Association of ATP1B1, RGS5 and SELE polymorphisms with hypertension and blood pressure in African-Americans

Methylome profile of medaka eggs and sperm

Eggs and sperm are responsible for the continuation of generations. Following the epigenetic reprogramming of the embryo, core epigenetic information present in the sperm and eggs is transmitted to offspring somatic cells prior to the blastula stage, which specifically influences gene expression in the cells. Differences in the patterns of DNA methylation between the paternal and maternal genomes are critical to regulating allele-specific gene expression in the developing embryo, constituting the basis of genomic imprinting in mammals. While the information on allele-specific epigenetic information has been limited to mammals, it is not clearly understood whether non-mammalian vertebrate gametes possess any sex-specific allelic epigenetic information and whether somatic cells maintain the allele-specific epigenetic information, particularly DNA methylation. To determine the landscape of DNA methylation in paternal and maternal alleles in a non-mammalian vertebrate, we profiled the methylome of egg in medaka fish and compared it with our previously published medaka sperm methylome. We identified a set of gamete-specific differentially methylated regions (DMRs) in the genome- medaka eggs maintained a significantly lower global methylation profile than the sperm. Based on our sequencing depth and data, 10 DMRs were hypermethylated, and 237 DMRs were hypomethylated in the eggs compared to the sperm methylome. Somatic cells in blastula maintained some of those parental gamete-specific DNA methylation profiles. Those DMRs are associated with 70 genes, suggesting that they may have imprinted-like functions and warrant further investigation.

The roles of RGS proteins in cardiometabolic disease

G protein-coupled receptors (GPCRs) are the most prominent receptors on the surface of the cell and play a central role in the regulation of cardiac and metabolic functions. GPCRs transmit extracellular stimuli to the interior of the cells by activating one or more heterotrimeric G proteins. The duration and intensity of G protein-mediated signalling are tightly controlled by a large array of intracellular mediators, including the regulator of G protein signalling (RGS) proteins. RGS proteins selectively promote the GTPase activity of a subset of Gα subunits, thus serving as negative regulators in a pathway-dependent manner. In the current review, we summarise the involvement of RGS proteins in cardiometabolic function with a focus on their tissue distribution, mechanisms of action and dysregulation under various disease conditions. We also discuss the potential therapeutic applications for targeting RGS proteins in treating cardiometabolic conditions and current progress in developing RGS modulators. LINKED ARTICLES: This article is part of a themed issue Therapeutic Targeting of G Protein-Coupled Receptors: hot topics from the Australasian Society of Clinical and Experimental Pharmacologists and Toxicologists 2021 Virtual Annual Scientific Meeting. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.14/issuetoc.

USP18 Curbs the Progression of Metabolic Hypertension by Suppressing JAK/STAT Pathway

Hypertension is a pathological state of the metabolic syndrome that increases the risk of cardiovascular disease. Managing hypertension is challenging, and we aimed to identify the pathogenic factors and discern therapeutic targets for metabolic hypertension (MHR). An MHR rat model was established with the combined treatment of a high-sugar, high-fat diet and ethanol. Histopathological observations were performed using hematoxylin-eosin and Sirius Red staining. Transcriptome sequencing was performed to screen differentially expressed genes. The role of ubiquitin-specific protease 18 (USP18) in the proliferation, apoptosis, and oxidative stress of HUVECs was explored using Cell Counting Kit-8, flow cytometry, and enzyme-linked immunosorbent assays. Moreover, USP18 downstream signaling pathways in MHR were screened, and the effects of USP18 on these signaling pathways were investigated by western blotting. In the MHR model, total cholesterol and low-density lipoprotein levels increased, while high-density lipoprotein levels decreased. Moreover, high vessel thickness and percentage of collagen were noted along with increased malondialdehyde, decreased superoxide dismutase and catalase levels. The staining results showed that the MHR model exhibited an irregular aortic intima and disordered smooth muscle cells. There were 78 differentially expressed genes in the MHR model, and seven hub genes, including USP18, were identified. USP18 overexpression facilitated proliferation and reduced apoptosis and oxidative stress in HUVECs treated with Ang in vitro. In addition, the JAK/STAT pathway was identified as a USP18 downstream signaling pathway, and USP18 overexpression inhibited the expression of JAK/STAT pathway-related proteins. Conclusively, USP18 restrained MHR progression by promoting cell proliferation, reversing apoptosis and oxidative stress, and suppressing the JAK/STAT pathway.

