Presentation Authors: Zhe Yu*, Zhe Tang, Jun Yang, Jihong Liu, Wuhan, China, People's Republic of
Introduction: Cavernosal smooth muscle relaxation is a key composition for normal erection. MicroRNAs (miRs) are noncoding single-stranded RNAs that regulate the expression of genes involved in various pathophysiologic processes. In the present study, we explored the miRs profile in the corpus cavernosum (CC) of diabetic rats with erectile dysfunction (ED) and investigated the role of selected miR in regulating the contraction of CC smooth muscle (CCSM) in diabetic ED rats.
Methods: Agilent Rat miRNA V18.0 microarray was used to determine the expression profile of miRs in diabetic ED rats. After comparative analysis, 3 miRs appeared distinctly expressed in diabetic ED group (fold change â‰¥ 3), and the aberrantly expressed miRs were further confirmed by qPCR. Among them, the expression of â€œmyomiRâ€, miR-133b, was identified as a candidate for CCSM contraction processes. CCSM cells were cultured in high glucose conditions as a diabetic model. Streptozotocin-induced Sprague-Dawley rats were set up, and an apomprphine test was conducted to confirm diabetic ED. The role of miR-133b in regulating CCSM was then explored by up- and downregulation its expression in vitro and in vivo.
Results: The protein expressions of p-MYPT1 and p-CPI-17 were increased while expression of miR-133b was decreased in diabetic condition. A luciferase reporter assay confirmed that miR-133b targeted 3â€™-UTR of the specificity protein 1 (SP1). ChIP assay demonstrated that SP1 can interact with the GC-rich region in the MYPT1 promoter and CPI-17 gene promoters were governed by the proximal GC-boxes, where SP1 transcription factors bound. Up-regulation of miR-133b could down-regulate the expression of SP1, dramatically revert HG-induced phosphorylation level of MYPT1 at The853 of MLCP and CPI-17 at Thr38. In vivo experiment exhibited erectile function in miR-133b agomir group was markedly increased in the diabetic rats compared with the negative control groups and diabetic ED group. Mechanistically, consistented with in vitro experiments, miR-133b supplementation induced relaxation of the CCSM via nitric oxide-independent pathways.
Conclusions: Three miRs were found in diabetic ED rat model. The present results indicate that miR-133b supplementation could improve erectile function in diabetic ED rats probably by regulating the contractility of CCSM via myosin light chain phosphatase inhibition.
Source of Funding: National Natural Science Foundation of China