Association of the G-protein β3 subunit gene polymorphism with the incidence of cardiovascular disease independent of hypertension: the Funagata study

Association of G-protein beta3 subunit gene C825T polymorphism with cardiac and cerebrovascular events in Chinese hypertensive patients

Several recent studies showed that C825T polymorphism is related to cardiovascular diseases in normal population. However, studies on whether 825T allele influences the incidence of cardiovascular diseases in hypertensive patients are rare. In the current study, 729 patients (CC, n = 332; CT, n = 313; TT, n = 84) with essential hypertension were genotyped for C825T polymorphism of the GNB3 gene and followed 8 years for major adverse cardiovascular events (MACEs) which include stroke, the onset of coronary artery disease (CAD), and all-cause death. Established cardiovascular risk factors were used to adjust the multivariate Cox analysis. After a mean follow-up period of 7.60 ± 1.12 years, a significantly higher incidence of MACEs was seen in the TT genotype group than CC and CT genotypes. The TT variant was significantly and independently predictive of MACEs (relative risk = 2.574; p < 0.001), CAD (relative risk = 2.963; p < 0.001), but not stroke, CAD+stroke or death. The GNB3 TT genotype is a risk factor for CAD independent of other established cardiovascular risk factors in Chinese hypertensive patients.

Estimation of the relationship between the polymorphisms of selected genes: ACE, AGTR1, TGFβ1 and GNB3 with the occurrence of primary vesicoureteral reflux

PURPOSE

Etiopathogenesis of VUR is composite and not fully understood. Many data indicate the importance of genetic predisposition. The aim of this study was to establish the relationship of selected polymorphisms: 14094 polymorphism of the ACE, polymorphism rs1800469 of TGFβ-1, rs5443 gene polymorphism of the GNB3 and receptor gene polymorphism rs5186 type 1 AGTR1 with the occurrence of the primary vesicoureteral reflux.

MATERIAL

The study included 190 children: 90 with the primary VUR confirmed with the voiding cystourethrogram and excluded secondary VUR and a control group of 100 children without a history of the diseases of the genitourinary tract.

METHODS

The study was planned in the scheme: "tested case versus control." Genomic DNA was isolated from the leukocytes of peripheral blood samples. The results were statistically analyzed in the Statistica 10 using χ ² test and analysis of the variance Anova.

RESULTS

Any of the four studied polymorphisms showed no difference in the distribution of genotypes between patients with primary vesicoureteral reflux and the control group. In patients with VUR and TT genotype polymorphism rs5443 GNB3 gene, the glomerular filtration rate was significantly higher than in patients with genotype CC or CT.

CONCLUSIONS

(1) No relationship was found between the studied polymorphisms (14094 ACE gene, rs1800469 gene TGFβ1, GNB3 gene rs5443, rs5186 AGTR1 gene) and the occurrence of primary vesicoureteral reflux. (2) TT genotype polymorphism rs5443 GNB3 gene may be a protective factor for the improved renal function in patients with primary vesicoureteral reflux in patients with genotype CC or CT.

Correction of the Pathogenic Alternative Splicing, Caused by the Common GNB3 c.825C>T Allele, Using a Novel, Antisense Morpholino

The very common GNB3 c.825C>T polymorphism (rs5443) is present in approximately half of all human chromosomes. Significantly, the presence of the GNB3 825T allele has been strongly associated with predisposition to essential hypertension. Paradoxically the presence of the GNB3 825T allele, in exon 10, introduces a pathogenic alternative RNA splice site into the middle of exon 9. To attempt to correct this pathogenic aberrant splicing, we, therefore, bioinformatically designed, using a Gene Tools(®) algorithm, a GNB3-specific, antisense morpholino. It was hoped that this morpholino would behave in vitro as either a potential splice blocker and/or exon skipper, to both bind and inhibit/reduce the aberrant splicing of the GNB3 825T allele. On transfecting a human lymphoblast cell line homozygous for the 825T allele, with this antisense morpholino, we encouragingly observed both a significant reduction (from ∼58% to ∼5%) in the production of the aberrant smaller GNB3 transcript, and a subsequent increase in the normal GNB3 transcript (from ∼42% to ∼95%). Our results demonstrate the potential use of a GNB3-specific antisense morpholino, as a pharmacogenetic therapy for essential hypertension.

G-Protein β3-Subunit Gene C825T Polymorphism and Cardiovascular Risk: An Updated Review

Hypertension is a common disorder of multifactorial origin that constitutes a major risk factor for cardiovascular events such as stroke and myocardial infarction. The subunits of the heterotrimeric G proteins are attractive candidate gene products for susceptibility to hypertension, obesity and insulin resistance syndrome. A polymorphism (825C/T) in exon 10 of the GNB3 gene, encoding for the Gβ3 subunit, has been described. The 825T allele is associated with alternative splicing of the gene and formation of a truncated but functionally active β3 subunit. Many studies have investigated whether carriers of the 825T allele are at increased risk for hypertension, obesity, insulin-resistance and left ventricular hypertrophy with apparently conflicting results. The present review demonstrates that GNB3 825T allele is a useful genetic marker for better defining the risk profile of hypertensive patients, as it is associated with increased risk of stroke and myocardial infarction in longitudinal studies in Caucasians.

