Mirnome analysis reveals novel molecular determinants in the pathogenesis of diet-induced nonalcoholic fatty liver disease

Nonalcoholic fatty liver disease (NAFLD) is an emerging disease with a broad spectrum of liver conditions. The complex molecular pathogenesis of NAFLD is still unclear. In this study, we conducted an analysis of microRNA (miRNA) expression profiles in liver of rats made NAFLD by different diets. To this aim, Sprague-Dawley rats were fed ad libitum for 3 months with different diets: standard diet (SD), diet enriched in fats and low in carbohydrates (HFD), SD with high fructose (SD-HF) and diet with high levels of fats and fructose (HFD-HF). Our results demonstrated that the treatment with different dietetic regimens caused a significant increase of the body weight and the alteration of some metabolic parameters compared with control animals, as well as various liver injuries. The miRNAs analysis showed the significant downregulation of three miRNAs (miR-122, miR-451 and miR-27) and the upregulation of miR-200a, miR-200b and miR-429 in HFD, SD-HF and HFD-HF rats. Besides, miR-21 expression was significantly decreased only in fructose-enriched diets. These miRNAs target molecules involved in the control of lipid and carbohydrate metabolism, signal transduction, cytokine and chemokine-mediated signaling pathway and apoptosis. Western blot analysis of PKC delta, LITAF, ALDOLASE-A, p38MAPK, PTEN, LIPIN1, EPHRIN-A1, EPHA2 and FLT1 showed a diet-induced deregulation of all these proteins. Interestingly, the expression pattern of LITAF, PTEN, LIPIN1, EPHRIN-A1, EPHA2 and FLT1 might be well explained by the trend of their specific mRNAs, by potentially regulatory miRNAs, or both. In conclusion, we highlight for the first time the potential involvement of novel determinants (miRNAs and proteins) in the molecular pathogenesis of diet-induced NAFLD. Laboratory Investigation (2011) 91, 283-293; doi:10.1038/labinvest.2010.166; published online 18 October 2010