RGS Proteins in Heart: Brakes on the Vagus

Admixture Mapping of Chronic Kidney Disease and Risk Factors in Hispanic/Latino Individuals From Central America Country of Origin

BACKGROUND

Chronic kidney disease (CKD) is highly prevalent in Central America, and genetic factors may contribute to CKD risk. To understand the influences of genetic admixture on CKD susceptibility, we conducted an admixture mapping screening of CKD traits and risk factors in US Hispanic and Latino individuals from Central America country of origin.

METHODS

We analyzed 1023 participants of HCHS/SOL (Hispanic Community Health Study/Study of Latinos) who reported 4 grandparents originating from the same Central America country. Ancestry admixture findings were validated on 8191 African Americans from WHI (Women's Health Initiative), 3141 American Indians from SHS (Strong Heart Study), and over 1.1 million European individuals from a multistudy meta-analysis.

RESULTS

We identified 3 novel genomic regions for albuminuria (chromosome 14q24.2), CKD (chromosome 6q25.3), and type 2 diabetes (chromosome 3q22.2). The 14q24.2 locus driven by a Native American ancestry had a protective effect on albuminuria and consisted of 2 nearby regions spanning the RGS6 gene. Variants at this locus were validated in American Indians. The 6q25.3 African ancestry-derived locus, encompassing the ARID1B gene, was associated with increased risk for CKD and replicated in African Americans through admixture mapping. The European ancestry type 2 diabetes locus at 3q22.2, encompassing the EPHB1 and KY genes, was validated in European individuals through variant association.

CONCLUSIONS

US Hispanic/Latino populations are culturally and genetically diverse. This study focusing on Central America grandparent country of origin provides new loci discovery and insights into the ancestry-of-origin influences on CKD and risk factors in US Hispanic and Latino individuals.

Exploring the impact of electrocardiographic parameters on the risk of common arrhythmias: a two-sample Mendelian randomization study

Background

Observational studies have shown that heart rate (HR), heart rate variability (HRV), P-wave terminal force, P-wave duration, T-wave amplitude and PR interval are associated with risk factors for atrial fibrillation (AF) or bradycardia. Arrhythmias are associated with many causes of hospitalization. However, observational studies are susceptible to confounding factors that have not yet been identified. The objective of this study was to clarify the causal relationships by Mendelian randomization analysis.

Methods

We conducted a two-sample and multivariate Mendelian randomization (MVMR) analysis using genome-wide association study (GWAS) data from a European population to assess the total and direct causal effects of HR, three HRV traits, P-wave terminal force, P-wave duration, T-wave top amplitude in five-lead modes, and the PR interval on the risk of AF (N=191,205), bradycardia (N=463,010), and supraventricular tachycardia (SVT) (N=463,010).

Results

The results of the univariate MR analysis revealed the following significant causal effects: the higher the genetically predicted PR interval, the lower the risk of AF; the higher the HR and T-wave top amplitude (aVR leads and V3 + V4 + aVL leads), the lower the risk of bradycardia; and the higher HR and the lower PR interval, the higher the risk of SVT. The multivariate MR results indicated that the HRV_standard deviation of the normal-to-normal (SDNN) interval had an independent causal effect on the risk of AF [odds ratio (OR): 0.515; 95% confidence interval (CI): 0.278-0.954; P=0.03], and the T-wave top amplitude in the aVR leads (OR: 0.998; 95% CI: 0.996-0.999; P<0.001) and the HRV_SDNN (OR: 0.988; 95% CI: 0.976-1.000; P=0.045) had independent causal effects on the risk of bradycardia.

Conclusions

The HRV_SDNN had an independent causal effect on AF, while the HRV_SDNN and T-wave top amplitude in the aVR leads had independent causal effects on bradycardia, which suggests that some of the electrocardiographic parameters have preventive effects on the incidence of AF and bradycardia.

Cardiac RGS Proteins in Human Heart Failure and Atrial Fibrillation: Focus on RGS4

The regulator of G protein signaling (RGS) proteins are crucial for the termination of G protein signals elicited by G protein-coupled receptors (GPCRs). This superfamily of cell membrane receptors, by far the largest and most versatile in mammals, including humans, play pivotal roles in the regulation of cardiac function and homeostasis. Perturbations in both the activation and termination of their G protein-mediated signaling underlie numerous heart pathologies, including heart failure (HF) and atrial fibrillation (AFib). Therefore, RGS proteins play important roles in the pathophysiology of these two devasting cardiac diseases, and several of them could be targeted therapeutically. Although close to 40 human RGS proteins have been identified, each RGS protein seems to interact only with a specific set of G protein subunits and GPCR types/subtypes in any given tissue or cell type. Numerous in vitro and in vivo studies in animal models, and also in diseased human heart tissue obtained from transplantations or tissue banks, have provided substantial evidence of the roles various cardiomyocyte RGS proteins play in cardiac normal homeostasis as well as pathophysiology. One RGS protein in particular, RGS4, has been reported in what are now decades-old studies to be selectively upregulated in human HF. It has also been implicated in protection against AFib via knockout mice studies. This review summarizes the current understanding of the functional roles of cardiac RGS proteins and their implications for the treatment of HF and AFib, with a specific focus on RGS4 for the aforementioned reasons but also because it can be targeted successfully with small organic molecule inhibitors.

Role of G-Proteins and GPCRs in Cardiovascular Pathologies

Cell signaling is a fundamental process that enables cells to survive under various ecological and environmental contexts and imparts tolerance towards stressful conditions. The basic machinery for cell signaling includes a receptor molecule that senses and receives the signal. The primary form of the signal might be a hormone, light, an antigen, an odorant, a neurotransmitter, etc. Similarly, heterotrimeric G-proteins principally provide communication from the plasma membrane G-protein-coupled receptors (GPCRs) to the inner compartments of the cells to control various biochemical activities. G-protein-coupled signaling regulates different physiological functions in the targeted cell types. This review article discusses G-proteins' signaling and regulation functions and their physiological relevance. In addition, we also elaborate on the role of G-proteins in several cardiovascular diseases, such as myocardial ischemia, hypertension, atherosclerosis, restenosis, stroke, and peripheral artery disease.

The therapeutic potential of targeting cardiac RGS4

G protein-coupled receptors (GPCRs) play pivotal roles in regulation of cardiac function and homeostasis. To function properly, every cell needs these receptors to be stimulated only when a specific extracellular stimulus is present, and to be silenced the moment that stimulus is removed. The regulator of G protein signaling (RGS) proteins are crucial for the latter to occur at the cell membrane, where the GPCR normally resides. Perturbations in both activation and termination of G protein signaling underlie numerous heart pathologies. Although more than 30 mammalian RGS proteins have been identified, each RGS protein seems to interact only with a specific set of G protein subunits and GPCR types/subtypes in any given tissue or cell type, and this applies to the myocardium as well. A large number of studies have provided substantial evidence for the roles various RGS proteins expressed in cardiomyocytes play in cardiac physiology and heart disease pathophysiology. This review summarizes the current understanding of the functional roles of cardiac RGS proteins and their implications for the treatment of specific heart diseases, such as heart failure and atrial fibrillation. We focus on cardiac RGS4 in particular, since this isoform appears to be selectively (among the RGS protein family) upregulated in human heart failure and is also the target of ongoing drug discovery efforts for the treatment of a variety of diseases.

Autonomic Nervous System Regulation of Epicardial Adipose Tissue: Potential Roles for Regulator of G Protein Signaling-4

The epicardial adipose tissue (EAT) or epicardial fat is a visceral fat depot in the heart that contains intrinsic adrenergic and cholinergic nerves, through which it interacts with the cardiac sympathetic (adrenergic) and parasympathetic (cholinergic) nervous systems. These EAT nerves represent a significant source of several adipokines and other bioactive molecules, including norepinephrine, epinephrine, and free fatty acids. The production of these molecules is biologically relevant for the heart, since abnormalities in EAT secretion are implicated in the development of pathological conditions, including coronary atherosclerosis, atrial fibrillation, and heart failure. Sympathetic hyperactivity and parasympathetic (cholinergic) derangement are associated with EAT dysfunction, leading to a variety of adverse cardiac conditions, such as heart failure, diastolic dysfunction, atrial fibrillation, etc.; therefore, several studies have focused on exploring the autonomic regulation of EAT as it pertains to heart disease pathogenesis and progression. In addition, Regulator of G protein Signaling (RGS)-4 is a protein with significant regulatory roles in both adrenergic and muscarinic receptor signaling in the heart. In this review, we provide an overview of the autonomic regulation of EAT, with a specific focus on cardiac RGS4 and the potential roles this protein plays in this regulation.

