Different expression of adrenoceptors and GRKs in the human myocardium depends on heart failure ethiology and correlates to clinical variables

Abstract

. Different expression of adrenoceptors and GRKs in the human myocardium depends on heart failure ethiology and correlates to clinical variables. Am J Physiol Heart Circ Physiol 303: H368 -H376, 2012. First published June 8, 2012; doi:10.1152/ajpheart.01061.2011.-Downregulation of ␤ 1-adrenergic receptors (␤ 1-ARs) and increased expression/function of G-protein-coupled receptor kinase 2 (GRK2) have been observed in human heart failure, but changes in expression of other ARs and GRKs have not been established. Another unresolved question is the incidence of these compensatory mechanisms depending on heart failure etiology and treatment. To analyze these questions, we quantified the mRNA/protein expressions of six ARs (␣ 1A, ␣1B, ␣1D, ␤1, ␤ 2, and ␤3) and three GRKs (GRK2, GRK3, and GRK5) in left (LV) and right ventricle (RV) from four donors, 10 patients with ischemic cardiomyopathy (IC), 14 patients with dilated cardiomyopathy (DC), and 10 patients with nonischemic, nondilated cardiopathies (NINDC). We correlated the changes in the expressions of ARs and GRKs with clinical variables such as left ventricular ejection fraction (LVEF) and left ventricular end-systolic and left ventricular end-diastolic diameter (LVESD and LVEDD, respectively). The main findings were 1) the expression of the ␣ 1A-AR in the LV positively correlates with LVEF; 2) the expression of GRK3 and GRK5 inversely correlates with LVESD and LVEDD, supporting previous observations about a protective role for both kinases in failing hearts; and 3) ␤ 1-AR expression is downregulated in the LV and RV of IC, in the LV of DC, and in the RV of NINDC. This difference, better than an increased expression of GRK2 (not observed in IC), determines the lower LVEF in IC and DC vs. NINDC. G-protein-coupled receptor kinasesHUMAN HEART FAILURE (HF) is recognized as a major public health problem arising from multiple causes that will affect one in five adults, conferring elevated mortality rates (20). Regardless of the cause, multiple organ systems attempt to compensate for the deteriorating heart and the sympathetic nervous system responds to HF with increased activity, resulting in increased levels of catecholamines and in an enhanced stimulation of adrenergic receptors (ARs; 33). Consequently, catecholamines powerfully stimulate the heart function at the expense of overproportional increases in energy consumption (13). This is a nonrigid signaling system that adapts to continuous stimulation by reducing the abundance of ␤ 1 -ARs and increasing the expression and enzymatic activity of G-proteincoupled receptor kinases (GRKs), which phosphorylate agonist-occupied receptors and facilitate their endocytosis and desensitization (26). As a result of these adaptations, cardiomyocytes in failing hearts (FH) lose their responsiveness to catecholamines over time (13).In spite of this simple scenario, many fundamental questions remain unanswered. The heart expresses different ␤-ARs (␤ 1 , ␤ 2 , and ␤ 3 ) and ␣ 1 -ARs (␣ 1A , ␣ 1B , and ␣ 1D

RyR2R420Q catecholaminergic polymorphic ventricular tachycardia mutation induces bradycardia by disturbing the coupled clock pacemaker mechanism

“…Blood samples were treated as previously described (31) using Lymphoprep (STEMCELL Technologies or Progen Biotechnik or AXIS-SHIELD Density Gradient Media) to isolate the peripheral blood mononuclear cells following the manufacture's conditions. To perform the quantitative PCR (qPCR), total RNA was obtained as previously described (53) and was quantified and analyzed by running 1 μg of each sample by microfluidic electrophoresis using the Experion automated electrophoresis system (BioRad) following the manufacture's conditions. cDNA synthesis was carried out with 500 ng of total RNA and 250 ng of oligo(dT) as a primer at 70°C in diethyl pyrocarbonate-treated (DEPC-treated) water.…”

Balancing GRK2 and EPAC1 levels prevents and relieves chronic pain

“…Mice were deeply anesthetized with sodium pentobarbital (50 mg/kg i.p.) and transcardially perfused with PBS followed by 4% paraformaldehyde, after which DRG (lumbar [L3-L5] and are likely to regulate a wide array of physiological processes (18,19,(54)(55)(56)(57)(58). Therefore, changes in the protein levels of GRK2 and EPAC1 in other tissues may have important consequences for cAMP signaling and (patho)physiology.…”

The Evolving Impact of G Protein-Coupled Receptor Kinases in Cardiac Health and Disease

“…In the human heart there is evidence for expression of GRK2, GRK3, GRK5, and GRK6 (67). The most prominent cardiac GRK isoforms are 2 and 5, although 3 and 6 have also been reported at low levels (1,67,162). Moreover, it is important to note that a particular GRK does not have to be the most prominently expressed GRK in a tissue to be crucial for a specific GPCR signaling regulation as its cellular localization and activity are key measures determining GPCR-GRK interactions.…”

“…In this study, ␤-blockade led to GRK5 mRNA levels that were comparable to nonfailing hearts, although protein content only showed a decreased trend compared with failing hearts (3). Finally, in human studies comprised of ischemic, dilated, and nonischemic/nondilated cardiomyopathies, expression levels of GRK5 inversely correlated with left ventricular end-systolic and diastolic diameters (162). On the basis of these human studies, it has been proposed that GRK5 is a potential therapeutic target for the treatment of heart failure (reviewed in Ref.…”

“…GRK3 and the Heart GRK3 has been shown to be expressed in the human heart although to a much lesser extent than GRK2 and GRK5 (2,67,162). Clinical studies have shown that decreased heart performance inversely correlates with levels of GRK3 (162).…”