Methylation of promoter regions of genes of the human intrauterine Renin Angiotensin system and their expression

Fetal Membrane Epigenetics

The characteristics of fetal membrane cells and their phenotypic adaptations to support pregnancy or promote parturition are defined by global patterns of gene expression controlled by chromatin structure. Heritable epigenetic chromatin modifications that include DNA methylation and covalent histone modifications establish chromatin regions permissive or exclusive of regulatory interactions defining the cell-specific scope and potential of gene activity. Non-coding RNAs acting at the transcriptional and post-transcriptional levels complement the system by robustly stabilizing gene expression patterns and contributing to ordered phenotype transitions. Here we review currently available information about epigenetic gene regulation in the amnion and the chorion laeve. In addition, we provide an overview of epigenetic phenomena in the decidua, which is the maternal tissue fused to the chorion membrane forming the anatomical and functional unit called choriodecidua. The relationship of gene expression with DNA (CpG) methylation, histone acetylation and methylation, micro RNAs, long non-coding RNAs and chromatin accessibility is discussed in the context of normal pregnancy, parturition and pregnancy complications. Data generated using clinical samples and cell culture models strongly suggests that epigenetic events are associated with the phenotypic transitions of fetal membrane cells during the establishment, maintenance and termination of pregnancy potentially driving and consolidating the changes as pregnancy progresses. Disease conditions and environmental factors may produce epigenetic footprints that indicate exposures and mediate adverse pregnancy outcomes. Although knowledge is expanding rapidly, fetal membrane epigenetics is still in an early stage of development necessitating further research to realize its remarkable basic and translational potential.

Functional relevance of promoter CpG island of human Angiotensin II type 1 receptor (AT1R) gene

Angiotensin II type 1 receptor can activate number of signalling pathways upon stimulation and consequently its involvement in cancer progression have also been revealed. But which epigenetic mechanisms are involved in its regulation, need to be further explored. In-silico analysis revealed a promoter CpG island (CGI) which was cloned and assayed for functional activity using reporter gene system. The effect of methylation on this CGI was analysed through varying degree of methyltransferase treatment of cloned fragment. Results thus obtained were validated by direct sequencing. To further establish the status of this effect, in-vivo analysis was done through screening of methylation pattern in the targeted region among hypertensives (HTN) and normotensives (NTN) using PCR-Bisulphite sequencing. Additionally, clinical details of all participants, biochemical parameters and lifestyle related information was also collected and statistically evaluated. Reporter gene assay assigned functional activity to the cloned promoter CpG island. Increased dose and durations of methyltransferase treatment decreased the expression of reporter gene indicating the role of promoter DNA methylation. Among all the human samples screened, only one of the HTN individual was found to have single hemi-methylated CpG site at a position which happens to be a part of Sp1 transcription factor binding site. To conclude, CpG island in the promoter region of AT1R (CpG.P.AT1R) gets regulated through epigenetic mechanism of DNA methylation.

AGTR1 promoter hypermethylation in lung squamous cell carcinoma but not in lung adenocarcinoma

Aberrant DNA methylation is associated with non-small cell lung cancer (NSCLC), suggesting that gene promoter methylation may be a potential biomarker for the detection or risk prediction of NSCLC. The present study aimed to evaluate the potential usage of angiotensin II receptor type 1 (AGTR1) methylation in two major pathologic subtypes: Lung adenocarcinoma (LUAD) and lung squamous cell carcinoma (LUSC). Quantitative methylation-specific polymerase chain reaction was used to investigate the effect of AGTR1 promoter methylation in the tumor and the paired adjacent non-tumor tissue samples from 42 patients with LUSC, and 69 with LUAD. The percentage of methylated reference was calculated and presented as the median (interquartile range 25th-75th percentile). The results of the current study revealed that there was significantly increased AGTR1 promoter methylation in the tumor tissues compared with the paired adjacent non-tumor tissue [97.4 (57.22-130.5) vs. 85 (48.25-123); P=0.024]. Furthermore, higher AGTR1 promoter methylation was observed in patients with LUSC compared with LUAD (odds ratio=2.483; 95% confidence interval=1.125-5.480; P=0.023). Significant differences were identified in AGTR1 methylation between non-tumor and the tumor tissues in LUSC [113.5 (68.33-148.73) vs. 93.04 (45.94-140); P=0.008]. In addition, the Cancer Genome Atlas data of 378 patients with LUSC and 477 with LUAD revealed an inverse correlation between gene expression and the methylation status of AGTR1 promoter.. These data suggest that AGTR1 hypermethylation is a promising biomarker to assist in LUSC detection and diagnosis.

Preeclampsia and the brain: neural control of cardiovascular changes during pregnancy and neurological outcomes of preeclampsia

Preeclampsia (PE) is a form of gestational hypertension that complicates ∼5% of pregnancies worldwide. Over 70% of the fatal cases of PE are attributed to cerebral oedema, intracranial haemorrhage and eclampsia. The aetiology of PE originates from abnormal remodelling of the maternal spiral arteries, creating an ischaemic placenta that releases factors that drive the pathophysiology. An initial neurological outcome of PE is the absence of the autonomically regulated cardiovascular adaptations to pregnancy. PE patients exhibit sympathetic overactivation, in comparison with both normotensive pregnant and hypertensive non-pregnant females. Moreover, PE diminishes baroreceptor reflex sensitivity (BRS) beyond that observed in healthy pregnancy. The absence of the cardiovascular adaptations to pregnancy, combined with sympathovagal imbalance and a blunted BRS leads to life-threatening neurological outcomes. Behaviourally, the increased incidences of maternal depression, anxiety and post-traumatic stress disorder (PTSD) in PE are correlated to low fetal birth weight, intrauterine growth restriction (IUGR) and premature birth. This review addresses these neurological consequences of PE that present in the gravid female both during and after the index pregnancy.