scholarly journals Reciprocal regulation of two G protein-coupled receptors sensing extracellular concentrations of Ca2+ and H+

2015 ◽  
Vol 112 (34) ◽  
pp. 10738-10743 ◽  
Author(s):  
Wei-Chun Wei ◽  
Benjamin Jacobs ◽  
Esther B. E. Becker ◽  
Maike D. Glitsch
Keyword(s):  
G Protein ◽  
Interstitial Fluid ◽  
Cell Function ◽  
G Protein Coupled Receptors ◽  
Dependent Manner ◽  
Reciprocal Regulation ◽  
Surface Receptors ◽  
Wide Range ◽  
The Difference ◽  
G Protein Coupled

G protein-coupled receptors (GPCRs) are cell surface receptors that detect a wide range of extracellular messengers and convey this information to the inside of cells. Extracellular calcium-sensing receptor (CaSR) and ovarian cancer gene receptor 1 (OGR1) are two GPCRs that sense extracellular Ca2+ and H+, respectively. These two ions are key components of the interstitial fluid, and their concentrations change in an activity-dependent manner. Importantly, the interstitial fluid forms part of the microenvironment that influences cell function in health and disease; however, the exact mechanisms through which changes in the microenvironment influence cell function remain largely unknown. We show that CaSR and OGR1 reciprocally inhibit signaling through each other in central neurons, and that this is lost in their transformed counterparts. Furthermore, strong intracellular acidification impairs CaSR function, but potentiates OGR1 function. Thus, CaSR and OGR1 activities can be regulated in a seesaw manner, whereby conditions promoting signaling through one receptor simultaneously inhibit signaling through the other receptor, potentiating the difference in their relative signaling activity. Our results provide insight into how small but consistent changes in the ionic microenvironment of cells can significantly alter the balance between two signaling pathways, which may contribute to disease progression.

scholarly journals Mini-review: antibody therapeutics targeting G protein-coupled receptors and ion channels

2020 ◽  
Vol 3 (4) ◽  
pp. 257-264
Author(s):  
Catherine J Hutchings
Keyword(s):  
Ion Channels ◽  
Research And Development ◽  
Small Molecules ◽  
G Protein ◽  
Clinical Studies ◽  
G Protein Coupled Receptors ◽  
Protein Targets ◽  
Antibody Therapeutics ◽  
Wide Range ◽  
G Protein Coupled

Abstract Antibodies are now well established as therapeutics with many additional advantages over small molecules and peptides relative to their selectivity, bioavailability, half-life and effector function. Major classes of membrane-associated protein targets include G protein-coupled receptors (GPCRs) and ion channels that are linked to a wide range of disease indications across all therapeutic areas. This mini-review summarizes the antibody target landscape for both GPCRs and ion channels as well as current progress in the respective research and development pipelines with some example case studies highlighted from clinical studies, including those being evaluated for the treatment of symptoms in COVID-19 infection.

scholarly journals Assembly of G Protein-Coupled Receptors onto Nanosized Bacterial Magnetic Particles Using Mms16 as an Anchor Molecule

2004 ◽  
Vol 70 (5) ◽  
pp. 2880-2885 ◽  
Author(s):  
Tomoko Yoshino ◽  
Masayoshi Takahashi ◽  
Haruko Takeyama ◽  
Yoshiko Okamura ◽  
Fukuichi Kato ◽  
...  
Keyword(s):  
G Protein ◽  
Magnetic Particles ◽  
Lipid Membrane ◽  
Specific Protein ◽  
G Protein Coupled Receptors ◽  
Native Conformation ◽  
Wide Range ◽  
Bacterial Magnetic Particles ◽  
Magnetospirillum Magneticum ◽  
G Protein Coupled

ABSTRACT G protein-coupled receptors (GPCRs) play a central role in a wide range of biological processes and are prime targets for drug discovery. GPCRs have large hydrophobic domains, and therefore purification of GPCRs from cells is frequently time-consuming and typically results in loss of native conformation. In this work, GPCRs have been successfully assembled into the lipid membrane of nanosized bacterial magnetic particles (BMPs) produced by the magnetic bacterium Magnetospirillum magneticum AMB-1. A BMP-specific protein, Mms16, was used as an anchor molecule, and localization of heterologous Mms16 on BMPs was confirmed by luciferase fusion studies. Stable luminescence was obtained from BMPs bearing Mms16 fused with luciferase at the C-terminal region. D1 dopamine receptor (D1R), a GPCR, was also efficiently assembled onto BMPs by using Mms16 as an anchor molecule. D1R-BMP complexes were simply extracted by magnetic separation from ruptured AMB-1 transformants. After washing, the complexes were ready to use for analysis. This system conveniently refines the native conformation of GPCRs without the need for detergent solubilization, purification, and reconstitution after cell disruption.

