301
|
Wang B, Means CK, Yang Y, Mamonova T, Bisello A, Altschuler DL, Scott JD, Friedman PA. Ezrin-anchored protein kinase A coordinates phosphorylation-dependent disassembly of a NHERF1 ternary complex to regulate hormone-sensitive phosphate transport. J Biol Chem 2012; 287:24148-63. [PMID: 22628548 PMCID: PMC3397842 DOI: 10.1074/jbc.m112.369405] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 05/19/2012] [Indexed: 12/14/2022] Open
Abstract
Congenital defects in the Na/H exchanger regulatory factor-1 (NHERF1) are linked to disordered phosphate homeostasis and skeletal abnormalities in humans. In the kidney, these mutations interrupt parathyroid hormone (PTH)-responsive sequestration of the renal phosphate transporter, Npt2a, with ensuing urinary phosphate wasting. We now report that NHERF1, a modular PDZ domain scaffolding protein, coordinates the assembly of an obligate ternary complex with Npt2a and the PKA-anchoring protein ezrin to facilitate PTH-responsive cAMP signaling events. Activation of ezrin-anchored PKA initiates NHERF1 phosphorylation to disassemble the ternary complex, release Npt2a, and thereby inhibit phosphate transport. Loss-of-function mutations stabilize an inactive NHERF1 conformation that we show is refractory to PKA phosphorylation and impairs assembly of the ternary complex. Compensatory mutations introduced in mutant NHERF1 re-establish the integrity of the ternary complex to permit phosphorylation of NHERF1 and rescue PTH action. These findings offer new insights into a novel macromolecular mechanism for the physiological action of a critical ternary complex, where anchored PKA coordinates the assembly and turnover of the Npt2a-NHERF1-ezrin complex.
Collapse
Affiliation(s)
- Bin Wang
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - Chris K. Means
- the Howard Hughes Medical Institute, Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195
| | - Yanmei Yang
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - Tatyana Mamonova
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - Alessandro Bisello
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - Daniel L. Altschuler
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| | - John D. Scott
- the Howard Hughes Medical Institute, Department of Pharmacology, University of Washington School of Medicine, Seattle, Washington 98195
| | - Peter A. Friedman
- From the Laboratory for G Protein-coupled Receptor Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261 and
| |
Collapse
|
302
|
Abstract
PAQR10 (progestin and adipoQ receptor 10) is a Golgi-localized protein that is able to enhance the retention and activation of Ras proteins in the Golgi apparatus, subsequently leading to a sustained ERK (extracellular-signal-regulated kinase) signalling. However, little is known about the topology and functional domains of PAQR10. In the present study, we extensively dissected and analysed the structure of PAQR10. The topology analysis reveals that PAQR10 is an integral membrane protein with its N-terminus facing the cytosol. Multiple domains, including the membrane-proximal region at the N-terminus, the membrane-proximal region at the C-terminus and the three loops facing the cytosol, were found to be required for PAQR10 to reside in the Golgi apparatus, to stimulate ERK phosphorylation and to tether Ras to the Golgi apparatus. Furthermore, when PAQR10 was artificially forced to be expressed in the endoplasmic reticulum, it could neither mobilize Ras to the Golgi apparatus nor increase ERK phosphorylation. Finally, the PAQR10 mutants that lost Golgi localization failed to promote differentiation of PC12 cells. Collectively, the results of the present study indicate that Golgi localization is indispensable for PAQR10 to implement its regulatory functions in the Ras signalling cascade.