Regulator of G-Protein Signaling-4 Attenuates Cardiac Adverse Remodeling and Neuronal Norepinephrine Release-Promoting Free Fatty Acid Receptor FFAR3 Signaling

Propionic acid is a cell nutrient but also a stimulus for cellular signaling. Free fatty acid receptor (FFAR)-3, also known as GPR41, is a Gi/o protein-coupled receptor (GPCR) that mediates some of the propionate's actions in cells, such as inflammation, fibrosis, and increased firing/norepinephrine release from peripheral sympathetic neurons. The regulator of G-protein Signaling (RGS)-4 inactivates (terminates) both Gi/o- and Gq-protein signaling and, in the heart, protects against atrial fibrillation via calcium signaling attenuation. RGS4 activity is stimulated by β-adrenergic receptors (ARs) via protein kinase A (PKA)-dependent phosphorylation. Herein, we examined whether RGS4 modulates cardiac FFAR3 signaling/function. We report that RGS4 is essential for dampening of FFAR3 signaling in H9c2 cardiomyocytes, since siRNA-mediated RGS4 depletion significantly enhanced propionate-dependent cAMP lowering, Gi/o activation, p38 MAPK activation, pro-inflammatory interleukin (IL)-1β and IL-6 production, and pro-fibrotic transforming growth factor (TGF)-β synthesis. Additionally, catecholamine pretreatment blocked propionic acid/FFAR3 signaling via PKA-dependent activation of RGS4 in H9c2 cardiomyocytes. Finally, RGS4 opposes FFAR3-dependent norepinephrine release from sympathetic-like neurons (differentiated Neuro-2a cells) co-cultured with H9c2 cardiomyocytes, thereby preserving the functional βAR number of the cardiomyocytes. In conclusion, RGS4 appears essential for propionate/FFAR3 signaling attenuation in both cardiomyocytes and sympathetic neurons, leading to cardioprotection against inflammation/adverse remodeling and to sympatholysis, respectively.

Vagus Nerve Stimulation as a Treatment for Fear and Anxiety in Individuals with Autism Spectrum Disorder

Anxiety disorders affect a large percentage of individuals who have an autism spectrum disorder (ASD). In children with ASD, excessive anxiety is also linked to gastrointestinal problems, self-injurious behaviors, and depressive symptoms. Exposure-based cognitive behavioral therapies are effective treatments for anxiety disorders in children with ASD, but high relapse rates indicate the need for additional treatment strategies. This perspective discusses evidence from preclinical research, which indicates that vagus nerve stimulation (VNS) paired with exposure to fear-provoking stimuli and situations could offer benefits as an adjuvant treatment for anxiety disorders that coexist with ASD. Vagus nerve stimulation is approved for use in the treatment of epilepsy, depression, and more recently as an adjuvant in rehabilitative training following stroke. In preclinical models, VNS shows promise in simultaneously enhancing consolidation of extinction memories and reducing anxiety. In this review, we will present potential mechanisms by which VNS could treat fear and anxiety in ASD. We also discuss potential uses of VNS to treat depression and epilepsy in the context of ASD, and noninvasive methods to stimulate the vagus nerve.

A network pharmacology approach to explore the potential role of Panax ginseng on exercise performance

[Purpose]

As Panax ginseng C. A. Meyer (ginseng) exhibits various physiological activities and is associated with exercise, we investigated the potential active components of ginseng and related target genes through network pharmacological analysis. Additionally, we analyzed the association between ginseng-related genes, such as the G-protein-coupled receptors (GPCRs), and improved exercise capacity.

[Methods]

Active compounds in ginseng and the related target genes were searched in the Traditional Chinese Medicine Database and Analysis Platform (TCMSP). Gene ontology functional analysis was performed to identify biological processes related to the collected genes, and a compound-target network was visualized using Cytoscape 3.7.2.

[Results]

A total of 21 ginseng active compounds were detected, and 110 targets regulated by 17 active substances were identified. We found that the active compound protein was involved in the biological process of adrenergic receptor activity in 80%, G-protein-coupled neurotransmitter in 10%, and leucocyte adhesion to arteries in 10%. Additionally, the biological response centered on adrenergic receptor activity showed a close relationship with G protein through the beta-1 adrenergic receptor gene reactivity.

[Conclusion]

According to bioavailability analysis, ginseng comprises 21 active compounds. Furthermore, we investigated the ginseng-stimulated gene activation using ontology analysis. GPCR, a gene upregulated by ginseng, is positively correlated to exercise. Therefore, if a study on this factor is conducted, it will provide useful basic data for improving exercise performance and health.

Selection of safe artemisinin derivatives using a machine learning-based cardiotoxicity platform and in vitro and in vivo validation

The majority of drug candidates fails the approval phase due to unwanted toxicities and side effects. Establishment of an effective toxicity prediction platform is of utmost importance, to increase the efficiency of the drug discovery process. For this purpose, we developed a toxicity prediction platform with machine-learning strategies. Cardiotoxicity prediction was performed by establishing a model with five parameters (arrhythmia, cardiac failure, heart block, hypertension, myocardial infarction) and additional toxicity predictions such as hepatotoxicity, reproductive toxicity, mutagenicity, and tumorigenicity are performed by using Data Warrior and Pro-Tox-II software. As a case study, we selected artemisinin derivatives to evaluate the platform and to provide a list of safe artemisinin derivatives. Artemisinin from Artemisia annua was described first as an anti-malarial compound and later its anticancer properties were discovered. Here, random forest feature selection algorithm was used for the establishment of cardiotoxicity models. High AUC scores above 0.830 were achieved for all five cardiotoxicity indications. Using a chemical library of 374 artemisinin derivatives as a case study, 7 compounds (deoxydihydro-artemisinin, 3-hydroxy-deoxy-dihydroartemisinin, 3-desoxy-dihydroartemisinin, dihydroartemisinin-furano acetate-d3, deoxyartemisinin, artemisinin G, artemisinin B) passed the toxicity filtering process for hepatotoxicity, mutagenicity, tumorigenicity, and reproductive toxicity in addition to cardiotoxicity. Experimental validation with the cardiomyocyte cell line AC16 supported the findings from the in silico cardiotoxicity model predictions. Transcriptomic profiling of AC16 cells upon artemisinin B treatment revealed a similar gene expression profile as that of the control compound, dexrazoxane. In vivo experiments with a Zebrafish model further substantiated the in silico and in vitro data, as only slight cardiotoxicity in picomolar range was observed. In conclusion, our machine-learning approach combined with in vitro and in vivo experimentation represents a suitable method to predict cardiotoxicity of drug candidates.

Neurohumoral Control of Sinoatrial Node Activity and Heart Rate: Insight From Experimental Models and Findings From Humans

The sinoatrial node is perhaps one of the most important tissues in the entire body: it is the natural pacemaker of the heart, making it responsible for initiating each-and-every normal heartbeat. As such, its activity is heavily controlled, allowing heart rate to rapidly adapt to changes in physiological demand. Control of sinoatrial node activity, however, is complex, occurring through the autonomic nervous system and various circulating and locally released factors. In this review we discuss the coupled-clock pacemaker system and how its manipulation by neurohumoral signaling alters heart rate, considering the multitude of canonical and non-canonical agents that are known to modulate sinoatrial node activity. For each, we discuss the principal receptors involved and known intracellular signaling and protein targets, highlighting gaps in our knowledge and understanding from experimental models and human studies that represent areas for future research.

Regulator of G Protein Signaling 6 Facilities Cardiac Hypertrophy by Activating Apoptosis Signal-Regulating Kinase 1-P38/c-JUN N-Terminal Kinase 1/2 Signaling

Background

Regulator of G protein signaling 6 (RGS6) is an important member of the RGS family and produces pleiotropic regulatory effects on cardiac pathophysiology. However, the role of RGS6 protein in cardiomyocytes during angiotensin II– and pressure overload–induced cardiac hypertrophy remain unknown.

Methods and Results

Here, we used a genetic approach to study the regulatory role of RGS6 in cardiomyocytes during pathological cardiac hypertrophy. RGS6 expression was significantly increased in failing human hearts and in hypertrophic murine hearts. The extent of aortic banding–induced cardiac hypertrophy, dysfunction, and fibrosis in cardiac‐specific RGS6 knockout mice was alleviated, whereas the hearts of transgenic mice with cardiac‐specific RGS6 overexpression exhibited exacerbated responses to pressure overload. Consistent with these findings, RGS6 also facilitated an angiotensin II–induced hypertrophic response in isolated cardiomyocytes. According to the mechanistic studies, RGS6 mediated cardiac hypertrophy by directly interacting with apoptosis signal–regulating kinase 1, which further activates the P38‐c‐JUN N‐terminal kinase 1/2 signaling pathway.

