RRBS-based quantitative methylation analysis define 100% methylation fidelity CpG sites

Stable maintenance of cytosine methylation is essential for mammalian biological processes such as gene transcription. This study introduced a RRBS-based quantitative method to identify CpG sites of high methylation fidelity (especially those 100% methylation fidelity sites). To separate the 100% methylation fidelity sites , we cultured the ARPE-19, Jurkat and SW1353 cells for lasting 10 generations, and we detected the methylation level of each CpG sites in the 20th generation and the 30th generation by performing reduced representation bisulfite sequencing (RRBS), to obtain the 100% methylation fidelity sites. The result shows that the number of overlapped fidelity methylation CpG sites of the two different time is smaller than number of each generation. Our results also showed that the proportion of high-fidelity 100% methylated sites in Jurkat and ARPE-19 cells is about 4.4% and 8.9%, and the proportion in SW1353 cells is 1.98%. The fidelity methylation sites obtained by the comparison of the two different time periods are the truly unchanged CpG sites during cell passage, which improves the reliability of the fidelity methylation sites. In summary, we provide new insights into the DNA methylation fidelity study. Using RRBS to detect the methylation level of two generation cells.