To analyze the dynamic changes of N6-methyladenine (m6A) methyltransferase-like 3 (METTL3) in renal ischemia-reperfusion injury (IRI) rat models.

Twenty healthy adult male SD rats were selected and divided into IRI group and sham operation group (Sham group) according to the random number method. The IRI group was further divided into three subgroups as IRI 24 h group, IRI 48 h group and IRI 72 h group according to different phases after renal ischemia-reperfusion. There are 5 rats in each group. Rat serum creatinine and urea nitrogen levels were measured, and renal tissue HE staining was performed. Real-time quantitative polymerase chain reaction was used to detect the relative transcription level of METTL3 mRNA, and Western blot was used to detect the relative expression of METTL3 protein. One-way analysis of variance was used for comparison among multiple groups, and the LSD method was used for pairwise comparisons. When the data did not meet normal distribution and homogeneity of variance, the Kruskal-Wallis H test was used for comparisons between multiple groups, and the Bonfferoni method was used for pairwise comparisons. Correlation analysis was performed using the Pearson method. P<0.05 was regarded as statistically significant.

The serum creatinine of rats in the Sham group and the IRI 24 h, 48 h and 72 h groups were (15.8±2.28), (57.8±6.50), (37.0±6.00) and (29.8±5.02) μmol/L, respectively, and the urea nitrogen of all groups were (3.86±0.45), (16.48±2.49), (7.09±0.91) and (5.49±0.75) mmol/L, respectively. The differences were statistically significant (F=56.44 and 81.83, P all <0.05). Pathological staining of rat kidney tissue showed that the morphology of the rat kidney tissue in the Sham group was normal, and acute lesions had appeared in the IRI 24 h group, aggravated in the IRI 48 h group, and were still obvious in the IRI 72 h group. The relative modification levels of total m6A in the Sham group and the IRI 24 h, 48 h and 72 h groups were (1.00±0.36), (8.53±3.29), (4.41±1.12) and (2.40±0.93), respectively. Relative expression levels of METTL3 protein were (1.00±0.29), (6.37±2.59), (2.06±0.76) and (1.55±0.63), respectively. The relative transcription levels of METTL3 mRNA were (1.00±0.04), (2.52±0.67), (1.86±0.21) and (0.84±0.22), respectively. The differences were all statistically significant (F=16.43, 15.54 and 13.56, all P<0.05). The total m6A modification level was positively correlated with serum creatinine and urea nitrogen (r=0.7963 and 0.7670, all P<0.05). The mRNA level of METTL3 was positively correlated with serum creatinine, urea nitrogen and total m6A modification level (r=0.7208, 0.7957 and 0.8313, all P<0.05).

In the early process of IRI, the expression level of METTL3 and the level of total m6A modification increased, suggesting that the level of METTL3 and total m6A modification may be of great significance for the early real-time assessment of IRI.