Conclusions

Based on our findings, RGS6 aggravates cardiac hypertrophy, and the RGS6‐apoptosis signal–regulating kinase 1 pathway represents a potential therapeutic target to attenuate pressure overload–driven cardiac remodeling.

Ischemia/Reperfusion Injury Revisited: An Overview of the Latest Pharmacological Strategies

Ischemia/reperfusion injury (IRI) permeates a variety of diseases and is a ubiquitous concern in every transplantation proceeding, from whole organs to modest grafts. Given its significance, efforts to evade the damaging effects of both ischemia and reperfusion are abundant in the literature and they consist of several strategies, such as applying pre-ischemic conditioning protocols, improving protection from preservation solutions, thus providing extended cold ischemia time and so on. In this review, we describe many of the latest pharmacological approaches that have been proven effective against IRI, while also revisiting well-established concepts and presenting recent pathophysiological findings in this ever-expanding field. A plethora of promising protocols has emerged in the last few years. They have been showing exciting results regarding protection against IRI by employing drugs that engage several strategies, such as modulating cell-surviving pathways, evading oxidative damage, physically protecting cell membrane integrity, and enhancing cell energetics.

Flip-Flopping Retinal in Microbial Rhodopsins as a Template for a Farnesyl/Prenyl Flip-Flop Model in Eukaryote GPCRs

Thirty years after the first description and modeling of G protein coupled receptors (GPCRs), information about their mode of action is still limited. One of the questions that is hard to answer is: how do the allosteric changes in the GPCR induced by, e.g., ligand binding in the end activate a G protein-dependent intracellular pathway (e.g., via the cAMP or the phosphatidylinositol signal pathways). Another question relates to the role of prenylation of G proteins. Today's "consensus model" states that protein prenylation is required for the assembly of GPCR-G protein complexes. Although it is well-known that protein prenylation is the covalent addition of a farnesyl- or geranylgeranyl moiety to the C terminus of specific proteins, e.g., α or γ G protein, the reason for this strong covalent binding remains enigmatic. The arguments for a fundamental role for prenylation of G proteins other than just being a hydrophobic linker, are gradually accumulating. We uncovered a dilemma that at first glance may be considered physiologically irrelevant, however, it may cause a true change in paradigm. The consensus model suggests that the only functional role of prenylation is to link the G protein to the receptor. Does the isoprenoid nature of the prenyl group and its exact site of attachment somehow matter? Or, are there valid arguments favoring the alternative possibility that a key role of the G protein is to guide the covalently attached prenyl group to - and it hold it in - a very specific location in between specific helices of the receptor? Our model says that the farnesyl/prenyl group - aided by its covalent attachment to a G protein -might function in GPCRs as a horseshoe-shaped flexible (and perhaps flip-flopping) hydrophobic valve for restricting (though not fully inhibiting) the untimely passage of Ca2+, like retinal does for the passage of H+ in microbial rhodopsins that are ancestral to many GPCRs.

Genetic Analysis of Rare Human Variants of Regulators of G Protein Signaling Proteins and Their Role in Human Physiology and Disease

Regulators of G protein signaling (RGS) proteins modulate the physiologic actions of many neurotransmitters, hormones, and other signaling molecules. Human RGS proteins comprise a family of 20 canonical proteins that bind directly to G protein-coupled receptors/G protein complexes to limit the lifetime of their signaling events, which regulate all aspects of cell and organ physiology. Genetic variations account for diverse human traits and individual predispositions to disease. RGS proteins contribute to many complex polygenic human traits and pathologies such as hypertension, atherosclerosis, schizophrenia, depression, addiction, cancers, and many others. Recent analysis indicates that most human diseases are due to extremely rare genetic variants. In this study, we summarize physiologic roles for RGS proteins and links to human diseases/traits and report rare variants found within each human RGS protein exome sequence derived from global population studies. Each RGS sequence is analyzed using recently described bioinformatics and proteomic tools for measures of missense tolerance ratio paired with combined annotation-dependent depletion scores, and protein post-translational modification (PTM) alignment cluster analysis. We highlight selected variants within the well-studied RGS domain that likely disrupt RGS protein functions and provide comprehensive variant and PTM data for each RGS protein for future study. We propose that rare variants in functionally sensitive regions of RGS proteins confer profound change-of-function phenotypes that may contribute, in newly appreciated ways, to complex human diseases and/or traits. This information provides investigators with a valuable database to explore variation in RGS protein function, and for targeting RGS proteins as future therapeutic targets.

Regulators of G protein signaling in cardiovascular function during pregnancy

G protein-coupled receptor signaling mechanisms are implicated in many aspects of cardiovascular control, and dysfunction of such signaling mechanisms is commonly associated with disease states. Investigators have identified a large number of regulator of G protein signaling (RGS) proteins that variously contribute to the modulation of intracellular second-messenger signaling kinetics. These many RGS proteins each interact with a specific set of second-messenger cascades and receptor types and exhibit tissue-specific expression patterns. Increasing evidence supports the contribution of RGS proteins, or their loss, in the pathogenesis of cardiovascular dysfunctions. This review summarizes the current understanding of the functional contributions of RGS proteins, particularly within the B/R4 family, in cardiovascular disorders of pregnancy including gestational hypertension, uterine artery dysfunction, and preeclampsia.

Expression and relevance of the G protein-gated K+ channel in the mouse ventricle

The atrial G protein-gated inwardly rectifying K⁺ (GIRK) channel is a critical mediator of parasympathetic influence on cardiac physiology. Here, we probed the details and relevance of the GIRK channel in mouse ventricle. mRNAs for the atrial GIRK channel subunits (GIRK1, GIRK4), M2 muscarinic receptor (M₂R), and RGS6, a negative regulator of atrial GIRK-dependent signaling, were detected in mouse ventricle at relatively low levels. The cholinergic agonist carbachol (CCh) activated small GIRK currents in adult wild-type ventricular myocytes that exhibited relatively slow kinetics and low CCh sensitivity; these currents were absent in ventricular myocytes from Girk1^-/- or Girk4^-/- mice. While loss of GIRK channels attenuated the CCh-induced shortening of action potential duration and suppression of ventricular myocyte excitability, selective ablation of GIRK channels in ventricle had no effect on heart rate, heart rate variability, or electrocardiogram parameters at baseline or after CCh injection. Additionally, loss of ventricular GIRK channels did not impact susceptibility to ventricular arrhythmias. These data suggest that the mouse ventricular GIRK channel is a GIRK1/GIRK4 heteromer, and show that while it contributes to the cholinergic suppression of ventricular myocyte excitability, this influence does not substantially impact cardiac physiology or ventricular arrhythmogenesis in the mouse.

Regulating the regulators: Epigenetic, transcriptional, and post-translational regulation of RGS proteins

Regulators of G protein signaling (RGS) are a family of proteins classically known to accelerate the intrinsic GTPase activity of G proteins, which results in accelerated inactivation of heterotrimeric G proteins and inhibition of G protein coupled receptor signaling. RGS proteins play major roles in essential cellular processes, and dysregulation of RGS protein expression is implicated in multiple diseases, including cancer, cardiovascular and neurodegenerative diseases. The expression of RGS proteins is highly dynamic and is regulated by epigenetic, transcriptional and post-translational mechanisms. This review summarizes studies that report dysregulation of RGS protein expression in disease states, and presents examples of drugs that regulate RGS protein expression. Additionally, this review discusses, in detail, the transcriptional and post-transcriptional mechanisms regulating RGS protein expression, and further assesses the therapeutic potential of targeting these mechanisms. Understanding the molecular mechanisms controlling the expression of RGS proteins is essential for the development of therapeutics that indirectly modulate G protein signaling by regulating expression of RGS proteins.