Collapse
|
303
|
Denis C, Saulière A, Galandrin S, Sénard JM, Galés C. Probing heterotrimeric G protein activation: applications to biased ligands. Curr Pharm Des 2012; 18:128-44. [PMID: 22229559 DOI: 10.2174/138161212799040466] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2011] [Accepted: 11/09/2011] [Indexed: 12/17/2022]
Abstract
Cell surface G protein-coupled receptors (GPCRs) drive numerous signaling pathways involved in the regulation of a broad range of physiologic processes. Today, they represent the largest target for modern drugs development with potential application in all clinical fields. Recently, the concept of "ligand-directed trafficking" has led to a conceptual revolution in pharmacological theory, thus opening new avenues for drug discovery. Accordingly, GPCRs do not function as simple on-off switch but rather as filters capable of selecting the activation of specific signals and thus generating texture responses to ligands, a phenomenon often referred to as ligand-biased signaling. Also, one challenging task today remains optimization of pharmacological assays with increased sensitivity so to better appreciate the inherent texture of ligands. However, considering that a single receptor has pleiotropic signaling properties and that each signal can crosstalk at different levels, biased activity remains thus difficult to evaluate. One strategy to overcome these limitations would be examining the initial steps following receptor activation. Even, if some G protein independent functions have been recently described, heterotrimeric G protein activation remains a general hallmark for all GPCRs families and the first cellular event subsequent to agonist binding to the receptor. Herein, we review the different methodologies classically used or recently developed to monitor G protein activation and discussed them in the context of G protein biased-ligands.
Collapse
Affiliation(s)
- Colette Denis
- Institut des Maladies Métaboliques et Cardiovasculaires, Université Toulouse III Paul Sabatier, Centre Hospitalier Universitaire de Toulouse, France.
| | | | | | | | | |
Collapse
|
304
|
Navarro G, Hradsky J, Lluís C, Casadó V, McCormick PJ, Kreutz MR, Mikhaylova M. NCS-1 associates with adenosine A(2A) receptors and modulates receptor function. Front Mol Neurosci 2012; 5:53. [PMID: 22529776 PMCID: PMC3328853 DOI: 10.3389/fnmol.2012.00053] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Accepted: 04/02/2012] [Indexed: 11/13/2022] Open
Abstract
Modulation of G protein-coupled receptor (GPCR) signaling by local changes in intracellular calcium concentration is an established function of Calmodulin (CaM) which is known to interact with many GPCRs. Less is known about the functional role of the closely related neuronal EF-hand Ca2+-sensor proteins that frequently associate with CaM targets with different functional outcome. In the present study we aimed to investigate if a target of CaM—the A2A adenosine receptor is able to associate with two other neuronal calcium binding proteins (nCaBPs), namely NCS-1 and caldendrin. Using bioluminescence resonance energy transfer (BRET) and co-immunoprecipitation experiments we show the existence of A2A—NCS-1 complexes in living cells whereas caldendrin did not associate with A2A receptors under the conditions tested. Interestingly, NCS-1 binding modulated downstream A2A receptor intracellular signaling in a Ca2+-dependent manner. Taken together this study provides further evidence that neuronal Ca2+-sensor proteins play an important role in modulation of GPCR signaling.
Collapse
Affiliation(s)
- Gemma Navarro
- Faculty of Biology, Centro de Investigación Biomédica en Red Sobre Enfermedades Neurodegenerativas and Department of Biochemistry and Molecular Biology, University of Barcelona Barcelona, Spain
| | | | | | | | | | | | | |
Collapse
|
305
|
Neurabin scaffolding of adenosine receptor and RGS4 regulates anti-seizure effect of endogenous adenosine. J Neurosci 2012; 32:2683-95. [PMID: 22357852 DOI: 10.1523/jneurosci.4125-11.2011] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Endogenous adenosine is an essential protective agent against neural damage by various insults to the brain. However, the therapeutic potential of adenosine receptor-directed ligands for neuroprotection is offset by side effects in peripheral tissues and organs. An increase in adenosine receptor responsiveness to endogenous adenosine would enhance neuroprotection while avoiding the confounding effects of exogenous ligands. Here we report novel regulation of adenosine-evoked responses by a neural tissue-specific protein, neurabin. Neurabin attenuated adenosine A(1) receptor (A1R) signaling by assembling a complex between the A1R and the regulator of G-protein signaling 4 (RGS4), a protein known to turn off G-protein signaling. Inactivation of the neurabin gene enhanced A1R signaling and promoted the protective effect of adenosine against excitotoxic seizure and neuronal death in mice. Furthermore, administration of a small molecule inhibitor of RGS4 significantly attenuated seizure severity in mice. Notably, the dose of kainate capable of inducing an ∼50% rate of death in wild-type (WT) mice did not affect neurabin-null mice or WT mice cotreated with an RGS4 inhibitor. The enhanced anti-seizure and neuroprotective effect achieved by disruption of the A1R/neurabin/RGS4 complex is elicited by the on-site and on-demand release of endogenous adenosine, and does not require administration of A1R ligands. These data identify neurabin-RGS4 as a novel tissue-selective regulatory mechanism for fine-tuning adenosine receptor function in the nervous system. Moreover, these findings implicate the A1R/neurabin/RGS4 complex as a valid therapeutic target for specifically manipulating the neuroprotective effects of endogenous adenosine.
