Expression and significance of histone methyltransferase SET domain containing 2 with histone H3 lysine 36 trimethylation in mouse hepatic oval cells differentiated into bile duct epithelial cells in vitro.

The present study aimed to identify the function and expression of trimethylated protein histone H3 lysine 36 (H3K36)me3 and the upstream specific enzyme histone methyltransferase SET domain containing 2 (SETD2), during the differentiation of hepatic oval cells (HOCs) into cholangiocytes in mice following partial liver resection and fed with 2­acetamidofluorene. HOCs were isolated from Kunming male mice fed with 2­acetamidofluorene for 10 days. Their liver tissues were then isolated following partial liver resection and another week of 2­acetamidofluorene treatment. HOCs were collected following a two­step enzyme digestion procedure involving protease E and collagenase 4. The target cells were cultured in DMEM/F12 supplemented with 10 µg/ml EGF, 5 µg/ml stem cell growth factor and 5 µg/ml leukemia inhibitory factor. Target cells using the markers OV­6, CK­19, SETD2, H3K36me3, were detected with flow cytometry and immunofluorescence microscopy; reverse transcription­quantitative PCR and western blotting were used to quantify the protein levels of SETD2 and H3K36me3. The retrieved primary hepatocytes developed into cholangiocytes with increasing CK­19 and decreasing OV­6 expression in each subsequent passage, whereas the SETD2 and H3K36me3 levels gradually increased, suggesting the possible involvement of both of these factors in differentiation.