Genetic loci associated with heart rate variability and their effects on cardiac disease risk

Reduced cardiac vagal control reflected in low heart rate variability (HRV) is associated with greater risks for cardiac morbidity and mortality. In two-stage meta-analyses of genome-wide association studies for three HRV traits in up to 53,174 individuals of European ancestry, we detect 17 genome-wide significant SNPs in eight loci. HRV SNPs tag non-synonymous SNPs (in NDUFA11 and KIAA1755), expression quantitative trait loci (eQTLs) (influencing GNG11, RGS6 and NEO1), or are located in genes preferentially expressed in the sinoatrial node (GNG11, RGS6 and HCN4). Genetic risk scores account for 0.9 to 2.6% of the HRV variance. Significant genetic correlation is found for HRV with heart rate (-0.74 Collapse

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MESH Headings

• Blood Pressure
• Cohort Studies
• Genetic Predisposition to Disease
• Genome-Wide Association Study
• Heart Diseases/genetics
• Heart Diseases/physiopathology
• Heart Rate
• Humans
• Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels/genetics
• Muscle Proteins/genetics
• Polymorphism, Single Nucleotide
• Potassium Channels/genetics
• Quantitative Trait Loci
• RGS Proteins/genetics
• Risk Factors
• White People/genetics

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Grants

• R01 HL120393 NHLBI NIH HHS
• U01 HL130114 NHLBI NIH HHS
• P01 GM099568 NIGMS NIH HHS
• UL1 TR000124 NCATS NIH HHS
• R01 HL105756 NHLBI NIH HHS
• S10 OD020069 NIH HHS
• K23 HL114724 NHLBI NIH HHS
• R01 HL116747 NHLBI NIH HHS
• P30 DK063491 NIDDK NIH HHS
• I01 BX002558 BLRD VA
• MC_UU_12019/1 Medical Research Council
• UL1 TR001881 NCATS NIH HHS
• P2C HD050924 NICHD NIH HHS

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Affiliation(s)

