Effects Of Glucose,Insulin And Dexamethasone On The Regulatory Activity Of The Musclin Promoter In Sheep

Musclin is a kind of myokines which can regulate the metabolism of glucose in muscle cells. Till now, its mechanism of transcription and expression regulation has not been clarified. The studies on the effects of glucose, insulin and dexamethasone on the musclin promoter activity has not been reported. Our research group had finished the construction and identification of the sheep musclin promotor-report gene (EGFP) expression vector. Therefore, in this test we treated C2C12 cells transfected with the musclin promoter expression vector with glucose, insulin and dexamethasone (a kind of synthetic glucocorticoid) in order to explore the effects of these factors on the transcriptional regulation of musclin promoter in sheep.The C2C12 cells transfected with sheep musclin promoter-reporter gene (EGFP) expression vector were treated separately with different concentrations of glucose (0,5,15,25,35mM), insulin (0,10?20? 30?40nM) alone or in combination with 35mM glucose and dexamethasone (0?10?100?1000 nM). After culturing for 24h,48h and 72h in normal medium (undifferentiation state) or induction and differentiation medium(differentiation state), we compared the changes of sheep musclin promoter activity with different treatment methods through the detection of EGFP mRNA expression by fluorescence quantitative PCR. The results as follows:1) Compared with that in the undifferentiated state, the sheep musclin promoter activity significantly increased after differentiation for 48h and its activity were highest in 72h.2) The sheep musclin promoter activities in undifferentiated and differentiated C2C12 cells at different time were all up-regulated by different concentrations of glucose and the total regularity is that the 35mM glucose group showed a relatively stable and high up-regulation at different time points.3) The sheep musclin promoter activities were all up-regulated by different concentrations of insulin whether in undifferentiated or differentiated C2C12 cells and whether in normal or hyper-glucose cultured C2C12 cells. The total regularity is that the 40nM insulin group showed a relatively stable and high up-regulation at different time points.4) Dexamethasone up-regulated the musclin promoter activity in the undifferentiated cells but the effects of dexamethasone on differentiated cells changed with the dose of dexamethasone and the differentiation state of the cells.