Hepatic expression profiling has revealed miRNA changes in liver diseases,while hepatic miR-155 expression was increased in murine non-alcoholic fatty liver disease,suggesting that miR-155 might regulate the biological process of lipid metabolism.To illustrate the ef-fects of miR-155 gain of function in transgenic mouse liver on lipid metabolism,transgenic mice (i.e.,Rm155LG mice) for the conditional overexpression of mouse miR-155 transgene mediated by Cre/lox P system were firstly generated around the world in this study.