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Abstract
Diabetes is a major risk factor for the development of heart failure. One of the hallmarks of diabetes is insulin resistance associated with hyperinsulinemia. The literature shows that insulin and adrenergic signaling is intimately linked to each other; however, whether and how insulin may modulate cardiac adrenergic signaling and cardiac function remains unknown. Notably, recent studies have revealed that insulin receptor and β2 adrenergic receptor (β2AR) forms a membrane complex in animal hearts, bringing together the direct contact between 2 receptor signaling systems, and forming an integrated and dynamic network. Moreover, insulin can drive cardiac adrenergic desensitization via protein kinase A and G protein-receptor kinases phosphorylation of the β2AR, which compromises adrenergic regulation of cardiac contractile function. In this review, we will explore the current state of knowledge linking insulin and G protein-coupled receptor signaling, especially β-adrenergic receptor signaling in the heart, with emphasis on molecular insights regarding its role in diabetic cardiomyopathy.
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Demonstration of a direct interaction between β2-adrenergic receptor and insulin receptor by BRET and bioinformatics. PLoS One 2014; 9:e112664. [PMID: 25401701 PMCID: PMC4234468 DOI: 10.1371/journal.pone.0112664] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2014] [Accepted: 10/06/2014] [Indexed: 12/23/2022] Open
Abstract
Glucose metabolism is under the cooperative regulation of both insulin receptor (IR) and β2-adrenergic receptor (β2AR), which represent the receptor tyrosine kinases (RTKs) and seven transmembrane receptors (7TMRs), respectively. Studies demonstrating cross-talk between these two receptors and their endogenous coexpression have suggested their possible interactions. To evaluate the effect of IR and prospective heteromerization on β2AR properties, we showed that IR coexpression had no effect on the ligand binding properties of β2AR; however, IR reduced β2AR surface expression and accelerated its internalization. Additionally, both receptors displayed a similar distribution pattern with a high degree of colocalization. To test the possible direct interaction between β2AR and IR, we employed quantitative BRET2 saturation and competition assays. Saturation assay data suggested constitutive β2AR and IR homo- and heteromerization. Calculated acceptor/donor (AD50) values as a measure of the relative affinity for homo- and heteromer formation differed among the heteromers that could not be explained by a simple dimer model. In heterologous competition assays, a transient increase in the BRET2 signal with a subsequent hyperbolical decrease was observed, suggesting higher-order heteromer formation. To complement the BRET2 data, we employed the informational spectrum method (ISM), a virtual spectroscopy method to investigate protein-protein interactions. Computational peptide scanning of β2AR and IR identified intracellular domains encompassing residues at the end of the 7th TM domain and C-terminal tail of β2AR and a cytoplasmic part of the IR β chain as prospective interaction domains. ISM further suggested a high probability of heteromer formation and homodimers as basic units engaged in heteromerization. In summary, our data suggest direct interaction and higher-order β2AR:IR oligomer formation, likely comprising heteromers of homodimers.
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Cattaneo F, Guerra G, Parisi M, De Marinis M, Tafuri D, Cinelli M, Ammendola R. Cell-surface receptors transactivation mediated by g protein-coupled receptors. Int J Mol Sci 2014; 15:19700-28. [PMID: 25356505 PMCID: PMC4264134 DOI: 10.3390/ijms151119700] [Citation(s) in RCA: 136] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 09/30/2014] [Accepted: 10/13/2014] [Indexed: 12/17/2022] Open
Abstract
G protein-coupled receptors (GPCRs) are seven transmembrane-spanning proteins belonging to a large family of cell-surface receptors involved in many intracellular signaling cascades. Despite GPCRs lack intrinsic tyrosine kinase activity, tyrosine phosphorylation of a tyrosine kinase receptor (RTK) occurs in response to binding of specific agonists of several such receptors, triggering intracellular mitogenic cascades. This suggests that the notion that GPCRs are associated with the regulation of post-mitotic cell functions is no longer believable. Crosstalk between GPCR and RTK may occur by different molecular mechanism such as the activation of metalloproteases, which can induce the metalloprotease-dependent release of RTK ligands, or in a ligand-independent manner involving membrane associated non-receptor tyrosine kinases, such as c-Src. Reactive oxygen species (ROS) are also implicated as signaling intermediates in RTKs transactivation. Intracellular concentration of ROS increases transiently in cells stimulated with GPCR agonists and their deliberated and regulated generation is mainly catalyzed