Alternations in Mirna Expression in Chronic Stress-Induced Ageing of Leydig Cells

Purpose: Chronic stress represents a critical influence on ageing of Leydig cells in testis. We aimed to investigate expression changes of microRNA (miRNA) associated with stress-induced ageing in Leydig cells. Methods: Brown Norway rats were separated into three groups, young control group, stress group and age group. Physiological changes, including serum corticosterone and testosterone levels, 11β-HSD (11βhydroxysteroiddehydrogenase) activity, GSH/GSSG (glutathione/glutathione disulfide) ratio and DNA damage after chronic stress treatment were tested by radioimmunoassay and Immunohistochemistry. Differentially expressed miRNAs in Leydig cells between young control group and stress group were identified by miRNA microarray analysis, followed by target prediction of miRNAs. Functional annotation of predicted targets of miRNA was carried out using GeneSpring software and miRNA-target gene interaction network was built by String software. Results: Under chronic stress, increased serum corticosterone levels and reduced testosterone levels were observed. Meanwhile, decline of 11β-HSD activity and GSH/GSSG ratio, increase of DNA damage were also shown in stress group. After performed miRNA microarray analysis, three differentially expressed miRNAs were screened out, including rno-miR-31a-5p, rno-miR-192-5p and rno-miR-191a-3p. Targets of them were mainly involved in apoptosis, cell cycle and transport. In miRNA-target gene interaction network, targets of miR-31a-5p (Tp53, Ywhae and Ndel1), and targets of miR-192-5p (Cdk2, Rac2, Stk3) were with higher degree. Conclusion: These data suggest a central role of miRNA-regulated gene expression in response to chronic stress, especially dys-regulation of rno-miR-31a-5p and rno-miR-192-5p play a vital role in ageing of Leydig cells in testis.