Project description:TLR4/NF-κB signaling plays a central mediator in response to danger signals released in the muscle ischemia-reperfusion injury (IRI). This study was designed to profile TLR4/NF-κB-responsive microRNAs (miRNAs) in the skeletal muscles following IRI. Following 2 h of ischemia and subsequent reperfusion for indicated times (0 h, 4 h, 1 d, and 7 d) of the isolated thigh skeletal muscles based on femoral artery perfusion of C57BL/6, Tlr4–/–, and NF-κB–/–mice, the muscle specimens were analyzed with an miRNA array to detect the TLR4/NF-κB-responsive miRNAs.
Project description:TLR4/NF-κB signaling plays a central mediator in response to danger signals released in the muscle ischemia-reperfusion injury (IRI). This study was designed to profile TLR4/NF-κB-responsive microRNAs (miRNAs) in the skeletal muscles following IRI. Following 2 h of ischemia and subsequent reperfusion for indicated times (0 h, 4 h, 1 d, and 7 d) of the isolated thigh skeletal muscles based on femoral artery perfusion of C57BL/6, Tlr4â/â, and NF-κBâ/âmice, the muscle specimens were analyzed with an miRNA array to detect the TLR4/NF-κB-responsive miRNAs. Male C57BL/6 mice (10â12 weeks of age, 22â35 g) were purchased from BioLasco (Taiwan). Tlr4â/â (C57BL/10ScNJ) and NF-κBâ/â (B6.Cg-Nfkb1tm1Bal/J) mice were purchased from Jackson Laboratory (Bar Harbor, ME, USA). All housing conditions were established and surgical procedures, analgesia, and assessments were performed in an AAALAC-accredited, SPF facility following national and institutional guidelines. Animal protocols were approved by the IACUC of Chang Gung Memorial Hospital. Mice were anesthetized with an anesthetic cocktail consisting of 0.1 mg/g ketamine and 0.01 mg/g xylazine, given as an intraperitoneal injection (0.01 ml/g body weight). After the induction of anesthesia, the mice were restrained in a supine position on a heating pad to maintain body temperature at 37°C. The quadriceps muscle perfused based on the femoral artery of the mouse was carefully isolated away from the femoral bone and the underlying adductor muscle group. In the ischemic group, ischemia was induced by placing a microvascular clamp carefully across the proximal site of vascular pedicle for 2 h and then the microvascular clamp was removed. Good vascular inflow and outflow through the pedicle was verified under direct magnified vision. In the sham-operated control group, the muscle was isolated without microvascular clamp being applied. The incision wound was closed with interrupted sutures (4-0 nylon) and the animals were allowed to awaken in the remaining periods of reperfusion. The harvested muscles were frozen in isopentane chilled in liquid nitrogen and stored at -80°C. For the miRNA array experiments, the isolated skeletal muscles of C57BL/6 mice after 2 h of ischemia and 0 h, 4 h, 1 d, and 7 d of reperfusion as well as of Tlr4â/âand NF-κBâ/â mice after 2 h of ischemia and 1 d of reperfusion were used in 3 replicate experiments.
Project description:Heart disease remains the leading cause of death globally. Although reperfusion following myocardial ischemia can prevent death by restoring nutrient flow, ischemia/reperfusion injury can cause significant heart damage. The mechanisms that drive ischemia/reperfusion injury are not well understood; currently, few methods can predict the state of the cardiac muscle cell and its metabolic conditions during ischemia. Here, we explored the energetic sustainability of cardiomyocytes, using a model for cellular metabolism to predict the levels of ATP following hypoxia. We modeled glycolytic metabolism with a system of coupled ordinary differential equations describing the individual metabolic reactions within the cardiomyocyte over time. Reduced oxygen levels and ATP consumption rates were simulated to characterize metabolite responses to ischemia. By tracking biochemical species within the cell, our model enables prediction of the cell’s condition up to the moment of reperfusion. The simulations revealed a distinct transition between energetically sustainable and unsustainable ATP concentrations for various energetic demands. Our model illustrates how even low oxygen concentrations allow the cell to perform essential functions. We found that the oxygen level required for a sustainable level of ATP increases roughly linearly with the ATP consumption rate. An extracellular O2 concentration of ~0.007 mM could supply basic energy needs in non-beating cardiomyocytes, suggesting that increased collateral circulation may provide an important source of oxygen to sustain the cardiomyocyte during extended ischemia. Our model provides a time-dependent framework for studying various intervention strategies to change the outcome of reperfusion.
