Antihypertensive effects of an aromatase inhibitor in inbred salt-sensitive rats

EZH2 reduction is an essential mechanoresponse for the maintenance of super-enhancer polarization against compressive stress in human periodontal ligament stem cells

Despite the ubiquitous mechanical cues at both spatial and temporal dimensions, cell identities and functions are largely immune to the everchanging mechanical stimuli. To understand the molecular basis of this epigenetic stability, we interrogated compressive force-elicited transcriptomic changes in mesenchymal stem cells purified from human periodontal ligament (PDLSCs), and identified H3K27me3 and E2F signatures populated within upregulated and weakly downregulated genes, respectively. Consistently, expressions of several E2F family transcription factors and EZH2, as core methyltransferase for H3K27me3, decreased in response to mechanical stress, which were attributed to force-induced redistribution of RB from nucleoplasm to lamina. Importantly, although epigenomic analysis on H3K27me3 landscape only demonstrated correlating changes at one group of mechanoresponsive genes, we observed a genome-wide destabilization of super-enhancers along with aberrant EZH2 retention. These super-enhancers were tightly bounded by H3K27me3 domain on one side and exhibited attenuating H3K27ac deposition and flattening H3K27ac peaks along with compensated EZH2 expression after force exposure, analogous to increased H3K27ac entropy or decreased H3K27ac polarization. Interference of force-induced EZH2 reduction could drive actin filaments dependent spatial overlap between EZH2 and super-enhancers and functionally compromise the multipotency of PDLSC following mechanical stress. These findings together unveil a specific contribution of EZH2 reduction for the maintenance of super-enhancer stability and cell identity in mechanoresponse.

Sex differences in primary hypertension

Men have higher blood pressure than women through much of life regardless of race and ethnicity. This is a robust and highly conserved sex difference that it is also observed across species including dogs, rats, mice and chickens and it is found in induced, genetic and transgenic animal models of hypertension. Not only do the differences between the ovarian and testicular hormonal milieu contribute to this sexual dimorphism in blood pressure, the sex chromosomes also play a role in and of themselves. This review primarily focuses on epidemiological studies of blood pressure in men and women and experimental models of hypertension in both sexes. Gaps in current knowledge regarding what underlie male-female differences in blood pressure control are discussed. Elucidating the mechanisms underlying sex differences in hypertension may lead to the development of anti-hypertensives tailored to one's sex and ultimately to improved therapeutic strategies for treating this disease and preventing its devastating consequences.

Sex and Body Mass Index Specific Regulation of Blood Pressure by CYP19A1 Gene Variants

Sexual dimorphism in blood pressure (BP) regulation has been observed both in humans and experimental animals, and estrogens have been shown to contribute to this epidemiological observation. A key enzyme in determining estrogen levels is aromatase cytochrome P450. The aim of this study was to evaluate the role of the gene encoding aromatase, CYP19A1, as an independent risk factor for hypertension and its relationship with systolic and diastolic BP measures. We genotyped 2 polymorphisms within the CYP19A1 gene, IVS4 rs11575899 and 3'UTR rs10046, in 3448 individuals. In quantitative analysis, we observed significant associations between the 2 polymorphisms and BP values in women, being these associations dependent on BMI and independent of menopause status. The case-control analysis revealed that the most prominent associations were found for nonobese women in diastolic hypertension (DHT): the IVS4_22 and 3'UTR_11 are risk genotypes (OR=1.61, P=0.027 and OR=1.59, P=0.012, respectively), whereas IVS4_11 and 3'UTR_22 genotypes have a protective effect against DHT (OR=0.63, P=0.009, and OR=0.61, P=0.020, respectively). Haplotype analysis confirmed the above associations: among nonobese women the haplotype 21 is overrepresented in hypertensive women (OR=1.33, P=0.004, for DHT and OR=1.25, P=0.026, for systolic hypertension, SHT) and, conversely, the haplotype 12 protects against hypertension (OR=0.78, P=0.015 for DHT and OR=0.82, P=0.04 for SHT). Our study has shown that the CYP19A1 gene may be involved in the genetic regulation of BP in women. This effect is dependent on BMI and independent of menopause status, suggesting that this action is mainly driven by aromatase activity in fat tissue.

