Levels of histone modifications in activated primarily cultured rat hepatic stellate cells

AIM: To investigate the changes of histone modifications during the activation of primarily cultured rat hepatic stellate cells (HSCs) and the relationship between histone modification patterns and α-smooth muscle actin (α-SMA) expression, and to explore the roles of histone modifications in the activation of HSCs. METHODS: The rat HSCs were isolated by in situ perfusion of collagenase combined with density gradient centrifugation, cultured in vitro and identified by immunofluorescence staining. The morphological features of the cells were observed under inverted microscope. The changes of desmin and α-SMA during the activation of HSCs were detected by immunofluorescence staining and Western blotting. The levels of histone 3 lysine 4 dimethylation (H3K4me2), histone 3 lysine 9 dimethylation (H3K9me2), histone 3 lysine 9 acetylation (acH3K9) and histone 4 lysine 12 acetylation (acH4K12) in quiescent HSCs and activated HSCs were determined by Western blotting.RESULTS: The morphology of HSCs shifted from a quiescent phenotype to highly activated myofibroblast during the culture. Immunofluorescence staining and Western blotting showed that the expression levels of α-SMA and desmin were increased over time and reached maximum at 15 d. According to the results of cell morphology and immunofluorescence staining, the cells cultured for 24 h and 15 d were quiescent and activated HSCs, respectively. Compared with quiescent HSCs, there were higher H3K4me2 and lower H3K9me2, acH3K9 and acH4K12 modification levels in activated HSCs (P<0.01). CONCLUSION: Histone modifications show anomalous expression during the activation of primarily cultured rat HSCs. Histone modifications may contribute to the transdifferentiation of HSCs and the development of hepatic fibrosis.