quality Assurance/Quality Control' (QA/QC) criteria.

Project description:Coronary heart disease is the leading cause of death worldwide. After an acute myocardial infarction, early reperfusion reduces infarct size, which correlates with improved clinical outcomes. Paradoxically, reperfusion although relieving ischemia, accelerates apoptosis in injured cardiomyocytes, which has led to the view that myocardial salvage is futile beyond the first few hours of reperfusion. In murine hearts subjected to 90 min of coronary artery occlusion and then 48 h of reperfusion, we show transient activation of intrinsic prosurvival insulin-like growth factor-1 (IGF-1) signaling. In these hearts, acute IGF-1 receptor inhibition decreases the abundance of prosurvival signaling molecules, and markedly activates caspase-3, a potent effector of apoptosis, in infarct border zone cardiomyocytes. We found that mouse mast cell protease-4 (MMCP-4) degraded IGF-1 in vitro by a novel catalytic activity of chymases. In vivo, this degradation, which is triggered by mast cell infiltration into the peri-infarct region and MMCP-4 extravasation, between 48 and 72 h post-ischemia/reperfusion (I/R), attenuates IGF-1 prosurvival signaling. In MMCP-4-deficient mice, while infarct size is not reduced at 24 h post-I/R, at 72 h post-I/R myocardial IGF-1 levels and signaling are increased, resulting in activation of the survival kinases Akt and ERK, inhibition of caspase-3, and reduced myocardial cell death. As a consequence, I/R-mediated loss of viable myocardium, adverse cardiac remodeling and contractile impairment are markedly reduced. Cardiomyocyte survival with consequent myocardial salvage may thus be possible even days after an ischemic insult, making them a novel therapeutic target for delayed cardioprotective therapy. Group 1 is wild type C57Bl6 uninjured hearts. These mice were not undergone any surgery and used as controls. Group 2 are wild type C57Bl6 72 h post-ischemia reperfusion (IR) injury hearts. These mice for subjected to ischemia reperfusion (IR) involving 90 min of left anterior descending coronary artery occlusion followed by reperfusion for 3 days or 72 h.

Project description:The management of cardiac ischemic injury has been challenged by ischemia and reperfusion (I/R) injury. Reactive oxygen species (ROS) generated from mitochondrial reverse electron transport (RET) during the early phase of reperfusion is considered to be the initiating cause for ischemia and reperfusion injury. Ginsenosides and their prescriptions are widely used in the clinic for treatment of myocardial ischemia, however, the action to combat ROS remains to be elucidated. In this work, we used TMT-based proteomic approach to detect differential proteins from mitochondrial fractions of mice hearts with ischemia-reperfusion. Results indicated that the mass error of identified peptides was within 10 ppm, and most of the identified peptides were composed of 7-23 amino acids. Using these qualified data, 17,262 peptides, with a confidence level ≥ 95%, were mapped to 3,054 protein groups. PCA analysis showed that the model group was clearly separated from the blank group, while the protein pattern was partly reversed with Rb1 treatment. With a criteria of p-value < 0.05, 591 significantly changed proteins including 186 increased and 405 decreased ones in the model group were identified compared with the blank group. These proteins were divided into 4 clusters. Proteins in Cluster I highly increased in the model group, but clearly decreased in the Rb1 group. Proteins in Cluster IV clearly decreased in the model group, but markedly increased in the Rb1 group. Proteins in Cluster III and in Cluster IV were not significantly or slightly regulated by the Rb1 treatment. GO analysis of Cluster I and II indicated that the molecular function of these proteins were closely related to oxidoreductase activity and NADH dehydrogenase activity. Our result showed that Rb1 administration before ischemia markedly decreased infarct size (48 h post-I/R), and preserved cardiac function (2 weeks post-I/R), and subsequently limited tissue fibrosis (28 days post-I/R). These results indicated that targeted inhibition of mitochondrial complex I in the early stage of reperfusion by Rb1 is a potential therapeutic strategy for alleviating IR injury. This work not only indicates a potent molecular target for the precision therapy of myocardial ischemia by Rb1, but also provides novel knowledge for the management of cardiac ischemic injury by traditional Chinese medicine.

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