Abstract 075: Novel Role for GRK2 in Cardiac Hypertrophy and Heart Failure

2013 ◽  
Vol 113 (suppl_1) ◽  
Author(s):  
Sarah M Schumacher-Bass ◽  
Erhe Gao ◽  
Kurt Chuprun ◽  
Jessica I Gold ◽  
Walter J Koch

During heart failure (HF), cardiac levels and activity of the G protein-coupled receptor (GPCR) kinase (GRK) GRK2 are elevated, increasing phosphorylation, desensitization and down-regulation of β-adrenergic receptors (βARs) and other cardiac GPCRs. Increased GRK2 has been shown to participate in adverse remodeling and contractile dysfunction during HF, while GRK2 inhibition via a carboxy-terminal peptide, βARKct, enhances heart function and can prevent HF development. Mounting evidence supports the idea of a dynamic GRK2 “interactome” in which GRK2 can uncouple GPCRs via novel protein-protein interactions. Several novel GRK2 interacting partners are important for adaptive and maladaptive myocyte growth including Gq, the signaling trigger for maladaptive cardiac hypertrophy, leading to HF. Importantly, GRK2 contains a putative amino-terminal Regulator of G protein Signaling (RGS) domain (termed βARK-RGS). This domain directly interacts with Gq and appears to inhibit signaling without altering Gq enzymatic activity. Therefore, this domain of GRK2 may alter hypertrophic responses in the heart and represent a novel role for GRK2 and also a potential therapeutic target to limit maladaptive cardiac hypertrophy. We have begun to address this by generation of novel transgenic mice with cardiac-specific expression of the RGS domain of GRK2. Data from mice with cardiac expression of βARK-RGS demonstrate anti-hypertrophic effects in a trans-aortic constriction (TAC) model of pressure overload hypertrophy. Echocardiographic analysis post-TAC revealed reduced left ventricular posterior wall thickness in βARK-RGS compared to non-transgenic littermate controls (1.34 vs 1.57 mm LVPWd at 4 weeks). RT-PCR analysis found decreased hypertrophic factor transcripts, such as ANF for which the nearly 18-fold increase post TAC was completely inhibited in βARK-RGS mice. Other hypertrophic phenotypic markers have been studied and mechanistic characterization is underway. These data support our hypothesis that the RGS domain of GRK2 may serve as a non-canonical inhibitor of Gq-mediated hypertrophic signaling in the heart and highlight how this research may pave the way for novel GRK2-based therapeutic approaches to prevent hypertrophy and HF.

2014 ◽  
Vol 115 (suppl_1) ◽  
Author(s):  
Sarah M Schumacher ◽  
Erhe Gao ◽  
Jess I Gold ◽  
Maya Cohen ◽  
Kurt Chuprun ◽  
...  

During heart failure (HF), cardiac levels and activity of the G protein-coupled receptor (GPCR) kinase (GRK) GRK2 are elevated, increasing phosphorylation, desensitization and down-regulation of β-adrenergic receptors (βARs) and other cardiac GPCRs. Increased GRK2 participates in adverse remodeling and contractile dysfunction during HF, while inhibition via a carboxy-terminal peptide, βARKct, enhances heart function and can prevent HF development. Mounting evidence supports the idea of a dynamic “interactome” in which GRK2 can uncouple GPCRs via novel protein-protein interactions. Several novel GRK2 interacting partners are important for adaptive and maladaptive myocyte growth including Gq, the signaling trigger for maladaptive cardiac hypertrophy, leading to HF. Importantly, GRK2 contains a putative amino-terminal Regulator of G protein Signaling (RGS) domain (βARK-RGS). This domain directly interacts with Gq and appears to inhibit signaling without altering Gq enzymatic activity. Therefore, this domain may alter hypertrophic responses in the heart and represent a novel role for GRK2 and a potential therapeutic target to limit maladaptive cardiac hypertrophy. We have begun to address this by generation of novel transgenic (Tg) mice with cardiac-specific expression of the RGS domain of GRK2. Using a trans-aortic constriction (TAC) model of pressure overload hypertrophy, we found that expression of βARK-RGS demonstrates anti-hypertrophic effects. Echocardiographic analysis post-TAC revealed reduced left ventricular posterior wall thickness (LVPW) in βARK-RGS compared to non-transgenic littermate controls (NLC) (0.85 vs 1.0 mm LVPWd at 4 weeks). RT-PCR analysis found decreased hypertrophic factor transcripts, such as ANF for which the nearly 18-fold increase post TAC was completely inhibited in βARK-RGS mice. Further, the progression to HF was inhibited in βARK-RGS mice, but not NLCs, 14 weeks post-TAC. While mechanistic characterization is underway, these data support our hypothesis that the RGS domain of GRK2 may serve as a non-canonical inhibitor of Gq-mediated hypertrophic signaling in the heart and highlight how this research may pave the way for novel GRK2-based therapeutic approaches to prevent hypertrophy and HF.


