Changes Of MiRNA-210, MiRNA-320 And MiRNA-92a After Renal Ischemia/Reperfusion And It's Involvement With Angiogenesis

Renal ischemia injury is in relation with renal transplantation and renal operation. As an important pathological process, the timely reconstruction of renal blood flow in ischemic region is a key treatment for renal ischemic injury. Animal experiments and clinical studies showed that compensatory angiogenesis was increased after issues ischemia. Most studies have confirmed that the VEGF pathway signalling has the critical regulatory role in endothelial cell proliferation, differentiation, migration and angiogenesis and involved in the regulation of ischemia-induced angiogenesis in tissue ischemia, which are perhaps the most important mechanism in regulation of angiogenesis in renal ischemia. Recently, studies have showed that microRNAs (miRNAs) are small noncoding RNAs and regulate gene expression at the post-transcriptional level by either degradation or translational repression of a target mRNA that regulate physiological and pathological processes. And a few specific miRNAs targeting endothelial cell function and angiogenesis in tissue ischemia-induced have been identified. Our results showed that some of miRNAs expression changes after renal ischemia may be involved in targeting VEGF pathway signaling to regulate angiogenesis.Methods: Mice were subjected to a standard renal I/R to induce acute kidney injury after 45 min of bilateral renal artery clamping. The expression of CD31 was examined in tissue sections by immunohistochemistry staining, and the microvessels in ischemic region of each group were counted. MiRNAs expression changes used Quantitative Real-time RT-PCR analysis at 4h and 24 h following I/R. VEGF and Flk-1 mRNA expression changes used Quantitative Real-time RT-PCR analysis at 4h and 24h following I/R. Flk-1 protein expression changes used western Blotting analysis at 24h and 72h following I/R.Results: 1.Blood samples were obtained at 24 h and at the time of animal death to evaluate the degree of AKI by serum creatinine (SCr) and urea nitrogen(BUN)(P﹤0.05), and the renal tissue were obtained to evaluate histological changes after I/R at 24h. 2. Quantitative Real-time RT-PCR analysis showed that ischemic kidney injury significantly increased miRNA-210, miRNA-320 and miRNA-92a expression compared to the sham controls, with prominent changes at 4h and 24h after recovery (P< 0.05).3. The immunohistochemistry staining results of CD31 showed a significant increase of microvessels in ischemic region in renal ischemia compared with control group.4. VEGF and Flk-1 mRNA expression were increased in I/R injury at 4h and 24h compared to the sham controls (P<0.05). And Flk-1 protein expression was increased in I/R injury at 24h and 72h compared to the sham controls (P< 0.05).Conclusion: Renal I/R to induce acute kidney injury (AKI) significantly increased miRNA-210, miRNA-320 and miRNA-92a expression with prominent changes at 4h and 24h after recovery.And compensatory angiogenesis was increased significantly after renal ischemia.Meanwhile,VEGF and Flk-1 mRNA expression were increased in I/R injury compared to the sham controls. And Flk-1 protein expression were also increased in renal I/R injury compared to the sham controls .These results provided evidence that miR-210,miRNA-320 and miRNA-92a may be somehow involved in the mechanisms of renal ischemic injury disease through targeting VEGF pathway to regulate angiogenesis.