BACKGROUND: The deficiency of liver regeneration needs to be addressed in the fields of liver surgery, split liver transplantation and living donor liver transplantation. Researches of microRNAs would broad our understandings on various diseases mechanisms. Our previous research has confirmed that miR-26a regulated liver regeneration in mice, however, the relationship between miR-26a and its target Mdm2, directly or indirectly, was remain unclearly. Therefore, we further investigated the detailed mechanism of miR-26a regulating mouse hepatocyte proliferation in the current study.

METHODS: The established mouse liver cell line, Nctc-1469, was cultured in vitro. The relationship between miR-26a and Mdm2 were assessed by dual-luciferase reporter assays. The effect of Mdm2, p53, as well as co-transfection of miR-26a and Mdm2 on cell proliferation and apoptosis were examined through flow cytometry. RT-qPCR and Western Blot were used to examine the expression of miR-26a and p53 in Mdm2 knockdown or over-expressed cells. The expressions of Mdm2, p53, caspase3, cyclinD1, p21 and p27 were assessed by Western Blot when miR-26a expression was inhibited or enhanced, as well as when miR-26a and Mdm2 were co-transfected.

RESULTS: Our results showed that Mdm2 was the direct targeted gene of miR-26a, in miR-26a downregulated cells, the expressions of Mdm2 and cyclinD1 were increased, while p53, caspase3, p21 and p27 were downregulated. When Mdm2 gene was overexpressed, the expressions of miR-26a and p53 were downregulated, the overexpression of Mdm2 gene promoted the proliferation of hepatocytes and inhibited cell apoptosis. The p53 gene inhibited the proliferation of hepatocytes and increased cell apoptosis. In the miR-26a and Mdm2 co-transfected hepatocytes, when expression of miR-26a was inhibited accompanied by upregulated Mdm2 gene, the proliferation of hepatocytes was increased and cell apoptosis was inhibited, the expressions of Mdm2 and cyclinD1 were increased, and p53, caspase3, p21 and p27 were downregulated. Meanwhile, previous study has confirmed the negative feedback regulation of p53 and Mdm2.

CONCLUSIONS: This study demonstrated that miR-26a regulated mouse hepatocyte proliferation by miR-26a:Mdm2:p53 pathway. It is suggested that miR-26a:Mdm2:p53 play a novel effect on mouse liver regeneration.

CITATION INFORMATION: Zhou J, Ju W, Yuan X, Jiao X, Wang D, Zhu X, He X. Novel Effect of miR-26a:Mdm2:p53 Pathway on Mouse Liver Regeneration. Am J Transplant. 2016;16 (suppl 3).

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