Alternative polyadenylation regulation in cardiac development and cardiovascular disease

Cleavage and polyadenylation of pre-mRNAs is a necessary step for gene expression and function. Majority of human genes exhibit multiple polyadenylation sites, which can be alternatively used to generate different mRNA isoforms from a single gene. Alternative polyadenylation (APA) of pre-mRNAs is important for the proteome and transcriptome landscape. APA is tightly regulated during development and contributes to tissue-specific gene regulation. Mis-regulation of APA is linked to a wide range of pathological conditions. APA-mediated gene regulation in the heart is emerging as a new area of research. Here, we will discuss the impact of APA on gene regulation during heart development and in cardiovascular diseases. First, we will briefly review how APA impacts gene regulation and discuss molecular mechanisms that control APA. Then, we will address APA regulation during heart development and its dysregulation in cardiovascular diseases. Finally, we will discuss pre-mRNA targeting strategies to correct aberrant APA patterns of essential genes for the treatment or prevention of cardiovascular diseases. The RNA field is blooming due to advancements in RNA-based technologies. RNA-based vaccines and therapies are becoming the new line of effective and safe approaches for the treatment and prevention of human diseases. Overall, this review will be influential for understanding gene regulation at the RNA level via APA in the heart and will help design RNA-based tools for the treatment of cardiovascular diseases in the future.

Distinct Brain Proteomic Signatures in Cerebral Small Vessel Disease Rat Models of Hypertension and Cerebral Amyloid Angiopathy

Cerebral small vessel diseases (CSVDs) are prominent contributors to vascular cognitive impairment and dementia and can arise from a range of etiologies. Cerebral amyloid angiopathy (CAA) and hypertension (HTN), both prevalent in the elderly population, lead to cerebral microhemorrhages, macrohemorrhages, and white matter damage. However, their respective underlying mechanisms and molecular events are poorly understood. Here, we show that the transgenic rat model of CAA type 1 (rTg-DI) exhibits perivascular inflammation that is lacking in the spontaneously hypertensive stroke-prone (SHR-SP) rat model of HTN. Alternatively, SHR-SP rats display notable dilation of arteriolar perivascular spaces. Comparative proteomics analysis revealed few shared altered proteins, with key proteins such as ANXA3, H2A, and HTRA1 unique to rTg-DI rats, and Nt5e, Flot-1 and Flot-2 unique to SHR-SP rats. Immunolabeling confirmed that upregulation of ANXA3, HTRA1, and neutrophil extracellular trap proteins were distinctly associated with rTg-DI rats. Pathway analysis predicted activation of TGF-β1 and TNFα in rTg-DI rat brain, while insulin signaling was reduced in the SHR-SP rat brain. Thus, we report divergent protein signatures associated with distinct cerebral vessel pathologies in the SHR-SP and rTg-DI rat models and provide new mechanistic insight into these different forms of CSVD.

Effect of interaction between occupational stress and polymorphisms of MTHFR gene and SELE gene on hypertension

BACKGROUND

Gene-environment interaction is related to the prevalence of hypertension, but the impact of genetic polymorphisms on hypertension may vary due to different geography and population.

OBJECTIVE

To explore the impact of the interaction among occupational stress and MTHFR gene and SELE gene polymorphism on the prevalence of hypertension in Xinjiang oil workers.

METHODS

A case-control study was conducted on 310 oil workers. In an oilfield base in Karamay City, Xinjiang, 155 hypertensive patients aged 18~60 years old with more than one year of service were selected as the case group, and 155 oil workers without hypertension were selected as the control group according to the 1:1 matching principle (matching conditions: the gender and shift were the same. The age is around 2 years old). The Occupational Stress Scale was used to evaluate the degree of occupational stress, PCR technique was used to detect MTHFR and SELE gene polymorphism, Logistic regression analysis was used to analyze the effects of gene and occupational stress on hypertension, and gene-gene and gene-environment interactions were analyzed by generalized multi-factor dimension reduction method.

RESULTS

The G98T polymorphism of SELE gene (χ² = 6.776, P = 0.034), the C677T (χ² = 7.130, P = 0.028) and A1298C (χ² = 12.036, P = 0.002) loci of MTHFR gene and the degree of occupational stress (χ² = 11.921, P = 0.003) were significantly different between the case group and the control group. The genotypes GT at the G98T polymorphism of the SELE gene (OR = 2.151, 95% CI [1.227-3.375]), and the dominant model (AC/CC vs AA, OR = 1.925, 95% CI [1.613-3.816]); AC and CC at the A1298C polymorphism of the MTHFR gene (OR _AC = 1.917, 95% CI [1.064-3.453]; OR _CC = 2.233, 95% CI [1.082-4.609]), the additive model (CC vs AA, OR = 2.497, 95% CI [1.277-4.883]) and the dominant model (AC/CC vs AA, OR = 2.012, 95% CI [1.200-3.373]); at the C677T polymorphism of the MTHFR gene CT and TT (OR _CT = 1.913, 95% CI [1.085-3.375]; OR _TT = 3.117, 95% CI [1.430-6.795]), the additive model (CC vs AA, OR = 1.913, 95% CI [1.085-3.375]) and the dominant model (AC/CC vs AA, OR = 2.012, 95% CI [1.200-3.373]), which could increase hypertension risk (P < 0.05). The gene-gene interaction showed that there was a positive interaction between the A1298C and C677T sites of the MTHFR gene, and the gene-occupational stress interaction showed that there was a positive interaction between the A1298C and C677T sites of the MTHFR gene and the occupational stress.

CONCLUSION

The interaction of gene mutation and occupational stress in Xinjiang oil workers maybe increase the risk of hypertension.

