Polymorphisms in genes coding for GRK2 and GRK5 and response differences in antihypertensive-treated patients. Pharmacogenet Genomics. 2011;21:42-49. [PMID: 21127457 DOI: 10.1097/fpc.0b013e328341e911]

G protein-coupled receptor kinases in hypertension: physiology, pathogenesis, and therapeutic targets

G protein-coupled receptors (GPCRs) mediate cellular responses to a myriad of hormones and neurotransmitters that play vital roles in the regulation of physiological processes such as blood pressure. In organs such as the artery and kidney, hormones or neurotransmitters, such as angiotensin II (Ang II), dopamine, epinephrine, and norepinephrine exert their functions via their receptors, with the ultimate effect of keeping normal vascular reactivity, normal body sodium, and normal blood pressure. GPCR kinases (GRKs) exert their biological functions, by mediating the regulation of agonist-occupied GPCRs, non-GPCRs, or non-receptor substrates. In particular, increasing number of studies show that aberrant expression and activity of GRKs in the cardiovascular system and kidney inhibit or stimulate GPCRs (e.g., dopamine receptors, Ang II receptors, and α- and β-adrenergic receptors), resulting in hypertension. Current studies focus on the effect of selective GRK inhibitors in cardiovascular diseases, including hypertension. Moreover, genetic studies show that GRK gene variants are associated with essential hypertension, blood pressure response to antihypertensive medicines, and adverse cardiovascular outcomes of antihypertensive treatment. In this review, we present a comprehensive overview of GRK-mediated regulation of blood pressure, role of GRKs in the pathogenesis of hypertension, and highlight potential strategies for the treatment of hypertension. Schematic representation of GPCR desensitization process. Activation of GPCRs begins with the binding of an agonist to its corresponding receptor. Then G proteins activate downstream effectors that are mediated by various signaling pathways. GPCR signaling is halted by GRK-mediated receptor phosphorylation, which causes receptor internalization through β-arrestin.

Effect of Clinical and Genetic Factors on the Development of Postoperative Atrial Fibrillation After Coronary Artery Bypass Grafting (CABG) in Egyptian Patients Receiving Beta-Blockers

PURPOSE

Prophylactic beta-blockers are recommended to prevent postoperative atrial fibrillation (POAF) after coronary artery bypass grafting (CABG). Polymorphisms in the beta-1 adrenergic receptor (ADRB1) and G protein-coupled receptor kinase 5 (GRK5) genes are associated with variable responses to beta-blockers. The aim of this study was to determine the clinical and genetic factors that influence the response to beta-blockers for POAF prophylaxis after CABG.

METHODS

Patients undergoing isolated CABG and receiving prophylactic beta-blockers (n = 249) were prospectively recruited and followed up for 6 postoperative days. Genotyping of ADRB1 rs1801253, and 3 GRK5 SNPs (rs3740563, rs10787959, and rs17098707) was performed.

RESULTS

Of the 249 patients, 52 patients (20.8%) experienced POAF. Age, hypertension, vasopressor use, calculated POAF risk score, GRK5 rs2230345 T-allele, and GRK5 rs3740563 A-allele were associated with POAF despite beta-blocker prophylaxis. The multivariate analysis revealed that age [odds ratio (OR) 1.06, 95% CI 1.02-1.11, p = 0.003] and GRK5 rs2230345 T-allele [OR 2.81, 95% CI 1.39-5.67, p = 0.004] were independent predictors of POAF after CABG despite beta-blocker prophylaxis.

CONCLUSION

GRK5 rs2230345 T-allele carriers were less responsive than AA genotype carriers to prophylactic beta-blockers for the prevention of POAF after CABG. The study was registered on http://clinicaltrials.gov in March 2019, with trial registration number (TRN): NCT03871647.

Pharmacogenetics to guide cardiovascular drug therapy

Over the past decade, pharmacogenetic testing has emerged in clinical practice to guide selected cardiovascular therapies. The most common implementation in practice is CYP2C19 genotyping to predict clopidogrel response and assist in selecting antiplatelet therapy after percutaneous coronary intervention. Additional examples include genotyping to guide warfarin dosing and statin prescribing. Increasing evidence exists on outcomes with genotype-guided cardiovascular therapies from multiple randomized controlled trials and observational studies. Pharmacogenetic evidence is accumulating for additional cardiovascular medications. However, data for many of these medications are not yet sufficient to support the use of genotyping for drug prescribing. Ultimately, pharmacogenetics might provide a means to individualize drug regimens for complex diseases such as heart failure, in which the treatment armamentarium includes a growing list of medications shown to reduce morbidity and mortality. However, sophisticated analytical approaches are likely to be necessary to dissect the genetic underpinnings of responses to drug combinations. In this Review, we examine the evidence supporting pharmacogenetic testing in cardiovascular medicine, including that available from several clinical trials. In addition, we describe guidelines that support the use of cardiovascular pharmacogenetics, provide examples of clinical implementation of genotype-guided cardiovascular therapies and discuss opportunities for future growth of the field.

Pharmacogenetic factors affecting β-blocker metabolism and response

INTRODUCTION

β-blockers are among the most widely prescribed of all drugs, used for treatment of a large number of cardiovascular diseases. Herein we evaluate literature pertaining to pharmacogenetics of β-blocker therapy, provide insight into the robustness of the genetic associations, and determine the appropriateness for translating these genetic associations into clinical practice.

AREAS COVERED

A literature search was conducted using PubMed to collate evidence on associations between CYP2D6, ADRB1, ADRB2, and GRK5 genetic variation and drug-response outcomes in the presence of β-blocker exposure. Pharmacokinetic, pharmacodynamic, and clinical outcomes studies were included if genotype data and β-blocker exposure were documented.

EXPERT OPINION

Substantial data suggest that specific ADRB1 and GRK5 genotypes are associated with improved β-blocker efficacy and have potential for use to guide therapy decisions in the clinical setting. While the data do not justify ordering a CYP2D6 pharmacogenetic test, if CYP2D6 genotype is available in the electronic health record, there may be clinical utility for understanding dosing of β-blockers.

The Roles of GRKs in Hemostasis and Thrombosis

Along with cancer, cardiovascular and cerebrovascular diseases remain by far the most common causes of death. Heart attacks and strokes are diseases in which platelets play a role, through activation on ruptured plaques and subsequent thrombus formation. Most platelet agonists activate platelets via G protein-coupled receptors (GPCRs), which make these receptors ideal targets for many antiplatelet drugs. However, little is known about the mechanisms that provide feedback regulation on GPCRs to limit platelet activation. Emerging evidence from our group and others strongly suggests that GPCR kinases (GRKs) are critical negative regulators during platelet activation and thrombus formation. In this review, we will summarize recent findings on the role of GRKs in platelet biology and how one specific GRK, GRK6, regulates the hemostatic response to vascular injury. Furthermore, we will discuss the potential role of GRKs in thrombotic disorders, such as thrombotic events in COVID-19 patients. Studies on the function of GRKs during platelet activation and thrombus formation have just recently begun, and a better understanding of the role of GRKs in hemostasis and thrombosis will provide a fruitful avenue for understanding the hemostatic response to injury. It may also lead to new therapeutic options for the treatment of thrombotic and cardiovascular disorders.