Collapse
|
306
|
Kukkonen JP. International symposium on G-protein-coupled receptors (GPCRs), TRP (ion) channels and lipid signalling - GPCR-Helsinki 2010. Acta Physiol (Oxf) 2012; 204:148-50. [PMID: 22222216 DOI: 10.1111/j.1748-1716.2011.02393.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
|
307
|
Bruno A, Costantino G. Molecular Dynamics Simulations of G Protein-Coupled Receptors. Mol Inform 2012; 31:222-30. [DOI: 10.1002/minf.201100138] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2011] [Accepted: 12/18/2011] [Indexed: 12/14/2022]
|
308
|
Abstract
Ingestion of a meal triggers a range of physiological responses both within and outside the gut, and results in the remote modulation of appetite and glucose homeostasis. Luminal contents are sensed by specialised chemosensitive cells scattered throughout the intestinal epithelium. These enteroendocrine and tuft cells make direct contact with the gut lumen and release a range of chemical mediators, which can either act in a paracrine fashion interacting with neighbouring cells and nerve endings or as classical circulating hormones. At the molecular level, the chemosensory machinery involves multiple and complex signalling pathways including activation of G-protein-coupled receptors and solute carrier transporters. This chapter will discuss our current knowledge of the molecular mechanisms underlying intestinal chemosensation with a particular focus on the relatively well-characterised nutrient-triggered secretion from the enteroendocrine system.
Collapse
Affiliation(s)
- Gwen Tolhurst
- Cambridge Institute for Medical Research, Wellcome Trust/MRC Building, Addenbrooke's Hospital, Hills Road, Cambridge, CB2 0XY, UK
| | | | | |
Collapse
|
309
|
Li X, Lynn BD, Nagy JI. The effector and scaffolding proteins AF6 and MUPP1 interact with connexin36 and localize at gap junctions that form electrical synapses in rodent brain. Eur J Neurosci 2012; 35:166-81. [PMID: 22211808 DOI: 10.1111/j.1460-9568.2011.07947.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Electrical synapses formed by neuronal gap junctions composed of connexin36 (Cx36) occur in most major structures in the mammalian central nervous system. These synapses link ensembles of neurons and influence their network properties. Little is known about the macromolecular constituents of neuronal gap junctions or how transmission through electrical synapses is regulated at the level of channel conductance or gap junction assembly/disassembly. Such knowledge is a prerequisite to understanding the roles of gap junctions in neuronal circuitry. Gap junctions share similarities with tight and adhesion junctions in that all three reside at close plasma membrane appositions, and therefore may associate with similar structural and regulatory proteins. Previously, we reported that the tight junction-associated protein zonula occludens-1 (ZO-1) interacts with Cx36 and is localized at gap junctions. Here, we demonstrate that two proteins known to be associated with tight and adherens junctions, namely AF6 and MUPP1, are components of neuronal gap junctions in rodent brain. By immunofluorescence, AF6 and MUPP1 were co-localized with Cx36 in many brain areas. Co-immunoprecipitation and pull-down approaches revealed an association of Cx36 with AF6 and MUPP1, which required the C-terminus PDZ domain interaction motif of Cx36 for interaction with the single PDZ domain of AF6 and with the 10th PDZ domain of MUPP1. As AF6 is a target of the cAMP/Epac/Rap1 signalling pathway and MUPP1 is a scaffolding protein that interacts with CaMKII, the present results suggest that AF6 may be a target for cAMP/Epac/Rap1 signalling at electrical synapses, and that MUPP1 may contribute to anchoring CaMKII at these synapses.