Regulator of G-Protein Signaling 5 Maintains Brain Endothelial Cell Function in Focal Cerebral Ischemia

Background

Regulator of G‐protein signaling 5 (RGS5) is a negative modulator of G‐protein–coupled receptors. The role of RGS5 in brain endothelial cells is not known. We hypothesized that RGS5 in brain microvascular endothelial cells may be an important mediator of blood‐brain barrier function and stroke severity after focal cerebral ischemia.

Methods and Results

Using a transient middle cerebral artery occlusion model, we found that mice with global and endothelial‐specific deletion of Rgs5 exhibited larger cerebral infarct size, greater neurological motor deficits, and increased brain edema. In our in vitro models, we observed increased G_q activity and elevated intracellular Ca²⁺ levels in brain endothelial cells. Furthermore, the loss of endothelial RGS5 leads to decreased endothelial NO synthase expression and phosphorylation, relocalization of endothelial tight junction proteins, and increased cell permeability. Indeed, RGS5 deficiency leads to increased Rho‐associated kinase and myosin light chain kinase activity, which were partially reversed in our in vitro model by pharmacological inhibition of G_q, metabotropic glutamate receptor 1, and ligand‐gated ionotropic glutamate receptor.

Conclusions

Our findings indicate that endothelial RGS5 plays a novel neuroprotective role in focal cerebral ischemia. Loss of endothelial RGS5 leads to hyperresponsiveness to glutamate signaling pathways, enhanced Rho‐associated kinase– and myosin light chain kinase–mediated actin‐cytoskeleton reorganization, endothelial dysfunction, tight junction protein relocalization, increased blood‐brain barrier permeability, and greater stroke severity. These findings suggest that preservation of endothelial RGS5 may be an important therapeutic strategy for maintaining blood‐brain barrier integrity and limiting the severity of ischemic stroke.

RGS5 rs4657251 polymorphism is associated with small vessel occlusion stroke in Taiwan Han Chinese

BACKGROUND

The regulator of G-protein signaling protein 5 (RGS5) has been demonstrated to play a role in regulating blood pressure and cardiovascular function. Studies have shown that RGS5 polymorphisms exhibit susceptibility to hypertension. However, no study has yet been performed among stroke patients.

METHODS

To evaluate whether RGS5 rs4657251 is a susceptibility gene for stroke, we performed a case-control association study involving 714 large-artery atherosclerosis (LAA) patients, 383 small vessel occlusion (SVO) patients, 401 hypertensive intracranial hemorrhages (HICH), and 626 controls. The RGS5 rs4657251 polymorphism was analyzed through polymerase chain reaction.

RESULTS

The TC genotype was significantly higher in the SVO group compared with that in the control group (odds ratio [OR] = 1.34, 95% confidence interval [CI] = 1.02-1.76, p = 0.035). In addition, the dominant phenotype (TC + CC vs TT) was also significantly different between the SVO and the control groups (OR = 1.31, 95% CI = 1.01-1.70, p = 0.046). However, no association was found between RGS5 rs4657251 and LAA an HICH. After adjustment with gender, diabetes, smoking, cholesterol and low-density lipoprotein levels, RGS5 rs4657251 polymorphism remained an independent risk factor for SVO (OR = 1.49; 95% CI = 1.12-1.98) but not for LAA or HICH.

CONCLUSION

Our findings, obtained among Taiwan Han Chinese subjects, provide the first evidence that RGS5 rs4657251 polymorphism is an independent risk factor for SVO.

Gene-Centric Analysis of Preeclampsia Identifies Maternal Association at PLEKHG1

The genetic susceptibility to preeclampsia, a pregnancy-specific complication with significant maternal and fetal morbidity, has been poorly characterized. To identify maternal genes associated with preeclampsia risk, we assembled 498 cases and 1864 controls of European ancestry from preeclampsia case-control collections in 5 different US sites (with additional matched population controls), genotyped samples on a cardiovascular gene-centric array composed of variants from ≈2000 genes selected based on prior genetic studies of cardiovascular and metabolic diseases and performed case-control genetic association analysis on 27 429 variants passing quality control. In silico replication testing of 9 lead signals with P<10-4 was performed in independent European samples from the SOPHIA (Study of Pregnancy Hypertension in Iowa) and Inova cohorts (212 cases, 456 controls). Multiethnic assessment of lead signals was then performed in samples of black (26 cases, 136 controls), Hispanic (132 cases, 468 controls), and East Asian (9 cases, 80 controls) ancestry. Multiethnic meta-analysis (877 cases, 3004 controls) revealed a study-wide statistically significant association of the rs9478812 variant in the pleiotropic PLEKHG1 gene (odds ratio, 1.40 [1.23-1.60]; Pmeta=5.90×10-7). The rs9478812 effect was even stronger in the subset of European cases with known early-onset preeclampsia (236 cases diagnosed <37 weeks, 1864 controls; odds ratio, 1.59 [1.27-1.98]; P=4.01×10-5). PLEKHG1 variants have previously been implicated in genome-wide association studies of blood pressure, body weight, and neurological disorders. Although larger studies are required to further define maternal preeclampsia heritability, this study identifies a novel maternal risk locus for further investigation.

