DNA methylation in the norepinephrine transporter gene promoter region is not associated with depression and hypertension

Serum Angiotensin-Converting Enzyme Methylation Level and Its Significance in Patients With Comorbid Major Depressive Disorder and Hypertension

OBJECTIVE

Major depressive disorder (MDD) often coexists with hypertension (HYT). DNA methylation has elicited vital functionality in their development. Angiotensin-converting enzyme (ACE) is a vital enzyme in blood pressure. This study investigated the effect of ACE methylation on depression and HYT severity in patients with comorbid MDD and HYT (MDD + HYT).

METHODS

A total of 119 patients (41 men, 78 women, average age: 56.8 ± 9.1 years) with MDD + HYT were enrolled, with 89 healthy subjects (29 men, 60 women, average age: 57.4 ± 9.7 years) were enrolled. The Hamilton Depression Rating Scale-17 and self-rating depression scale scoring scales were used to assess the depression degree of patients, serum ACE methylation level in MDD + HYT patients was measured by means of bisulfite sequencing polymerase chain reaction, with subsequent analysis of the diagnostic efficacy of ACE methylation for MDD + HYT. The independent risk factors for sMDD + HYT were explored.

RESULTS

Serum ACE methylation levels were significantly increased in MDD + HYT patients. The area under the curve of serum ACE methylation level for accurate diagnosis of MDD + HYT was 0.8471, and the cut-off value was 26.9 (sensitivity 83.19%, specificity 73.03%). ACE methylation was an independent risk factor for sMDD + HYT (P = 0.014; odds ratio, 1.071; 95% confidence interval = 1.014-1.131).

CONCLUSION

The elevated serum ACE methylation level (P < 0.001) in patients with MDD + HYT elicited definite diagnostic values for MDD + HYT, and ACE methylation level was independently correlated with sMDD + HYT (P < 0.05).

The role of DNA methylation and histone modifications in blood pressure: a systematic review

Epigenetic mechanisms might play a role in the pathophysiology of hypertension, a major risk factor for cardiovascular disease and renal failure. We aimed to systematically review studies investigating the association between epigenetic marks (global, candidate-gene or genome-wide methylation of DNA, and histone modifications) and blood pressure or hypertension. Five bibliographic databases were searched until the 7th of December 2018. Of 2984 identified references, 26 articles based on 25 unique studies met our inclusion criteria, which involved a total of 28,382 participants. The five studies that assessed global DNA methylation generally found lower methylation levels with higher systolic blood pressure, diastolic blood pressure, and/or presence of hypertension. Eighteen candidate-gene studies reported, in total, 16 differentially methylated genes, including renin-angiotensin-system-related genes (ACE promoter and AGTR1) and genes involved in sodium homeostasis and extracellular fluid volume maintenance system (NET promoter, SCNN1A, and ADD1). Between the three identified epigenome-wide association studies (EWAS), lower methylation levels of SULF1, EHMT2, and SKOR2 were found in hypertensive patients as compared with normotensive subjects, and lower methylation levels of PHGDH, SLC7A11, and TSPAN2 were associated with higher systolic and diastolic blood pressure. In summary, the most convincing evidence has been reported from candidate-gene studies, which show reproducible epigenetic changes in the interconnected renin-angiotensin and inflammatory systems. Our study highlights gaps in the literature on the role of histone modifications in blood pressure and the need to conduct high-quality studies, in particular, hypothesis-generating studies that may help to elucidate new molecular mechanisms.

Altered expression of norepinephrine transporter participate in hypertension and depression through regulated TNF-α and IL-6

Aim: We explored the role of histone modification in the association of depression-hypertension by comparing norepinephrine transporter (NET) gene levels in different depression-hypertensive patients. Then, we analyzed the expression of NET correlation with inflammatory cytokines to provide a new direction for detecting the association mechanism between depression and hypertension.Methods: NE expression levels in serum of diverse groups were detected by enzyme-linked immunosorbent assay. Then histone acetyltransferase (HAT), histone deacetylase (HDAC), H3K27ac, NET, TNF-α, and interleukin-6 (IL-6) were detected by western blot in nine female subjects in different depression and hypertension groups, and Chromatin immunoprecipitation-polymerase chain reaction (Chip-PCR) were used to confirm the degree of acetylation affecting on the transcription level of NET gene. Meanwhile, correlation between NET with TNF/IL-6 was analyzed by SPSS19.0 software program. Finally, Quantitative real-time polymerase chain reaction (qPCR) and western blot were used to detect TNF-α and IL-6 expression levels after NET overexpression or interference treatment in human umbilical vein endothelial cells and Neuro-2a cells.Results: The expression of HAT and H3K27ac had lower levels in D-H and nonD-H group than nonD-nonH group. The results showed that higher acetylation could promote expression of NET genes. Meanwhile, the expression of NET had a significant negative correlation with IL-6 (R = -0.933, p < 0.01) and tumor necrosis factor (TNF) (R = -0.817, p < 0.01) in subjects. In addition, the results confirmed that TNF-α and IL-6 mRNA and protein partial expressions could be inhibited by NET in both HUVECs and Neuronal cells (p < 0.01).Conclusion: In conclusion, differential expression of NET gene might function as an important factor in interaction between depression and hypertension by partially targeting TNF-α and IL-6.