Liver is uniquely capable to repair itself after injury. Multiple molecular and biochemical processes initiated after partial hepatectomy, lead to proliferation of all cells within the liver. MicroRNAs (miRNAs) are a class of highly abundant non-coding RNA molecules that cause post-transcriptional gene repression and are involved in several biological processes including cell cycle regulation and differentiation. In this study, we examined the expression levels of miRNAs in liver tissue received from control mice (L0) and compared them with the corresponding levels in liver tissue 12 h after liver regeneration induced by 2/3 partial hepatectomy (L12). MiRNA expression was investigated using microRNA profiling. Further qPCR analysis was used for validation of the differentially expressed miRNAs at an early stage of liver regeneration, induced by 2/3 partial hepatectomy. TargetScan and Gene Ontology (GO) analyses were performed in order to identify the possible miRNA target genes and their ontology, respectively. A subset of miRNAs was found to be differentially expressed during liver regeneration. Mmu-miR-21 and mmu-miR-30b* showed the higher levels of up-regulation in liver tissue from the hepatectomized mice at the end of the experiment (L12) compared to the sham operated mice (L0). Mmu-miR-21 up-regulation was further confirmed by qPCR. In situ hybridization (ISH) revealed that mmu-miR-21 exhibited the higher levels of expression at 12 h post hepatectomy. On the contrary, mmu-miR-34c*, mmu-miR-144, mmu-miR-207, mmu-miR-207, mmu-miR-451, mmu-miR-582-3p and mmu-miR-290-5p exhibited <0.5 down-regulation in liver tissue after partial hepatectomy in L12 vs. L0 mice. The results from microarray and qPCR analyses were in good agreement. In conclusion, our results provide important information regarding the differentially expressed miRNAs in murine liver tissue before and after partial hepatectomy. The early up-regulation of mmu-miR-21 during the process of liver regeneration suggests a regulatory role in liver regeneration in vivo.

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