The Roles Of H3K9 Methylation In Phenotypic Switching Of Vascular Smooth Muscle Cells Induced By High Glucose

Objective To explore the impact of high glucose on the cell proliferation and the expression of H3K9 methylation and vascular smooth muscle cells(VSMCs)-specific genes SM22α and SMA-α in rat A7r5-derived aortic smooth muscle cells;To explore the impact of H3K9 methylation inhibitor chaetocin on the cell proliferation and the expression of VSMCs-specific genes SM22α and SMA-α in rat A7r5-derived aortic smooth muscle cells;To observe the impact of H3K9 methylation inhibitor chaetocin on the phenotypic switching of vascular smooth muscle cells and atherosclerosis in Apo E-knockout mice.Methods Cell experiments : 1)Both MTT and Ed U methods were applied to explore the impact of high glucose on the cell proliferation of rat A7r5-derived aortic smooth muscle cells.2)Both Western blot and Q-PCR methods were used to explore the impact of high glucose on the expression of VSMCs-specific genes SM22α and SMA-α in protein and RNA levels respectively,in rat A7r5-derived aortic smooth muscle cells.3)Western blot was applied to explore the impact of high glucose on the expression of H3K9 methylation in rat A7r5-derived aortic smooth muscle cells.4)Western blot method was used to explore the impact of H3K9 methylation inhibitor on the expression of VSMCs-specific genes SM22α and SMA-α in rat A7r5-derived aortic smooth muscle cells.5)The impact of the H3K9 methylation inhibitor on the cell proliferation of rat A7r5-derived aortic smooth muscle cells was explored by MTT method.Animal experiments : The Apo E-knockout mice of experimental groups were treated with H3K9 methylation inhibitor chaetocin by intraperitoneal injections.At the same time,the mice of control groups receiced the same volume of vehicle.After 16 weeks of high fat diet,the mice were euthanized to collect the root of aorta and the full-length aorta.Oil red O,Masson’s trichrome,hematoxylin-eosin staining and immunohistochemistry for the abundance of H3K9me3,SM22α and SMA-α were performed to assess the atherosclerosis and the changes of artery structures.Results Compared with the cells treated by normal glucose,high glucose significantly enhanced the cell proliferation,markedly increased the expression of H3k9 methylation,obviously decreased the expression of VSMCs-specific genes SM22α and SMA-α in rat A7r5-derived aortic smooth muscle cells.In addition,H3K9 methylation inhibitor significantly suppressed the cell proliferation,while obviously increased the expression of VSMCs-specific genes SM22α and SMA-α in rat A7r5-derived aortic smooth muscle cells.Finally,compared with the mice of control groups,the atherosclerosis leison area and the necosis area significantly decreased in the mice of experimental groups;the collagen content significantly rised in the mice of experimental groups;the expresion of H3K9me3 significantly decreased while the exprssion of VSMCs-specific genes SM22α and SMA-α remarkably increased in the mice of experimental groups.Conclusions H3K9 methylation may play an important role in the down-expression of VSMCs-specific genes SM22α and SMA-α induced by high glucose in A7r5-derived aortic smooth muscle cells,which may further promote the phenotypic switching of vascular smooth muscle cells and cell proliferation.