by enzymes that belong to nicotinamide adenine dinucleotide phosphate (NADPH) oxidase family. Oxidation and/or reduction of cysteine sulfhydryl groups of phosphatases tightly controls the activity of RTKs and ROS-mediated inhibition of cellular phosphatases results in an equilibrium shift from the non-phosphorylated to the phosphorylated state of RTKs. Many GPCR agonists activate phospholipase C, which catalyze the hydrolysis of phosphatidylinositol 4,5-bis-phosphate to produce inositol 1,4,5-triphosphate and diacylglicerol. The consequent mobilization of Ca2+ from endoplasmic reticulum leads to the activation of protein kinase C (PKC) isoforms. PKCα mediates feedback inhibition of RTK transactivation during GPCR stimulation. Recent data have expanded the coverage of transactivation to include Serine/Threonine kinase receptors and Toll-like receptors. Herein, we discuss the main mechanisms of GPCR-mediated cell-surface receptors transactivation and the pathways involved in intracellular responses induced by GPCR agonists. These studies may suggest the design of novel strategies for therapeutic interventions.
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Affiliation(s)
- Fabio Cattaneo
- Department of Molecular Medicine and Medical Biotechnology, School of Medicine, University of Naples Federico II, Naples 80131, Italy.
| | - Germano Guerra
- Department of Medicine and Health Sciences, University of Molise, Campobasso 86100, Italy.
| | - Melania Parisi
- Department of Molecular Medicine and Medical Biotechnology, School of Medicine, University of Naples Federico II, Naples 80131, Italy.
| | - Marta De Marinis
- Department of Molecular Medicine and Medical Biotechnology, School of Medicine, University of Naples Federico II, Naples 80131, Italy.
| | - Domenico Tafuri
- Department of Sport Science and Wellness, University of Naples Parthenope, Naples 80133, Italy.
| | - Mariapia Cinelli
- Department of Public Health, School of Medicine, University of Naples Federico II, Naples 80131, Italy.
| | - Rosario Ammendola
- Department of Molecular Medicine and Medical Biotechnology, School of Medicine, University of Naples Federico II, Naples 80131, Italy.
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Reprogramming of G protein-coupled receptor recycling and signaling by a kinase switch. Proc Natl Acad Sci U S A 2013; 110:15289-94. [PMID: 24003153 DOI: 10.1073/pnas.1306340110] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The postendocytic recycling of signaling receptors is subject to multiple requirements. Why this is so, considering that many other proteins can recycle without apparent requirements, is a fundamental question. Here we show that cells can leverage these requirements to switch the recycling of the beta-2 adrenergic receptor (B2AR), a prototypic signaling receptor, between sequence-dependent and bulk recycling pathways, based on extracellular signals. This switch is determined by protein kinase A-mediated phosphorylation of B2AR on the cytoplasmic tail. The phosphorylation state of B2AR dictates its partitioning into spatially and functionally distinct endosomal microdomains mediating bulk and sequence-dependent recycling, and also regulates the rate of B2AR recycling and resensitization. Our results demonstrate that G protein-coupled receptor recycling is not always restricted to the sequence-dependent pathway, but may be reprogrammed as needed by physiological signals. Such flexible reprogramming might provide a versatile method for rapidly modulating cellular responses to extracellular signaling.
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García-Sáinz JA, Romero-Ávila MT, Medina LDC. Dissecting how receptor tyrosine kinases modulate G protein-coupled receptor function. Eur J Pharmacol 2010; 648:1-5. [PMID: 20828551 DOI: 10.1016/j.ejphar.2010.08.049] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2010] [Revised: 08/30/2010] [Accepted: 08/31/2010] [Indexed: 02/06/2023]
Abstract
Receptor tyrosine kinases and G protein-coupled receptors modulate physiological processes and are also involved in the pathogenesis of some diseases. These receptors have intense bidirectional crosstalks leading to interactions in their signaling pathways and also modulation of the receptors themselves. In some cases, the receptor tyrosine kinases phosphorylate G protein-coupled receptors whereas in others phosphoinositide 3-kinase, protein kinase B and protein kinase C are key elements in these crosstalks. Two paracrine/ autocrine processes also participate, i.e., epidermal growth factor transactivation and sphingosine 1-phosphate generation and signaling. G proteins seem to mediate actions of receptor tyrosine kinases, but how this takes place is far from completely understood; some models are presented. Recent data indicate that the mitogen activated protein kinase cascade also mediate crosstalks. In the present perspective these processes are outlined using information from receptors that have been intensively studied, and important gaps in our knowledge are indicated.