Insights into the genetics of blood pressure in black South African individuals: the Birth to Twenty cohort

Background

Cardiovascular diseases (CVDs) are the leading cause of non-communicable disease deaths globally, with hypertension being a major risk factor contributing to CVDs. Blood pressure is a heritable trait, with relatively few genetic studies having been performed in Africans. This study aimed to identify genetic variants associated with variance in systolic (SBP) and diastolic (DBP) blood pressure in black South Africans.

Methods

Genotyping was performed using the Metabochip in a subset of participants (mixed sex; median age 17.9) and their adult female caregivers (median age 41.0) from the Birth to Twenty cohort (n = 1947). Data were analysed as a merged dataset (all participants and caregivers together) in GEMMA (v0.94.1) using univariate linear mixed models, incorporating a centered relatedness matrix to account for the relatedness between individuals and with adjustments for age, sex, BMI and principal components of the genotype information.

Results

Association analysis identified regions of interest in the NOS1AP (DBP: rs112468105 - p = 7.18 × 10⁻⁵ and SBP: rs4657181 - p = 4.04 × 10⁻⁵), MYRF (SBP: rs11230796 - p = 2.16 × 10⁻⁷, rs400075 - p = 2.88 × 10⁻⁷) and POC1B (SBP: rs770373 - p = 7.05 × 10⁻⁵, rs770374 - p = 9.05 × 10⁻⁵) genes and some intergenic regions (DACH1|LOC440145 (DBP: rs17240498 - p = 4.91 × 10⁻⁶ and SBP: rs17240498 - p = 2.10 × 10⁻⁵) and INTS10|LPL (SBP: rs55830938 - p = 1.30 × 10⁻⁵, rs73599609 - p = 5.78 × 10⁻⁵, rs73667448 - p = 6.86 × 10⁻⁵)).

Conclusions

The study provided further insight into the contribution of genetic variants to blood pressure in black South Africans. Future functional and replication studies in larger samples are required to confirm the role of the identified loci in blood pressure regulation and whether or not these variants are African-specific.

Electronic supplementary material

The online version of this article (10.1186/s12920-018-0321-6) contains supplementary material, which is available to authorized users.

Maternal Metabolism and Vascular Adaptation in Pregnancy: The PPAR Link

Current therapies for pregnancy-related hypertension and its complications remain inadequate, although an increasing role for maternal susceptibility is becoming evident. Systemic vascular dysfunction in response to imbalances in angiogenic, inflammatory, and constricting factors is implicated in the pathogenesis of gestational hypertension, and growing evidence now links these factors with maternal metabolism. In particular, the crucial role of peroxisome proliferator-activated receptors (PPARs) in maternal vascular adaptation provides further insights into how obesity and gestational diabetes may be linked to pregnancy-induced hypertension and preeclampsia. This is especially important given the rapidly growing prevalence of obesity during pregnancy, and highlights a new approach to treat pregnancy-related hypertension and its complications.

Recent Advances in the Genetics of Hypertension

Hypertension is a silent killer worldwide, caused by both genetic and environmental factors. Until now, genetic and genomic association studies of hypertension are reporting different degree of association on hypertension. Hence, it is essential to gather all the available information on the reported genetic loci and to determine if any biomarker(s) is/are significantly associated with hypertension. Current review concluded the potential biomarkers for hypertension, with regards to electrolyte and fluid transports, as well as sodium/potassium ions homeostasis, which are supported by the results of case-controls and meta-analyses.

Regulator of G protein signaling 5 is a determinant of gestational hypertension and preeclampsia

Preeclampsia is a systemic vascular disorder of pregnancy and is associated with increased sensitivity to angiotensin II (AngII) and hypertension. The cause of preeclampsia remains unknown. We identified the role of regulator of G protein (heterotrimeric guanine nucleotide–binding protein) signaling 5 (RGS5) in blood pressure regulation during pregnancy and preeclampsia. RGS5 expression in human myometrial vessels is markedly suppressed in gestational hypertension and/or preeclampsia. In pregnant RGS5-deficient mice, reduced vascular RGS5 expression causes gestational hypertension by enhancing vascular sensitivity to AngII. Further challenge by increasing AngII results in preeclampsia-like symptoms, namely, more severe hypertension, proteinuria, placental pathology, and reduced birth weight. In pregnant heterozygote null mice, treatment with peroxisome proliferator–activated receptor (PPAR) agonists normalizes vascular function and blood pressure through effects on RGS5. These findings highlight a key role of RGS5 at the interface between AngII and PPAR signaling. Because preeclampsia is refractory to current standard therapies, our study opens an unrecognized and urgently needed opportunity for treatment of gestational hypertension and preeclampsia.

