| Objective MicroRNA(miRNA) are a class of endogenous small noncoding RNAs thatnegatively regulate gene expression at the post-transcriptional level by base-pairing with the3’untranslated region (3’UTR) of their target mRNAs and triggering degradation or inhibitingtheir translation. Recent studies have demonstrated that there are a close correlation betweenmiRNA and cardiovascular diseases. MiRNA expression profile that repaired ofischemia-induced neovascularization in cardiac muscle tissues in diabetic rat has significantlychanges.And a few specific miRNAs targeting ischemia-induced angiogenesis in tissue havebeen identified. Up to now, there was few research addressing the relationship between themiRNA-503and the impaired of ischemia-induced neovascularization in diabetic rat.Therefore, we aimed to investigate the potential roles of miRNA-503and target genesCCNE1and cdc25A in angiogenesis after acute myocardial infarction by detecting itsexpression changes in ischemia area after myocardial ischemia in diabetic rats.Methods126Sprague-Dawley rats were randomly divided into2groups: Type2diabetic group treated with intraperitoneal injection of10%NA (230mg/kg), after15mins,following with caudal vein injection of1%STZ(65mg/kg); Non-diabetic group treated withintraperitoneal injection of10%NA (230mg/kg), after15mins, following with the intravenousinjection of citrate buffer (6.5ml/kg). Rats were fed with normal diet after injection, and theirfasting plasma glucose (FPG) and Body weight(BW) were regularly monitored. Nine weekslater, each group was then divided into2sub-groups: AMI group and Sham group. AMIanimal model were established by the ligation of left anterior descending coronaryartery(LAD). Sham group threading without occluding. Rats that suffered ligation of LADwere randomly divided into3days group,7days group,14days group and28days group.Heart Weight Index(HWI) were calculated at the end of the experimental protocol; Myocardial infarction size was analyzed by Masson staining; The capillary density around theregion of myocardial infarction were detected by using Factor VIII-related antigen staining;miRNA-503levels were detected by real-time polymerase chain reaction(qRT-PCR); TheCCNE1and cdc25A protein level was analyzed by Western blot.Results (1) HWI, Infarct size and capillary density of NDM+AMI group in3days grouphad no significant difference compared with DM+AMI group(p＞0.05), with the increaseingof ischemia days, DM+AMI group showed increase in infarct size and decrease in HWI andcapillary density(p<0.05).(2) The expression of miR-503mRNA significantly increased in3days DM+AMI group, the level of miR-503mRNA reached the peak at14days, and were stilla high expression at28days(p<0.05), It was about2.15±0.29fold,3.09±0.7fold,4.18±0.72fold and3.82±0.55fold of NDM+Sham group respectively(p<0.01).(3) With the increaseingof ischemia days, the expression of cdc25A gene in DM+AMI group was significantly lowerthan that in NDM+Sham group, It was about0.83±0.1fold,0.77±0.11fold,0.53±0.09fold,0.43±0.09fold of NDM+Sham group respectively(p<0.05);While the expression of CCNE1gene in DM+AMI group had no significant difference compared with NDM+Sham group, Itwas about0.94±0.14fold,1.1±0.06fold,0.98±0.16fold,1.08±0.1fold of NDM+Sham grouprespectively (p>0.05).(4) Spearman correlation analysis showed that there was a inverselycorrelation between miRNA-503and cdc25A expression (r=-0.748，p=0.005). No correlationwas found between miR-503and CCNE1（r=-0.245，p=0.443）.Conclusion. The ischemia-induced neovascularization in type2diabetic rats up-regulatedthe level of the expression of miR-503and inhibit the expression of cdc25A protein intime-dependent manner via post-transcriptional pathway. While the expression of miR-503and cdc25A protein in ischemia area after myocardial ischemia in no diabetic rats had nosignificant difference compared with control group,This pathophysiological mechanismmay be involved in impaired ischemia-induced neovascularization in diabetic rat. |
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