Ilja M. Nolte Department of Epidemiology, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands
M. Loretto Munoz Department of Epidemiology, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands
Vinicius Tragante Department of Cardiology, Division Heart and Lungs, University Medical Center Utrecht, Heidelberglaan 100, Utrecht 3584CX, The Netherlands
Azmeraw T. Amare Department of Epidemiology, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands Department of Epidemiology, School of Medicine, University of Adelaide, Adelaide, South Australia 5005, Australia College of Medicine and Health Sciences, Bahir Dar University, Bahir Dar 6000, Ethiopia
Rick Jansen Department of Psychiatry, EMGO Institute for Health and Care Research and Neuroscience Campus Amsterdam, VU University Medical Center/GGZ inGeest, Amsterdam 1081 BT, The Netherlands
Ahmad Vaez Department of Epidemiology, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands School of Medicine, Isfahan University of Medical Sciences, Isfahan 81746-73461, Iran
Benedikt von der Heyde Department of Medical Sciences, Molecular Epidemiology, Uppsala University, Uppsala 75237, Sweden Science for Life Laboratory, Uppsala University, Uppsala 75237, Sweden
Christy L. Avery Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina 27599, USA
Joshua C. Bis Cardiovascular Health Research Unit, Department of Medicine, University of Washington, Seattle, Washington 98104, USA
Bram Dierckx Department of Child and Adolescent Psychiatry/Psychology, Department of Child and Adolescent Psychiatry, PO Box 2060, Rotterdam 3000 CB, The Netherlands The Generation R Study Group, Erasmus MC, PO Box 2060, Rotterdam 3000 CB, The Netherlands
Jenny van Dongen Department of Biological Psychology, Behavioral and Movement Sciences, VU University, Amsterdam 1081 BT, The Netherlands
Stephanie M. Gogarten Department of Biostatistics, School of Public Health, University of Washington, Seattle, Washington 98195, USA
Philippe Goyette Montreal Heart Institute, Montreal, Quebec, Canada H1T 1C8
Jussi Hernesniemi Department of Clinical Chemistry, Fimlab Laboratories, Tampere 33520, Finland Department of Clinical Chemistry, University of Tampere School of Medicine, Tampere 33014, Finland Department of Cardiology, Heart Hospital, Tampere University Hospital, Tampere 33521, Finland
Ville Huikari Center for Life Course Health Research, University of Oulu, Oulu 90014, Finland
Shih-Jen Hwang Framingham Heart Study, Framingham, Massachusetts 01702, USA Population Sciences Branch, National Heart, Lung and Blood Institute, Bethesda, Maryland 20892, USA
Deepali Jaju Department of Clinical Physiology, Sultan Qaboos University Hospital, Muscat—Al Khoudh 123, Sultanate of Oman
Kathleen F. Kerr Department of Biostatistics, School of Public Health, University of Washington, Seattle, Washington 98195, USA
Alexander Kluttig Institute of Medical Epidemiology, Biostatistics and Informatics, Martin-Luther-University Halle-Wittenberg, Halle (Saale) 06097, Germany
Bouwe P. Krijthe Department of Epidemiology, Erasmus MC, University Medical Center Rotterdam, PO Box 2060, Rotterdam 3000 CB, The Netherlands
Jitender Kumar Department of Medical Sciences, Molecular Epidemiology, Uppsala University, Uppsala 75237, Sweden Science for Life Laboratory, Uppsala University, Uppsala 75237, Sweden
Sander W. van der Laan Laboratory of Experimental Cardiology, Department of Heart and Lung, University Medical Center Utrecht, Heidelberglaan 100, Utrecht 3584 CX, The Netherlands
Leo-Pekka Lyytikäinen Department of Clinical Chemistry, Fimlab Laboratories, Tampere 33520, Finland Department of Clinical Chemistry, University of Tampere School of Medicine, Tampere 33014, Finland
Adam X. Maihofer Department of Psychiatry, University of California, San Diego, San Diego, California 92093, USA Center for Stress and Mental Health (CESAMH), VA San Diego Healthcare System, San Diego, California 92161, USA
Arpi Minassian Department of Psychiatry, University of California, San Diego, San Diego, California 92093, USA Center for Stress and Mental Health (CESAMH), VA San Diego Healthcare System, San Diego, California 92161, USA
Peter J. van der Most Department of Epidemiology, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands
Martina Müller-Nurasyid Institute of Genetic Epidemiology, Helmholtz Zentrum München—German Research Center for Environmental Health, Neuherberg 85764, Germany Department of Medicine, University Hospital Munich, Ludwig-Maximilians-University, Munich 80539, Germany DZHK (German Centre for Cardiovascular Research), Partner site Munich Heart Alliance, Munich 80336, Germany
Michel Nivard Department of Biological Psychology, Behavioral and Movement Sciences, VU University, Amsterdam 1081 BT, The Netherlands EMGO+ Institute for Health and Care Research, VU University & VU University Medical Center, Amsterdam 1081 HV, The Netherlands
Erika Salvi Department of Health Sciences, University of Milano, Milano 20122, Italy
James D. Stewart Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina 27599, USA Carolina Population Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
Julian F. Thayer Department of Psychology, The Ohio State University, 1835 Neil Avenue, Columbus, Ohio 43210, USA
Niek Verweij Department of Cardiology, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands
Andrew Wong MRC Unit for Lifelong Health and Ageing, University College London, 33 Bedford Place, London WC1B 5JU, UK
Delilah Zabaneh Institute of Psychiatry, Psychology & Neuroscience, King's College London, De Crespigny Park, London SE5 8AF, UK University College London Genetics Institute, University College London, London WC1E 6BT, UK
Mohammad H. Zafarmand Department of Public Health, Academic Medical Center (AMC), University of Amsterdam, Amsterdam 1105 AZ, The Netherlands Department of Obstetrics and Gynaecology, Academic Medical Centre, University of Amsterdam, Amsterdam 1105 AZ, The Netherlands
Abdel Abdellaoui Department of Biological Psychology, Behavioral and Movement Sciences, VU University, Amsterdam 1081 BT, The Netherlands EMGO+ Institute for Health and Care Research, VU University & VU University Medical Center, Amsterdam 1081 HV, The Netherlands
Sulayma Albarwani Department of Physiology, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat Al-Khoudh 123, Sultanate of Oman
Christine Albert Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA
Alvaro Alonso Department of Epidemiology, Rollins School of Public Health, Emory University, Atlanta, Georgia 30322, USA
Foram Ashar McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA
Juha Auvinen Center for Life Course Health Research, University of Oulu, Oulu 90014, Finland Unit of Primary Health Care, Oulu University Hospital, Oulu 90220, Finland
Tomas Axelsson Department of Medical Sciences, Molecular Medicine, Uppsala University, Uppsala 75237, Sweden
Dewleen G. Baker Department of Psychiatry, University of California, San Diego, San Diego, California 92093, USA Center for Stress and Mental Health (CESAMH), VA San Diego Healthcare System, San Diego, California 92161, USA
Paul I. W. de Bakker Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht 3584 CX, The Netherlands Department of Epidemiology, Julius Center for Health Sciences and Primary Care, University Medical Center Utrecht, Utrecht, The Netherlands
Matteo Barcella Department of Health Sciences, University of Milano, Milano 20122, Italy
Riad Bayoumi College of Medicine, Mohammed Bin Rashid University, PO Box 505055, Dubai Healthcare City, United Arab Emirates
Rob J. Bieringa Department of Epidemiology, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands
Dorret Boomsma Department of Biological Psychology, Behavioral and Movement Sciences, VU University, Amsterdam 1081 BT, The Netherlands EMGO+ Institute for Health and Care Research, VU University & VU University Medical Center, Amsterdam 1081 HV, The Netherlands
Gabrielle Boucher Montreal Heart Institute, Montreal, Quebec, Canada H1T 1C8
Annie R. Britton Department of Epidemiology and Public Health, University College London, London WC1E 6BT, UK
Ingrid Christophersen Cardiovascular Research Center, Massachusetts General Hospital, Boston, Massachusetts 02114, USA Program in Medical and Population Genetics, The Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02114, USA Department of Medical Research, Bærum Hospital, Vestre Viken Hospital Trust, Rud 1346, Norway
Andrea Dietrich Department of Child- and Adolescent Psychiatry, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands
George B. Ehret Center for Complex Disease Genomics, McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205, USA Cardiology, Department of Specialties of Internal Medicine, Geneva University Hospital, Geneva 1211, Switzerland
Patrick T. Ellinor Program in Medical and Population Genetics, The Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02114, USA Cardiac Arrhythmia Service & Cardiovascular Research Center, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
Markku Eskola Department of Cardiology, Heart Hospital, Tampere University Hospital, Tampere 33521, Finland Department of Cardiology, University of Tampere School of Medicine, Tampere 33014, Finland
Janine F. Felix Department of Epidemiology, Erasmus MC, University Medical Center Rotterdam, PO Box 2060, Rotterdam 3000 CB, The Netherlands
John S. Floras University Health Network and Mount Sinai Hospital Division of Cardiology, Department of Medicine, University of Toronto, Ontario, Canada M5S Toronto General Research Institute, University Health Network, Toronto, Canada
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Peter Friberg Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska University Hospital, University of Gothenburg, Gothenburg, Sweden
Maaike G. J. Gademan Department of Public Health, Academic Medical Center (AMC), University of Amsterdam, Amsterdam 1105 AZ, The Netherlands
Mark A. Geyer Department of Psychiatry, University of California, San Diego, San Diego, California 92093, USA
Vilmantas Giedraitis Department of Public Health and Caring Sciences, Molecular Geriatrics, Uppsala University, Uppsala 75237, Sweden
Catharina A. Hartman Interdisciplinary Center Psychopathology and Emotion regulation, Department of Psychiatry, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands
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Albert Hofman Department of Epidemiology, Erasmus MC, University Medical Center Rotterdam, PO Box 2060, Rotterdam 3000 CB, The Netherlands
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Heikki Huikuri Research Unit of Internal Medicine, Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu 90220, Finland
Nina Hutri-Kähönen Department of Pediatrics, Tampere University Hospital, Tampere 33521, Finland Department of Pediatrics, University of Tampere School of Medicine, Tampere 33014, Finland
Xavier Jouven INSERM U970, Paris Descartes University, Paris 75006, France
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Markus Juonala Department of Medicine, University of Turku, Turku 20520, Finland Division of Medicine, Turku University Hospital, Turku 20521, Finland
Antti M. Kiviniemi Research Unit of Internal Medicine, Medical Research Center Oulu, Oulu University Hospital and University of Oulu, Oulu 90220, Finland
Jan A. Kors Department of Medical Informatics, Erasmus Medical Center, Rotterdam 3015 CE, The Netherlands
Meena Kumari Department of Epidemiology and Public Health, University College London, London WC1E 6BT, UK ISER, Essex University, Colchester, Essex CO4 3SQ, UK
Tatiana Kuznetsova Studies Coordinating Centre, Research Unit Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven 3000, Belgium
Cathy C. Laurie Department of Biostatistics, School of Public Health, University of Washington, Seattle, Washington 98195, USA
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Yong Li Division of Genetic Epidemiology, Institute for Medical Biometry and Statistics, Medical Center—University of Freiburg, Faculty of Medicine, University of Freiburg, Freiburg 79110, Germany
Yun Li Department of Genetics, University of North Carolina, Chapel Hill, North Carolina 27599, USA Department of Biostatistics, University of North Carolina, Chapel Hill, North Carolina 27599, USA Department of Computer Science, University of North Carolina, Chapel Hill, North Carolina 27599, USA
Duanping Liao Division of Epidemiology, Department of Public Health Sciences, Penn State University College of Medicine, Hershey, Pennsylvania 17033, USA
Marian C. Limacher Division of Cardiovascular Medicine, University of Florida College of Medicine, Gainesville, Florida 32611, USA
Henry J. Lin Institute for Translational Genomics and Population Sciences, Department of Pediatrics, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California 90502, USA Division of Medical Genetics, Department of Pediatrics, Harbor-UCLA Medical Center, Torrance, California 90502, USA
Cecilia M. Lindgren Li Ka Shing Centre for Health Information and Discovery, The Big Data Institute, University of Oxford, Oxford OX3 7BN, UK Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
Steven A. Lubitz Program in Medical and Population Genetics, The Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02114, USA Cardiac Arrhythmia Service & Cardiovascular Research Center, Massachusetts General Hospital, Boston, Massachusetts 02114, USA
Anubha Mahajan Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK
Barbara McKnight Cardiovascular Health Research Unit, Department of Medicine, University of Washington, Seattle, Washington 98104, USA Department of Biostatistics, School of Public Health, University of Washington, Seattle, Washington 98195, USA Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
Henriette Meyer zu Schwabedissen Biopharmacy, Department Pharmaceutical Sciences, University of Basel, Basel CH-4056, Switzerland
Yuri Milaneschi Department of Psychiatry, EMGO Institute for Health and Care Research and Neuroscience Campus Amsterdam, VU University Medical Center/GGZ inGeest, Amsterdam 1081 BT, The Netherlands
Nina Mononen Department of Clinical Chemistry, Fimlab Laboratories, Tampere 33520, Finland Department of Clinical Chemistry, University of Tampere School of Medicine, Tampere 33014, Finland
Andrew P. Morris Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, UK Department of Biostatistics, University of Liverpool, Liverpool L69 3GL, UK
Mike A. Nalls Laboratory of Neurogenetics, National Institute on Aging, National Institutes of Health, Bethesda, Maryland 20892, USA
Gerjan Navis Department of Internal Medicine, Division of Nephrology, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands
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Kjell Nikus Department of Cardiology, Heart Hospital, Tampere University Hospital, Tampere 33521, Finland Department of Cardiology, University of Tampere, School of Medicine, Tampere 33014, Finland
Kari E. North Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina 27599, USA Carolina Center for Genome Sciences, University of North Carolina, Chapel Hill, North Carolina 27599, USA
Daniel T. O'Connor Department of Medicine, University of California, San Diego, San Diego, California 92093, USA
Johan Ormel Interdisciplinary Center Psychopathology and Emotion regulation, Department of Psychiatry, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands
Siegfried Perz Institute of Epidemiology II, Helmholtz Zentrum München—German Research Center for Environmental Health, Neuherberg 85764, Germany
Annette Peters DZHK (German Centre for Cardiovascular Research), Partner site Munich Heart Alliance, Munich 80336, Germany Institute of Epidemiology II, Helmholtz Zentrum München—German Research Center for Environmental Health, Neuherberg 85764, Germany German Center for Diabetes Research, Neuherberg 85764, Germany
Bruce M. Psaty Cardiovascular Health Research Unit, Department of Medicine, University of Washington, Seattle, Washington 98104, USA Departments of Epidemiology and Health Services, University of Washington, Seattle, Washington 98195, USA Group Health Research Institute, Group Health Cooperative, Seattle, Washington 98101, USA
Olli T. Raitakari Department of Clinical Physiology and Nuclear Medicine, Turku University Hospital, Turku 20521, Finland Research Centre of Applied and Preventive Cardiovascular Medicine, University of Turku, Turku 20520, Finland
Victoria B. Risbrough Department of Psychiatry, University of California, San Diego, San Diego, California 92093, USA Center for Stress and Mental Health (CESAMH), VA San Diego Healthcare System, San Diego, California 92161, USA
Moritz F. Sinner Department of Medicine, University Hospital Munich, Ludwig-Maximilians-University, Munich 80539, Germany DZHK (German Centre for Cardiovascular Research), Partner site Munich Heart Alliance, Munich 80336, Germany
David Siscovick The New York Academy of Medicine, New York, New York 10029, USA
Johannes H. Smit Department of Psychiatry, EMGO Institute for Health and Care Research and Neuroscience Campus Amsterdam, VU University Medical Center/GGZ inGeest, Amsterdam 1081 BT, The Netherlands
Nicholas L. Smith Group Health Research Institute, Group Health Cooperative, Seattle, Washington 98101, USA Department of Epidemiology, School of Public Health, University of Washington, Seattle, Washington 98195, USA Seattle Epidemiologic Research and Information Center, Veterans Affairs Office of Research and Development, Seattle, Washington 98108, USA
Elsayed Z. Soliman Epidemiological Cardiology Research Center (EPICARE), Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina 27157, USA
Nona Sotoodehnia Cardiovascular Health Research Unit, Division of Cardiology, Departments of Medicine and Epidemiology, University of Washington, Seattle, Washington 98101, USA
Jan A. Staessen Studies Coordinating Centre, Research Unit Hypertension and Cardiovascular Epidemiology, KU Leuven Department of Cardiovascular Sciences, University of Leuven, Leuven 3000, Belgium
Phyllis K. Stein Heart Rate Variability Lab, Washington University School of Medicine, St Louis, Missouri 63108, USA
Adrienne M. Stilp Department of Biostatistics, School of Public Health, University of Washington, Seattle, Washington 98195, USA
Katarzyna Stolarz-Skrzypek First Department of Cardiology, Interventional Electrocardiology and Hypertension, Jagiellonian University Medical College, Cracow 31-008, Poland
Konstantin Strauch Institute of Genetic Epidemiology, Helmholtz Zentrum München—German Research Center for Environmental Health, Neuherberg 85764, Germany Institute of Medical Informatics, Biometry and Epidemiology, Chair of Genetic Epidemiology, Ludwig-Maximilians-Universität, Munich 81377, Germany
Johan Sundström Department of Medical Sciences, Cardiovascular Epidemiology, Uppsala University, Uppsala 751 85, Sweden
Cees A. Swenne Department of Cardiology, Leiden University Medical Center, Leiden 2300 RC, The Netherlands
Ann-Christine Syvänen Department of Medical Sciences, Molecular Medicine, Uppsala University, Uppsala 75237, Sweden
Jean-Claude Tardif Montreal Heart Institute, Montreal, Quebec, Canada H1T 1C8 Université de Montréal, Montreal, Quebec, Canada H3T IJ4
Kent D. Taylor Institute for Translational Genomics and Population Sciences, Departments of Pediatrics and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California 90509, USA
Alexander Teumer Institute for Community Medicine, University Medicine Greifswald, Greifswald 17475, Germany
Timothy A. Thornton Department of Biostatistics, School of Public Health, University of Washington, Seattle, Washington 98195, USA
Lesley E. Tinker Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
André G. Uitterlinden Department of Epidemiology, Erasmus MC, University Medical Center Rotterdam, PO Box 2060, Rotterdam 3000 CB, The Netherlands Department of Internal Medicine, Erasmus University Medical Center, Rotterdam 3015 CE, The Netherlands Netherlands Genomics Initiative (NGI)-sponsored Netherlands Consortium for Healthy Aging NCHA), Leiden 2300 RC, The Netherlands
Jessica van Setten Department of Cardiology, Division Heart and Lungs, University Medical Center Utrecht, Heidelberglaan 100, Utrecht 3584CX, The Netherlands
Andreas Voss Institute of Innovative Health Technologies—IGHT Jena Ernst-Abbe-Hochschule Jena, Jena 07745, Germany
Melanie Waldenberger Institute of Epidemiology II, Helmholtz Zentrum München—German Research Center for Environmental Health, Neuherberg 85764, Germany Research Unit of Molecular Epidemiology, Helmholtz Zentrum München—German Research Center for Environmental Health, Neuherberg 85764, Germany
Kirk C. Wilhelmsen Departments of Genetics and Neurology University of North Carolina, Chapel Hill, North Carolina 27599, USA The Renaissance Computing Institute, Chapel Hill, North Carolina 27599, USA
Gonneke Willemsen Department of Biological Psychology, Behavioral and Movement Sciences, VU University, Amsterdam 1081 BT, The Netherlands EMGO+ Institute for Health and Care Research, VU University & VU University Medical Center, Amsterdam 1081 HV, The Netherlands
Quenna Wong Department of Biostatistics, School of Public Health, University of Washington, Seattle, Washington 98195, USA
Zhu-Ming Zhang Epidemiological Cardiology Research Center (EPICARE), Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina 27157, USA Department of Epidemiology & Prevention, Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina 27157, USA
Alan B. Zonderman Laboratory of Epidemiology and Population Sciences, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, USA
Daniele Cusi Institute of Biomedical Technologies, CNR—Italian National Research Council, Milan 20090, Italy KOS Genetic SRL, Bresso (Milano) 20091, Italy
Michele K. Evans Laboratory of Epidemiology and Population Sciences, National Institute on Aging, National Institutes of Health, Baltimore, Maryland 21224, USA
Halina K. Greiser German Cancer Research Centre, Division of Cancer Epidemiology, Heidelberg 69210, Germany
Pim van der Harst Department of Cardiology, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands
Mohammad Hassan Department of Physiology, College of Medicine and Health Sciences, Sultan Qaboos University, Muscat Al-Khoudh 123, Sultanate of Oman
Erik Ingelsson Department of Medical Sciences, Molecular Epidemiology, Uppsala University, Uppsala 75237, Sweden Science for Life Laboratory, Uppsala University, Uppsala 75237, Sweden Department of Medicine, Division of Cardiovascular Medicine, Stanford University School of Medicine, Stanford, California 94305, USA
Marjo-Riitta Järvelin Center for Life Course Health Research, University of Oulu, Oulu 90014, Finland Unit of Primary Health Care, Oulu University Hospital, Oulu 90220, Finland Department of Epidemiology and Biostatistics, School of Public Health, Faculty of Medicine, St Mary’s campus, Imperial College London, London W2 1PG, UK Biocenter Oulu University of Oulu, Oulu 90014, Finland
Stefan Kääb Department of Medicine, University Hospital Munich, Ludwig-Maximilians-University, Munich 80539, Germany DZHK (German Centre for Cardiovascular Research), Partner site Munich Heart Alliance, Munich 80336, Germany
Mika Kähönen Department of Clinical Physiology, Tampere University Hospital, Tampere 33521, Finland Department of Clinical Physiology, University of Tampere, School of Medicine, Tampere 33014, Finland
Mika Kivimaki Department of Epidemiology and Public Health, University College London, London WC1E 6BT, UK
Charles Kooperberg Public Health Sciences Division, Fred Hutchinson Cancer Research Center, Seattle, Washington 98109, USA
Diana Kuh MRC Unit for Lifelong Health and Ageing, University College London, 33 Bedford Place, London WC1B 5JU, UK
Terho Lehtimäki Department of Clinical Chemistry, Fimlab Laboratories, Tampere 33520, Finland Department of Clinical Chemistry, University of Tampere School of Medicine, Tampere 33014, Finland
Lars Lind Department of Medical Sciences, Cardiovascular Epidemiology, Uppsala University, Uppsala 751 85, Sweden
Caroline M. Nievergelt Department of Psychiatry, University of California, San Diego, San Diego, California 92093, USA Center for Stress and Mental Health (CESAMH), VA San Diego Healthcare System, San Diego, California 92161, USA
Chris J. O'Donnell Framingham Heart Study, Framingham, Massachusetts 01702, USA Population Sciences Branch, National Heart, Lung and Blood Institute, Bethesda, Maryland 20892, USA Cardiology Section, Boston Veteran’s Administration Healthcare, Boston, Maryland 02132, USA
Albertine J. Oldehinkel Interdisciplinary Center Psychopathology and Emotion regulation, Department of Psychiatry, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands
Brenda Penninx Department of Psychiatry, EMGO Institute for Health and Care Research and Neuroscience Campus Amsterdam, VU University Medical Center/GGZ inGeest, Amsterdam 1081 BT, The Netherlands
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Arie M. van Roon Department of Internal Medicine, Division of Vascular Medicine, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands
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Jerome I. Rotter Institute for Translational Genomics and Population Sciences, Departments of Pediatrics and Medicine, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, California 90509, USA
Tamar Sofer Department of Biostatistics, School of Public Health, University of Washington, Seattle, Washington 98195, USA
Bruno H. Stricker Department of Epidemiology, Erasmus MC, University Medical Center Rotterdam, PO Box 2060, Rotterdam 3000 CB, The Netherlands Inspectorate for Health Care, The Hague 2511 VX, The Netherlands
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Folkert W. Asselbergs Department of Cardiology, Division Heart and Lungs, University Medical Center Utrecht, Heidelberglaan 100, Utrecht 3584CX, The Netherlands Institute of Cardiovascular Science, University College London, 222 Euston Road, London NW1 2DA, UK Durrer Center for Cardiogenetic Research, ICIN-Netherlands Heart Institute, Utrecht 3501 DG, The Netherlands
Bianca J. J. M. Brundel Department of Physiology, Institute for Cardiovascular Research, VU University Medical Center, De Boelelaan 1118, Amsterdam 1081 HV, The Netherlands
Susan R. Heckbert Cardiovascular Health Research Unit, Department of Medicine, University of Washington, Seattle, Washington 98104, USA Department of Epidemiology, School of Public Health, University of Washington, Seattle, Washington 98195, USA
Eric A. Whitsel Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina 27599, USA Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599, USA
Marcel den Hoed Department of Medical Sciences, Molecular Epidemiology, Uppsala University, Uppsala 75237, Sweden Science for Life Laboratory, Uppsala University, Uppsala 75237, Sweden
Harold Snieder Department of Epidemiology, University of Groningen, University Medical Center Groningen, PO Box 30001, Groningen 9700 RB, The Netherlands
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Regulator of G Protein Signaling 6 Protects the Heart from Ischemic Injury

