[Establishment and application of HPLC-MS/MS method for detecting m6A level in RNA]

Objective: Explore the establishment of a fast, stable and sensitive high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method for detecting the level of m6A modification in RNA and its application. Methods: The degree of m6A in RNA can be expressed as the ratio of m6A and adenosine (A) in concentration, which can be determined by ESI source positive ion multiple reaction monitoring (MRM) mode. The established method was verified by analyzing three quality control samples (m6A: 4, 40, 400 nmol/L; A: 40, 400, 4 000 nmol/L) with three different concentrations of low, medium, and high. The method was used to detect the degree of m6A in RNA from mouse spleen T cells treated in different ways. The t test was used to compare the differences between the two groups of data. Results: The established method had a good Linearity (R²>0.99) in a range of 1-500 nmol/L for m6A and 10-5 000 nmol/L for A. The limit of detection (LOD) was 1 nmol/L for m6A and 10 nmol/L for A. The recoveries were between 98.9% and 116.5%. The intra-day (n=5) RSDs and the inter-day (n=15, 5 days) RSDs were 2.4%-9.5% and 4.4%-9.6%, respectively. And this method was used to detect the degree of m6A in the RNA from mouse spleen T cells cultured in different conditions. The results showed that the m6A modification level in the RNA of primary CD8⁺T cell was 0.271 5±0.017 9, and the m6A modification level in the RNA of primary CD8⁺T cell with IL-27 was 0.251 7±0.015 0, indicating that primary CD8⁺T cells have a higher level of RNA methylation. Conclusion: This research has established a fast, simplemethylation degree in RNA with HPLC-MS/MS. This method is easy to be popularized and is suitable for the detection of large quantity of samples, and of great significance in analyzing the relationship between methylation and diseases.