2015 ◽  
Vol 117 (suppl_1) ◽  
Author(s):  
Sarah M Schumacher ◽  
Erhe Gao ◽  
J. Kurt Chuprun ◽  
Walter J Koch

During heart failure (HF), cardiac levels and activity of the G protein-coupled receptor (GPCR) kinase (GRK) GRK2 are elevated and contribute to adverse remodeling and contractile dysfunction, while inhibition via a carboxyl-terminal peptide, βARKct, enhances heart function and can prevent HF development. Mounting evidence supports the idea of a dynamic “interactome” in which GRK2 can uncouple GPCRs via novel protein-protein interactions. Several GRK2 interacting partners are important for adaptive and maladaptive myocyte growth; therefore, an understanding of domain-specific interactions with signaling and regulatory molecules could lead to novel targets for HF therapy. For instance, GRK2 contains a putative amino-terminal Regulator of G protein Signaling (RGS) domain (βARK-RGS) that directly interacts with Gq and appears to inhibit signaling without altering Gq enzymatic activity. Previously, our lab investigated cardiac-specific transgenic (Tg) expression of a fragment of this RGS domain (βARKnt). This fragment did not alter acute hypertrophy after pressure overload or demonstrate RGS activity in vivo against Gq-mediated signaling. In contrast, βARKnt induced hypertrophy and elevated β-adrenergic receptor (βAR) density without altering agonist-induced contractility or adenylyl cyclase activity, due to a compensatory increase in GRK2 activity. Importantly, though, βAR downregulation in response to chronic agonist administration was attenuated by βARKnt expression, indicating a novel regulation of βAR receptor density. Given these findings we have recently investigated the effect of βARKnt expression during chronic pressure overload post trans-aortic constriction (TAC). Echocardiographic analysis revealed increased posterior wall thickness and left-ventricular mass 4 weeks post-TAC compared to non-transgenic littermate controls (NLC). Importantly, despite enhanced hypertrophy, the progression to HF was inhibited in βARKnt mice 14 weeks post-TAC (%LV Ejection Fraction of 36.1 ± 0.2 in NLC versus 56.6 ± 0.9 in Tg mice). While mechanistic characterization is underway, these data indicate that βARKnt-mediated regulation of βAR density may provide a novel means of cardioprotection during pressure-overload induced HF.


2016 ◽  
Vol 119 (suppl_1) ◽  
Author(s):  
Sarah M Schumacher ◽  
Erhe Gao ◽  
J. Kurt Chuprun ◽  
Walter J. Koch