Gαi-coupled receptors play important roles in protecting the heart from ischemic injury. Regulator of G protein signaling (RGS) proteins suppress Gαi signaling by accelerating the GTPase activity of Gαi subunits. However, the roles of individual RGS proteins in modulating ischemic injury are unknown. In this study, we investigated the effect of RGS6 deletion on myocardial sensitivity to ischemic injury. Hearts from RGS6 knockout (RGS6^-/-) and RGS6 wild-type (RGS6^+/+) mice were subjected to 30 minutes of ischemia and 2 hours of reperfusion on a Langendorff heart apparatus. Infarcts in RGS6^-/- hearts were significantly larger than infarcts in RGS6^+/+ hearts. RGS6^-/- hearts also exhibited increased phosphorylation of β₂-adrenergic receptors and G protein-coupled receptor kinase 2 (GRK2). Mitochondrial GRK2 as well as caspase-3 cleavage were increased significantly in RGS6^-/- hearts compared with RGS6^+/+ hearts after ischemia. Chronic propranolol treatment of mice prevented the observed increases in ischemic injury and the GRK2 phosphorylation observed in RGS6^-/- hearts. Our findings suggest that loss of RGS6 predisposes the ventricle to prodeath signaling through a β₂AR-GRK2-dependent signaling mechanism, and they provide evidence for a protective role of RGS6 in the ischemic heart. Individuals expressing genetic polymorphisms that suppress the activity of RGS6 may be at increased risk of cardiac ischemic injury. Furthermore, the development of agents that increase RGS6 expression or activity might provide a novel strategy for the treatment of ischemic heart disease.

