Abstract
The importance of dysregulation of microRNA (miRNA) expression in nonalcoholic steatohepatitis (NASH) has been increasingly recognized; however, the association between altered expression of miRNAs and pathophysiological features of NASH and whether there is a connection between susceptibility to NASH and altered expression of miRNAs are largely unknown. In this study, male inbred C57BL/6J and DBA/2J mice were fed a lipogenic methyl-deficient diet that causes liver injury similar to human NASH, and the expression of miRNAs and the level of proteins targeted by these miRNAs in the livers were determined. Administration of the methyl-deficient diet triggered NASH-specific changes in the livers of C57BL/6J and DBA/2J mice, with the magnitude being more severe in DBA/2J mice. This was evidenced by a greater extent of expression of fibrosis-related genes in the livers of methyl-deficient DBA/2J mice. The development of NASH was accompanied by prominent changes in the expression of miRNAs, including miR-29c, miR-34a, miR-155, and miR-200b. Interestingly, changes in the expression of these miRNAs and protein levels of their targets, including Cebp-β, Socs 1, Zeb-1, and E-cadherin, in the livers of DBA/2J mice fed a methyl-deficient diet were more pronounced as compared with those in C57BL/6J mice. These results show that alterations in the expression of miRNAs are a prominent event during development of NASH induced by methyl deficiency and strongly suggest that severity of NASH and susceptibility to NASH may be determined by variations in miRNA expression response. More important, our data provide a mechanistic link between alterations in miRNA expression and pathophysiological and pathomorphological features of NASH.