Mechanism of Sos2 inhibiting NFATc1-mediated podocyte injury in diabetic nephropathy

AIM: To observe the effect of high glucose (HG) stimulation on the expression of guanine nucleotide exchange factor Sos2 (Son of Sevenless homolog 2) in mouse podocytes, and to explore the role of Sos2 in HG-induced podocyte damage and its possible molecular mechanisms. METHODS: The expression of Sos2 in the podocytes of diabetic nephropathy patients was observed by immunofluorescence staining and laser confocal microscopy. In vitro, the Sos2 expression at mRNA and protein levels in immortalized podocytes with HG (30 mmol/L glucose) stimulation for 48 h was determined by the methods of RT-PCR, Western blot and immunofluorescence. Using Western blot, immunofluorescence and wound-healing assay, the expression of podocin, the translocation of NFATc1 into the nucleus and the podocyte migration with or without Sos2 silencing or overexpression were analyzed. The expression of downstream target genes for NFATc1 was detected by RT-PCR. RESULTS: The expression of Sos2 was significantly decreased in the podocytes of diabetic nephropathy patients and in vitro cultured podocytes with HG stimulation (P<0.05). When Sos2 was silenced, the expression of podocin was significantly decreased, the migration ability of podocytes was increased, and the translocation of NFATc1 into the nucleus was increased (P<0.05). In contrast, after overexpression of Sos2 in the podocytes with HG stimulation, the podocin expression level was obviously higher, and the podocyte migration ability and the translocation of NFATc1 into the nucleus were decreased (P<0.05).CONCLUSION: Sos2 may attenuate the diabetic nephropathy-induced podocyte injury by inhibiting NFATc1.