Influence of GRK5 gene polymorphisms on ritodrine efficacy and adverse drug events in preterm labor treatment

The present prospective follow-up study aimed to evaluate the effects of GRK5 polymorphisms on ritodrine efficacy and adverse drug events (ADEs) in pregnant women undergoing preterm labor. A total of 162 women undergoing preterm labor were included in the study. Seven single nucleotide polymorphisms (SNPs) in the GRK5 gene (rs915120, rs2230345, rs2230349, rs7923896, rs1020672, rs4752308, and rs4752292) were assessed. Homozygous variant carriers of rs4752292 and rs1020672 had 0.6 times the hazard of delivery compared to wild-type allele carriers (95% confidence interval [CI], 0.41~0.99 and 0.38~0.99, respectively). In addition, homozygous variant carriers of rs4752292 and rs1020672 had 2.4-fold more (95% CI, 1.10~4.98) and 2.3-fold more (95% CI, 1.04~5.06) ADEs compared to those with the wild-type homozygotes, respectively. Among demographic variables, gestational age and modified Bishop score were significant factors associated with time to delivery, while body weight and maximum ritodrine infusion rate were significant factors associated with ADEs. In silico analysis showed that both rs4752292 and rs1020672 had the potential to affect mRNA splicing by alteration of splicing motifs. The present study shows that ritodrine efficacy and ADEs are associated with GRK5 gene polymorphisms in pregnant women undergoing preterm labor.

G protein-coupled receptor kinase 2 (GRK2) as a multifunctional signaling hub

Accumulating evidence indicates that G protein-coupled receptor kinase 2 (GRK2) is a versatile protein that acts as a signaling hub by modulating G protein-coupled receptor (GPCR) signaling and also via phosphorylation or scaffolding interactions with an extensive number of non-GPCR cellular partners. GRK2 multifunctionality arises from its multidomain structure and from complex mechanisms of regulation of its expression levels, activity, and localization within the cell, what allows the precise spatio-temporal shaping of GRK2 targets. A better understanding of the GRK2 interactome and its modulation mechanisms is helping to identify the GRK2-interacting proteins and its substrates involved in the participation of this kinase in different cellular processes and pathophysiological contexts.

The relationship between red blood cell distribution width and metabolic syndrome in elderly Chinese: a cross-sectional study

OBJECTIVE

Metabolic syndrome (MS) is a group of risk factors which includes hypertension, hyperglycemia, abnormal cholesterol levels, and obesity. Red blood cell distribution width (RDW) is a parameter that reflects the heterogeneity of erythrocyte volume. But the relationship between MS and RDW is intricate and remains poorly understood. We hypothesized that high RDW was associated with MS via inflammation. Our study aimed to investigate the association between RDW and MS in Chinese elderly large cohort. If RDW had a strong correlation with MS, RDW could become a predictor of MS?

METHODS

We recruited 10,887 ostensibly healthy participants aged from 60 to 93 (5795 male, 5092 female). Associations between RDW and other variables were assessed by Pearson correlation. Crude and adjusted odds ratio for MS with 95% confidence intervals was calculated by binary logistic regression models.

RESULTS

In elderly Chinese, RDW was significantly higher in males than in females. The prevalence of both men and women decreased with the rise of RDW. For both sexes, RDW demonstrated positive correlations with age, systolic blood pressure (0.070 in males,0.058 in females), high density lipoprotein(0.027in males,0.064 in females), negative correlations with triglycerides (- 0.120 in males,-0.074 in females) and fasting glucose (- 0.048 in males,-0.016 in females). Notably, we detected the associated reduced risks at the the third and fourth quartile of RDW in males. In women, there was no statistical significance.

CONCLUSION

We found the adjusted odds ratios of MS was lower at the third and fourth quartile of RDW in males.

A Literature Review of Genetic Markers Conferring Impaired Response to Cardiovascular Drugs

Pharmacogenetics is an emerging area of medicine, and more work is needed to fully integrate it into a clinical setting for the benefit of patients. Genetic markers can influence the action of many drugs, including those that prevent and treat cardiovascular conditions. Genotyping is not yet commonplace, but guidelines are being put in place to help practitioners determine the effect a genetic marker may have on certain drugs. With advancements in genetic technology and falling costs, genotyping could be available to all patients via a simple saliva test. This would be a cost-effective way for practitioners to determine the most effective treatment for individuals, reducing "trial and error," adverse effects, and rehospitalization rates and increasing patient compliance. Cardiovascular diseases are the leading causes of death worldwide, so using the most effective medication to treat or prevent them is of utmost importance in reducing incidence and mortality.

The influence of two functional genetic variants of GRK5 on tau phosphorylation and their association with Alzheimer's disease risk

Our work explores the relationship between G protein-coupled receptor kinase-5 (GRK5) single nucleotide polymorphisms and Alzheimer's disease risk. We confirmed that GRK5 translocates from the cellular membrane to the cytosol in the hippocampus of Alzheimer's disease mice and that GRK5 deficiency promotes tau hyperphosphorylation, a hallmark of Alzheimer's disease pathology. Our results indicate that one functional variant, or mutant, of GRK5 (GRK5-Gln41Leu) decreased GRK5 translocation from the membrane to the cytoplasm and reduced tau hyperphosphorylation, whereas, another GRK5 mutant (GRK5-Arg304His) increased GRK5 translocation to the cytoplasm and promoted tau hyperphosphorylation. In addition, case-control studies revealed that GRK5-Gln41Leu is associated with a lower risk of late-onset Alzheimer's disease. Our findings suggest that the GRK5-Gln41Leu mutant may resist tau hyperphosphorylation by promoting GRK5 membrane stability and, in effect, may contribute to lower Alzheimer's disease risk.