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Affiliation(s)
- J Adolfo García-Sáinz
- Departamento de Biología Celular y Desarrollo, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Ap. Postal 70-248, México D.F. 04510.
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Jiang Y, Walker RJ, Kern TS, Steinle JJ. Application of isoproterenol inhibits diabetic-like changes in the rat retina. Exp Eye Res 2010; 91:171-9. [PMID: 20493839 DOI: 10.1016/j.exer.2010.04.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2009] [Revised: 02/05/2010] [Accepted: 04/27/2010] [Indexed: 10/19/2022]
Abstract
Diabetic retinopathy is the leading cause of blindness to working-age adults. We have recently shown that surgical removal or genetic manipulations to eliminate sympathetic neurotransmission produces many of the retinal changes similar to rodent diabetic retinopathy with normal glucose levels. We hypothesized that application of a beta-adrenergic receptor agonist, isoproterenol, could reach the retina to elicit normal cellular signaling and inhibit the functional and morphological markers of early stage diabetic retinopathy in the rat. Rats were made diabetic by injection of 60 mg/kg streptozotocin. Within 3 days of diabetes-induction, rats were placed into 1 of 3 groups (control, diabetes, or diabetic + isoproterenol). Dose and time course studies were done for isoproterenol using a PKA ELISA and CREB analyses. Once the optimal dose and time course were established, electrical activity of the retina was analyzed by electroretinogram each month for the 8-month study. Western blotting was done for insulin receptor signaling and Akt and ELISA analyses for TNFalpha concentration and cleavage of caspase 3 at 2- and 8-months of diabetes. Diabetes-induced degeneration of neural cells and retinal thickness were assessed at 2 months, while degenerate capillaries were quantitated at 8 months of treatment. Daily application of 50 mM isoproterenol was effective in inhibiting the diabetes-induced loss of a- and b-wave and oscillatory potential amplitudes in the electroretinogram. Isoproterenol blocked the increase in TNFalpha and apoptosis in the diabetic retina. The numbers of degenerate capillaries were also reduced in the treated + diabetes retina. These data strongly suggest that loss of beta-adrenergic receptor signaling may be a key factors in early stage diabetic retinopathy. Resolution of this loss of adrenergic receptor signaling can inhibit some of the hallmarks of diabetic retinopathy in the retina.
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Affiliation(s)
- Youde Jiang
- Department of Ophthalmology, Hamilton Eye Institute, University of Tennessee Health Science Center, Memphis, TN 38163, USA
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Cruse G, Yang W, Duffy SM, Chachi L, Leyland M, Amrani Y, Bradding P. Counterregulation of beta(2)-adrenoceptor function in human mast cells by stem cell factor. J Allergy Clin Immunol 2009; 125:257-63.e1-5. [PMID: 19864009 DOI: 10.1016/j.jaci.2009.08.020] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2009] [Revised: 07/10/2009] [Accepted: 08/05/2009] [Indexed: 02/01/2023]
Abstract
BACKGROUND Mast cells contribute to the pathophysiology of asthma with the sustained release of both preformed and newly generated mediators in response to allergens and other diverse stimuli. Stem cell factor (SCF) is the key human mast cell growth factor, but also primes mast cells for mediator release. SCF expression is markedly increased in asthmatic airways. Short-acting beta(2)-adrenoceptor drugs such as albuterol inhibit human lung mast cell (HLMC) degranulation in vitro in the absence of SCF, but their effect in the presence of SCF is not known. OBJECTIVE The aim of this study was to elucidate the effects of albuterol on HLMC function in the presence of SCF. METHODS Mediator release and K(Ca)3.1 ion channel activity were analyzed in purified HLMC. Intracellular signalling and beta(2)-adrenoceptor phosphorylation and internalization were analyzed in the HMC-1 human mast cell line. RESULTS beta(2)-Adrenoceptor agonist-dependent inhibition of K(Ca)3.1 ion channels and HLMC mediator release was markedly attenuated in the presence of SCF. Remarkably, albuterol actually potentiated IgE-induced histamine release in a dose-dependent manner when both SCF and IgE were present. These effects were related to the SCF-dependent phosphorylation of Tyr350 on the beta(2)-adrenoceptor with immediate uncoupling of the receptor followed by receptor internalization. CONCLUSION The potentially beneficial effects of beta(2)-adrenoceptor agonists in asthmatic airways may be blunted as a result of the high concentrations of SCF present.