Collapse
Affiliation(s)
- X Li
- Department of Physiology, Faculty of Medicine, University of Manitoba, 745 Bannatyne Ave., Winnipeg, Manitoba, Canada
| | | | | |
Collapse
|
310
|
Frooninckx L, Van Rompay L, Temmerman L, Van Sinay E, Beets I, Janssen T, Husson SJ, Schoofs L. Neuropeptide GPCRs in C. elegans. Front Endocrinol (Lausanne) 2012; 3:167. [PMID: 23267347 PMCID: PMC3527849 DOI: 10.3389/fendo.2012.00167] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Accepted: 12/04/2012] [Indexed: 12/19/2022] Open
Abstract
Like most organisms, the nematode Caenorhabditis elegans relies heavily on neuropeptidergic signaling. This tiny animal represents a suitable model system to study neuropeptidergic signaling networks with single cell resolution due to the availability of powerful molecular and genetic tools. The availability of the worm's complete genome sequence allows researchers to browse through it, uncovering putative neuropeptides and their cognate G protein-coupled receptors (GPCRs). Many predictions have been made about the number of C. elegans neuropeptide GPCRs. In this review, we report the state of the art of both verified as well as predicted C. elegans neuropeptide GPCRs. The predicted neuropeptide GPCRs are incorporated into the receptor classification system based on their resemblance to orthologous GPCRs in insects and vertebrates. Appointing the natural ligand(s) to each predicted neuropeptide GPCR (receptor deorphanization) is a crucial step during characterization. The development of deorphanization strategies resulted in a significant increase in the knowledge of neuropeptidergic signaling in C. elegans. Complementary localization and functional studies demonstrate that neuropeptides and their GPCRs represent a rich potential source of behavioral variability in C. elegans. Here, we review all neuropeptidergic signaling pathways that so far have been functionally characterized in C. elegans.
Collapse
Affiliation(s)
- Lotte Frooninckx
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Liesbeth Van Rompay
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Liesbet Temmerman
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Elien Van Sinay
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Isabel Beets
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Tom Janssen
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Steven J. Husson
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
| | - Liliane Schoofs
- Laboratory of Functional Genomics and Proteomics, Department of Biology, Katholieke Universiteit LeuvenLeuven, Belgium
- *Correspondence: Liliane Schoofs, Laboratory of Functional Genomics and Proteomics, Zoological Institute, Naamsestraat 59, 3000 Leuven, Belgium. e-mail:
| |
Collapse
|
311
|
Abstract
INTRODUCTION Although endomorphins-1 (EM-1; H-Tyr-Pro-Phe-Trp-NH(2)) and -2 (EM-2; H-Tyr-Pro-Phe-Phe-NH(2)) are primarily considered agonists for the μ-opioid receptor (MOR), systematic alterations to specific residues provided antagonists and ligands with mixed μ/δ-opioid properties, suitable for application to health-related topics. While the application of endomorphins as antinociceptive agents and numerous biological endpoints were experimentally delineated in laboratory animals and in vitro, clinical use is currently absent. However, structural alterations provide enhanced stability; formation of MOR antagonists or mixed and dual μ/δ-acting ligands could find considerable therapeutic potential. AREAS COVERED This review attempts to succinctly provide insight on the development and bioactivity of endomorphin analogues during the past decade. Rational design approaches will focus on the engineering of endomorphin agonists, antagonists and mixed ligands for their application as a multi-target ligand. EXPERT OPINION Aside from alleviating pain, EM analogues open new horizons in the treatment of medical syndromes involving neural reward mechanisms and extraneural regulation effects on homeostasis. Highly selective MOR antagonists may be promising to reduce inflammation, attenuate addiction to drugs and excess consumption of high-caloric food, ameliorate alcoholism, affect the immune system and combat opioid bowel dysfunction.
