Expression And Significance Of MicroRNA In Myocardial Tissue Of Rat Model With Stress

Background:The cause and development of myocardial injury induced by stress is a complicated biological process, which involves many mechanisms. After receiving outside stimulation, the cell will transfer these stimulating signals into itself through a variety of ways, then consequently a series of reactions will happen, such as protein's synthesis and degradation, cytokines secrete and so on. As a result, these reactions trigger necrosis and apoptosis, which are the cytology foundation of the disease. miRNA is a small uncoding RNA, whose length is 18-26bp. By specific base pairing, miRNA combines target mRNA and induces target RNA's degradation or inhibit its translation, thus to regulate the gene translation. Researches found that miRNA has strict organizational specificity and scheduling in terms of expression. miRNA plays an important role at different developmental stages of cardiovascular system, such as adjusting physiology and pathology condition of myocardial cell proliferation differentiation and apoptosis. Dozens of miRNA have been identified in myocardial cells, for example, miR-133a,miR-133b,miR-ld,miR-296,miR-21,miR-208,miR-195 etc, all of which have a important role in the regulation of myocardial hypertrophy, cardiac electrophysiology and angiogenesis. Therefore, the application of myocardial genomics research into the study of myocardial injury induced by stress will enrich the thorough knowledge of this disease.Objective:By use of microRNA array technology, we will test the differential myocardial miRNA expressed by stress rats model to provide the alternative miRNA for intervention therapy.Methods:24 2-month-old male wistar rats, which are in clean level, are randomly divided into normal control group (OR) 8, chronic stress group (CS) 8, acute stress group (AS) 8. Through bounding and suspension method, acute and chronic stress model of rats are made. Experimental rats and rats in the comparative group were executed respectively and myocardial tissue were collected immediately, which were kept in-80 degrees temperature for preservation. By use of Trizol extraction reagent, total RNA myocardial tissue were collected. Through a series of process of RNA quality testing, miRNA markers. miRNA array hybridization and washing, followed by scanning images by use of GenePix Axon 4000B array scanners, array hybrid mapping were produced. Applying relevant software were compare the data from GenePixPro6.0 analysis with experimental data for significant difference analysis in order to test miRNA differences.Results:Compared with the normal control group, a part of the miRNA in rats have difference in stress model expression (see table 4.1 and 4.2).68 miRNA have differences in acute stress model, including 32 up-regulation and 36 down-regulation, while 55 miRNA have differences in chronic stress model expression, including 20 up-regulation and 35 down-regulation. There are 15 miRNA having differences in both acute and chronic stress group, among which rno-miR-141,rno-miR-382, rno-miR-219-5p and rno-miR-296 are up-regulate(see table 4.3) and the rest 11 miRNA are down-regulate(see table 4.4), among which rno-miR-135a and rno-miR-466b are significant down-regulate.Conclusion:(1) In the process of making model suspension and bounding, it reveals that stress can cause myocardial injury.(2) Myocardial injury may cause discrepancy in the expression of parts of miRNA.(3) Psychological stress can cause down-regulate in miRNA like miR-141, miR-382, miR-219-5p and miR-296 while significant down-regulate in miR-135a and miR-466b(see table 4.3)(4) On the basis of this study, it can be accurately predicted which miRNA involves in myocardial injury induced by stress, miRNA target genes and the signal route of their participation. Applying the relevant bioinformatics method, we can retrieve and analyze the relating miRNA and meanwhile we can construct myocardial cells in vitro culture which relate to antagonism and over-expression of miRNA. We suppose that the application of protective miRNA is beneficial for the interruption of myocardial injury induced by stress, thus provide evidences for the development of new drugs in prevention and cure of myocardial injury induced by stress.