Arrestin-2 Regulates Akt Activation by G Protein-Coupled Receptors in Platelets.

Blood ◽  
2006 ◽  
Vol 108 (11) ◽  
pp. 1525-1525
Author(s):  
Dongjun Li ◽  
Donna S. Woulfe
Keyword(s):  
G Protein ◽  
Genetic Manipulation ◽  
Embryonic Stem ◽  
Phosphatidyl Inositol ◽  
G Protein Coupled Receptors ◽  
Resting Cells ◽  
Dependent Manner ◽  
Akt Phosphorylation ◽  
Receptor Sites ◽  
G Protein Coupled

Abstract Arrestins have been shown to play important roles in G Protein-Coupled Receptor (GPCR) function in many cells, but their roles in platelets remain uncharacterized. While the classical role of arrestins is considered to be the internalization and desensitization of GPCRs, more recent studies suggest that arrestins can serve as scaffolds to recruit phosphatidyl inositol-3 kinases (PI3K)s to Gq-coupled receptors and promote PI3K-dependent signaling. Thrombin stimulates the PI3K-dependent activation of Akt in platelets in a Gq-dependent manner. Therefore, we sought to determine whether arrestins are involved in the PI3K-dependent activation of Akt in platelets. Comparative immunoblots show that of the two non-visual mammalian arrestins, only one, arrestin-2 (β-arrestin-1), is expressed in human and mouse platelets. Immunoprecipitation of arrestin-2 or p85-PI3K from platelet lysates demonstrated that arrestin-2 associates with the p85 subunit of PI3Ka/b in thrombin or ADP-stimulated platelets, but not resting cells. The association can be inhibited by inhibitors of the P2Y12 receptor for ADP, but not by P2Y1 inhibitors. p85-arrestin association is also blocked by inhibitors of src family kinases, as is Akt phosphorylation. To determine whether src family members were part of the p85-arrestin complexes, immunoblots were re-probed with antibodies to src, lyn and fyn. The results show that Lyn is incorporated into thrombin-stimulated arrestin complexes in a P2Y12-dependent manner. To determine whether arrestin-2 is important for Akt phosphorylation in platelets, megakaryocytes differentiated in culture from mouse embryonic stem cells were used as models of platelet signaling, since these cells are amenable to genetic manipulation. Arrestin-2 was inhibited in the cultured megakaryocytes using a siRNA approach, then cells were stimulated with thrombin and Akt phosphorylation was assessed by immunoblotting. Arrestin-2 expression in the cultured megakaryocytes treated with arrestin-2 specific siRNA was suppressed by an average of 53% compared to cells treated with scrambled siRNA, while thrombin-stimulated Akt phosphorylation was suppressed by 98% compared to scrambled siRNA-treated control cells (n=3 experiments, difference is significant, p=.01, unpaired student’s t-test). In conclusion, the results show that arrestin-2, lyn and PI3Kform a tri-molecular complex following stimulation of platelets with ADP or thrombin. Formation of arrestin complexes at activated receptor sites is important for the localized recruitment and src-dependent activation of p85-PI3K, thus promoting activation of Akt by G protein-coupled receptors.

scholarly journals Methods used to study the oligomeric structure of G-protein-coupled receptors

2017 ◽  
Vol 37 (2) ◽  
Author(s):  
Hui Guo ◽  
Su An ◽  
Richard Ward ◽  
Yang Yang ◽  
Ying Liu ◽  
...  
Keyword(s):  
Energy Transfer ◽  
G Protein ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
G Protein Coupled Receptors ◽  
Experimental Techniques ◽  
Distribution Analysis ◽  
Wide Range ◽  
And Function ◽  
G Protein Coupled