During heart failure (HF), cardiac levels and activity of the G protein-coupled receptor (GPCR) kinase (GRK) GRK2 are elevated and contribute to adverse remodeling and contractile dysfunction, while inhibition via a carboxyl-terminal peptide, βARKct, enhances heart function and can prevent HF. Mounting evidence supports the idea of a dynamic “interactome” in which GRK2 can uncouple GPCRs via novel protein-protein interactions. Several GRK2 interacting partners are important for adaptive and maladaptive myocyte growth; therefore, an understanding of domain-specific interactions with signaling and regulatory molecules could lead to novel targets for HF therapy. For instance, GRK2 contains a putative amino-terminal R egulator of G protein S ignaling (RGS) domain (βARKrgs) that directly interacts with Gαq and inhibits signaling. Previously, our lab investigated cardiac-specific transgenic expression of a fragment of this RGS domain (βARKnt), that did not reduce acute hypertrophy after pressure overload or demonstrate RGS activity in vivo against Gαq-mediated signaling. In contrast, βARKnt induced hypertrophy and elevated β-adrenergic receptor (βAR) density without altering agonist-induced contractility or adenylyl cyclase activity, due to a compensatory increase in GRK2 activity. Importantly, βAR downregulation in response to chronic agonist administration was attenuated by βARKnt expression, indicating a novel regulation of βAR receptor density. Herein, we investigated the effect of βARKnt expression during chronic pressure overload post trans-aortic constriction (TAC). Echocardiographic analysis revealed increased posterior wall thickness and left-ventricular mass 4 weeks post-TAC compared to non-transgenic littermate controls. Importantly, despite enhanced hypertrophy, the progression to HF was inhibited in βARKnt mice 14 weeks post-TAC. Histological analysis of interstitial fibrosis and cross-sectional area is underway to determine alterations in maladaptive remodeling. Further, cardiomyocyte signaling and βARKnt protein-binding partners are a focus, since our data indicate that βARKnt-mediated regulation of βAR density may provide a novel means of cardioprotection during pressure-overload induced HF.


2019 ◽  
Vol 40 (Supplement_1) ◽  
Author(s):  
J Ruedebusch ◽  
A Benkner ◽  
N Nath ◽  
L Kaderali ◽  
K Klingel ◽  
...  

Abstract Background Heart Failure (HF) is associated with endothelial dysfunction and reduced bioavailability of NO with insufficient stimulation of sGC and reduced production of cGMP. Therefore, the impairment of the NO-sGC-cGMP pathway results in vasoconstriction, platelet aggregation, inflammation, fibrosis and most importantly maladaptive cardiac hypertrophy. The restoration of the NO-sGC -cGMP pathway is an attractive pharmacological target for HF therapy. Purpose Riociguat is an NO independent stimulator of the sGC that sensitizes the sGC to endogenous NO and directly stimulates sGC to produce cGMP. We therefore hypothesized that Riociguat prevents pathological effects occurring during HF. Methods Pressure overload was induced by transverse aortic constriction (TAC) in 8 weeks old male C57Bl6/N mice. Three weeks after TAC when cardiac hypertrophy has developed either Riociguat (RIO; 3 mg/kg) or a Solvent was administered daily for 5 more weeks (n=12 per group). Animals with sham surgery and same drug regime served as controls. The heart function in all groups was evaluated weekly by small animal echocardiography. Eight weeks after surgery, the transcriptome of the left ventricles (LV) of sham and TAC mice were analysed by RNA Sequencing. Differentially expressed genes (DEG) were categorised using Ingenuity Pathway Analysis (IPA). Results TAC resulted in a steady decrease of left ventricular fractional shortening (FS) in the mice until week 3. When Riociguat treatment commenced, the systolic LV function of the TAC+Rio group recovered significantly whereas the solvent group showed a further decline until week 8 (FS 21.4±3.4% vs. 9.5±2%, p<0.001). Both sham groups (Sham+Sol and Sham+Rio) showed no changes in the heart function over timer. Regarding the hypertrophic response to LV pressure overload, Riociguat treatment attenuated significantly the increase of the left ventricular mass (LVM 208.3±15.8mg vs. 148.9±11.8mg, p<0.001) after TAC. In line with the reduced LVM, histological staining showed a significantly reduced fibrosis and myocyte cross sectional area in the TAC+Rio group compared to TAC+Sol group. Regarding the myocardial transcriptome, the treatment with Riociguat resulted in less changes of gene expression pattern after TAC (TAC+Sol vs. Sham+Sol 3160 DEG; TAC+Rio vs. Sham+Rio 2237 DEG). The expression of heart failure marker genes like ANP (Nppa), BNP (Nppb), β-Myosin Heavy Chain (Myh7) and the Collagens 1 and 3 (Col1a1, Col1a2, Col3a1) were significantly decreased in TAC+Rio, when compared to TAC+Sol. IPA analysis revealed that the activation of biological pathways in response to TAC, like actin cytoskeleton- and Integrin signalling, renin-angiotensin or cardiac hypertrophy signalling was attenuated when Riociguat was administered. Conclusion Riociguat attenuates pressure overload induced LV remodelling resulting in less hypertrophy, improved heart function and less alteration of gene expression pattern.