Fcγ receptors and ligands and cardiovascular disease

Fcγ receptors (FcγRs) classically modulate intracellular signaling on binding of the Fc region of IgG in immune response cells. How FcγR and their ligands affect cardiovascular health and disease has been interrogated recently in both preclinical and clinical studies. The stimulation of activating FcγR in endothelial cells, vascular smooth muscle cells, and monocytes/macrophages causes a variety of cellular responses that may contribute to vascular disease pathogenesis. Stimulation of the lone inhibitory FγcR, FcγRIIB, also has adverse consequences in endothelial cells, antagonizing NO production and reparative mechanisms. In preclinical disease models, activating FcγRs promote atherosclerosis, whereas FcγRIIB is protective, and activating FcγRs also enhance thrombotic and nonthrombotic vascular occlusion. The FcγR ligand C-reactive protein (CRP) has undergone intense study. Although in rodents CRP does not affect atherosclerosis, it causes hypertension and insulin resistance and worsens myocardial infarction. Massive data have accumulated indicating an association between increases in circulating CRP and coronary heart disease in humans. However, Mendelian randomization studies reveal that CRP is not likely a disease mediator. CRP genetics and hypertension warrant further investigation. To date, studies of genetic variants of activating FcγRs are insufficient to implicate the receptors in coronary heart disease pathogenesis in humans. However, a link between FcγRIIB and human hypertension may be emerging. Further knowledge of the vascular biology of FcγR and their ligands will potentially enhance our understanding of cardiovascular disorders, particularly in patients whose greater predisposition for disease is not explained by traditional risk factors, such as individuals with autoimmune disorders.

Associations SELE gene haplotype variant and hypertension in Mongolian and Han populations

Genetic variation is thought to contribute to the etiology of hypertension, and E-selectin is a candidate essential hypertension-associated gene.

OBJECTIVE

In this study, we attempted to test the hypothesis that subtle haplotype variants of SELE genes may be sources of essential hypertension in Mongolian and Han populations.

MATERIALS

A total of 429 unrelated Mongolian herdsmen and 416 Han farmers were enrolled, including 212 Mongolian essential hypertension (EH) patients, 217 Mongolian normotensives (controls), 200 Han EH patients and 216 Han normotensives (controls).

METHODS

All nine tag single-nucleotide polymorphisms (SNPs) within the SELE gene were retrieved from HapMap and the genotyping was performed using a polymerase chain reaction (PCR)/ligase detection reaction assay. Results The distributions of the A-allele frequency of rs3917458 and the C-allele frequency of rs2179172 differed significantly between the hypertensive subjects and controls in the Han population. The frequency of haplotype GGC was significantly higher in the EH group than in the controls in the Mongolian population. In the Han population, a significant difference was observed in the haplotype frequency of TCC between the patients and controls, whereas haplotype ACA was detected significantly less often in the EH subjects than in the controls.

CONCLUSION

Meanwhile, the haplotype TCC in the Han hypertensive patients and the haplotype GGC in the Mongolian patients had independent effects in increasing the risk for EH and maybe used as risk factors for predicting high blood pressure. However, the haplotype ACA had an independent effect in decreasing the risk of hypertension and may be protective in normotensive subjects in the Han population. Therefore, multiple SNPs in combination in SELE may confer a risk of hypertension.

Association of E-selectin gene polymorphism and serum PAPP-A with carotid atherosclerosis in end-stage renal disease

BACKGROUND

Atherosclerotic vascular disease represents a significant cause of morbidity and mortality in patients with end-stage renal disease (ESRD). The endothelium plays a crucial role in vascular inflammation. E-selectin is exclusively expressed on activated endothelial cells and is upregulated following an inflammatory response and oxidative stress, while serum pregnancy-associated plasma protein-A (PAPP-A) concentrations are related to the presence and stability of carotid atherosclerotic plaques.

OBJECTIVE

The aim of this study was to investigate whether there is an association between SELE rs5355C>T gene polymorphism, serum PAPP-A level and the presence of carotid atherosclerosis in ESRD patients.

SUBJECTS AND METHODS

Seventy subjects were recruited into this study; 40 ESRD patients [age (mean ± SD) 43.42 ± 13.94 years] and 30 age- and gender-matched healthy individuals assigned to the control group. Polymerase chain reaction-restriction fragment length polymorphism was performed for the analysis of SELE rs5355C>T gene polymorphism, while serum PAPP-A concentrations were measured using electro-chemiluminescence immunoassay. Routine laboratory tests were measured on an automated chemistry analyzer. Carotid ultrasonographic studies were performed by a bilateral high-resolution B-mode ultrasound.

RESULTS

There was no significant relationship between the SELE rs5355C>T gene polymorphism and ESRD incidence. Serum PAPP-A levels were significantly higher in ESRD patients compared with controls [median (interquartile range) 5.8 (5.1-11.6) and 5.1 (4.1-6.7), respectively; p = 0.005]. Serum PAPP-A correlated positively with urea, creatinine, systolic and diastolic blood pressure (DBP). Serum PAPP-A showed a statistically significant increase in SELE rs5355TT versus CC in both patients and controls. There was no association on comparing right intima-media thickness (IMT), left IMT, right cross-sectional area (CSA) and left CSA with the CC, CT and TT genotypes of SELE rs5355C>T. No correlation between serum PAPP-A with each of the above-mentioned carotid doppler findings was observed. There was a statistically significant increase in DBP in TT genotype carriers when compared with CC genotype carriers (p = 0.009). Serum PAPP-A levels were higher in hypertensive ESRD patients when compared with normotensive ESRD patients. There was a statistically significant decrease in high-density lipoprotein cholesterol (HDL-C) in TT genotype carriers when compared with CT genotype carriers in the whole study group (p = 0.003). Serum PAPP-A correlated negatively with HDL-C.

