Epigenetic silencing of microRNA-874-3p implicates in erectile dysfunction in diabetic rats by activating the Nupr1/Chop-mediated pathway.

Diabetes is a global medical problem that causes many deaths every year. Complications caused by diabetes are serious and affect patients' quality of life. Diabetes mellitus erectile dysfunction (DMED) affects more than half of male diabetes patients. In this study, we determined the role of microRNA-874-3p (miR-874-3p) and nuclear protein-1 (Nupr1) in streptozocin-induced DMED rats. Control rats received equal amount of vehicle. These rats were also injected with lentiviral vector or agomir to silence or overexpress miR-874-3p or Nupr1. Apomorphine (100 μg/kg, s.c.) was used to induce erection and time of erection was recorded. Intracavernosal and mean arterial pressure ratio (ICP/MAP) were also recorded. O2- level and concentration of thiobarbituric acid reactive substances (TBARs) were detected using lucigenin-derived chemiluminescence method and Colorimetry. Rat cavernosum tissues were collected for subsequent experiments. Cavernosum smooth muscle cells (CSMCs) were also used for in vitro experiments. Nupr1 was found highly expressed (by RT-qPCR and Western blot analysis) in cavernosum tissues from DMED rats. Nupr1 silencing improved the ICP/MAP ratio and erection time. Nupr1 silencing also reduced CSMC apoptosis (by TUNEL assay) as well as decreased O2- level and TBAR concentration. Nupr1 was targeted and inhibited by miR-874-3p (by luciferase activity and RNA immunoprecipitation assays), which was downregulated in DMED. miR-874-3p downregulation was due to increased methylation at the promoter region (methylation-specific PCR). miR-874-3p overexpression improved erection time and reduced apoptosis. In summary, miR-874-3p was downregulated which led to increased apoptosis and erectile dysfunction in DMED rats, through inhibition of Nupr1-mediated pathway. This study may also provide a new therapeutic direction for the treatment of DMED.