2021 ◽  
Vol 14 (676) ◽  
pp. eabb5968
Author(s):  
Ryan C. Coleman ◽  
Akito Eguchi ◽  
Melissa Lieu ◽  
Rajika Roy ◽  
Eric W. Barr ◽  
...  

Aberrant changes in gene expression underlie the pathogenesis and progression of pressure-overload heart failure, leading to maladaptive cardiac hypertrophy, ventricular remodeling, and contractile dysfunction. Signaling through the G protein Gq triggers maladaptation and heart failure, in part through the activation of G protein–coupled receptor kinase 5 (GRK5). Hypertrophic stimuli induce the accumulation of GRK5 in the nuclei of cardiomyocytes, where it regulates pathological gene expression through multiple transcription factors including NFAT. The nuclear targeting of GRK5 is mediated by an amino-terminal (NT) domain that binds to calmodulin (CaM). Here, we sought to prevent GRK5-mediated pathology in pressure-overload maladaptation and heart failure by expressing in cardiomyocytes a peptide encoding the GRK5 NT (GRK5nt) that encompasses the CaM binding domain. In cultured cardiomyocytes, GRK5nt expression abrogated Gq-coupled receptor–mediated hypertrophy, including attenuation of pathological gene expression and the transcriptional activity of NFAT and NF-κB. We confirmed that GRK5nt bound to and blocked Ca2+-CaM from associating with endogenous GRK5, thereby preventing GRK5 nuclear accumulation after pressure overload. We generated mice that expressed GRKnt in a cardiac-specific fashion (TgGRK5nt mice), which exhibited reduced cardiac hypertrophy, ventricular dysfunction, pulmonary congestion, and cardiac fibrosis after chronic transverse aortic constriction. Together, our data support a role for GRK5nt as an inhibitor of pathological GRK5 signaling that prevents heart failure.


2021 ◽  
Vol 8 ◽  
Author(s):  
Helena Kerp ◽  
Georg Sebastian Hönes ◽  
Elen Tolstik ◽  
Judith Hönes-Wendland ◽  
Janina Gassen ◽  
...  

Purpose: Thyroid hormones (TH) play a central role for cardiac function. TH influence heart rate and cardiac contractility, and altered thyroid function is associated with increased cardiovascular morbidity and mortality. The precise role of TH in onset and progression of heart failure still requires clarification.Methods: Chronic left ventricular pressure overload was induced in mouse hearts by transverse aortic constriction (TAC). One week after TAC, alteration of TH status was induced and the impact on cardiac disease progression was studied longitudinally over 4 weeks in mice with hypo- or hyperthyroidism and was compared to euthyroid TAC controls. Serial assessment was performed for heart function (2D M-mode echocardiography), heart morphology (weight, fibrosis, and cardiomyocyte cross-sectional area), and molecular changes in heart tissues (TH target gene expression, apoptosis, and mTOR activation) at 2 and 4 weeks.Results: In diseased heart, subsequent TH restriction stopped progression of maladaptive cardiac hypertrophy and improved cardiac function. In contrast and compared to euthyroid TAC controls, increased TH availability after TAC propelled maladaptive cardiac growth and development of heart failure. This was accompanied by a rise in cardiomyocyte apoptosis and mTOR pathway activation.Conclusion: This study shows, for the first time, a protective effect of TH deprivation against progression of pathological cardiac hypertrophy and development of congestive heart failure in mice with left ventricular pressure overload. Whether this also applies to the human situation needs to be determined in clinical studies and would infer a critical re-thinking of management of TH status in patients with hypertensive heart disease.


2020 ◽  
Author(s):  
Sarah M. Schumacher ◽  
Kamila M. Bledzka ◽  
Jessica Grondolsky ◽  
Rajika Roy ◽  
Erhe Gao ◽  
...  