CONCLUSION

The lack of a direct association between SELE rs5355C>T gene polymorphism, serum PAPP-A level and IMT suggests that their hypothesized association with carotid atherosclerosis might reflect an indirect mechanism of SELE rs5355C>T gene polymorphism and serum PAPP-A with cardiovascular risk factors such as blood pressure and HDL-C rather than a direct effect on the vasculature.

Regulator of G-protein signaling-5 is a marker of hepatic stellate cells and expression mediates response to liver injury

Liver fibrosis is mediated by hepatic stellate cells (HSCs), which respond to a variety of cytokine and growth factors to moderate the response to injury and create extracellular matrix at the site of injury. G-protein coupled receptor (GPCR)-mediated signaling, via endothelin-1 (ET-1) and angiotensin II (AngII), increases HSC contraction, migration and fibrogenesis. Regulator of G-protein signaling-5 (RGS5), an inhibitor of vasoactive GPCR agonists, functions to control GPCR-mediated contraction and hypertrophy in pericytes and smooth muscle cells (SMCs). Therefore we hypothesized that RGS5 controls GPCR signaling in activated HSCs in the context of liver injury. In this study, we localize RGS5 to the HSCs and demonstrate that Rgs5 expression is regulated during carbon tetrachloride (CCl₄)-induced acute and chronic liver injury in Rgs5^LacZ/LacZ reporter mice. Furthermore, CCl₄ treated RGS5-null mice develop increased hepatocyte damage and fibrosis in response to CCl₄ and have increased expression of markers of HSC activation. Knockdown of Rgs5 enhances ET-1-mediated signaling in HSCs in vitro. Taken together, we demonstrate that RGS5 is a critical regulator of GPCR signaling in HSCs and regulates HSC activation and fibrogenesis in liver injury.

E-selectin gene polymorphism (A561C) and essential hypertension. Meta-analysis in the Chinese population

BACKGROUND

The A561C polymorphism of the E-selectin gene (SELE) has been reported to be associated with essential hypertension (EH) in several studies; however, results among these studies were inconsistent. Here, we conducted a meta-analysis to explore the association of the A561C polymorphism with EH.

METHODS

Publications were retrieved through searching PubMed, Web of Science, the China National Knowledge Infrastructure (CNKI), China Biological Medicine, and the Wanfang database. Odds ratios (OR) and 95 % confidence intervals (CI) were calculated to estimate the strength of association of A561C with EH. Subgroup analysis was also performed to assess ethnic discrepancies. A total of seven studies comprising 2,127 EH patients and 2,078 controls were analyzed.

RESULTS

In the dominant model analysis, we found significant associations between the A561C polymorphism and EH in all subjects (CC+AC vs. AA, OR = 1.96, 95 %CI 1.57-2.44, P heterogeneity = 0.381), in a Han Chinese subgroup (CC+AC vs. AA, OR = 2.38, 95 %CI 1.73-3.29, P heterogeneity = 0.269), and in non-Han Chinese minorities (CC+AC vs. AA, OR = 1.62, 95 %CI 1.19-2.21, P heterogeneity = 0.84).

CONCLUSION

The findings suggest that C allele carriers of the SELE gene polymorphism (A561C) might be predisposed to EH in the Chinese population. Further investigations in other ethnic populations should be conducted to verify these findings.

RGS5 gene and therapeutic response to short acting bronchodilators in paediatric asthma patients

Short-acting β2-adrenergic receptor agonists are commonly used bronchodilators for symptom relief in asthmatics. Recent evidence demonstrated that prolonged exposure of cultured airway smooth muscle cells to β2 agonists directly augments procontractile signaling pathways with the change in expression of regulator of G protein signaling 5 (RGS5). The aim of this study was to test whether genetic variants in RGS5 gene affect the response to short acting β2-agonists. Bronchodilator responsiveness was assessed in 137 asthmatic children by % change in baseline forced expiratory volume in 1 sec (FEV1 ) after administration of albuterol. The analyses were performed in patients with FEV1 /FVC ratio below 0.9 (FVC-forced vital capacity, n = 99). FEV1 % change adjusted for baseline FEV1 values was significantly different between genotypes of rs10917696 C/T polymorphism (P = 0.008). The association remained significant with inclusion of age, sex, atopy, parental smoking, and controller medications into multivariate model (P = 0.005). We also identified additive effect on the treatment outcome with previously published genetic variant G/A rs1544791 in phosphodiesterase 4 (PDE4D) gene. Carriers of two risk alleles (C and G) had adjusted mean % FEV1 change value 4.6 ± 1.3, while carriers of one and none of the risk alleles had 8.1 ± 0.7% and 13.5 ± 2.4%, respectively, P = 0.001. Our work identifies a new genetic variant in RGS5 demonstrating additive effect with PDE4D, both implicated in modulation of asthma treatment.

