Diabetic erectile dysfunction (DMED) is one of the common complications of diabetes, which seriously affects the quality of life in diabetic men. As a frontier of epigenetic research, RNA m5C modification has been shown to be closely related to cardiovascular disease and diabetic complications, but its role in DMED has not yet been clarified. Therefore, this study aims to explore the role of m5C in DMED and its potential mechanism.

1. Streptozotocin was used to establish the model of diabetic rat. Primary corpus cavernosum smooth muscle cells (CCSMC) were extracted and continuously cultured in the high glucose environment (30mmol/L) in vitro. The m5C modification level and the expression of related methyltransferases in tissues and cells were determined by WB, Q-PCR, RNA-seq and other methods. 2. CRISPRi/dCas9 technology was used to downregulate the expression of NSUN2 in CCSMC, and m5C MeRIP-seq was used to detect the m5C modification level and m5C differentially modified genes. 3. CCSMC were divided into control group, high glucose group, and high glucose + NSUN2-CRISPRi group, and cellular function and related molecules in each group were detected with a series of methods.

1. Compared with normal rats, the erectile function of rats in the DMED group was impaired. The m5C modification level and the expression of methyltransferase NSUN2 in the corpus cavernosum increased, and the results in CCSMC were consistent with those in the tissue. 2. After downregulating the expression of NSUN2 in CCSMC, the cellular m5C modification level decreased, and the changes of DPP4 among the m5C differentially modified genes were the most significant. Enrichment analysis showed that m5C differentially modified genes were closely related to the processes of oxidative stress and ferroptosis. 3. Under high glucose conditions, CCSMC cellular viability decreased, while the levels of DPP4 expression, oxidative stress and ferroptosis increased. Down-regulating NSUN2 expression could reverse the above changes to a certain extent.

RNA m5C modification is closely related to the onset of diabetic ED. NSUN2 could regulate DPP4 m5C modification to aggravate cellular ferroptosis and promote the occurrence of DMED. Our study provides new ideas and scientific basis for the treatment of DMED.