AbstractG protein-coupled receptor (GPCR) kinase 2 (GRK2) expression and activity are elevated early on in response to several forms of cardiovascular stress and are a hallmark of heart failure. Interestingly, though, in addition to its well-characterized role in regulating GPCRs, mounting evidence suggests a GRK2 “interactome” that underlies a great diversity in its functional roles. Several such GRK2 interacting partners are important for adaptive and maladaptive myocyte growth; therefore, an understanding of domain-specific interactions with signaling and regulatory molecules could lead to novel targets for heart failure therapy. While elevated cardiac levels and activity of GRK2 contribute to adverse heart remodeling and contractile dysfunction, inhibition of GRK2 via overexpression of a carboxyl-terminal peptide, βARKct, or its amino-terminal domain Regulator of G protein Signaling (RGS) homology domain (βARKrgs) can enhance cardiac function and can prevent heart failure development via Gβγ or Gαq sequestration, respectively. Previously, our lab investigated cardiac-specific transgenic expression of a fragment of this RGS domain (βARKnt) (residues 50-145). In contrast to βARKrgs this fragment did not alter acute hypertrophy after pressure overload or demonstrate RGS activity in vivo against Gq-mediated signaling. Herein, we subjected these transgenic mice to pressure overload and found that unlike their littermate controls or previous GRK2 fragments, they exhibited an increased left ventricular wall thickness and mass prior to cardiac stress that underwent proportional hypertrophic growth to controls after acute pressure overload. Importantly, despite this enlarged heart, βARKnt mice did not undergo the expected transition to heart failure observed in controls. Further, βARKnt expression limited adverse left ventricular remodeling and increased cell survival signaling. These data support the idea that the βARKnt peptide embodies a distinct functional interaction and novel means of cardioprotection during pressure-overload induced heart failure.


2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Thanachai Methatham ◽  
Shota Tomida ◽  
Natsuka Kimura ◽  
Yasushi Imai ◽  
Kenichi Aizawa

AbstractIn heart failure (HF) caused by hypertension, the myocyte size increases, and the cardiac wall thickens. A low-molecular-weight compound called ICG001 impedes β-catenin-mediated gene transcription, thereby protecting both the heart and kidney. However, the HF-preventive mechanisms of ICG001 remain unclear. Hence, we investigated how ICG001 can prevent cardiac hypertrophy and fibrosis induced by transverse aortic constriction (TAC). Four weeks after TAC, ICG001 attenuated cardiac hypertrophy and fibrosis in the left ventricular wall. The TAC mice treated with ICG001 showed a decrease in the following: mRNA expression of brain natriuretic peptide (Bnp), Klf5, fibronectin, β-MHC, and β-catenin, number of cells expressing the macrophage marker CD68 shown in immunohistochemistry, and macrophage accumulation shown in flow cytometry. Moreover, ICG001 may mediate the substrates in the glycolysis pathway and the distinct alteration of oxidative stress during cardiac hypertrophy and HF. In conclusion, ICG001 is a potential drug that may prevent cardiac hypertrophy and fibrosis by regulating KLF5, immune activation, and the Wnt/β-catenin signaling pathway and inhibiting the inflammatory response involving macrophages.


2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
M Barki ◽  
M Losito ◽  
M.M Caracciolo ◽  
F Bandera ◽  
M Rovida ◽  
...  