A polymorphic 3'UTR element in ATP1B1 regulates alternative polyadenylation and is associated with blood pressure

Although variants in many genes have previously been shown to be associated with blood pressure (BP) levels, the molecular mechanism underlying these associations are mostly unknown. We identified a multi-allelic T-rich sequence (TRS) in the 3’UTR of ATP1B1 that varies in length and sequence composition (T_22-27 and T₁₂GT ₃GT₆). The 3’UTR of ATP1B1 contains 2 functional polyadenylation signals and the TRS is downstream of the proximal polyadenylation site (A2). Therefore, we hypothesized that alleles of this TRS might influence ATP1B1 expression by regulating alternative polyadenylation. In vitro, the T₁₂GT ₃GT₆ allele increases polyadenylation at the A2 polyadenylation site as compared to the T₂₃ allele. Consistent with our hypothesis, the relative abundance of the A2-polyadenylated ATP1B1 mRNA was higher in human kidneys with at least one copy of the T₁₂GT ₃GT₆ allele than in those lacking this allele. The T₁₂GT ₃GT₆ allele is also associated with higher systolic BP (beta = 3.3 mmHg, p = 0.014) and diastolic BP (beta = 2.4 mmHg, p = 0.003) in a European-American population. Therefore, we have identified a novel multi-allelic TRS in the 3’UTR of ATP1B1 that is associated with higher BP and may mediate its effect by regulating the polyadenylation of the ATP1B1 mRNA.

Common genetic variants in the endothelial system predict blood pressure response to sodium intake: the GenSalt study

BACKGROUND We examined the association between 14 endothelial system genes and salt-sensitivity of blood pressure (BP). METHODS After a 3-day baseline examination, during which time the usual diet was consumed, 1,906 Chinese participants received a 7-day low-sodium diet (51.3 mmol of sodium/day) followed by a 7-day high-sodium diet (307.8 mmol of sodium/day). BP measurements were obtained at baseline and at the end of each intervention using a random-zero sphygmomanometer. RESULTS The DDAH1 rs11161637 variant was associated with reduced BP salt sensitivity, conferring attenuated systolic BP (SBP) and mean arterial pressure (MAP) decreases from baseline to the low-sodium intervention (both P = 2×10(-4)). Examination of genotype-sex interactions revealed that this relation was driven by the strong associations observed in men (P for interactions = 1.10×10(-4) and 0.008, respectively). When switching from the low- to high-sodium intervention, increases in diastolic BP (DBP) and MAP were attenuated by the COL18A1 rs2838944 minor A allele (P = 1.41×10(-4) and 1.55×10(-4), respectively). Conversely, the VWF rs2239153 C variant was associated with increased salt sensitivity, conferring larger DBP and MAP reductions during low-sodium intervention (P = 1.22×10(-4) and 4.44×10(-5), respectively). Ten variants from 3 independent SELE loci displayed significant genotype-sex interactions on DBP and MAP responses to low-sodium (P for interaction = 1.56×10(-3) to 1.00×10(-4)). Among men, minor alleles of 4 correlated markers attenuated BP responses to low-sodium intake, whereas minor alleles of another 4 correlated markers increased BP responses. No associations were observed in women for these variants. Further, qualitative interactions were shown for 2 correlated SELE markers. CONCLUSIONS These data support a role for the endothelial system genes in salt sensitivity.

Regulator of G-protein signaling 5 controls blood pressure homeostasis and vessel wall remodeling

RATIONALE

Regulator of G-protein signaling 5 (RGS5) modulates G-protein-coupled receptor signaling and is prominently expressed in arterial smooth muscle cells. Our group first reported that RGS5 is important in vascular remodeling during tumor angiogenesis. We hypothesized that RGS5 may play an important role in vessel wall remodeling and blood pressure regulation.

OBJECTIVE

To demonstrate that RGS5 has a unique and nonredundant role in the pathogenesis of hypertension and to identify crucial RGS5-regulated signaling pathways.

METHODS AND RESULTS

We observed that arterial RGS5 expression is downregulated with chronically elevated blood pressure after angiotensin II infusion. Using a knockout mouse model, radiotelemetry, and pharmacological inhibition, we subsequently showed that loss of RGS5 results in profound hypertension. RGS5 signaling is linked to the renin-angiotensin system and directly controls vascular resistance, vessel contractility, and remodeling. RGS5 deficiency aggravates pathophysiological features of hypertension, such as medial hypertrophy and fibrosis. Moreover, we demonstrate that protein kinase C, mitogen-activated protein kinase/extracellular signal-regulated kinase, and Rho kinase signaling pathways are major effectors of RGS5-mediated hypertension.