RGS proteins as targets in the treatment of intestinal inflammation and visceral pain: New insights and future perspectives

Regulators of G protein signaling (RGS) proteins provide timely termination of G protein-coupled receptor (GPCR) responses. Serving as a central control point in GPCR signaling cascades, RGS proteins are promising targets for drug development. In this review, we discuss the involvement of RGS proteins in the pathophysiology of the gastrointestinal inflammation and their potential to become a target for anti-inflammatory drugs. Specifically, we evaluate the emerging evidence for modulation of selected receptor families: opioid, cannabinoid and serotonin by RGS proteins. We discuss how the regulation of RGS protein level and activity may modulate immunological pathways involved in the development of intestinal inflammation. Finally, we propose that RGS proteins may serve as a prognostic factor for survival rate in colorectal cancer. The ideas introduced in this review set a novel conceptual framework for the utilization of RGS proteins in the treatment of gastrointestinal inflammation, a growing major concern worldwide.

RGS Redundancy and Implications in GPCR-GIRK Signaling

Regulators of G protein signaling (RGS proteins) are key components of GPCR complexes, interacting directly with G protein α-subunits to enhance their intrinsic GTPase activity. The functional consequence is an accelerated termination of G protein effectors including certain ion channels. RGS proteins have a profound impact on the membrane-delimited gating behavior of G-protein-activated inwardly rectifying K(+) (GIRK) channels as demonstrated in reconstitution assays and recent RGS knockout mice studies. Akin to GPCRs and G protein αβγ subunits, multiple RGS isoforms are expressed within single GIRK-expressing neurons, suggesting functional redundancy and/or specificity in GPCR-GIRK channel signaling. The extent and impact of RGS redundancy in neuronal GPCR-GIRK channel signaling is currently not fully appreciated; however, recent studies from RGS knockout mice are providing important new clues on the impact of individual endogenous RGS proteins and the extent of RGS functional redundancy. Incorporating "tools" such as engineered RGS-resistant Gαi/o subunits provide an important assessment method for determining the impact of all endogenous RGS proteins on a given GPCR response and an accounting benchmark to assess the impact of individual RGS knockouts on overall RGS redundancy within a given neuron. Elucidating the degree of regulation attributable to specific RGS proteins in GIRK channel function will aid in the assessment of individual RGS proteins as viable therapeutic targets in epilepsy, ataxia's, memory disorders, and a growing list of neurological disorders.

Two for the Price of One: G Protein-Dependent and -Independent Functions of RGS6 In Vivo

Regulator of G protein signaling 6 (RGS6) is unique among the members of the RGS protein family as it remains the only protein with the demonstrated capacity to control G protein-dependent and -independent signaling cascades in vivo. RGS6 inhibits signaling mediated by γ-aminobutyric acid B receptors, serotonin 1A receptors, μ opioid receptors, and muscarinic acetylcholine 2 receptors. RGS6 deletion triggers distinct behavioral phenotypes resulting from potentiated signaling by these G protein-coupled receptors namely ataxia, a reduction in anxiety and depression, enhanced analgesia, and increased parasympathetic tone, respectively. In addition, RGS6 possesses potent proapoptotic and growth suppressive actions. In heart, RGS6-dependent reactive oxygen species (ROS) production promotes doxorubicin (Dox)-induced cardiomyopathy, while in cancer cells RGS6/ROS signaling is necessary for activation of the ataxia telangiectasia mutated/p53/apoptosis pathway required for the chemotherapeutic efficacy of Dox. Further, by facilitating Tip60 (trans-acting regulator protein of HIV type 1-interacting protein 60 kDa)-dependent DNA methyltransferase 1 degradation, RGS6 suppresses cellular transformation in response to oncogenic Ras. The culmination of these G protein-independent actions results in potent tumor suppressor actions of RGS6 in the murine mammary epithelium. This work summarizes evidence from human genetic studies and model animals implicating RGS6 in normal physiology, disease, and the pharmacological actions of multiple drugs. Though efforts by multiple laboratories have contributed to the ever-growing RGS6 oeuvre, the pleiotropic nature of this gene will likely lead to additional work detailing the importance of RGS6 in neuropsychiatric disorders, cardiovascular disease, and cancer.

Structural Neuroimaging Genetics Interactions in Alzheimer's Disease

This article investigates late-onset cognitive impairment using neuroimaging and genetics biomarkers for Alzheimer's Disease Neuroimaging Initiative (ADNI) participants. Eight-hundred and eight ADNI subjects were identified and divided into three groups: 200 subjects with Alzheimer's disease (AD), 383 subjects with mild cognitive impairment (MCI), and 225 asymptomatic normal controls (NC). Their structural magnetic resonance imaging (MRI) data were parcellated using BrainParser, and the 80 most important neuroimaging biomarkers were extracted using the global shape analysis Pipeline workflow. Using Plink via the Pipeline environment, we obtained 80 SNPs highly-associated with the imaging biomarkers. In the AD cohort, rs2137962 was significantly associated bilaterally with changes in the hippocampi and the parahippocampal gyri, and rs1498853, rs288503, and rs288496 were associated with the left and right hippocampi, the right parahippocampal gyrus, and the left inferior temporal gyrus. In the MCI cohort, rs17028008 and rs17027976 were significantly associated with the right caudate and right fusiform gyrus, rs2075650 (TOMM40) was associated with the right caudate, and rs1334496 and rs4829605 were significantly associated with the right inferior temporal gyrus. In the NC cohort, Chromosome 15 [rs734854 (STOML1), rs11072463 (PML), rs4886844 (PML), and rs1052242 (PML)] was significantly associated with both hippocampi and both insular cortices, and rs4899412 (RGS6) was significantly associated with the caudate. We observed significant correlations between genetic and neuroimaging phenotypes in the 808 ADNI subjects. These results suggest that differences between AD, MCI, and NC cohorts may be examined by using powerful joint models of morphometric, imaging and genotypic data.

