Abstract: Objective To explore the relationship between microRNA let-7a-3 gene promoter methylation and diabetic nephropathy(DN). Methods Methylation sites were predicted in the promoter region of let-7a-3 gene by bioinformatics methods. Real-time PCR and real-time methylation specific PCR (qMSP) were used to detect the expression and methylation levels in 20 cases of diabetic nephropathy patients (DN group), 20 patients with diabetes mellitus (DM group) and 20 cases of normal control (CON group). Results Let-7a-3 was down-expressed in DN group compared with that in DM and CON groups. Moreover, the average methylation ratio of let-7a-3 was 96.2% ± 6.2% in DN group, 76.6% ± 18.9% in DM group, and 63.2% ± 28.4% in CON group. The average methylation ratio of let-7a-3 in DN group was significantly higher than that in CON and DM groups (P<0.01). Conclusion Promoter hypermethylation of let-7a-3 may play a role in the down-expression of let-7a-3, and may participate in the regulation of the occurrence and development of diabetic nephropathy.

Key words: diabetic nephropathy, let-7a-3, methylation