Secreted miR-27a Induced by Cyclic Stretch Modulates the Proliferation of Endothelial Cells in Hypertension via GRK6

Abnormal proliferation of endothelial cells (ECs) is important in vascular remodeling during hypertension, but the mechanisms are still unclear. In hypertensive rats caused by abdominal aortic coarctation, the expression of G-protein-coupled receptor kinase 6 (GRK6) in ECs at common carotid artery was repressed in vivo, and EC proliferation was increased. 15% cyclic stretch in vitro, which mimics the pathologically increased stretch in hypertension, repressed EC GRK6 expression via paracrine control by vascular smooth muscle cells (VSMCs). Furthermore, VSMC-derived microparticles (VSMC-MPs) were detected in the conditioned medium from VSMCs and in artery. VSMC-MPs from cells exposed to 15% cyclic stretch decreased GRK6 expression and increased EC proliferation. miR-27a was detected in VSMC-MPs and was upregulated by 15% cyclic stretch. miR-27a was transferred from VSMCs to ECs via VSMC-MPs and directly targeted on GRK6. Finally, a multi-point injection of antagomiR-27a around carotid artery decreased miR-27a expression in vivo, induced GRK6 expression, and reversed the abnormal EC proliferation. Pathologically elevated cyclic stretch increased the secretion of miR-27a, which was transferred from VSMCs to ECs via the VSMC-MPs, subsequently targeted GRK6, and induced EC proliferation. Locally decreasing miR-27a could be a novel therapeutic approach to attenuate the abnormal EC proliferation in hypertension.

Association of hematocrit with blood pressure and hypertension

BACKGROUND

Hypertension (HTN) is a risk factor for stroke, renal failure, and cardiovascular disease. The association between biochemical and hematological parameters with high blood pressure may provide a more precise approach to risk prediction conferred by HTN in these patients.

OBJECTIVE

The aim of current study was to explore whether biochemical and hematological parameters are associated with HTN in a cohort study with a 7-year follow-up.

MATERIALS AND METHODS

A total of 9808 individuals were enrolled and recruited as part of the Mashhad Stroke and Heart Atherosclerotic Disorders (MASHAD) cohort study, and biochemical and hematological factors were measured in all subjects. Univariate and multivariate logistic regression analysis were performed to determine the association of biochemical and hematological parameters with HTN.

RESULTS

Several biochemical parameters including fasting plasma glucose (FBG), serum high-sensitivity C-reactive protein (hs-CRP), triglyceride (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and uric acid were increased in hypertensive participants. In contrast, serum high-density lipoprotein cholesterol (HDL-C) was lower in hypertensive individuals. Furthermore, we demonstrated that hematological parameters including white blood cell (WBC) count, red blood cell (RBC) count, hemoglobin (HGB), hematocrit (HCT), and mean corpuscular hemoglobin (MCH) were higher in the hypertensive group compared to the control group. But mean corpuscular volume (MCV), and red cell distribution width (RDW), were decreased in the hypertensive group. Furthermore, our results strongly suggested that among these parameters, hematocrit was the independent risk factor for hypertension in the population.

CONCLUSION

We demonstrated the association of altered biochemical and hematological factors with hypertension supporting the value of emerging markers for early prediction of high blood pressure in prone individuals.

Identifying changes in punitive transcriptional factor binding sites from regulatory single nucleotide polymorphisms that are significantly associated with disease or sickness

AIM

To identify punitive transcriptional factor binding sites (TFBS) from regulatory single nucleotide polymorphisms (rSNPs) that are significantly associated with disease.

METHODS

The genome-wide association studies have provided us with nearly 6500 disease or trait-predisposing SNPs where 93% are located within non-coding regions such as gene regulatory or intergenic areas of the genome. In the regulatory region of a gene, a SNP can change the DNA sequence of a transcriptional factor (TF) motif and in turn may affect the process of gene regulation. SNP changes that affect gene expression and impact gene regulatory sequences such as promoters, enhancers, and silencers are known as rSNPs. Computational tools can be used to identify unique punitive TFBS created by rSNPs that are associated with disease or sickness. Computational analysis was used to identify punitive TFBS generated by the alleles of these rSNPs.

RESULTS

rSNPs within nine genes that have been significantly associated with disease or sickness were used to illustrate the tremendous diversity of punitive unique TFBS that can be generated by their alleles. The genes studied are the adrenergic, beta, receptor kinase 1, the v-akt murine thymoma viral oncogene homolog 3, the activating transcription factor 3, the type 2 demodkinase gene, the endothetal Per-Arnt-Sim domain protein 1, the lysosomal acid lipase A, the signal Transducer and Activator of Transcription 4, the thromboxane A2 receptor and the vascular endothelial growth factor A. From this sampling of SNPs among the nine genes, there are 73 potential unique TFBS generated by the common alleles compared to 124 generated by the minor alleles indicating the tremendous diversity of potential TFs that are capable of regulating these genes.

CONCLUSION

From the diversity of unique punitive binding sites for TFs, it was found that some TFs play a role in the disease or sickness being studied.

The analysis of heterotaxy patients reveals new loss-of-function variants of GRK5

G protein-coupled receptor kinase 5 (GRK5) is a regulator of cardiac performance and a potential therapeutic target in heart failure in the adult. Additionally, we have previously classified GRK5 as a determinant of left-right asymmetry and proper heart development using zebrafish. We thus aimed to identify GRK5 variants of functional significance by analysing 187 individuals with laterality defects (heterotaxy) that were associated with a congenital heart defect (CHD). Using Sanger sequencing we identified two moderately frequent variants in GRK5 with minor allele frequencies <10%, and seven very rare polymorphisms with minor allele frequencies <1%, two of which are novel variants. Given their evolutionarily conserved position in zebrafish, in-depth functional characterisation of four variants (p.Q41L, p.G298S, p.R304C and p.T425M) was performed. We tested the effects of these variants on normal subcellular localisation and the ability to desensitise receptor signalling as well as their ability to correct the left-right asymmetry defect upon Grk5l knockdown in zebrafish. While p.Q41L, p.R304C and p.T425M responded normally in the first two aspects, neither p.Q41L nor p.R304C were capable of rescuing the lateralisation phenotype. The fourth variant, p.G298S was identified as a complete loss-of-function variant in all assays and provides insight into the functions of GRK5.

Association Between Polymorphisms of ADRBK1 Gene and Plasma Renin Activity in Hypertensive Patients: A Case-Control Study

Background

Renin is the first step of the RAS cascade, which is a major regulator of salt-volume homeostasis. Adrenergic beta receptor kinase 1 (ADRBK1) plays important roles in regulating blood pressure via the epithelial Na⁺ channel (ENaC), which plays an important role in Na⁺ reabsorption in the renal collecting duct. The present case-control study was designed to investigate the potential relationship between polymorphisms of ADRBK1 and plasma renin activity (PRA) in hypertension.

Material/Methods

We recruited 1831 hypertensive and 422 normotensive Han Chinese subjects. Sitting PRA (ng/mL/h) was measured using radioimmunoassay method. Hypertensive patients were classified into 4 renin categories via PRA quartile. Single-nucleotide polymorphisms (SNPs) of the ADRBK1 gene (rs1894111, rs4930416, rs7127431, rs12286664, and rs3730147) were identified via TaqMan polymerase chain reaction.

