G protein-coupled receptor kinase 2 (GRK2) as a potential therapeutic target in cardiovascular and metabolic diseases

G protein-coupled receptor kinase 2 (GRK2) is a central signaling node involved in the modulation of many G protein-coupled receptors (GPCRs) and also displaying regulatory functions in other cell signaling routes. GRK2 levels and activity have been reported to be enhanced in patients or in preclinical models of several relevant pathological situations, such as heart failure, cardiac hypertrophy, hypertension, obesity and insulin resistance conditions, or non-alcoholic fatty liver disease (NAFLD), and to contribute to disease progression by a variety of mechanisms related to its multifunctional roles. Therefore, targeting GRK2 by different strategies emerges as a potentially relevant approach to treat cardiovascular disease, obesity, type 2 diabetes, or NAFLD, pathological conditions which are frequently interconnected and present as co-morbidities.Our laboratories are supported by Ministerio de Economía; Industria y Competitividad (MINECO) of Spain (grant SAF2017- 84125-R to FM and CM and SAF2016-80305-P to MS and AMB), CIBERCV-Instituto de Salud Carlos III, Spain (grants CB16/11/00278 and CB16/11/00286 to FM and MS, respectively, co-funded with European FEDER contribution), and Programa de Actividades en Biomedicina de la Comunidad de Madrid (grants B2017/BMD-3671-INFLAMUNE to FM and B2017/ BMD-3676-AORTASANA to MS)

G Protein-Coupled Receptor Kinase 2 (GRK2) as a Potential Therapeutic Target in Cardiovascular and Metabolic Diseases

G protein-coupled receptor kinase 2 (GRK2) is a central signaling node involved in the modulation of many G protein-coupled receptors (GPCRs) and also displaying regulatory functions in other cell signaling routes. GRK2 levels and activity have been reported to be enhanced in patients or in preclinical models of several relevant pathological situations, such as heart failure, cardiac hypertrophy, hypertension, obesity and insulin resistance conditions, or non-alcoholic fatty liver disease (NAFLD), and to contribute to disease progression by a variety of mechanisms related to its multifunctional roles. Therefore, targeting GRK2 by different strategies emerges as a potentially relevant approach to treat cardiovascular disease, obesity, type 2 diabetes, or NAFLD, pathological conditions which are frequently interconnected and present as co-morbidities

GRK2 regulates GLP-1R-mediated early phase insulin secretion in vivo

© The Author(s).[Background]: Insulin secretion from the pancreatic β-cell is finely modulated by different signals to allow an adequate control of glucose homeostasis. Incretin hormones such as glucagon-like peptide-1 (GLP-1) act as key physiological potentiators of insulin release through binding to the G protein-coupled receptor GLP-1R. Another key regulator of insulin signaling is the Ser/Thr kinase G protein-coupled receptor kinase 2 (GRK2). However, whether GRK2 affects insulin secretion or if GRK2 can control incretin actions in vivo remains to be analyzed. [Results]: Using GRK2 hemizygous mice, isolated pancreatic islets, and model β-cell lines, we have uncovered a relevant physiological role for GRK2 as a regulator of incretin-mediated insulin secretion in vivo. Feeding, oral glucose gavage, or administration of GLP-1R agonists in animals with reduced GRK2 levels (GRK2+/− mice) resulted in enhanced early phase insulin release without affecting late phase secretion. In contrast, intraperitoneal glucose-induced insulin release was not affected. This effect was recapitulated in isolated islets and correlated with the increased size or priming efficacy of the readily releasable pool (RRP) of insulin granules that was observed in GRK2+/− mice. Using nanoBRET in β-cell lines, we found that stimulation of GLP-1R promoted GRK2 association to this receptor and that GRK2 protein and kinase activity were required for subsequent β-arrestin recruitment. [Conclusions]: Overall, our data suggest that GRK2 is an important negative modulator of GLP-1R-mediated insulin secretion and that GRK2-interfering strategies may favor β-cell insulin secretion specifically during the early phase, an effect that may carry interesting therapeutic applications.We acknowledge support by Ministerio de Economía y Competitividad (MINECO/FEDER), Spain (grant SAF2017-84125-R to FM and CM and BFU2017-89336-R to MV); CIBER de Enfermedades Cardiovasculares (CIBERCV). Instituto de Salud Carlos III, Spain (grant CB16/11/00278 to F.M., co-funded with European FEDER contribution); CIBER de Diabetes y Enfermedades Metabólicas Asociadas (Ciberdem), Instituto de Salud Carlos III (CB07/08/0029 to MV); and Programa de Actividades en Biomedicina de la Comunidad de Madrid-B2017/BMD-3671-INFLAMUNE to FM; Medical Research Council to AT and BJ