Collapse
Affiliation(s)
- Lawrence H Lazarus
- National Institute of Environmental Health Sciences, Laboratory of Toxicology and Pharmacology, 111 South TW Alexander Drive, Research Triangle Park, NC 27709, USA.
| | | |
Collapse
|
312
|
Hazell GG, Hindmarch CC, Pope GR, Roper JA, Lightman SL, Murphy D, O’Carroll AM, Lolait SJ. G protein-coupled receptors in the hypothalamic paraventricular and supraoptic nuclei--serpentine gateways to neuroendocrine homeostasis. Front Neuroendocrinol 2012; 33:45-66. [PMID: 21802439 PMCID: PMC3336209 DOI: 10.1016/j.yfrne.2011.07.002] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/23/2011] [Revised: 06/24/2011] [Accepted: 07/06/2011] [Indexed: 12/31/2022]
Abstract
G protein-coupled receptors (GPCRs) are the largest family of transmembrane receptors in the mammalian genome. They are activated by a multitude of different ligands that elicit rapid intracellular responses to regulate cell function. Unsurprisingly, a large proportion of therapeutic agents target these receptors. The paraventricular nucleus (PVN) and supraoptic nucleus (SON) of the hypothalamus are important mediators in homeostatic control. Many modulators of PVN/SON activity, including neurotransmitters and hormones act via GPCRs--in fact over 100 non-chemosensory GPCRs have been detected in either the PVN or SON. This review provides a comprehensive summary of the expression of GPCRs within the PVN/SON, including data from recent transcriptomic studies that potentially expand the repertoire of GPCRs that may have functional roles in these hypothalamic nuclei. We also present some aspects of the regulation and known roles of GPCRs in PVN/SON, which are likely complemented by the activity of 'orphan' GPCRs.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | - Stephen J. Lolait
- Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Dorothy Hodgkin Building, School of Clinical Sciences, University of Bristol, Whitson Street, Bristol BS1 3NY, UK
| |
Collapse
|
313
|
A switch of G protein-coupled receptor binding preference from phosphoinositide 3-kinase (PI3K)-p85 to filamin A negatively controls the PI3K pathway. Mol Cell Biol 2011; 32:1004-16. [PMID: 22203038 DOI: 10.1128/mcb.06252-11] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Frequent oncogenic alterations occur in the phosphoinositide 3-kinase (PI3K) pathway, urging identification of novel negative controls. We previously reported an original mechanism for restraining PI3K activity, controlled by the somatostatin G protein-coupled receptor (GPCR) sst2 and involving a ligand-regulated interaction between sst2 with the PI3K regulatory p85 subunit. We here identify the scaffolding protein filamin A (FLNA) as a critical player regulating the dynamic of this complex. A preexisting sst2-p85 complex, which was shown to account for a significant basal PI3K activity in the absence of ligand, is disrupted upon sst2 activation. FLNA was here identified as a competitor of p85 for direct binding to two juxtaposed sites on sst2. Switching of GPCR binding preference from p85 toward FLNA is determined by changes in the tyrosine phosphorylation of p85- and FLNA-binding sites on sst2 upon activation. It results in the disruption of the sst2-p85 complex and the subsequent inhibition of PI3K. Knocking down FLNA expression, or abrogating FLNA recruitment to sst2, reversed the inhibition of PI3K and of tumor growth induced by sst2. Importantly, we report that this FLNA inhibitory control on PI3K can be generalized to another GPCR, the mu opioid receptor, thereby providing an unprecedented mechanism underlying GPCR-negative control on PI3K.
Collapse
|
314
|
Fanelli F, De Benedetti PG. Update 1 of: computational modeling approaches to structure-function analysis of G protein-coupled receptors. Chem Rev 2011; 111:PR438-535. [PMID: 22165845 DOI: 10.1021/cr100437t] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Francesca Fanelli
- Dulbecco Telethon Institute, University of Modena and Reggio Emilia, via Campi 183, 41125 Modena, Italy.
| | | |
Collapse
|
315
|
Delta opioid receptor analgesia: recent contributions from pharmacology and molecular approaches. Behav Pharmacol 2011; 22:405-14. [PMID: 21836459 DOI: 10.1097/fbp.0b013e32834a1f2c] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Delta opioid receptors represent a promising target for the development of novel analgesics. A number of tools have been developed recently that have significantly improved our knowledge of δ receptor function in pain control. These include several novel δ agonists with potent analgesic properties, and genetic mouse models with targeted mutations in the δ opioid receptor gene. Also, recent findings have further documented the regulation of δ receptor function at cellular level, which impacts on the pain-reducing activity of the receptor. These regulatory mechanisms occur at transcriptional and post-translational levels, along agonist-induced receptor activation, signaling and trafficking, or in interaction with other receptors and neuromodulatory systems. All these tools for in-vivo research, and proposed mechanisms at molecular level, have tremendously increased our understanding of δ receptor physiology, and contribute to designing innovative strategies for the treatment of chronic pain and other diseases such as mood disorders.
