Abstract:

Objective To investigate the effects of recombinant human erythropoietin (rHuEPO) on the expression of erythropoietin receptor (EPOR) and its downstream signaling pathway in normal and insulin-resistant 3T3-L1 adipocytes. Methods The model of insulin-resistant 3T3-L1 adipocytes were induced by 1 μmol/L dexamethasone (model group), and the welldifferentiated normal 3T3-L1 adipocytes were served as control group. The expression of EPOR protein in cells was detected by immunofluorescence staining and Western blotting, and the expression of EPOR mRNA was determined by Real-Time PCR. Cells in model group and control group were intervened with rHuEPO, phosphatidylinositol-3-kinase (PI3K) inhibitor (LY294002) and signal transducer and activator of transcription 5(STAT5), and the effects of different interventions on the expression of EPOR protein and phosphorylation of downstream molecules of serine/threonine kinase (AKT) and STAT5 (p-Akt and p-STAT5 protein) were examined by Western blotting. Results The expression of EPOR protein and mRNA in model group was significantly lower than that in control group (P<0.05). The intervention experiment revealed that the relative expression of EPOR, p-Akt and p-STAT5 protein in rHuEPO+control group or model group was significantly higher than that in corresponding control group or model group (P<0.05), and the relative expression of p-Akt and p-STAT5 protein in rHuEPO+LY29400 or STAT5 blocker+control group or model group was significantly lower than that in corresponding rHuEPO+control group or model group (P<0.05). Conclusion EPOR exists in normal 3T3-L1 adipocytes, the expression of EPOR protein and mRNA in insulin-resistant 3T3-L1 adipocytes decreases, and rHuEPO can activate PI3K-Akt and JAK2-STAT5 signaling pathway through EPOR mediation.

Key words: 3T3-L1 adipocytes, insulin resistance, erythropoietin receptor, human erythropoietin