The Effects Of Limb Ischemic Preconditioning On MAPK Pathway Genes In Myocardium In Rats

Objective: To screen and analyze different expressed genes of microarray in limbischemic preconditioning process with whole genome expression chip,and understandthe limb ischemic preconditioning on myocardial MAPK-related changes in geneexpression profiles.Method Ten rats were randomly assigned into two groups (n=5each): limb ischemiapreconditioning group (group LIP) and control group (group C).Group LIP consistedof three cycles of5-minute ischemia followed by5-minute reperfusion in righthind-limb by tourniquet application. Group C was only a sham treatment. In delayphase of LIP within24h, the apical tissues of left ventricle were taken from twogroups, with thickness less than0.5cm, weight about50-100mg, preserved in-80℃RNA solution. Total RNA of group LIP and group C was extracted, and thenamplified by RT-PCR. The product cDNA was labeled with Cy3and hybridized onAgilent4x44K mouse whole gene chip. Fluorescence scanning，Gene Ontology(GO)and pathway analysis were used to screen the different expressed genes in the MAPKsignaling pathway．The analytic result was validated by Real-time Quantitative PCR,to explore the inherence relation between MAPK signaling pathway and limbischemic preconditioning.Result The results showed that there were1364genes that fold change cut-off≥2.0in gene microarray. Gene Ontology analysis showed that the external stimuli were themajority different genes within biological process (BP); The most different gene wasreceptor binding in the molecular function (MF); Channel-related genes in the cellschanged significantly in the cell components (CC). Pathway analysis of dataprocessing showed there were10up pathway and10down pathway, including MAPKsignaling pathway. In the MAPK signaling pathway, there were19up-regulated genes and15down-regulated genes. Map3k6、Il1r2、Grb2、AKT and HSP fold changecut-off is more then2.0in the MAPK signaling pathway, and Map3k6changedsignificantly. The results of Real-Time Quantitative PCR and microarrays showed nosignificant difference.Conclusion Myocardial expression gene between group LIP and group C wasanalyzed by Kyoto Encyclopedia of Genes and Genomes. It showed that they hadmany different myocardial expression genes between each other; In the P38MAPKsignaling pathway, the AKT gene and HSP gene played positive regulatory role of LIPin myocardium in rats. In the ERK1/2signaling pathway, the Grb2gene play positiveregulatory role of the delay phase of LIP in myocardium in rats. In the classic MAPKsignaling pathway, the Il1r2gene played negative regulatory role of the delay phase ofLIP in myocardium in rats. MAPK pathway might play different regulatory roles inthe delay phase LIP in myocardium in rats.