Obesity-induced cardiac lipid accumulation in adult mice is modulated by G protein-coupled receptor kinase 2 levels

[Background] The leading cause of death among the obese population is heart failure and stroke prompted by structural and functional changes in the heart. The molecular mechanisms that underlie obesity-related cardiac remodeling are complex, and include hemodynamic and metabolic alterations that ultimately affect the functionality of the myocardium. G protein-coupled receptor kinase 2 (GRK2) is an ubiquitous kinase able to desensitize the active form of several G protein-coupled receptors (GPCR) and is known to play an important role in cardiac GPCR modulation. GRK2 has also been recently identified as a negative modulator of insulin signaling and systemic insulin resistance.[Methods] We investigated the effects elicited by GRK2 downregulation in obesity-related cardiac remodeling. For this aim, we used 9 month-old wild type (WT) and GRK2+/− mice, which display circa 50% lower levels of this kinase, fed with either a standard or a high fat diet (HFD) for 30 weeks. In these mice we studied different parameters related to cardiac growth and lipid accumulation.[Results] We find that GRK2+/− mice are protected from obesity-promoted cardiac and cardiomyocyte hypertrophy and fibrosis. Moreover, the marked intracellular lipid accumulation caused by a HFD in the heart is not observed in these mice. Interestingly, HFD significantly increases cardiac GRK2 levels in WT but not in GRK2+/− mice, suggesting that the beneficial phenotype observed in hemizygous animals correlates with the maintenance of GRK2 levels below a pathological threshold. Low GRK2 protein levels are able to keep the PKA/CREB pathway active and to prevent HFD-induced downregulation of key fatty acid metabolism modulators such as Peroxisome proliferator-activated receptor gamma co-activators (PGC1), thus preserving the expression of cardioprotective proteins such as mitochondrial fusion markers mitofusin MFN1 and OPA1.[Conclusions] Our data further define the cellular processes and molecular mechanisms by which GRK2 down-regulation is cardioprotective during diet-induced obesity, reinforcing the protective effect of maintaining low levels of GRK2 under nutritional stress, and showing a role for this kinase in obesity-induced cardiac remodeling and steatosis.This work was supported by the Spanish Ministerio de Economía y Competitividad (MINECO, Grant SAF2014-55511-R to F. M and C. M); Fundación Ramón Areces (to C. M.); Comunidad de Madrid Grant S2010/BMD-2332 (Inter-Disciplinary Research Network); Ministerio Sanidad y Consumo-Instituto Carlos III Cardiovascular Network (Grant RD12/0042/0012 to F. M. and RD12/0042/0033 (to V. C.); and PI15/01060 (to V. C.). R. V. B. is recipient of a postdoctoral contract by the MINECO. We acknowledge the support of the publication fee by the CSIC Open Access Publication Support Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe

G protein–coupled receptor kinase 2 at crossroads of metabolic and cardiovascular diseases

G protein–coupled receptor kinase 2 (GRK2) is the center of a signaling hub shared by G protein–coupled receptors and insulin networks controlling heart function and metabolism as well as global energy homeostasis. GRK2 levels and activity are upregulated in the heart and in tissues that are the key to metabolic control during cardiovascular pathologies and in obesity and insulin resistance–related contexts, which are frequent comorbidities in the clinical practice, pointing to this protein as a potentially relevant therapeutic target. Recent research is unveiling the signals and mechanisms involved in the modulation of GRK2 expression and functionality in these physiopathological contexts and disclosing how altered GRK2 levels contribute to disease progression by modulating the functionality and cross talk of cardiac and metabolically relevant tissues.Agencia Estatal de Investigación of Spain (grant SAF2017-84125-R to FM and CM), CIBERCV-Instituto de Salud Carlos III, Spain (grant CB16/11/00278 to FM, cofunded with European FEDER contribution and Intramural CIBERCV project to FM and JI), Instituto de Salud Carlos III, Spain (grant PI17-00576 to PP), Fundación Ramón Areces (to FM), and Programa de Actividades en Biomedicina de la Comunidad de Madrid-B2017/BMD-3671-INFLAMUNE (to FM