Collapse
|
316
|
Yu PC, Du JL. Transient receptor potential canonical channels in angiogenesis and axon guidance. Cell Mol Life Sci 2011; 68:3815-21. [PMID: 21755360 PMCID: PMC11114694 DOI: 10.1007/s00018-011-0755-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2011] [Revised: 06/09/2011] [Accepted: 06/14/2011] [Indexed: 12/19/2022]
Abstract
Wiring of vascular and neural networks requires precise guidance of growing blood vessels and axons, respectively, to reach their targets during development. Both of the processes share common molecular signaling pathways. Transient receptor potential canonical (TRPC) channels are calcium-permeable cation channels and gated via receptor- or store-operated mechanisms. Recent studies have revealed the requirement of TRPC channels in mediating guidance cue-induced calcium influx and their essential roles in regulating axon navigation and angiogenesis. Dissecting TRPC functions in these physiological processes may provide therapeutic implications for suppressing pathological angiogenesis and improving nerve regeneration.
Collapse
Affiliation(s)
- Peng-chun Yu
- State Key Laboratory of Neuroscience, Institute of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue–Yang Road, Shanghai, 200031 China
| | - Jiu-lin Du
- State Key Laboratory of Neuroscience, Institute of Neuroscience, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 320 Yue–Yang Road, Shanghai, 200031 China
| |
Collapse
|
317
|
Katritch V, Cherezov V, Stevens RC. Diversity and modularity of G protein-coupled receptor structures. Trends Pharmacol Sci 2011; 33:17-27. [PMID: 22032986 DOI: 10.1016/j.tips.2011.09.003] [Citation(s) in RCA: 337] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2011] [Revised: 09/19/2011] [Accepted: 09/19/2011] [Indexed: 01/21/2023]
Abstract
G protein-coupled receptors (GPCRs) comprise the most 'prolific' family of cell membrane proteins, which share a general mechanism of signal transduction, but greatly vary in ligand recognition and function. Crystal structures are now available for rhodopsin, adrenergic, and adenosine receptors in both inactive and activated forms, as well as for chemokine, dopamine, and histamine receptors in inactive conformations. Here we review common structural features, outline the scope of structural diversity of GPCRs at different levels of homology, and briefly discuss the impact of the structures on drug discovery. Given the current set of GPCR crystal structures, a distinct modularity is now being observed between the extracellular (ligand-binding) and intracellular (signaling) regions. The rapidly expanding repertoire of GPCR structures provides a solid framework for experimental and molecular modeling studies, and helps to chart a roadmap for comprehensive structural coverage of the whole superfamily and an understanding of GPCR biological and therapeutic mechanisms.
Collapse
Affiliation(s)
- Vsevolod Katritch
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | | | | |
Collapse
|
318
|
Polter AM, Li X. Glycogen Synthase Kinase-3 is an Intermediate Modulator of Serotonin Neurotransmission. Front Mol Neurosci 2011; 4:31. [PMID: 22028682 PMCID: PMC3199786 DOI: 10.3389/fnmol.2011.00031] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2011] [Accepted: 09/28/2011] [Indexed: 01/22/2023] Open
Abstract
Serotonin is a neurotransmitter with broad functions in brain development, neuronal activity, and behaviors; and serotonin is the prominent drug target in several major neuropsychiatric diseases. The multiple actions of serotonin are mediated by diverse serotonin receptor subtypes and associated signaling pathways. However, the key signaling components that mediate specific function of serotonin neurotransmission have not been fully identified. This review will provide evidence from biochemical, pharmacological, and animal behavioral studies showing that serotonin regulates the activation states of brain glycogen synthase kinase-3 (GSK3) via type 1 and type 2 serotonin receptors. In return, GSK3 directly interacts with serotonin receptors in a highly selective manner, with a prominent effect on modulating serotonin 1B receptor activity. Therefore, GSK3 acts as an intermediate modulator in the serotonin neurotransmission system, and balanced GSK3 activity is essential for serotonin-regulated brain function and behaviors. Particularly important, several classes of serotonin-modulating drugs, such as antidepressants and atypical antipsychotics, regulate GSK3 by inhibiting its activity in brain, which reinforces the importance of GSK3 as a potential therapeutic target in neuropsychiatric diseases associated with abnormal serotonin function.