Results

Comparison of the hypertensive group and the control group showed significant differences in distribution of genotypes and alleles of rs1894111 (P<0.05). Moreover, distribution of the dominant model (CC vs. CT+TT) in rs1894111 was lower in the hypertensive group than in the control group (P<0.05). Subjects were classified into 4 subgroups based on PRA quartile; the dominant model (CC vs. CT+TT) of rs1894111 was significantly lower in the quartile 1 group (the group with the lowest PRA) than in the control group (P<0.05). Logistic regression analysis demonstrated that the dominant model (CC vs. CT+TT) of rs1894111 was significantly different in the hypertensive group (OR=1.590, 95%CI=1.022–2.474, P<0.05), particularly in the quartile 1 group (OR=1.845, 95%CI=1.119–3.042, P<0.05), but not in the quartile 4 group.

Conclusions

The dominant model (CC vs. CT+TT) of rs1894111 polymorphism in the ADRBK1 gene might be associated with low-renin hypertension in Han Chinese.

TET2 and CSMD1 genes affect SBP response to hydrochlorothiazide in never-treated essential hypertensives

BACKGROUND

Thiazide diuretics have been recommended as a first-line antihypertensive treatment, although the choice of 'the right drug in the individual essential hypertensive patient' remains still empirical. Essential hypertension is a complex, polygenic disease derived from the interaction of patient's genetic background with the environment. Pharmacogenomics could be a useful tool to pinpoint gene variants involved in antihypertensive drug response, thus optimizing therapeutic advantages and minimizing side effects.

METHODS AND RESULTS

We looked for variants associated with blood pressure response to hydrochlorothiazide over an 8-week follow-up by means of a genome-wide association analysis in two Italian cohorts of never-treated essential hypertensive patients: 343 samples from Sardinia and 142 from Milan. TET2 and CSMD1 as plausible candidate genes to affect SBP response to hydrochlorothiazide were identified. The specificity of our findings for hydrochlorothiazide was confirmed in an independent cohort of essential hypertensive patients treated with losartan. Our best findings were also tested for replication in four independent hypertensive samples of European Ancestry, such as GENetics of drug RESponsiveness in essential hypertension, Genetic Epidemiology of Responses to Antihypertensives, NORdic DILtiazem intervention, Pharmacogenomics Evaluation of Antihypertensive Responses, and Campania Salute Network-StayOnDiur. We validated a polymorphism in CSMD1 and UGGT2.

CONCLUSION

This exploratory study reports two plausible loci associated with SBP response to hydrochlorothiazide: TET2, an aldosterone-responsive mediator of αENaC gene transcription; and CSMD1, previously described as associated with hypertension in a case-control study.

Radial primary percutaneous coronary intervention is independently associated with decreased long-term mortality in high-risk ST-elevation myocardial infarction patients

AIM

To compare long-term clinical outcomes in patients with ST-elevation myocardial infarction (STEMI) treated by primary percutaneous coronary intervention (PPCI) using radial and femoral arterial access.

METHODS AND RESULTS

The present study was an observational cohort study of patients with STEMI treated consecutively with PPCI between 2004 and 2011 at a single centre. The primary end point was all-cause mortality at a median follow-up of 3 years.Among 2727 patients, 1600 (58.7%) underwent PPCI via the femoral route. The femoral group was older (64.7 vs. 61.7 years; P < 0.0001), and had higher rates of diabetes (18.6% vs. 16.0%; P < 0.0001), previous PCI (11.2 vs. 7.8%; P = 0.004), previous myocardial infarction (15.3 vs. 8.3%; P < 0.0001) and cardiogenic shock (9.8 vs. 1.3%; P < 0.0001). Bleeding complications were more frequent in the femoral group (4.7 vs. 1.2%; P < 0.0001). The 5-year death rate was significantly higher in the femoral group than in the radial group (10.4 vs. 3.0%; P < 0.0001). After adjustment for confounding variables, bleeding complications [heart rate 2.07 (95% confidence interval 1.05-4.08)] and femoral access [heart rate 1.60 (95% confidence interval 1.02-2.53)] were independent predictors of all-cause mortality. After stratification using the propensity score, excess long-term mortality in patients treated via the femoral approach was predominantly in patients with a high baseline risk of death.

CONCLUSION

Patients undergoing PPCI via the femoral route are at a higher risk of adverse short-term and long-term outcomes than patients undergoing PPCI via the radial route. Patients with a high baseline risk may benefit most from radial access, and future outcome studies should focus on the most at-risk patients.

Prehypertension in adolescents with cardiovascular risk: a comparison between type 1 diabetic patients and overweight subjects

BACKGROUND

Adolescents with type 1 diabetes and obesity present higher cardiovascular risk and ambulatory blood pressure measurements (ABPM) has been shown to predict vascular events, especially by identifying the nondipper status. The aim of our observational cross-sectional study conducted in adolescents with type 1 diabetes, overweight subjects and healthy controls was to assess mean blood pressure parameters to identify subclinical cardiovascular risk.

METHODS

The study included adolescents patients with type 1 diabetes followed in our Pediatric Department in University of Catania between January 2011 and 2013. A total of 60 patients were enrolled, and 48 (32 male and 16 female) completed the study. For each subject we performed systolic and diastolic Ambulatory Blood Pressure Measurements (ABPM) during wakefulness and sleep recording blood pressure every 30 min for 24 h with the Tonoport V/2 GE CardioSoft V6.51 device. We compared the data of patients with those of overweight subjects and healthy controls.

RESULTS

ABPM revealed no significant difference between type 1 diabetic patients and overweight subjects in 24 h Systolic, 24 h Diastolic, Day-time Systolic, Night-time systolic and Day-time Diastolic blood pressure values but significantly different values in Night-time Diastolic blood pressure values (p < 0.001). We found significant differences between type 1 diabetic patients and healthy controls in all 24 h Systolic (p < 0.001), 24 h Diastolic (p < 0.01), Day-time Systolic (p < 0.01), Night-time Systolic (p < 0.001), Day-time Diastolic (p < 0.05) and Night-time Diastolic (p < 0.001) blood pressure values. We detected hypertension in 12/48 (25%) type 1 diabetic patients and in 10/48 overweight subjects (p = 0.62; OR 1.2; CI 0.48-3.29), whereas no-one of healthy controls presented hypertension (p < 0.001). We observed nondipper pattern in 40/48 (83.3%) type 1 diabetic patients, in 33/48 (68.8%) overweight subjects (p = 0.094; OR 2.27; CI 0.85-6.01), and in 16/48 (33.3%) of healthy controls (p < 0.001; OR 10; CI 3.79-26.3).

CONCLUSIONS

ABPM studies might help to define a subset of patients at increased risk for the development of hypertension. In evaluating blood pressure in type 1 diabetes and overweight subjects, ABPM should be used since a reduced dipping can indicate incipient hypertension.