Abstract Background The right ventricle (RV) is extremely sensitive to hemodynamic changes and increased impedance. In acute heart failure (AHF), the development of pulmonary venous congestion and the increase of left ventricular (LV) filling pressures favors pulmonary vascular adverse remodeling and ultimately RV dysfunction, leading to the onset of symptoms and to a further decay of cardiac dynamics. Purpose The aim of the study was to evaluate RV morphology and functional dynamics at admission and discharge in patients hospitalized for AHF, analyzing the role and the response to treatment of the RV and its coupling with pulmonary circulation (PC). Methods Eighty-one AHF patients (mean age 75.75±10.6 years, 59% males) were prospectively enrolled within 24–48 hours from admission to the emergency department (ED). In either the acute phase and at pre-discharge all patients underwent M-Mode, 2-Dimensional and Doppler transthoracic echocardiography (TTE), as well as lung ultrasonography (LUS), to detect an increase of extravascular lung water (EVLW) and development of pleural effusion. Laboratory tests were performed in the acute phase and at pre-discharge including the evaluation of NT-proBNP. Results At baseline we observed a high prevalence of RV dysfunction as documented by a reduced RV systolic longitudinal function [mean tricuspid annular plane systolic excursion (TAPSE) at admission of 16.47±3.86 mm with 50% of the patients exhibiting a TAPSE&lt;16mm], a decreased DTI-derived tricuspid lateral annular systolic velocity (50% of the subjects showed a tricuspid s' wave&lt;10 cm/s) and a reduced RV fractional area change (mean FAC at admission of 36.4±14.6%). Furthermore, an increased pulmonary arterial systolic pressure (PASP) and a severe impairment in terms of RV coupling to PC was detected at initial evaluation (mean PASP at admission: 38.8±10.8 mmHg; average TAPSE/PASP at admission: 0.45±0.17 mm/mmHg). At pre-discharge a significant increment of TAPSE (16.47±3.86 mm vs. 17.45±3.88; p=0.05) and a reduction of PASP (38.8±10.8 mmHg vs. 30.5±9.6mmHg, p&lt;0.001) was observed. Furthermore, in the whole population we assisted to a significant improvement in terms of RV function and its coupling with PC as demonstrated by the significant increase of TAPSE/PASP ratio (TAPSE/PASP: 0.45±0.17 mm/mmHg vs 0.62±0.20 mm/mmHg; p&lt;0.001). Patients significantly reduced from admission to discharge the number of B-lines and NT-proBNP (B-lines: 22.2±17.1 vs. 6.5±5 p&lt;0.001; NT-proBNP: 8738±948 ng/l vs 4227±659 ng/l p&lt;0.001) (Figure 1). Nonetheless, no significant changes of left atrial and left ventricular dimensions and function were noted. Conclusions In AHF, development of congestion and EVLW significantly impact on the right heart function. Decongestion therapy is effective for restoring acute reversal of RV dysfunction, but the question remains on how to impact on the biological properties of the RV. Funding Acknowledgement Type of funding source: None


2021 ◽  
Vol 129 (Suppl_1) ◽  
Author(s):  
Jorg Taubel ◽  
Wilfried Hauke ◽  
Steffen Rump ◽  
Janika Viereck ◽  
Sandor Batkai ◽  
...  

Cardiac microRNA-132-3p (miR-132) levels are elevated in people suffering with heart failure (HF) and mechanistically drive remodelling processes in the heart. Here we present CDR132L, a specific antisense oligonucleotide. It is a first-in-class miR-132 inhibitor that attenuates and even reverses HF in preclinical models. The aim of this clinical Phase 1b study was to assess safety, pharmacokinetics, target engagement, and pharmacodynamics of CDR132L in patients on therapy for chronic ischaemic HF in a randomized, placebo-controlled, double-blind, dose-escalation study. Inclusion criteria for participant patients was left ventricular ejection fraction between 30 and 50% or levels of amino terminal fragment of pro-brain natriuretic peptide (NT-proBNP) higher than 125 ng/L at screening. Twenty-eight patients were randomized to receive CDR132L (0.32, 1, 3, and 10 mg/kg body weight) or placebo (0.9% saline) in two intravenous infusions, 4 weeks apart. Randomization separated participants into four cohorts of seven (five verum and two placebo). Results revealed that CDR132L was safe and well tolerated, and there was no detectable dose-limiting toxicity. A pharmacokinetic/pharmacodynamic dose modelling approach suggested an effective dose level of ≥1 mg/kg CDR132L. CDR132L treatment resulted in a dose-dependent, sustained miR-132 reduction in plasma. Patients who were administered ≥1 mg/kg of CDR132L displayed 23.3% NT-proBNP reduction, whereas patients receiving placebo experienced a 0.9% increase. In addition, CDR132L treatment was observed to significantly reduce duration of the QRS interval. This is the first clinical trial in which an antisense oligonucleotide was administered as a therapeutic agent to HF patients. Linear plasma pharmacokinetics were confirmed, and there were no signs of accumulation. The application of this drug suggests cardiac functional improvements and cardiac remodelling. The efficacy of this drug is encouraging, and further clinical work with larger patient populations should follow. Although the study used small patient numbers, results suggest some clinical benefit in chronic HF patients on the top of standard of care. This included an improvement in HF severity and narrowing of the QRS complex. The pharmacodynamic findings presented here are encouraging as they confirm efficacy results seen in animal studies.


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