Background. The current study aims to explore the effects of advanced glycation end products (AGEs) on the microRNA (miRNA) expression profile in kidney tissues in a murine diabetic nephropathy (DN) model, and to investigate the possible underlying mechanisms.
Methods. Wister rats were randomly divided into three equal experiment groups, the AGE group, the RSA group and the control group. The rats in the AGE group and the RSA group were administered with AGEs and rat serum albumin (RSA) via the tail vein, respectively, whereas those in the control group received no injection. Following the extraction of total RNA from the murine kidney tissues, miRNA profiling was performed using a miRNA microarray to determine the global differences in miRNA expression between the three experiment groups. The identified panel of aberrantly expressed miRNA candidates were subsequently validated by quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR). Bioinformatics analysis was performed to identify the target genes and enriched signaling pathway for the validated miRNAs.
Results. Compared with RSA group, miR-7d-3p, miR-92b-3p, miR-181b-5p and miR-196c-5p were found to be significantly up-regulated in the AGE group, whereas miR-7a-1-3p, miR-186-5p, miR-192-5P, miR-196b-5p and miR-345-5p were shown to be down-regulated (p<0.05). Among the nine miRNA candidates, miR-92b-3p was validated by qRT-PCR analysis. Subsequent bioinformatic study indicated that SMAD7 could be a potential downstream gene target of miR-92b-3p. Both immunohistochemical staining and western blotting showed that SMAD7 expression was significantly suppressed in the kidney tissues harvested from the AGE group compared to those from the control and the RSA group.
Discussion. The results of the current study revealed a correlation between increased renal level of miR-92b-3p and elevated serum level of AGEs in a murine model of DN.