Altered microRNA expression in stenoses of native arteriovenous fistulas in hemodialysis patients

Objective: Arteriovenous fistula (AVF) disfunction is largely due to venous stenosis characterized by a marked amount of intima-media hyperplasia. However, the molecular mechanisms are currently poorly understood. MicroRNAs (miRNAs), small noncoding RNAs that are post-transcriptional regulators of gene expression, could provide insights into a mechanism for the differential expression of genes in stenotic AVFs. Methods: A microarray study was done to detect differences in miRNA levels between stenotic AVF (n = 8) and controls (n = 4). Real-time quantitative reverse-transcription polymerase chain reaction assays with 12 stenotic AVF veins and eight control veins from predialytic patients were used for verification. Putative gene targets were retrieved from miRNA target prediction databases. Networks from the target gene set were created and examined. Western blotting and immunohistochemical staining were performed to confirm the bioinformatic findings. Results: A microarray study identified 33 miRNAs with markedly different expression levels between stenotic AVFs and control veins. Among them, nine miRNAs were upregulated and 24 miRNAs were downregulated in the stenotic AVFs. Real-time reverse-transcription polymerase chain reaction confirmed statistically consistent expression of six selected miRNAs with microarray analysis. The predicted miRNA target genes differentially expressed in stenotic AVF based on databases were identified. The mitogen-activated protein kinase signaling pathway might be regulated by miRNAs according to bioinformatic analyses and further confirmed by Western blotting and immunohistochemical staining. Conclusions: Our genome-wide approach identified several differentially expressed miRNAs in stenotic AVFs. This study also suggested that the mitogen-activated protein kinase signaling pathway might play a role in the pathogenesis of stenotic AVF.