G-protein-coupled receptors (GPCRs), which constitute the largest family of cell surface receptors, were originally thought to function as monomers, but are now recognized as being able to act in a wide range of oligomeric states and indeed, it is known that the oligomerization state of a GPCR can modulate its pharmacology and function. A number of experimental techniques have been devised to study GPCR oligomerization including those based upon traditional biochemistry such as blue-native PAGE (BN-PAGE), co-immunoprecipitation (Co-IP) and protein-fragment complementation assays (PCAs), those based upon resonance energy transfer, FRET, time-resolved FRET (TR-FRET), FRET spectrometry and bioluminescence resonance energy transfer (BRET). Those based upon microscopy such as FRAP, total internal reflection fluorescence microscopy (TIRFM), spatial intensity distribution analysis (SpIDA) and various single molecule imaging techniques. Finally with the solution of a growing number of crystal structures, X-ray crystallography must be acknowledged as an important source of discovery in this field. A different, but in many ways complementary approach to the use of more traditional experimental techniques, are those involving computational methods that possess obvious merit in the study of the dynamics of oligomer formation and function. Here, we summarize the latest developments that have been made in the methods used to study GPCR oligomerization and give an overview of their application.

Intracrine signaling through lipid mediators and their cognate nuclear G-protein-coupled receptors: a paradigm based on PGE2, PAF, and LPA1 receptorsThis paper is one of a selection of papers published in this Special Issue, entitled The Nucleus: A Cell Within A Cell.

2006 ◽  
Vol 84 (3-4) ◽  
pp. 377-391 ◽  
Author(s):  
Tang Zhu ◽  
Fernand Gobeil ◽  
Alejandro Vazquez-Tello ◽  
Martin Leduc ◽  
Lenka Rihakova ◽  
...  
Keyword(s):  
G Protein ◽  
Nuclear Localization ◽  
Platelet Activating Factor ◽  
Rat Hepatocytes ◽  
Lipid Mediators ◽  
G Protein Coupled Receptors ◽  
Membrane Receptors ◽  
Surface Receptors ◽  
A Cell ◽  
G Protein Coupled

Prostaglandins (PGs), platelet-activating factor (PAF), and lysophosphatidic acid (LPA) are ubiquitous lipid mediators that play important roles in inflammation, cardiovascular homeostasis, and immunity and are also known to modulate gene expression of specific pro-inflammatory genes. The mechanism of action of these lipids is thought to be primarily dependent on their specific plasma membrane receptors belonging to the superfamily of G-protein-coupled receptors (GPCR). Increasing evidence suggests the existence of a functional intracellular GPCR population. It has been proposed that immediate effects are mediated via cell surface receptors whereas long-term responses are dependent upon intracellular receptor effects. Indeed, receptors for PAF, LPA, and PGE2 (specifically EP1, EP3, and EP4) localize at the cell nucleus of cerebral microvascular endothelial cells of newborn pigs, rat hepatocytes, and cells overexpressing each receptor. Stimulation of isolated nuclei with these lipids reveals biological functions including transcriptional regulation of major genes, namely c-fos, cylooxygenase-2, and endothelial as well as inducible nitric oxide synthase. In the present review, we shall focus on the nuclear localization and signaling of GPCRs recognizing PGE2, PAF, and LPA phospholipids as ligands. Mechanisms on how nuclear PGE2, PAF, and LPA receptors activate gene transcription and nuclear localization pathways are presented. Intracrine signaling for lipid mediators uncover novel pathways to elicit their effects; accordingly, intracellular GPCRs constitute a distinctive mode of action for gene regulation.

scholarly journals The tyrosine phosphatase CD148 is an essential positive regulator of platelet activation and thrombosis

Blood ◽  
2009 ◽  
Vol 113 (20) ◽  
pp. 4942-4954 ◽  
Author(s):  
Yotis A. Senis ◽  
Michael G. Tomlinson ◽  
Stuart Ellison ◽  
Alexandra Mazharian ◽  
Jenson Lim ◽  
...  
Keyword(s):  
G Protein ◽  
Platelet Activation ◽  
Drug Target ◽  
Tyrosine Phosphatase ◽  
Underlying Mechanism ◽  
G Protein Coupled Receptors ◽  
Bleeding Tendency ◽  
Platelet Surface ◽  
Surface Receptors ◽  
G Protein Coupled

