Combined Methylome and Transcriptome Analysis During Rat Hepatic Stellate Cell Activation

Hepatic stellate cells (HSCs) are mesenchymal stem cells (MSCs) of the liver. They are unique among MSCs, since HSCs remain in a quiescent, retinoid-storing state in the normal liver but become activated after liver injury and contribute to tissue repair. The epigenetic mechanisms accompanying the transition of HSCs from a quiescent to an activated state are in the focus of the present study. We investigated the methylome and transcriptome during this process and observed profound changes. While the promoter methylation correlated negatively with gene expression, the gene-body methylation revealed no clear correlation. Most genes with altered expression were associated with cell differentiation. Among them, Wilms tumor 1 (Wt1) and Deltex4 (Dtx4) genes were identified as epigenetically regulated. Since HSCs were reported to derive from multipotent Wt1-positive cells and many differentially expressed genes were associated with cell differentiation during their activation, epigenetic alterations are presumably required to enable HSC development.