Sex differences in high fat diet-induced metabolic alterations correlate with changes in the modulation of GRK2 levels

A differential sex-related sensitivity has been reported in obesity and insulin resistance-related cardio-metabolic diseases, with a lower incidence of these pathologies being observed in young females when compared to age-matched males. However, such relative protection is lost with age. The mechanisms underlying such sex and age-related changes in the susceptibility to diabetes and obesity are not fully understood. Herein, we report that the relative protection that is displayed by young female mice, as compared to male littermates, against some of the metabolic alterations that are induced by feeding a high fat diet (HFD), correlates with a lower upregulation of the protein levels of G protein-coupled receptor kinase (GRK2), which is a key regulator of both insulin and G protein-coupled receptor signaling, in the liver and adipose tissue. Interestingly, when the HFD is initiated in middle-aged (32 weeks) female mice, these animals are no longer protected and display a more overt obese and insulin-resistant phenotype, along with a more evident increase in the GRK2 protein levels in metabolically relevant tissues in such conditions. Our data suggest that GRK2 dosage might be involved in the sex and age-biased sensitivity to insulin resistance-related pathologies.Agencia Estatal de Investigación of Spain (grant SAF2014-55511-R and SAF2017-84125-R to F.M.J. and C.M.), CIBERCV-Instituto de Salud Carlos III, Spain (grant CB16/11/00278 to F.M., co-funded with European Regional Development Fund-FEDER contribution), Programa de Actividades en Biomedicina de la Comunidad de Madrid (grant B2017/BMD-3671-INFLAMUNE to F.M.J.) and Fundación Ramón Areces.Peer reviewe

Cardiac GRK2 Protein Levels Show Sexual Dimorphism during Aging and Are Regulated by Ovarian Hormones

© 2021 by the authors.Cardiovascular disease (CVD) risk shows a clear sexual dimorphism with age, with a lower incidence in young women compared to age-matched men. However, this protection is lost after menopause. We demonstrate that sex-biased sensitivity to the development of CVD with age runs in parallel with changes in G protein-coupled receptor kinase 2 (GRK2) protein levels in the murine heart and that mitochondrial fusion markers, related to mitochondrial functionality and cardiac health, inversely correlate with GRK2. Young female mice display lower amounts of cardiac GRK2 protein compared to age-matched males, whereas GRK2 is upregulated with age specifically in female hearts. Such an increase in GRK2 seems to be specific to the cardiac muscle since a different pattern is found in the skeletal muscles of aging females. Changes in the cardiac GRK2 protein do not seem to rely on transcriptional modulation since adrbk1 mRNA does not change with age and no differences are found between sexes. Global changes in proteasomal or autophagic machinery (known regulators of GRK2 dosage) do not seem to correlate with the observed GRK2 dynamics. Interestingly, cardiac GRK2 upregulation in aging females is recapitulated by ovariectomy and can be partially reversed by estrogen supplementation, while this does not occur in the skeletal muscle. Our data indicate an unforeseen role for ovarian hormones in the regulation of GRK2 protein levels in the cardiac muscle which correlates with the sex-dependent dynamics of CVD risk, and might have interesting therapeutic applications, particularly for post-menopausal women.We acknowledge support by the Agencia Estatal de Investigación (MINECO/FEDER), Spain (grant SAF2017-84125-R to FM and CM and grant SAF2016-80384 R to ILL and AMP); the CIBER de Enfermedades Cardiovasculares (CIBERCV, Instituto de Salud Carlos III) Spain (grant CB16/11/00278 to F.M., co-funded with European FEDER contribution), and the Programa de Actividades en Biomedicina de la Comunidad de Madrid (B2017/BMD-3671-INFLAMUNE to FM). MR M-C was funded by a grant from Balearic Islands Government (FPI/1888/2016), after being selected in the framework of an operating program co-financed by the European Social Fund.Peer reviewe

Autophagy mediates hepatic GRK2 degradation to facilitate glucagon-induced metabolic adaptation to fasting