The effects of genes implicated in cardiovascular disease on blood pressure response to treatment among treatment-naive hypertensive African Americans in the GenHAT study

African Americans have the highest prevalence of hypertension in the United States. Blood-pressure control is important to reduce cardiovascular disease (CVD)-related morbidity and mortality in this ethnic group. Genetic variants have been found to be associated with BP response to treatment. Previous pharmacogenetic studies of blood-pressure response to treatment in African Americans suffer limitations of small sample size as well as a limited number of candidate genes, and often focused on one antihypertensive treatment. Using 1,131 African-American treatment naïve participants from the Genetics of Hypertension Associated Treatment (GenHAT) Study, we examined whether variants in 35 candidate genes might modulate blood-pressure response to four different antihypertensive medications, including an angiotensin converting enzyme (ACE) inhibitor (lisinopril), a calcium channel blocker (amlodipine), and an α-adrenergic blocker (doxazosin) as compared to a thiazide diuretic (chlorthalidone) after 6 months of follow-up. Several suggestive gene by treatment interactions were identified. For example, among participants with two minor alleles of REN rs6681776, diastolic blood-pressure response was much improved on doxazosin compared to chlorthalidone (on average −9.49 mmHg vs. −1.70 mmHg) (P=0.007). Although several suggestive loci were identified, none of the findings passed significance criteria after correction for multiple testing. Given the impact of hypertension and its sequelae in this population, this research highlights the potential for genetic factors to contribute to blood-pressure response to treatment. Continued concerted research efforts focused on genetics are needed to improve treatment response in this high risk group.

Genetics and heart failure: a concise guide for the clinician

The pathogenesis of heart failure involves a complex interaction between genetic and environmental factors. Genetic factors may influence the susceptibility to the underlying etiology of heart failure, the rapidity of disease progression, or the response to pharmacologic therapy. The genetic contribution to heart failure is relatively minor in most multifactorial cases, but more direct and profound in the case of familial dilated cardiomyopathy. Early studies of genetic risk for heart failure focused on polymorphisms in genes integral to the adrenergic and renin-angiotensin-aldosterone system. Some of these variants were found to increase the risk of developing heart failure, and others appeared to affect the therapeutic response to neurohormonal antagonists. Regardless, each variant individually confers a relatively modest increase in risk and likely requires complex interaction with other variants and the environment for heart failure to develop. Dilated cardiomyopathy frequently leads to heart failure, and a genetic etiology increasingly has been recognized in cases previously considered to be "idiopathic". Up to 50% of dilated cardiomyopathy cases without other cause likely are due to a heritable genetic mutation. Such mutations typically are found in genes encoding sarcomeric proteins and are inherited in an autosomal dominant fashion. In recent years, rapid advances in sequencing technology have improved our ability to diagnose familial dilated cardiomyopathy and those diagnostic tests are available widely. Optimal care for the expanding population of patients with heritable heart failure involves counselors and physicians with specialized training in genetics, but numerous online genetics resources are available to practicing clinicians.

The evolving impact of g protein-coupled receptor kinases in cardiac health and disease

G protein-coupled receptors (GPCRs) are important regulators of various cellular functions via activation of intracellular signaling events. Active GPCR signaling is shut down by GPCR kinases (GRKs) and subsequent β-arrestin-mediated mechanisms including phosphorylation, internalization, and either receptor degradation or resensitization. The seven-member GRK family varies in their structural composition, cellular localization, function, and mechanism of action (see sect. II). Here, we focus our attention on GRKs in particular canonical and novel roles of the GRKs found in the cardiovascular system (see sects. III and IV). Paramount to overall cardiac function is GPCR-mediated signaling provided by the adrenergic system. Overstimulation of the adrenergic system has been highly implicated in various etiologies of cardiovascular disease including hypertension and heart failure. GRKs acting downstream of heightened adrenergic signaling appear to be key players in cardiac homeostasis and disease progression, and herein we review the current data on GRKs related to cardiac disease and discuss their potential in the development of novel therapeutic strategies in cardiac diseases including heart failure.

Glycated peptides are associated with the variability of endothelial dysfunction in the cerebral vessels and the kidney in type 2 diabetes mellitus patients: a cross-sectional study

BACKGROUND

Diabetic atherosclerosis and microangiopathy parallel diabetic nephropathy. The aim of our study was to evaluate the pattern of endothelial dysfunction in two vascular territories, the kidney and the brain, both affected by diabetic vasculopathic complications. The endothelial variability was evaluated in relation to advanced glycation end-products modified peptides.

METHODS

Seventy patients with type 2 diabetes mellitus and 11 healthy subjects were assessed concerning urine albumin: creatinine ratio, plasma and urinary advanced glycation end-products, plasma asymmetric dimethyl-arginine, serum cystatin C, intima-media thickness in the common carotid arteries, the pulsatility index, the resistance index in the internal carotid arteries and the middle cerebral arteries, the cerebrovascular reactivity through the breath-holding test.

RESULTS

The breath-holding index correlated with asymmetric dimethyl-arginine (R²=0.151; p<0.001), plasma advanced glycation end-products (R²=0.173; p<0.001), C-reactive protein (R²=0.587; p<0.001), duration of diabetes mellitus (R²=0.146; p=0.001), cystatin C (R²=0.220; p<0.001), estimated glomerular filtration rate (R²=0.237; p=0.001). Urine albumin: creatinine ratio correlated with urinary advanced glycation end-products (R²=0.257; p<0.001), but not with asymmetric dimethyl-arginine (R²=0.029; p=0.147).

CONCLUSIONS

In type 2 diabetic patients endothelial dysfunction in the cerebral vessels appears to be dissociated from glomerular endothelial dysfunction in early diabetic nephropathy. Advanced glycation end-products could impact both the cerebral vessels and the glomerular endothelium.

Sudden cardiac death diagnosed with dilated cardiomyopathy in a Kuwaiti family: a case report

BACKGROUND

Dilated cardiomyopathy is myocardial disease characterized by dilatation and impaired contraction of the left ventricle or both left and right ventricle. The majority of these cases are secondary to coronary artery disease, hypertension and valvular cardiomyopathy. Patients diagnosed with dilated cardiomyopathy are further clinically evaluated for evidence of familial history of the disease. Those families have shown to have genetic predisposition to dilated cardiomyopathy; thus, currently there is no available single genetic test that allows comprehensive testing of all causative genes. We report a Kuwaiti case of dilated cardiomyopathy that was diagnosed at young age. The patient clinical presentation pointed out to the fact that this was a familial disease. This case is the first reported in Kuwait clinically presented with familial dilated cardiomyopathy implying a genetic susceptibility factor to be further investigated within the at-risk family members.