Abstract Platelets play a fundamental role in hemostasis and thrombosis. They are also involved in pathologic conditions resulting from blocked blood vessels, including myocardial infarction and ischemic stroke. Platelet adhesion, activation, and aggregation at sites of vascular injury are regulated by a diverse repertoire of tyrosine kinase–linked and G protein–coupled receptors. Src family kinases (SFKs) play a central role in initiating and propagating signaling from several platelet surface receptors; however, the underlying mechanism of how SFK activity is regulated in platelets remains unclear. CD148 is the only receptor-like protein tyrosine phosphatase identified in platelets to date. In the present study, we show that mutant mice lacking CD148 exhibited a bleeding tendency and defective arterial thrombosis. Basal SFK activity was found to be markedly reduced in CD148-deficient platelets, resulting in a global hyporesponsiveness to agonists that signal through SFKs, including collagen and fibrinogen. G protein–coupled receptor responses to thrombin and other agonists were also marginally reduced. These results highlight CD148 as a global regulator of platelet activation and a novel antithrombotic drug target.

scholarly journals Sphingosine 1-phosphate receptor 2 antagonist JTE-013 increases the excitability of sensory neurons independently of the receptor

2012 ◽  
Vol 108 (5) ◽  
pp. 1473-1483 ◽  
Author(s):  
Chao Li ◽  
Xian Xuan Chi ◽  
Wenrui Xie ◽  
J. A. Strong ◽  
J.-M. Zhang ◽  
...  
Keyword(s):  
G Protein ◽  
Sensory Neurons ◽  
Neuronal Excitability ◽  
Small Diameter ◽  
G Protein Coupled Receptors ◽  
Prostaglandin E ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Sphingosine 1 Phosphate ◽  
G Protein Coupled

Previously we demonstrated that sphingosine 1-phosphate receptor 1 (S1PR1) played a prominent, but not exclusive, role in enhancing the excitability of small-diameter sensory neurons, suggesting that other S1PRs can modulate neuronal excitability. To examine the potential role of S1PR2 in regulating neuronal excitability we used the established selective antagonist of S1PR2, JTE-013. Here we report that exposure to JTE-013 alone produced a significant increase in excitability in a time- and concentration-dependent manner in 70–80% of recorded neurons. Internal perfusion of sensory neurons with guanosine 5′- O-(2-thiodiphosphate) (GDP-β-S) via the recording pipette inhibited the sensitization produced by JTE-013 as well as prostaglandin E2. Pretreatment with pertussis toxin or the selective S1PR1 antagonist W146 blocked the sensitization produced by JTE-013. These results indicate that JTE-013 might act as an agonist at other G protein-coupled receptors. In neurons that were sensitized by JTE-013, single-cell RT-PCR studies demonstrated that these neurons did not express the mRNA for S1PR2. In behavioral studies, injection of JTE-013 into the rat's hindpaw produced a significant increase in the mechanical sensitivity in the ipsilateral, but not contralateral, paw. Injection of JTE-013 did not affect the withdrawal latency to thermal stimulation. Thus JTE-013 augments neuronal excitability independently of S1PR2 by unknown mechanisms that may involve activation of other G protein-coupled receptors such as S1PR1. Clearly, further studies are warranted to establish the causal nature of this increased sensitivity, and future studies of neuronal function using JTE-013 should be interpreted with caution.

scholarly journals Mechanisms of cross-talk between G-protein-coupled receptors resulting in enhanced release of intracellular Ca2+

2003 ◽  
Vol 374 (2) ◽  
pp. 281-296 ◽  
Author(s):  
Tim D. WERRY ◽  
Graeme F. WILKINSON ◽  
Gary B. WILLARS
Keyword(s):  
G Protein ◽  
Cross Talk ◽  
Cell Function ◽  
Feedback Regulation ◽  
G Protein Coupled Receptors ◽  
Negative Feedback Regulation ◽  
Cellular Processes ◽  
Heterologous Desensitization ◽  
G Protein Coupled