Project description:Hepatic ischemia reperfusion injury is a dynamic process consisting of two stages: ischemia and reperfusion, and triggers a cascade of physiological and biochemical events. Given the important role of microRNAs in regulating gene expression, we analyzed gene expression changes in mouse livers at sham control, ischemia stage, and reperfusion stage. We generated global expression profiles of microRNA and mRNA genes in mouse livers subjected to ischemia reperfusion injury at the three stages, respectively. Comparison analysis showed that reperfusion injury had a distinct expression profile whereas the ischemia sample and the sham control were clustered together. Consistently, there are 69 differentially expressed microRNAs between the reperfusion sample and the sham control whereas 28 differentially expressed microRNAs between the ischemia sample and the sham control. We further identified two modes of microRNA expression changes in ischemia reperfusion injury. Functional analysis of both the differentially expressed microRNAs in the two modes and their target mRNAs revealed that ischemia injury impaired mitochondria function, nutrient consumption, and metabolism process. In contrast, reperfusion injury led to severe tissue inflammation that is predominantly an innate-immune response in the ischemia reperfusion process. Our staged analysis of gene expression profiles provides new insights into regulatory mechanisms of microRNAs in mouse hepatic ischemia reperfusion injury.
Project description:Hepatic ischemia reperfusion injury is a dynamic process consisting of two stages: ischemia and reperfusion, and triggers a cascade of physiological and biochemical events. Given the important role of microRNAs in regulating gene expression, we analyzed gene expression changes in mouse livers at sham control, ischemia stage, and reperfusion stage. We generated global expression profiles of microRNA and mRNA genes in mouse livers subjected to ischemia reperfusion injury at the three stages, respectively. Comparison analysis showed that reperfusion injury had a distinct expression profile whereas the ischemia sample and the sham control were clustered together. Consistently, there are 69 differentially expressed microRNAs between the reperfusion sample and the sham control whereas 28 differentially expressed microRNAs between the ischemia sample and the sham control. We further identified two modes of microRNA expression changes in ischemia reperfusion injury. Functional analysis of both the differentially expressed microRNAs in the two modes and their target mRNAs revealed that ischemia injury impaired mitochondria function, nutrient consumption, and metabolism process. In contrast, reperfusion injury led to severe tissue inflammation that is predominantly an innate-immune response in the ischemia reperfusion process. Our staged analysis of gene expression profiles provides new insights into regulatory mechanisms of microRNAs in mouse hepatic ischemia reperfusion injury.
Project description:This SuperSeries is composed of the following subset Series: GSE21405: MicroRNA Profiling In Ischemia-Reperfusion Injury Of The Gracilis Muscle In Rats GSE21406: Potential Target Genes of MicroRNA-21 In Ischemia-Reperfusion Injury Of The Gracilis Muscle In Rats Refer to individual Series
Project description:Early reperfusion of ischemic cardiac tissue remains the most effective intervention for improving clinical outcome following myocardial infarction. However, abrupt increases in intracellular Ca2+ during myocardial reperfusion cause cardiomyocyte death and consequent loss of cardiac function, referred to as ischemia/reperfusion (IR) injury. Cardiac IR is accompanied by dynamic changes in expression of microRNAs (miRNAs), which inhibit specific mRNA targets. miR-214 is up-regulated during ischemic injury and heart failure in mice and humans, but its potential role in these processes is unknown. We show that genetic deletion of miR-214 in mice causes loss of cardiac contractility, increased apoptosis, and excessive fibrosis in response to IR injury. The microarray contains 6 samples, each containing cDNA pooled from 3 mice per group. There are no replicates. The array was designed to make 3 different pairwise comparisons between the following: P14 WT and miR-214 KO hearts; adult WT and miR-214 KO skeletal muscle; adult WT and miR-214 KO hearts
Project description:Ischemic preconditioning is effective in limiting subsequent ischemic acute kidney injury in experimental models. microRNAs are an important class of post-transcriptional regulator and show promise as biomarkers of kidney injury. An evaluation was performed of the time- and dose-dependent effects of ischemic preconditioning in a rat model of functional (bilateral) ischemia-reperfusion injury. A short, repetitive sequence of ischemic preconditioning resulted in optimal protection from subsequent ischemia-reperfusion injury. A detailed characterization of microRNA expression in ischemic preconditioning/ischemia-reperfusion injury was performed by small RNA-Seq.
Project description:Ischemic preconditioning is effective in limiting subsequent ischemic acute kidney injury in experimental models. microRNAs are an important class of post-transcriptional regulator and show promise as biomarkers of kidney injury. An evaluation was performed of the time- and dose-dependent effects of ischemic preconditioning in a rat model of functional (bilateral) ischemia-reperfusion injury. A short, repetitive sequence of ischemic preconditioning resulted in optimal protection from subsequent ischemia-reperfusion injury. A detailed characterization of microRNA expression in ischemic preconditioning/ischemia-reperfusion injury was performed by Exiqon miRCURY microRNA array.
Project description:Profile the microRNA expression in the Gracilis muscle of rat after 4h ischemia and 24 h reperfusion Following 4 h of ischemia and subsequent reperfusion for 4 h of the gracilis muscles, the specimens were analyzed with an Agilent rat miRNA array to detect the expressed miRNAs in the experimental muscles compared to those from the sham-operated controls. Two-condition experiment, Gracilis muscle after 4h ischemia and reperfusion injury for 24 h v.s. Gracilis muscle (sham control), Biological replicates: 2 control replicates, 2 experiement replicates