CASE PRESENTATION

23-year-old Arab ethnicity Kuwaiti male with strong family history of dilated cardiomyopathy was admitted witnessed with sudden cardiac death. The patient presented with sudden arrhythmic death and survived with permanent anoxic brain injury. Transthoracic echocardiography revealed dilated cardiomyopathy with severe global left ventricular systolic dysfunction. After thorough investigation, the patient shown to have strong family history of dilated cardiomyopathy.

CONCLUSION

Familial dilated cardiomyopathy is poorly documented in Kuwait. We present this case with future plan to study the genetic map of his family.

Relationship between red cell distribution width and serum uric acid in patients with untreated essential hypertension

We assessed whether red cell distribution width (RDW) is associated with serum uric acid (UA) level in a group of 512 patients with newly diagnosed hypertension, recruited in Beijing. Patients were divided into high uric acid group and low uric acid group according to the median (334.9 μmol/L) of serum uric acid. Compared with the low uric acid group, the patients with high uric acid had higher red blood cell count (P < 0.001) and RDW (P = 0.032). The multiple linear regression analysis showed that RDW (P = 0.001) was positively correlated with uric acid level after the adjustment of related factors. Stepwise multiple logistic regression model confirmed that RDW (odds ratio: OR = 1.75) was independent determinants of high serum uric acid as well as sex (OR = 6.03), triglycerides (OR = 1.84), and Blood Urea Nitrogen (BUN, OR = 1.30). RDW may be independently associated with serum UA level in patients with newly diagnosed hypertension. To firmly establish the causal role of RDW in the incidence of high uric acid level among hypertensive patients, large cohort studies are needed.

Regulatory SNPs and transcriptional factor binding sites in ADRBK1, AKT3, ATF3, DIO2, TBXA2R and VEGFA

Abstract Regulatory single nucleotide polymorphisms (rSNPs) which change the transcriptional factor binding sites (TFBS) for transcriptional factors (TFs) to bind DNA were reviewed for the ADRBK1 (GRK2), AKT3, ATF3, DIO2, TBXA2R and VEGFA genes. Changes in the TFBS where TFs attach to regulate these genes may result in human sickness and disease. The highlights of this previous work were reviewed for these genes.

Tailoring therapy for heart failure: the pharmacogenomics of adrenergic receptor signaling

Heart failure is one of the leading causes of mortality in Western countries, and β-blockers are a cornerstone of its treatment. However, the response to these drugs is variable among individuals, which might be explained, at least in part, by genetic differences. Pharmacogenomics is the study of genetic contributions to drug response variability in order to provide evidence for a tailored therapy in an individual patient. Several studies have investigated the pharmacogenomics of the adrenergic receptor system and its role in the context of the use of β-blockers in treating heart failure. In this review, we will focus on the most significant polymorphisms described in the literature involving adrenergic receptors and adrenergic receptor-related proteins, as well as genetic variations influencing β-blocker metabolism.

G protein-coupled receptor kinase 5 gene polymorphisms are associated with postoperative atrial fibrillation after coronary artery bypass grafting in patients receiving β-blockers

BACKGROUND

We hypothesized that genetic variations in the adrenergic signaling pathway and cytochrome P450 2D6 enzyme are associated with new-onset atrial fibrillation (AF) in patients who underwent coronary artery bypass grafting and were treated with perioperative β-blockers (BBs).

METHODS AND RESULTS

Two cohorts of patients who underwent coronary artery bypass grafting and received perioperative BBs at Duke University Medical Center were studied. In a discovery cohort of 563 individuals from the Perioperative Genetics and Safety Outcomes Study (PEGASUS), using a covariate-adjusted logistic regression analysis, we tested 492 single-nucleotide polymorphisms (SNPs) in 10 candidate genes of the adrenergic signaling pathway and cytochrome P450 2D6 for association with postoperative AF despite perioperative BB therapy. SNPs meeting a false discovery rate ≤0.20 (P<0.002) were then tested in the replication cohort of 245 individuals from the Catheterization Genetics biorepository. Of the 492 SNPs examined, 4 intronic SNPs of the G protein-coupled kinase 5 (GRK5) gene were significantly associated with postoperative AF despite perioperative BB therapy in the discovery cohort with additive odds ratios between 1.72 and 2.75 (P=4.78×10(-5) to 0.0015). Three of these SNPs met nominal significance levels in the replication cohort with odds ratios between 2.07 and 2.60 (P=0.007 to 0.016). However, meta-analysis of the 2 data sets cohorts suggested strong association with postoperative AF despite perioperative BB therapy in all 4 SNPs (meta-P values from 1.66×10(-6) to 3.39×10(-5)).

CONCLUSIONS

In patients undergoing coronary artery bypass grafting, genetic variation in GRK5 is associated with postoperative AF despite perioperative BB therapy.

Genetic variations in IL1A and IL1RN are associated with the risk of preeclampsia in Chinese Han population

Preeclampsia (PE) is an excessive systemic inflammation response with dysfunction of endothelial. Our study was to investigate the association between genetic variations in IL-1 and the susceptibility to PE in Chinese Han population. 402 PE patients and 554 normal pregnant women of third trimester were enrolled. The polymorphisms of rs315952 in IL1RN and rs17561 in IL1A were genotyped by TaqMan allelic discrimination real-time PCR. Obviously statistic difference of the genotypic frequencies were found in both of IL1RN rs315952 and IL1A rs17561 between cases and controls (for rs315952, P = 0.001; for rs17561, P = 0.021.). For rs315952, the C allele was associated with development of PE (P = 0.003, OR = 1.319, 95%CI 1.099–1.583). Patients with CC or CT genotype were less likely to develop severe PE than patients carrying TT genotype(P< 0.001, OR = 0.24, 95%CI 0.15–0.40). For rs17561, the C allele was the risk factor for predisposition to PE (P = 0.012, OR = 1.496, 95%CI 1.089–2.055). Our results suggest IL1RN and IL1A may involve in the development of PE in Chinese Han population.

Interactive contribution of serine/threonine kinase 39 gene multiple polymorphisms to hypertension among northeastern Han Chinese

Serine/threonine kinase 39 (STK39) gene has been reported to be a hypertension-susceptibility gene by a recent genome-wide association study in Western populations. To validate this finding in Chinese, we focused on five well-characterized common polymorphisms in STK39 gene to examine their potential association with hypertension in a large northeastern Han population. This is a hospital-based case-control study involving 1009 hypertensive patients and 756 normotensive controls. Data were analyzed by the Haplo.Stats and multifactor dimensionality reduction (MDR) softwares. The genotype and allele distributions of rs6749447, rs3754777 and rs6433027 differed significantly between patients and controls (P < 0.001) even after the Bonferroni correction. The majority of derived haplotypes also showed remarkable differences between the two groups (P ≤ 0.001). As indicated by MDR analysis, a three-locus model including rs6749447, rs35929607 and rs3754777 was selected as the overall best with a larger testing accuracy of 0.7309 and a maximum cross-validation consistency of 10 (P < 0.001). The utility of this model was reinforced by a Logistic regression analysis. Taken together, our findings suggest the potential interactive role of STK39 gene multiple polymorphisms in the development of hypertension among northeastern Han Chinese.

