Association of mitofusin 2 methylation and essential hypertension: a case-control study in a Chinese population

Mitofusin 2 (Mfn2), a gene that negatively regulates the proliferation of vascular smooth muscle cells (VSMCs), is expressed at low levels in the VSMCs of hypertensive patients. DNA methylation can inhibit gene expression. The purpose of this study was to investigate the relationship between Mfn2 methylation and essential hypertension (EH). After bioinformatics analysis, five EH patients and five normal control (NC) subjects were selected for methylation chip screening. Then, bisulfite DNA sequencing was used to analyze the methylation status of differentially methylated fragments of Mfn2 in 40 EH patients and 36 NC subjects. Mfn2 mRNA expression in the blood was detected by RT-qPCR. There were three CpG islands in the full length Mfn2 DNA sequence and some transcription factor binding sites in these regions, including Sp1, Ap2, GATA box, NF-κB, etc. The chip screening showed that only the third CpG island had a significantly high degree of methylation. Subsequent verification experiments found that the EH group had a significantly lower C base rate of methylation than the NC group (2.5% vs. 44.44%, P < 0.0001), but a similar CpG methylation rate (P > 0.05). RT-qPCR detection showed that the level of Mfn2 mRNA expression was significantly lower in the EH group than in the NC group (P = 0.013). Further association analysis showed that the level of Mfn2 methylation was associated with systolic blood pressure and diastolic blood pressure (r = -0.902, r = -0.713, respectively) but not the other indexes. The DNA methylation level of Mfn2 was significantly lower in hypertensive patients than in control subjects, which may be an independent risk factor for EH.