Association of functional genetic variants of A-kinase anchoring protein 10 with QT interval length in full-term Polish newborns

Cardiac function modulation depends on the A-kinase anchoring protein complex

The A‐kinase anchoring proteins (AKAPs) are a group of structurally diverse proteins identified in various species and tissues. These proteins are able to anchor protein kinase and other signalling proteins to regulate cardiac function. Acting as a scaffold protein, AKAPs ensure specificity in signal transduction by enzymes close to their appropriate effectors and substrates. Over the decades, more than 70 different AKAPs have been discovered. Accumulative evidence indicates that AKAPs play crucial roles in the functional regulation of cardiac diseases, including cardiac hypertrophy, myofibre contractility dysfunction and arrhythmias. By anchoring different partner proteins (PKA, PKC, PKD and LTCCs), AKAPs take part in different regulatory pathways to function as regulators in the heart, and a damaged structure can influence the activities of these complexes. In this review, we highlight recent advances in AKAP‐associated protein complexes, focusing on local signalling events that are perturbed in cardiac diseases and their roles in interacting with ion channels and their regulatory molecules. These new findings suggest that AKAPs might have potential therapeutic value in patients with cardiac diseases, particularly malignant rhythm.

Predisposition of functional genetic variants of A-kinase anchoring protein 10 toward acquired repolarization disorders in high-risk vascular surgery patients

Purpose

We aimed at assessing the predisposition of A-kinase anchoring protein 10 (AKAP10) polymorphism toward acquired repolarization disorders in high-risk vascular surgery patients.

Patients and methods

One hundred adult patients (age =44–85 years), scheduled for an elective high-risk “open” vascular surgery procedure, were recruited. The electrocardiogram Holter monitor was used to assess repolarization stability from the beginning of the operation up to 24 hours afterward. The AKAP10 gene rs203462 polymorphism and cardiac complications were analyzed.

Results

Repolarization disturbances defined as QT interval duration corrected for heart rate (QTc) interval prolongation >500 ms and QTc interval dispersion >65 ms were recorded in 46 patients. A model of multivariate logistic regression showed that only the presence of allele G of the AKAP10 polymorphism was an independent risk factor for repolarization disturbances in the perioperative period (odds ratio =14.35; 95% CI =4.65–44.23; p<0.0001).

Conclusion

When the acquired QTc interval prolongation or QTc dispersion is associated with AKAP10 polymorphism, it may remain clinically silent.

Roles of A-Kinase Anchoring Proteins and Phosphodiesterases in the Cardiovascular System

A-kinase anchoring proteins (AKAPs) and cyclic nucleotide phosphodiesterases (PDEs) are essential enzymes in the cyclic adenosine 3′-5′ monophosphate (cAMP) signaling cascade. They establish local cAMP pools by controlling the intensity, duration and compartmentalization of cyclic nucleotide-dependent signaling. Various members of the AKAP and PDE families are expressed in the cardiovascular system and direct important processes maintaining homeostatic functioning of the heart and vasculature, e.g., the endothelial barrier function and excitation-contraction coupling. Dysregulation of AKAP and PDE function is associated with pathophysiological conditions in the cardiovascular system including heart failure, hypertension and atherosclerosis. A number of diseases, including autosomal dominant hypertension with brachydactyly (HTNB) and type I long-QT syndrome (LQT1), result from mutations in genes encoding for distinct members of the two classes of enzymes. This review provides an overview over the AKAPs and PDEs relevant for cAMP compartmentalization in the heart and vasculature and discusses their pathophysiological role as well as highlights the potential benefits of targeting these proteins and their protein-protein interactions for the treatment of cardiovascular diseases.

Polymorphisms/Mutations in A-Kinase Anchoring Proteins (AKAPs): Role in the Cardiovascular System

A-kinase anchoring proteins (AKAPs) belong to a family of scaffolding proteins that bind to protein kinase A (PKA) by definition and a variety of crucial proteins, including kinases, phosphatases, and phosphodiesterases. By scaffolding these proteins together, AKAPs build a "signalosome" at specific subcellular locations and compartmentalize PKA signaling. Thus, AKAPs are important for signal transduction after upstream activation of receptors ensuring accuracy and precision of intracellular PKA-dependent signaling pathways. Since their discovery in the 1980s, AKAPs have been studied extensively in the heart and have been proven essential in mediating cyclic adenosine monophosphate (cAMP)-PKA signaling. Although expression of AKAPs in the heart is very low, cardiac-specific knock-outs of several AKAPs have a noteworthy cardiac phenotype. Moreover, single nucleotide polymorphisms and genetic mutations in crucial cardiac proteins play a substantial role in the pathophysiology of cardiovascular diseases (CVDs). Despite the significant role of AKAPs in the cardiovascular system, a limited amount of research has focused on the role of genetic polymorphisms and/or mutations in AKAPs in increasing the risk of CVDs. This review attempts to overview the available literature on the polymorphisms/mutations in AKAPs and their effects on human health with a special focus on CVDs.

Interleukin-21 gene polymorphism rs2221903 is associated with disease activity in patients with rheumatoid arthritis

INTRODUCTION

Interleukin-21 (IL-21) is a cytokine which plays a significant role in the pathogenesis and disease activity of rheumatoid arthritis (RA). Genetic polymorphisms in the IL-21 gene may alter the synthesis of IL-21. The aim of this study was to examine IL-21 and IL-21R polymorphisms in patients with RA.

MATERIAL AND METHODS

We examined 422 patients with RA and 338 healthy controls. Single nucleotide polymorphisms (SNPs) within the IL-21 (rs6822844 G>T, rs6840978 C>T, rs2221903 T>C) and IL-21R (rs2285452 G>A) genes were genotyped using TaqMan genotyping assays.

RESULTS

There were no statistically significant differences in the distribution of studied genotypes and alleles between RA patients and the control group. To examine whether IL-21 polymorphisms affect disease activity in RA patients, we compared the distribution of IL-21 genotypes between patients with DAS28 ≤ 2.5 (patients with remission of disease symptoms) and patients with DAS28 > 2.5 (patients with active RA). Among patients with DAS28 > 2.5, increased prevalence of rs2221903 CT and CC genotypes was observed (OR = 1.54; 95% CI: 1.04-2.28; p = 0.035).

CONCLUSIONS

The results of this study suggest that IL-21 and IL-21R gene polymorphisms are not risk loci for RA susceptibility, whereas the IL-21 rs2221903 polymorphism is associated with disease activity.