In this study, we investigated the association between altered methylation in the maternal placenta and hyperglycaemia and explored the epigenetic mechanisms underlying gestational diabetes mellitus (GDM). Reduced representation bisulphite sequencing (RRBS) and RNA sequencing (RNA-seq) were performed on placental tissues obtained from women with GDM and healthy controls. Further, pyrosequencing, correlation analyses, and linear regression analyses were performed to valuate relationships between aberrantly methylated-differentially expressed genes and clinical parameters. The EMBOSS and JASPAR databases were used for a computational analysis of CpG islands and transcription factor-binding sites in the TRIM67 promoter region. A CpG island with a length of 264 bp in the placental TRIM67 promoter region in the GDM group exhibited significant hypermethylation at four CpG sites. The hypermethylation of the TRIM67 promoter region in the maternal placenta showed a significant, positive correlation with the 1 h and 2 h oral glucose tolerance test (OGTT) values and a negative correlation with lipoprotein(a). Placental DNA methylation levels in the TRIM67 promoter region were markedly elevated in GDM and were associated with blood glucose and lipid levels during healthy pregnancy.
Keywords: DNA methylation; Gestational diabetes mellitus; TRIM67 promoter region; placenta.