Profile genome-wide DNA methylation of human granulosa cells in primary ovarian insufficiency

Background Premature ovarian failure which leads to loss of fertility and low level of estrogen have serlously affected women's physical and mental health, especially, women of child-bearing age. The etiology remains unclear. DNA methylation, as a key epigenetic modification might play an importan role in primary ovarian insufficiency (POI). We explore the whole DNA methylation of POI by whole genome bisulfite sequencing (WGBS), and find the pattern of DNA methylation in POI and analyze the differentially methylated regions (DMRs) genes related POI. Methods According to clinical and experimental standards, follicular fluid samples were collected from three women with POI and three women with normal ovarian reserve (NOR). Ovarian granulosa cells were purified from each follicular fluid sample. Whole genomic DNA methylation sequencing of the granulosa cells was performed by WGBS. Results We obtained whole-genome methylation maps of human granulosa cells. The average percentages of methylated cytosines in CG contexts exceeded 99%, in CHG and CHH contexts was less than 1%. The average methylation level in CG was about 80%, in CHG and CHH was less than 0.4%. there was no significant difference in CpG methylation level between NOR and POI. But there were DMRs between two groups. Distribution of DMRs was enriched in promoter and exon. Differentially methylated genes were used to perform Gene ontology(GO) analysis and enriched in GO items of cellular process, biological regulation, metabolic process, developmental process,binding and catalytic activities. Conclusion DNA methylation plays a critical role in POI and serve as resources for further investigation in the future.