Alteration in [Ca2+]i (the intracellular concentration of Ca2+) is a key regulator of many cellular processes. To allow precise regulation of [Ca2+]i and a diversity of signalling by this ion, cells possess many mechanisms by which they are able to control [Ca2+]i both globally and at the subcellular level. Among these are many members of the superfamily of GPCRs (G-protein-coupled receptors), which are characterized by the presence of seven transmembrane domains. Typically, those receptors able to activate PLC (phospholipase C) enzymes cause release of Ca2+ from intracellular stores and influence Ca2+ entry across the plasma membrane. It has been well documented that Ca2+ signalling by one type of GPCR can be influenced by stimulation of a different type of GPCR. Indeed, many studies have demonstrated heterologous desensitization between two different PLC-coupled GPCRs. This is not surprising, given our current understanding of negative-feedback regulation and the likely shared components of the signalling pathway. However, there are also many documented examples of interactions between GPCRs, often coupling preferentially to different signalling pathways, which result in a potentiation of Ca2+ signalling. Such interactions have important implications for both the control of cell function and the interpretation of in vitro cell-based assays. However, there is currently no single mechanism that adequately accounts for all examples of this type of cross-talk. Indeed, many studies either have not addressed this issue or have been unable to determine the mechanism(s) involved. This review seeks to explore a range of possible mechanisms to convey their potential diversity and to provide a basis for further experimental investigation.

scholarly journals Targeting islet G-protein-coupled receptors for type 2 diabetes therapy

2021 ◽  
Author(s):  
Shanta J. Persaud ◽  
Oladapo E. Olaniru ◽  
Patricio Atanes
Keyword(s):  
Type 2 Diabetes ◽  
G Protein ◽  
G Protein Coupled Receptors ◽  
Pharmaceutical Companies ◽  
Β Cells ◽  
Diabetes Therapy ◽  
Wide Range ◽  
Mass Expansion ◽  
G Protein Coupled

The majority of people with diabetes have type 2 diabetes (T2D), where hyperglycaemia occurs because the islet β-cells are unable to secrete enough insulin, usually in the context of insulin resistance that arises because of fat mass expansion. There are a range of pharmacotherapies in current use to treat T2D and pharmaceutical companies are actively engaged in the development of novel therapies for better glucose control. Ligands that target G-protein-coupled receptors (GPCRs) are obvious candidates because they are used successfully for a wide range of disorders and GLP-1 receptor agonists, which are a relatively recent class of diabetes therapy, have proved to be very effective in treating T2D. We provide here an overview of current successes, some drawbacks and future possibilities for GPCR-based T2D therapies.

scholarly journals G-protein-coupled receptors regulate autophagy by ZBTB16-mediated ubiquitination and proteasomal degradation of Atg14L

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Tao Zhang ◽  
Kangyun Dong ◽  
Wei Liang ◽  
Daichao Xu ◽  
Hongguang Xia ◽  
...  
Keyword(s):  
Mouse Model ◽  
Neurodegenerative Diseases ◽  
G Protein ◽  
Ubiquitin Ligase ◽  
E3 Ubiquitin Ligase ◽  
G Protein Coupled Receptors ◽  
Misfolded Proteins ◽  
Ubiquitin Ligase Complex ◽  
Wide Range ◽  
G Protein Coupled

Autophagy is an important intracellular catabolic mechanism involved in the removal of misfolded proteins. Atg14L, the mammalian ortholog of Atg14 in yeast and a critical regulator of autophagy, mediates the production PtdIns3P to initiate the formation of autophagosomes. However, it is not clear how Atg14L is regulated. In this study, we demonstrate that ubiquitination and degradation of Atg14L is controlled by ZBTB16-Cullin3-Roc1 E3 ubiquitin ligase complex. Furthermore, we show that a wide range of G-protein-coupled receptor (GPCR) ligands and agonists regulate the levels of Atg14L through ZBTB16. In addition, we show that the activation of autophagy by pharmacological inhibition of GPCR reduces the accumulation of misfolded proteins and protects against behavior dysfunction in a mouse model of Huntington's disease. Our study demonstrates a common molecular mechanism by which the activation of GPCRs leads to the suppression of autophagy and a pharmacological strategy to activate autophagy in the CNS for the treatment of neurodegenerative diseases.

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