RGS6, but not RGS4, is the dominant regulator of G protein signaling (RGS) modulator of the parasympathetic regulation of mouse heart rate

Parasympathetic activity decreases heart rate (HR) by inhibiting pacemaker cells in the sinoatrial node (SAN). Dysregulation of parasympathetic influence has been linked to sinus node dysfunction and arrhythmia. RGS (regulator of G protein signaling) proteins are negative modulators of the parasympathetic regulation of HR and the prototypical M2 muscarinic receptor (M2R)-dependent signaling pathway in the SAN that involves the muscarinic-gated atrial K(+) channel IKACh. Both RGS4 and RGS6-Gβ5 have been implicated in these processes. Here, we used Rgs4(-/-), Rgs6(-/-), and Rgs4(-/-):Rgs6(-/-) mice to compare the relative influence of RGS4 and RGS6 on parasympathetic regulation of HR and M2R-IKACh-dependent signaling in the SAN. In retrogradely perfused hearts, ablation of RGS6, but not RGS4, correlated with decreased resting HR, increased heart rate variability, and enhanced sensitivity to the negative chronotropic effects of the muscarinic agonist carbachol. Similarly, loss of RGS6, but not RGS4, correlated with enhanced sensitivity of the M2R-IKACh signaling pathway in SAN cells to carbachol and a significant slowing of M2R-IKACh deactivation rate. Surprisingly, concurrent genetic ablation of RGS4 partially rescued some deficits observed in Rgs6(-/-) mice. These findings, together with those from an acute pharmacologic approach in SAN cells from Rgs6(-/-) and Gβ5(-/-) mice, suggest that the partial rescue of phenotypes in Rgs4(-/-):Rgs6(-/-) mice is attributable to another R7 RGS protein whose influence on M2R-IKACh signaling is masked by RGS4. Thus, RGS6-Gβ5, but not RGS4, is the primary RGS modulator of parasympathetic HR regulation and SAN M2R-IKACh signaling in mice.

New insights into the therapeutic potential of Girk channels

G protein-dependent signaling pathways control the activity of excitable cells of the nervous system and heart, and are the targets of neurotransmitters, clinically relevant drugs, and drugs of abuse. G protein-gated inwardly rectifying potassium (K(+)) (Girk/Kir3) channels are a key effector in inhibitory signaling pathways. Girk-dependent signaling contributes to nociception and analgesia, reward-related behavior, mood, cognition, and heart-rate regulation, and has been linked to epilepsy, Down syndrome, addiction, and arrhythmias. We discuss recent advances in our understanding of Girk channel structure, organization in signaling complexes, and plasticity, as well as progress on the development of subunit-selective Girk modulators. These findings offer new hope for the selective manipulation of Girk channels to treat a variety of debilitating afflictions.

Essential role of the m2R-RGS6-IKACh pathway in controlling intrinsic heart rate variability

Normal heart function requires generation of a regular rhythm by sinoatrial pacemaker cells and the alteration of this spontaneous heart rate by the autonomic input to match physiological demand. However, the molecular mechanisms that ensure consistent periodicity of cardiac contractions and fine tuning of this process by autonomic system are not completely understood.

Here we examined the contribution of the m₂R-I_KACh intracellular signaling pathway, which mediates the negative chronotropic effect of parasympathetic stimulation, to the regulation of the cardiac pacemaking rhythm. Using isolated heart preparations and single-cell recordings we show that the m₂R-I_KACh signaling pathway controls the excitability and firing pattern of the sinoatrial cardiomyocytes and determines variability of cardiac rhythm in a manner independent from the autonomic input. Ablation of the major regulator of this pathway, Rgs6, in mice results in irregular cardiac rhythmicity and increases susceptibility to atrial fibrillation. We further identify several human subjects with variants in the RGS6 gene and show that the loss of function in RGS6 correlates with increased heart rate variability. These findings identify the essential role of the m₂R-I_KACh signaling pathway in the regulation of cardiac sinus rhythm and implicate RGS6 in arrhythmia pathogenesis.

Functional role, mechanisms of regulation, and therapeutic potential of regulator of G protein signaling 2 in the heart

G protein-mediated signal transduction is essential for the regulation of cardiovascular function, including heart rate, growth, contraction, and vascular tone. Regulators of G protein Signaling (RGS proteins) fine-tune G protein-coupled receptor-induced signaling by regulating its magnitude and duration through direct interaction with the α subunits of heterotrimeric G proteins. Changes in the RGS protein expression and/or function in the heart often lead to pathophysiological changes and are associated with cardiac disease in animals and humans, including hypertrophy, fibrosis development, heart failure, and arrhythmias. This article focuses on Regulator of G protein Signaling 2 (RGS2), which is widely expressed in many tissues and is highly regulated in its expression and function. Most information to date has been obtained in biochemical, cellular, and animal studies, but data from humans is emerging. We review recent advances on the functional role of cardiovascular RGS2 and the mechanisms that determine its signaling selectivity, expression, and functionality. We highlight key unanswered questions and discuss the potential of RGS2 as a therapeutic target.

Mx1-cre mediated Rgs12 conditional knockout mice exhibit increased bone mass phenotype

Regulators of G-protein Signaling (Rgs) proteins are the members of a multigene family of GTPase-accelerating proteins (GAP) for the Galpha subunit of heterotrimeric G-proteins. Rgs proteins play critical roles in the regulation of G protein couple receptor (GPCR) signaling in normal physiology and human diseases such as cancer, heart diseases, and inflammation. Rgs12 is the largest protein of the Rgs protein family. Some in vitro studies have demonstrated that Rgs12 plays a critical role in regulating cell differentiation and migration; however its function and mechanism in vivo is largely unknown. Here, we generated a floxed Rgs12 allele (Rgs12(flox/flox) ) in which the exon 2, containing both PDZ and PTB_PID domains of Rgs12, was flanked with two loxp sites. By using the inducible Mx1-cre and Poly I:C system to specifically delete Rgs12 at postnatal 10 days in interferon-responsive cells including monocyte and macrophage cells, we found that Rgs12 mutant mice had growth retardation with the phenotype of increased bone mass. We further found that deletion of Rgs12 reduced osteoclast numbers and had no significant effect on osteoblast formation. Thus, Rgs12(flox/flox) conditional mice provide a valuable tool for in vivo analysis of Rgs12 function and mechanism through time- and cell-specific deletion of Rgs12.

Mechano-sensitivity of cardiac pacemaker function: pathophysiological relevance, experimental implications, and conceptual integration with other mechanisms of rhythmicity

Cardiac pacemaker cells exhibit spontaneous, rhythmic electrical excitation, termed automaticity. This automatic initiation of action potentials requires spontaneous diastolic depolarisation, whose rate determines normal rhythm generation in the heart. Pacemaker mechanisms have been split recently into: (i) cyclic changes in trans-sarcolemmal ion flows (termed the ‘membrane-clock’), and (ii) rhythmic intracellular calcium cycling (the ‘calcium-clock’). These two ‘clocks’ undoubtedly interact, as trans-sarcolemmal currents involved in pacemaking include calcium-carrying mechanisms, while intracellular calcium cycling requires trans-sarcolemmal ion flux as the mechanism by which it affects membrane potential. The split into separate ‘clocks’ is, therefore, somewhat arbitrary. Nonetheless, the ‘clock’ metaphor has been conceptually stimulating, in particular since there is evidence to support the view that either ‘clock’ could be sufficient in principle to set the rate of pacemaker activation.

Of course, the same has also been shown for sub-sets of ‘membrane-clock’ ion currents, illustrating the redundancy of mechanisms involved in maintaining such basic functionality as the heartbeat, a theme that is common for vital physiological systems.

Following the conceptual path of identifying individual groups of sub-mechanisms, it is important to remember that the heart is able to adapt pacemaker rate to changes in haemodynamic load, even after isolation or transplantation, and on a beat-by-beat basis. Neither the ‘membrane-’ nor the ‘calcium-clock’ do, as such, inherently account for this rapid adaptation to circulatory demand (cellular Ca²⁺ balance changes over multiple beats, while variation of sarcolemmal ion channel presence takes even longer). This suggests that a third set of mechanisms must be involved in setting the pace. These mechanisms are characterised by their sensitivity to the cyclically changing mechanical environment, and – in analogy to the above terminology – this might be considered a ‘mechanics-clock’.

In this review, we discuss possible roles of mechano-sensitive mechanisms for the entrainment of membrane current dynamics and calcium-handling. This can occur directly via stretch-activation of mechano-sensitive ion channels in the sarcolemma and/or in intracellular membrane compartments, as well as by modulation of ‘standard’ components of the ‘membrane-’ or ‘calcium-clock’. Together, these mechanisms allow rapid adaptation to changes in haemodynamic load, on a beat-by-beat basis.

Additional relevance arises from the fact that mechano-sensitivity of pacemaking may help to explain pacemaker dysfunction in mechanically over- or under-loaded tissue. As the combined contributions of the various underlying oscillatory mechanisms are integrated at the pacemaker cell level into a single output – a train of pacemaker action potentials – we will not adhere to a metaphor that implies separate time-keeping units (‘clocks’), and rather focus on cardiac pacemaking as the result of interactions of a set of coupled oscillators, whose individual contributions vary depending on the pathophysiological context. We conclude by considering the utility and limitations of viewing the pacemaker as a coupled system of voltage-, calcium-, and mechanics-modulated oscillators that, by integrating a multitude of inputs, offers the high level of functional redundancy that is vitally important for cardiac automaticity.