Gene expression analysis of mouse liver after bile duct ligation (BDL) treated or not with anti-miR-873

Background & Aims. Glycine N-methyltransferase (GNMT) is an essential regulator of the total transmethylation flux in the mammalian liver. Distinct DNA methylation patterns are characteristic of liver development, hepatic de-differentiation and liver disease progression, processes in which the levels of GNMT decrease dramatically by mechanisms still poorly understood. Interestingly, putative binding sites for the microRNA miRNA-873-5p were identified in the 3´UTR of GNMT suggesting a potential role for miRNA-873-5p in GNMT regulation. Results. We have identified that the hepatic expression of miRNA-873-5p was increased in a cohort of cirrhotic and liver cancer patients associated with a down-regulation of GNMT levels. Moreover, during liver development, hepatic de-differentiation and fibrosis, the elevation of miRNA-873-5p coincided with the reduction of GNMT expression, indicating that miRNA-873-5p specifically targets the expression of GNMT. Under these circumstances, inhibition of miRNA-873-5p induced GNMT levels and decreased global CpG methylation and transmethylation flux. Indeed, reestablishment of GNMT expression by miRNA-873-5p inhibition reduced hepatocyte de-differentiation, and abolished completely the mortality produced after bile duct ligation as a result of decreased proinflamatory and profibrogenic markers. miRNA-873-5p knockdown-mediated antifibrotic effect was significantly blunted if its effect on GNMT was blocked. Conclusion. Taken together, our studies highlight the role of miRNA-873-5p as a key regulator of GNMT expression, paving the way for new therapeutical approaches in liver de-differentiation and fibrosis. Overall design: Genome-wide changes in gene Expression in mouse livers from BDL treated or not with anti-miR-873 were generated by RNAseq.

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Fernández-Ramos D, Fernández-Tussy P, Lopitz-Otsoa F, Gutiérrez-de-Juan V, Navasa N, Barbier-Torres L, Zubiete-Franco I, Simón J, Fernández AF, Arbelaiz A, Aransay AM, Lavín JL, Beraza N, Perugorria MJ, Banales JM, Villa E, Fraga MF, Anguita J, Avila MA, Berasain C, Iruzibieta P, Crespo J, Lu SC, Varela-Rey M, Mato JM, Delgado TC, Martínez-Chantar ML