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Affiliation(s)
- Glenn Cruse
- Department of Infection, Immunity and Inflammation, University of Leicester, Leicester, United Kingdom.
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Labovsky V, Smulski CR, Gómez K, Levy G, Levin MJ. Anti-beta1-adrenergic receptor autoantibodies in patients with chronic Chagas heart disease. Clin Exp Immunol 2007; 148:440-9. [PMID: 17419712 PMCID: PMC1941934 DOI: 10.1111/j.1365-2249.2007.03381.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Chronic Chagas heart disease (cChHD), a chronic manifestation of the Trypanosoma cruzi infection, is characterized by high antibody levels against the C-terminal region of the ribosomal P proteins (i.e. peptide R13, EEEDDDMGFGLFD) which bears similarity with the second extracellular loop of beta1-adrenergic receptor (beta1-AR, peptide H26R HWWRAESDEARRCYNDPKCCDFVTNR). Because it has not been demonstrated clearly that IgGs from cChHD patients bind to native human beta1-AR, the aim of this study was to investigate further the physical interaction between cChHD IgGs and the human beta1-AR. Immunofluorescence assays demonstrated the binding of these antibodies to the receptor expressed on stably transfected cells, together with a beta1-AR agonist-like effect. In addition, immunoadsorption of the serum samples from cChHD patients with a commercially available matrix, containing peptides representing the first and the second extracellular loop of the beta1-AR, completely abolished reactivity against the H26R peptide and the physiological response to the receptor. The follow-up of this specificity after in vitro immunoadsorption procedures suggests that this treatment might be used to diminish significantly the serum levels of anti-beta1-AR antibodies in patients with Chagas heart disease.
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Affiliation(s)
- V Labovsky
- Laboratorio de Biología Molecular de la Enfermedad de Chagas, Instituto de Investigaciones en Ingeniería Genética y Biología Molecular (INGEBI), Consejo Nacional de Investigación, Ciencia y Técnica (CONICET), Buenos Aires, Argentina
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Gavi S, Shumay E, Wang HY, Malbon CC. G-protein-coupled receptors and tyrosine kinases: crossroads in cell signaling and regulation. Trends Endocrinol Metab 2006; 17:48-54. [PMID: 16460957 DOI: 10.1016/j.tem.2006.01.006] [Citation(s) in RCA: 80] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/10/2005] [Revised: 12/19/2005] [Accepted: 01/19/2006] [Indexed: 12/11/2022]
Abstract
G-protein-coupled receptors and protein tyrosine kinases represent two prominent pathways for cellular signaling. As our knowledge of cell signaling pathways mediated by the superfamily of G-protein-coupled receptors and the smaller family of receptor tyrosine kinases expands, so does our appreciation of how these two major signaling platforms share information and modulate each other, otherwise termed "cross-talk". Cross-talk between G-protein-coupled receptors and tyrosine kinases can occur at several levels, including the receptor-to-receptor level, and at crucial downstream points (e.g. phosphatidylinositol-3-kinase, Akt/protein kinase B and the mitogen-activated protein kinase cascade). Regulation of G-protein-coupled receptors by non-receptor tyrosine kinases, such as Src family members, also operates in signaling. A broader understanding of how G-protein-coupled receptors and tyrosine kinases cross-talk reveals new insights into signaling modalities in both health and disease.
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Affiliation(s)
- Shai Gavi
- Department of Pharmacology, Diabetes and Metabolic Diseases Research Center, School of Medicine, State University of New York at Stony Brook, Stony Brook, NY 11794, USA.
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