Identification and Functional Analysis of MicroRNAs in Mice following Focal Cerebral Ischemia Injury.

Cuiying Liu,Dongguo Li,Song Han,Junfa Li,Lei Zhao

doi:10.3390/ijms161024302

Abstract

Numerous studies have demonstrated that genes, RNAs, and proteins are involved in the occurrence and development of stroke. In addition, previous studies concluded that microRNAs (miRNAs or miRs) are closely related to the pathological process of ischemic and hypoxic disease. Therefore, the aims of this study were to quantify the altered expression levels of miRNAs in the infarct region 6 h after middle cerebral artery occlusion (MCAO)-induced focal cerebral ischemia in mice using a large-scale miRNAs microarray. Firstly, MCAO-induced cerebral ischemic injuries were investigated by observing the changes of neurological deficits, infarct volume and edema ratio. One hundred and eighteen differentially expressed miRNAs were identified in the infarct region of mice following the MCAOs compared with sham group (p < 0.05 was considered as significant). Among these 118 significantly expressed microRNAs, we found that 12 miRNAs were up-regulated with fold changes lager than two, and 18 miRNAs were down-regulated with fold changes less than 0.5 in the infarct region of mice following the 6 h MCAOs, compared with the sham group. Then, these 30 miRNAs with expression in fold change larger than two or less than 0.5 was predicted, and the functions of the target genes of 30 miRNAs were analyzed using a bioinformatics method. Finally, the miRNA-gene network was established and the functional miRNA-mRNA pairs were identified, which provided insight into the roles of the specific miRNAs that regulated specified genes in the ischemic injuries. The miRNAs identified in this study may represent effective therapeutic targets for stroke, and further study of the role of these targets may increase our understanding of the mechanisms underlying ischemic injuries.

Highlights

Stroke is a leading cause of serious long-term disability in the United States [1]
The 2,3,5-triphenyltetrazoliumchloride (TTC) staining result indicated that a large area of infarction was observed in the cerebral cortex and striatum of the Ischemia group (Figure 1B)
The statistical results of the infarct volume and edema ratio remarkably increased after 6 h of middle cerebral artery occlusion (MCAO) when compared with those of the sham group (Figure 1C,D), respectively

Summary

Introduction

Thrombolytic therapy within a narrow time window is the only acute therapeutic intervention for ischemic stroke, and many clinical stroke trials have failed [2]. The effectiveness of neuroprotectants has been demonstrated in rodent experimental stroke models, it has shown a deficiency against stroke in clinical trials because focusing on neuroprotection is not sufficient [3]. MicroRNAs (miRNAs) are endogenous, short, small, non-coding RNA molecules of 21 to 23 nucleotides in length. Because miRNAs are endogenous and small RNAs, they have attracted much attention recently due to the fact that they have been found to regulate at least 30% of the genes in a cell [5]. Many studies have paid attention to the roles of microRNAs in stroke [7,8,9,10]

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Results

Conclusion