G-protein beta-3 subunit genotype predicts enhanced benefit of fixed-dose isosorbide dinitrate and hydralazine: results of A-HeFT

OBJECTIVES

The purpose of this study was to evaluate the influence of the guanine nucleotide-binding proteins (G-proteins), beta-3 subunit (GNB3) genotype on the effectiveness of a fixed-dose combination of isosorbide dinitrate and hydralazine (FDC I/H) in A-HeFT (African American Heart Failure Trial).

BACKGROUND

GNB3 plays a role in alpha2-adrenergic signaling. A polymorphism (C825T) exists, and the T allele is linked to enhanced alpha-adrenergic tone and is more prevalent in African Americans.

METHODS

A total of 350 subjects enrolled in the genetic substudy (GRAHF [Genetic Risk Assessment of Heart Failure in African Americans]) were genotyped for the C825T polymorphism. The impact of FDC I/H on a composite score (CS) that incorporated death, hospital stay for heart failure, and change in quality of life (QoL) and on event-free survival were assessed in GNB3 genotype subsets.

RESULTS

The GRAHF cohort was 60% male, 25% ischemic, 97% New York Heart Association functional class III, age 57 ± 13 years, with a mean qualifying left ventricular ejection fraction of 0.24 ± 0.06. For GNB3 genotype, 184 subjects were TT (53%), 137 (39%) CT, and 29 (8%) were CC. In GNB3 TT subjects, FDC I/H improved the CS (FDC I/H = 0.50 ± 1.6; placebo = -0.11 ± 1.8, p = 0.02), QoL (FDC I/H = 0.69 ± 1.4; placebo = 0.24 ± 1.5, p = 0.04), and event-free survival (hazard ratio: 0.51, p = 0.047), but not in subjects with the C allele (for CS, FDC I/H = -0.05 ± 1.7; placebo = -0.09 ± 1.7, p = 0.87; for QoL, FDC I/H = 0.28 ± 1.5; placebo = 0.14 ± 1.5, p = 0.56; and for event-free survival, p = 0.35).

CONCLUSIONS

The GNB3 TT genotype was associated with greater therapeutic effect of FDC I/H in A-HeFT. The role of the GNB3 genotype for targeting therapy with FDC I/H deserves further study.

GNB3 gene 825 TT variant predicts hard coronary events in the population-based Heinz Nixdorf Recall study

OBJECTIVE

The C825T polymorphism of the gene encoding the human G protein beta-3 subunit (GNB3) is associated with hypertension and obesity. Moreover, genotypes of the GNB3 polymorphism have been associated with development of coronary artery disease, and the 825T allele is thought to influence the process of atherosclerosis. However, the potential of the C825T polymorphism to predict coronary events has been poorly explored in a longitudinal setting at the population level.

METHODS

In 4159 Caucasian subjects from the Heinz Nixdorf Recall study cohort (age: 45-75 years, 48% male), genotypes of the GNB3 C825T polymorphism (rs5443) were determined and associated with fatal and non-fatal myocardial infarction (hard coronary events). Established cardiovascular risk factors were used to adjust for confounders.

RESULTS

The median follow-up time was 9.9 years (1st/3rd quartiles 9.5/10.2). 148 subjects (3.6%) experienced a hard coronary event. The 10-year event-free survival rate was CC, 96.1%; CT 96.9%, TT, 93.7% (p = 0.018). Multivariable analysis showed that the TT genotype is a significant risk factor for hard coronary events (hazard ratio (HR) = 1.9 (95% confidence interval (CI) 1.2-2.9); p = 0.008) after adjustment for age, sex, diabetes, systolic blood pressure, body mass index, high-density lipoprotein, and coronary artery calcification as determined by electron beam computed tomography at baseline. While prognosis in females was independent of GNB3 genotypes, analysis in males even elevated the HR for TT versus C-allele to 2.6 (95% CI 1.6-4.2; p < 0.001).

CONCLUSION

The GNB3 825 TT genotype is a significant and independent risk factor for hard coronary events independent of other established cardiovascular risk factors at a population level in males.

Differential localization of G protein βγ subunits

G protein βγ subunits play essential roles in regulating cellular signaling cascades, yet little is known about their distribution in tissues or their subcellular localization. While previous studies have suggested specific isoforms may exhibit a wide range of distributions throughout the central nervous system, a thorough investigation of the expression patterns of both Gβ and Gγ isoforms within subcellular fractions has not been conducted. To address this, we applied a targeted proteomics approach known as multiple-reaction monitoring to analyze localization patterns of Gβ and Gγ isoforms in pre- and postsynaptic fractions isolated from cortex, cerebellum, hippocampus, and striatum. Particular Gβ and Gγ subunits were found to exhibit distinct regional and subcellular localization patterns throughout the brain. Significant differences in subcellular localization between pre- and postsynaptic fractions were observed within the striatum for most Gβ and Gγ isoforms, while others exhibited completely unique expression patterns in all four brain regions examined. Such differences are a prerequisite for understanding roles of individual subunits in regulating specific signaling pathways throughout the central nervous system.