Anesthetic challenges of patients with cardiac comorbidities undergoing major urologic surgery

The cardiac patient undergoing major urologic surgery is a complex case requiring a great attention by the anesthesiologist. Number of this group of patients having to go through this procedure is constantly increasing, due to prolonged life, increased agressiveness of surgery and increased anesthesia's safety. The anesthesiologist usually has to deal with several problems of the patient, such as hypertension, chronic heart failure, coronary artery disease, rhythm disturbances, intraoperative hemodymanic changes, intraoperative bleeding, perioperative fluid imbalance, and metabolic disturbances. A cardiac patient undergoing major urologic surgery is a complex case requiring a great attention by the anesthesiologist. The scope of this review article is to present the most frequent issues encountered with this group of patients, and to synthetically discuss the respective strategies and maneuvers during perioperative period, which is the major challenge for the anesthesiologist.

Human pharmacogenomic variation of antihypertensive drugs: from population genetics to personalized medicine

Aim: To investigate the human pharmacogenetic variation related to antihypertensive drugs, providing a survey of functional interpopulation differences in hypertension pharmacogenes. Materials & methods: The study was divided into two stages. In the first stage, we analyzed 1249 variants located in 57 hypertension pharmacogenes. This first-stage analysis confirmed that geographic origin strongly affects hypertension pharmacogenomic variation and that 31 pharmacogenes are geographically differentiated. In the second stage, we focused our attention on the ethnic-differentiated pharmacogenes, investigating 55,521 genetic variants. In silico analyses were performed to predict the effect of genetic variation. Results: Our analyses indicated functional interpopulation differences, suggesting insight into the mechanisms of antihypertensive drug response. Moreover, our data suggested that rare variants mainly determine the functionality of genes related to antihypertensive drugs. Conclusion: Our study provided important knowledge about the genetics of the antihypertensive drug response, suggesting that next-generation sequencing technologies may develop reliable pharmacogenetic tests for antihypertensive drugs.

Original submitted 19 September 2013; Revision submitted 14 November 2013

Why do hypertensive patients of African ancestry respond better to calcium blockers and diuretics than to ACE inhibitors and β-adrenergic blockers? A systematic review

BACKGROUND

Clinicians are encouraged to take an individualized approach when treating hypertension in patients of African ancestry, but little is known about why the individual patient may respond well to calcium blockers and diuretics, but generally has an attenuated response to drugs inhibiting the renin-angiotensin system and to β-adrenergic blockers. Therefore, we systematically reviewed the factors associated with the differential drug response of patients of African ancestry to antihypertensive drug therapy.

METHODS

Using the methodology of the systematic reviews narrative synthesis approach, we sought for published or unpublished studies that could explain the differential clinical efficacy of antihypertensive drugs in patients of African ancestry. PUBMED, EMBASE, LILACS, African Index Medicus and the Food and Drug Administration and European Medicines Agency databases were searched without language restriction from their inception through June 2012.

RESULTS

We retrieved 3,763 papers, and included 72 reports that mainly considered the 4 major classes of antihypertensive drugs, calcium blockers, diuretics, drugs that interfere with the renin-angiotensin system and β-adrenergic blockers. Pharmacokinetics, plasma renin and genetic polymorphisms did not well predict the response of patients of African ancestry to antihypertensive drugs. An emerging view that low nitric oxide and high creatine kinase may explain individual responses to antihypertensive drugs unites previous observations, but currently clinical data are very limited.

CONCLUSION

Available data are inconclusive regarding why patients of African ancestry display the typical response to antihypertensive drugs. In lieu of biochemical or pharmacogenomic parameters, self-defined African ancestry seems the best available predictor of individual responses to antihypertensive drugs.

The role of G protein coupled receptor kinases in neurocardiovascular pathophysiology

In coronary artery disease the G protein related kinases (GRKs) play a role in desensitization of β-adrenoreceptors (AR) after coronary occlusion. Targeted deletion and lowering of cardiac myocyte GRK-2 decreases the risk of post-ischemic heart failure (HF). Studies carried out in humans confirm the role of GRK-2 as a marker for the progression of HF after myocardial infarction (MI). The level of GRK-2 could be an indicator of β-AR blocker efficacy in patients with acute coronary syndrome. Elevated levels of GRK-2 are an early ubiquitous consequence of myocardial injury. In hypertension an increased level of GRK-2 was reported in both animal models and human studies. The role of GRKs in vagally mediated disorders such as vasovagal syncope and atrial fibrillation remains controversial. The role of GRKs in the pathogenesis of neurocardiological diseases provides an insight into the molecular pathogenesis process, opens potential therapeutic options and suggests new directins for scientific research.

Pharmacogenomics of selective serotonin reuptake inhibitor treatment for major depressive disorder: genome-wide associations and functional genomics

A genome-wide association (GWA) study of treatment outcomes (response and remission) of selective serotonin reuptake inhibitors (SSRIs) was conducted using 529 subjects with major depressive disorder (MDD). While no SNP associations reached the genome-wide level of significance, 14 SNPs of interest were identified for functional analysis. The rs11144870 SNP in riboflavin kinase (RFK) gene on chromosome 9 was associated with eight week treatment response (OR = 0.42, p = 1.04×10⁻⁶). The rs915120 SNP in the G protein-coupled receptor kinase 5 (GRK5) gene on chromosome 10 was associated with eight week remission (OR = 0.50, p = 1.15×10⁻⁵). Both SNPs were shown to influence transcription by a reporter gene assay and to alter nuclear protein binding using an electrophoretic mobility shift assay. This report represents an example of joining functional genomics with traditional GWA study results derived from a GWA analysis of SSRI treatment outcomes. The goal of this analytic strategy is to provide insights into the potential relevance of biologically plausible observed associations.

Lymphoblastoid cell lines in pharmacogenomic discovery and clinical translation

The ability to predict how an individual patient will respond to a particular treatment is the ambitious goal of personalized medicine. The genetic make up of an individual has been shown to play a role in drug response. For pharmacogenomic studies, human lymphoblastoid cell lines (LCLs) comprise a useful model system for identifying genetic variants associated with pharmacologic phenotypes. The availability of extensive genotype data for many panels of LCLs derived from individuals of diverse ancestry allows for the study of genetic variants contributing to interethnic and interindividual variation in susceptibility to drugs. Many genome-wide association studies for drug-induced phenotypes have been performed in LCLs, often incorporating gene-expression data. LCLs are also being used in follow-up studies to clinical findings to determine how an associated variant functions to affect phenotype. This review describes the most recent pharmacogenomic findings made in LCLs, including the translation of some findings to clinical cohorts.