CONCLUSIONS

Loss of RGS5 results in hypertension. Loss of RGS5 signaling also correlates with hyper-responsiveness to vasoconstrictors and vascular stiffening. This establishes a significant, distinct, and causal role of RGS5 in vascular homeostasis. RGS5 modulates signaling through the angiotensin II receptor 1 and major Gαq-coupled downstream pathways, including Rho kinase. So far, activation of RhoA/Rho kinase has not been associated with RGS molecules. Thus, RGS5 is a crucial regulator of blood pressure homeostasis with significant clinical implications for vascular pathologies, such as hypertension.

Genetic analysis of albuminuria in collaborative cross and multiple mouse intercross populations

Albuminuria is an important marker of nephropathy that increases the risk of progressive renal and chronic cardiovascular diseases. The genetic basis of kidney disease is well-established in humans and rodent models, but the causal genes remain to be identified. We applied several genetic strategies to map and refine genetic loci affecting albuminuria in mice and translated the findings to human kidney disease. First, we measured albuminuria in mice from 33 inbred strains, used the data for haplotype association mapping (HAM), and detected 10 genomic regions associated with albuminuria. Second, we performed eight F(2) intercrosses between genetically diverse strains to identify six loci underlying albuminuria, each of which was concordant to kidney disease loci in humans. Third, we used the Oak Ridge National Laboratory incipient Collaborative Cross subpopulation to detect an additional novel quantitative trait loci (QTL) underlying albuminuria. We also performed a ninth intercross, between genetically similar strains, that substantially narrowed an albuminuria QTL on Chromosome 17 to a region containing four known genes. Finally, we measured renal gene expression in inbred mice to detect pathways highly correlated with albuminuria. Expression analysis also identified Glcci1, a gene known to affect podocyte structure and function in zebrafish, as a strong candidate gene for the albuminuria QTL on Chromosome 6. Overall, these findings greatly enhance our understanding of the genetic basis of albuminuria in mice and may guide future studies into the genetic basis of kidney disease in humans.

Functional epistatic interaction between rs6046G>A in F7 and rs5355C>T in SELE modifies systolic blood pressure levels

Background

Although numerous genetic studies have been performed, only 0.9% of blood pressure phenotypic variance has been elucidated. This phenomenon could be partially due to epistatic interactions. Our aim was to identify epistatic interaction(s) associated with blood pressure levels in a pre-planned two-phase approach.

Methods and Results

In a discovery cohort composed of 3,600 French individuals, we found rs6046A allele in F7 associated with decreased blood pressure levels (P≤3.7×10⁻³) and rs5355T allele in SELE associated with decreased diastolic blood pressure levels (P = 5×10⁻³). Both variants interacted in order to influence blood pressure levels (P≤0.048). This interaction was replicated with systolic blood pressure in 4,620 additional European individuals (P = 0.03). Similarly, in this replication cohort, rs6046A was associated with decreased blood pressure levels (P≤8.5×10⁻⁴). Furthermore, in peripheral blood mononuclear cells of a subsample of 90 supposed healthy individuals, we found rs6046A positively associated with NAMPT mRNA levels (P≤9.1×10⁻⁵), suggesting an eventual involvement of NAMPT expression in blood pressure regulation. Confirming this hypothesis, further transcriptomic analyses showed that increased NAMPT mRNA levels were positively correlated with ICAM1, SELL, FPR1, DEFA1-3, and LL-37 genes expression (P≤5×10⁻³). The last two mRNA levels were positively associated with systolic blood pressure levels (P≤0.01) and explained 4% of its phenotypic variation.

Conclusion

These findings reveal the importance of epistatic interactions in blood pressure genetics and give new insights for the role of inflammation in its complex regulation.

Patent Highlights

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Regulator of G-Protein Signaling 5 Reduces HeyA8 Ovarian Cancer Cell Proliferation and Extends Survival in a Murine Tumor Model

The regulator of G-protein signaling 5 (RGS5) belongs to a family of GTPase activators that terminate signaling cascades initiated by extracellular mediators and G-protein-coupled receptors. RGS5 has an interesting dual biological role. One functional RGS5 role is as a pericyte biomarker influencing the switch to angiogenesis during malignant progression. Its other functional role is to promote apoptosis in hypoxic environments. We set out to clarify the extent to which RGS5 expression regulates tumor progression—whether it plays a pathogenic or protective role in ovarian tumor biology. We thus constructed an inducible gene expression system to achieve RGS5 expression in HeyA8-MDR ovarian cancer cells. Through this we observed that inducible RGS5 expression significantly reduces in vitro BrdU-positive HeyA8-MDR cells, although this did not correlate with a reduction in tumor volume observed using an in vivo mouse model of ovarian cancer. Interestingly, mice bearing RGS5-expressing tumors demonstrated an increase in survival compared with controls, which might be attributed to the vast regions of necrosis observed by pathological examination. Additionally, mice bearing RGS5-expressing tumors were less likely to have ulcerated tumors. Taken together, this data supports the idea that temporal expression and stabilization of RGS5 could be a valuable tactic within the context of a multicomponent approach for modulating tumor progression.