Variation in estrogen-related genes and cross-sectional and longitudinal blood pressure in the Framingham Heart Study

OBJECTIVE

To examine the association between variation in estrogen-related genes and cross-sectional and longitudinal blood pressure in men and women.

DESIGN

In 1780 unrelated members of the community-based Framingham Heart Study offspring cohort, systolic blood pressure and diastolic blood pressure were measured over a total of six examination cycles encompassing 24 years of follow-up. Multivariate regression analyses were used to assess the relation between untreated cross-sectional and longitudinal blood pressure and polymorphisms at the estrogen receptor-alpha (ESR1), estrogen receptor-beta (ESR2), aromatase (CYP19A1), and nuclear receptor coactivator 1 (NCOA1) genes after adjustment for common risk factors.

RESULTS

In men, systolic blood pressure and pulse pressure (systolic blood pressure minus diastolic blood pressure) were associated with two polymorphisms in ESR1, while pulse pressure was also associated with variations in NCOA1 and CYP19A1. Polymorphisms in ESR1, CYP19A1, and NCOA1 were associated with diastolic blood pressure in women.

CONCLUSIONS

Although the underlying relations between genes involved in estrogen action and hypertension remain to be completely understood, our findings provide suggestive evidence of gender-specific contributions of estrogen-related genes to blood pressure variation. As no correction for multiple testing was performed in the analyses, we view these results as suggestive and not definitive. Further studies are warranted to confirm these results using a comprehensive set of polymorphisms in order to shed more light on the involvement of estrogen in blood pressure regulation.

19-Nor-corticosteroids in genetic hypertension. Effects of inhibitors of 11 beta, 18, 19-hydroxylase activity

The long-term objective is to understand the role of the adrenal in altering systemic arterial blood pressure. This paper summarizes research on genetic hypertension in the rat and bears a relationship to several forms of human hypertension in which defects of steroid hydroxylases lead to increased secretion of mineralocorticoids other than aldosterone in genetic and experimental hypertension in rats. We demonstrated that 19-nor-corticosteroids are produced in excess in genetic and experimental hypertension in rats and man. We studied the enzymatic alteration responsible for excessive production of 19-nor-deoxycorticosterone (19-nor-DOC) in the salt-sensitive hypertensive rat S/JR. Biosynthesis of 19-nor-steroids involves hydroxylation of the C-19 methyl group. We characterized the adrenal 11 beta, 18,19-hydroxylase enzyme system in inbred salt-sensitive and resistant rats (R/JR). This system is capable of all three hydroxylations. The Km for 19-hydroxylation was different from S/JR and R/JR but was much greater for 11 beta- and 18-hydroxylation in both. This suggested that the catalytic site for 19-hydroxylation is different from that for 11 beta and 18. The S/JR adrenal enzyme binds the substrate with higher affinity than does the R/JR adrenal enzyme. We were unable to distinguish the cDNAs of the S/JR from the R/JR adrenal enzyme from bovine 11 beta-hydroxylase cDNA by restriction mapping. We were unable to demonstrate restriction length polymorphism. 19-Acetylenic DOC is an inhibitor which preferentially inhibits the 19-hydroxylation of DOC, and does not interfere with the 18- and 11 beta-hydroxylation. This inhibition leads to a reduction in blood pressure in the S/JR Dahl rat. We suggest that an S/JR 19-nor-DOC is involved in the development of salt-sensitivity and hypertension and that inhibition of its formation by acetylenic DOC and other aromatase and non-aromatase inhibitors is associated with reversal of these phenomena.