Polymorphisms, hypertension and thiazide diuretics

It is 10 years since the discovery of the human genome; however, the study of the influence of genetic variants on drug effect - pharmacogenomics - has so far failed to create a major impact on day-to-day prescription practices. In the present article we analyze the main findings in candidate gene variants, gene combinations and whole-genome scans in relation to diuretic treatment. A critical analysis of the main reasons for some contrasting results will be discussed. The hypertension phases, in clinical trials dealing with genes and related pathophysiological mechanisms, may account for these inconsistent findings. The use of previously untreated versus treated patients is addressed. Finally, a positive study with a new genetic molecular strategy is described.

Gene-drug interaction in stroke

Stroke is the third cause of mortality and one of most frequent causes of long-term neurological disability, as well as a complex disease that results from the interaction of environmental and genetic factors. The focus on genetics has produced a large number of studies with the objective of revealing the genetic basis of cerebrovascular diseases. Furthermore, pharmacogenetic research has investigated the relation between genetic variability and drug effectiveness/toxicity. This review will examine the implications of pharmacogenetics of stroke; data on antihypertensives, statins, antiplatelets, anticoagulants, and recombinant tissue plasminogen activator will be illustrated. Several polymorphisms have been studied and some have been associated with positive drug-gene interaction on stroke, but the superiority of the genotype-guided approach over the clinical approach has not been proved yet; for this reason, it is not routinely recommended.

G protein-coupled receptor kinase-5 attenuates atherosclerosis by regulating receptor tyrosine kinases and 7-transmembrane receptors

OBJECTIVE

G protein-coupled receptor kinase-5 (GRK5) is a widely expressed Ser/Thr kinase that regulates several atherogenic receptors and may activate or inhibit nuclear factor-κB (NF-κB). This study sought to determine whether and by what mechanisms GRK5 affects atherosclerosis.

METHODS AND RESULTS

Grk5(-/-)/Apoe(-/-) mice developed 50% greater aortic atherosclerosis than Apoe(-/-) mice and demonstrated greater proliferation of macrophages and smooth muscle cells (SMCs) in atherosclerotic lesions. In Apoe(-/-) mice, carotid interposition grafts from Grk5(-/-) mice demonstrated greater upregulation of cell adhesion molecules than grafts from wild-type mice and, subsequently, more atherosclerosis. By comparing Grk5(-/-) with wild-type cells, we found that GRK5 desensitized 2 key atherogenic receptor tyrosine kinases: the platelet-derived growth factor receptor-β in SMCs, by augmenting ubiquitination/degradation; and the colony-stimulating factor-1 receptor (CSF-1R) in macrophages, by reducing CSF-1-induced tyrosyl phosphorylation. GRK5 activity in monocytes also reduced migration promoted by the 7-transmembrane receptor for monocyte chemoattractant protein-1 CC chemokine receptor-2. Whereas GRK5 diminished NF-κB-dependent gene expression in SMCs and endothelial cells, it had no effect on NF-κB activity in macrophages.

CONCLUSIONS

GRK5 attenuates atherosclerosis through multiple cell type-specific mechanisms, including reduction of SMC and endothelial cell NF-κB activity and desensitization of receptor-specific signaling through the monocyte CC chemokine receptor-2, macrophage CSF-1R, and the SMC platelet-derived growth factor receptor-β.

The genomic architecture of sporadic heart failure

Common or sporadic systolic heart failure (heart failure) is the clinical syndrome of insufficient forward cardiac output resulting from myocardial disease. Most heart failure is the consequence of ischemic or idiopathic cardiomyopathy. There is a clear familial predisposition to heart failure, with a genetic component estimated to confer between 20% and 30% of overall risk. The multifactorial etiology of this syndrome has complicated identification of its genetic underpinnings. Until recently, almost all genetic studies of heart failure were designed and deployed according to the common disease-common variant hypothesis, in which individual risk alleles impart a small positive or negative effect and overall genetic risk is the cumulative impact of all functional genetic variations. Early studies used a candidate gene approach focused mainly on factors within adrenergic and renin-angiotensin pathways that affect heart failure progression and are targeted by standard pharmacotherapeutics. Many of these reported allelic associations with heart failure have not been replicated. However, the preponderance of data supports risk-modifier effects for the Arg389Gly polymorphism of β1-adrenergic receptors and the intron 16 in/del polymorphism of angiotensin-converting enzyme. Recent unbiased studies using genome-wide single nucleotide polymorphism microarrays have shown fewer positive results than when these platforms were applied to hypertension, myocardial infarction, or diabetes, possibly reflecting the complex etiology of heart failure. A new cardiovascular gene-centric subgenome single nucleotide polymorphism array identified a common heat failure risk allele at 1p36 in multiple independent cohorts, but the biological mechanism for this association is still uncertain. It is likely that common gene polymorphisms account for only a fraction of individual genetic heart failure risk, and future studies using deep resequencing are likely to identify rare gene variants with larger biological effects.

Nuclear effects of G-protein receptor kinase 5 on histone deacetylase 5-regulated gene transcription in heart failure

BACKGROUND

G-protein receptor kinases (GRKs) modulate cardiac β-adrenergic signaling. GRK5 is upregulated in heart failure, and a gain-of-function polymorphism substituting leucine for wild-type glutamine at amino acid 41 (GRK5-Leu41) is associated with improved outcomes in heart failure and hypertension. GRK5 is distinguished by partial nuclear localization and class II histone deacetylases (HDAC) kinase activity that is postulated to regulate Gαq-stimulated cardiac gene expression.

METHODS AND RESULTS

We used in vitro tissue culture and in vivo mouse compound genetic models to examine the effects of GRK5 on HDAC phosphorylation, nucleo-cytoplasmic HDAC transport, and Gαq-dependent transcriptional regulation. In vitro, GRK5 stimulated HDAC5 nuclear export only in the context of Gαq signaling stimulated by angiotensin II. GRK5-Gln41 and Leu41 were similar inducers of HDAC5 nucleo-cytoplasmic shuttling. In vivo, GRK5-Gln41 and-Leu41 partitioned equally to nuclear and nonnuclear myocardial fractions. GRK5 increased cardiac HDAC5 phosphorylation and reversed the increase in nuclear HDAC5 content seen with cardiomyocyte-autonomous Gαq overexpression. Deep RNA sequencing showed few changes in gene expression induced by GRK5 overexpression or ablation alone, but GRK5 overexpression normalized steady-state expression levels of 48% (96 of 200) of all Gαq down-regulated mRNAs.

CONCLUSIONS

GRK5 is a transcriptional modifier of a subset of Gαq-downregulated genes, acting in opposition to the pathological effects of Gαq and normalizing levels of these transcripts. This transcriptional coregulator effect may act in concert with β-adrenergic receptor desensitization to protect against heart failure decompensation.