The liver plays a key role during fasting to maintain energy homeostasis and euglycemia via metabolic processes mainly orchestrated by the insulin/glucagon ratio. We report here that fasting or calorie restriction protocols in C57BL6 mice promote a marked decrease in the hepatic protein levels of G protein-coupled receptor kinase 2 (GRK2), an important negative modulator of both G protein-coupled receptors (GPCRs) and insulin signaling. Such downregulation of GRK2 levels is liver-specific and can be rapidly reversed by refeeding. We find that autophagy, and not the proteasome, represents the main mechanism implicated in fasting-induced GRK2 degradation in the liver in vivo. Reducing GRK2 levels in murine primary hepatocytes facilitates glucagon-induced glucose production and enhances the expression of the key gluconeogenic enzyme Pck1. Conversely, preventing full downregulation of hepatic GRK2 during fasting using adenovirus-driven overexpression of this kinase in the liver leads to glycogen accumulation, decreased glycemia, and hampered glucagon-induced gluconeogenesis, thus preventing a proper and complete adaptation to nutrient deprivation. Overall, our data indicate that physiological fasting-induced downregulation of GRK2 in the liver is key for allowing complete glucagon-mediated responses and efficient metabolic adaptation to fasting in vivo.Ministerio de Economia y Competitividad (MINECO/FEDER), Spain (grant SAF2017-84125-R to F.M. and C. M.); CIBER de Enfermedades Cardiovasculares (CIBERCV). Instituto de Salud Carlos III, Spain (grant CB16/11/00278 to FM, co-funded with European FEDER contribution); European Foundation for the Study of Diabetes (EFSD) Novo Nordisk Partnership for Diabetes Research in Europe Grant (to FM); NIH R01 DK089883 grant to P.P. and Programa de Actividades en Biomedicina de la Comunidad de Madrid-B2017/BMD-3671-INFLAMUNE to F.M and CBMSO from Fundacion Ramon Areces and Fundacion Banco de Santande

Myeloid GRK2 Regulates Obesity-Induced Endothelial Dysfunction by Modulating Inflammatory Responses in Perivascular Adipose Tissue

Perivascular adipose tissue (PVAT) is increasingly being regarded as an important endocrine organ that directly impacts vessel function, structure, and contractility in obesity-associated diseases. We uncover here a role for myeloid G protein-coupled receptor kinase 2 (GRK2) in the modulation of PVAT-dependent vasodilation responses. GRK2 expression positively correlates with myeloid- (CD68) and lymphoid-specific (CD3, CD4, and CD8) markers and with leptin in PVAT from patients with abdominal aortic aneurysms. Using mice hemizygous for GRK2 in the myeloid lineage (LysM-GRK2+/), we found that GRK2 deficiency in myeloid cells allows animals to preserve the endothelium-dependent acetylcholine or insulin-induced relaxation, which is otherwise impaired by PVAT, in arteries of animals fed a high fat diet (HFD). Downregulation of GRK2 in myeloid cells attenuates HFD-dependent infiltration of macrophages and T lymphocytes in PVAT, as well as the induction of tumor necrosis factor- (TNF) and NADPH oxidase (Nox)1 expression, whereas blocking TNF or Nox pathways by pharmacological means can rescue the impaired vasodilator responses to insulin in arteries with PVAT from HFD-fed animals. Our results suggest that myeloid GRK2 could be a potential therapeutic target in the development of endothelial dysfunction induced by PVAT in the context of obesityMinisterio de Economía y Competitividad (MINECO/FEDER), Spain (grant SAF2017-84125-R to F.M.J. and C.M.; SAF2016-80305P to M.S. and A.M.B.); CIBER de Enfermedades Cardiovasculares (CIBERCV); Instituto de Salud Carlos III, Spain (grant CB16/11/00278 to F.M.J. and CB16/11/00286 to M.S.); European Foundation for the Study of Diabetes (EFSD) Novo Nordisk Partnership for Diabetes Research in Europe Grant (to F.M.J.); and Programa de Actividades en Biomedicina de la Comunidad de Madrid—FEDER-a way to build Europe B2017/BMD-3671-INFLAMUNE to F.M.J. and B2017/BMD-3676-AORTASANA to M.S. M.G.-A. was supported by a FPI-UAM fellowship, R.R.-D. by a Juan de la Cierva contract (IJCI-2017-31399). We appreciate the help of the CBMSO Facilities, in particular Animal Care. We also acknowledge the institutional support to the CBMSO.from Funcación Ramón Arece