Collapse
Affiliation(s)
- Abigail M Polter
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham Birmingham, AL, USA
| | | |
Collapse
|
319
|
Duguay D, Bélanger-Nelson E, Mongrain V, Beben A, Khatchadourian A, Cermakian N. Dynein light chain Tctex-type 1 modulates orexin signaling through its interaction with orexin 1 receptor. PLoS One 2011; 6:e26430. [PMID: 22028875 PMCID: PMC3197643 DOI: 10.1371/journal.pone.0026430] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2011] [Accepted: 09/27/2011] [Indexed: 11/19/2022] Open
Abstract
Orexins (OX-A, OX-B) are neuropeptides involved in the regulation of the sleep-wake cycle, feeding and reward, via activation of orexin receptors 1 and 2 (OX1R, OX2R). The loss of orexin peptides or functional OX2R has been shown to cause the sleep disorder, narcolepsy. Since the regulation of orexin receptors remains largely undefined, we searched for novel protein partners of the intracellular tail of orexin receptors. Using a yeast two-hybrid screening strategy in combination with co-immunoprecipitation experiments, we found interactions between OX1R and the dynein light chains Tctex-type 1 and 3 (Dynlt1, Dynlt3). These interactions were mapped to the C-terminal region of the dynein light chains and to specific residues within the last 10 amino acids of OX1R. Hence, we hypothesized that dynein light chains could regulate orexin signaling. In HEK293 cells expressing OX1R, stimulation with OX-A produced a less sustained extracellular signal-regulated kinases 1/2 (ERK1/2) activation when Dynlt1 was co-expressed, while it was prolonged under reduced Dynlt1 expression. The amount of OX1R located at the plasma membrane as well as the kinetics and extent of OX-A-induced internalization of OX1R (disappearance from membrane) were not altered by Dynlt1. However, Dynlt1 reduced the localization of OX1R in early endosomes following initial internalization. Taken together, these data suggest that Dynlt1 modulates orexin signaling by regulating OX1R, namely its intracellular localization following ligand-induced internalization.
Collapse
Affiliation(s)
- David Duguay
- Laboratory of Molecular Chronobiology, Douglas Mental Health University Institute, Montréal, Quebec, Canada
- Department of Psychiatry, McGill University, Montréal, Quebec, Canada
| | - Erika Bélanger-Nelson
- Laboratory of Molecular Chronobiology, Douglas Mental Health University Institute, Montréal, Quebec, Canada
- Department of Neurology and Neurosurgery, McGill University, Montréal, Quebec, Canada
| | - Valérie Mongrain
- Laboratory of Molecular Chronobiology, Douglas Mental Health University Institute, Montréal, Quebec, Canada
- Department of Psychiatry, McGill University, Montréal, Quebec, Canada
| | - Anna Beben
- Laboratory of Molecular Chronobiology, Douglas Mental Health University Institute, Montréal, Quebec, Canada
| | - Armen Khatchadourian
- Laboratory of Molecular Chronobiology, Douglas Mental Health University Institute, Montréal, Quebec, Canada
| | - Nicolas Cermakian
- Laboratory of Molecular Chronobiology, Douglas Mental Health University Institute, Montréal, Quebec, Canada
- Department of Psychiatry, McGill University, Montréal, Quebec, Canada
- Department of Neurology and Neurosurgery, McGill University, Montréal, Quebec, Canada
| |
Collapse
|
320
|
Lachance V, Cartier A, Génier S, Munger S, Germain P, Labrecque P, Parent JL. Regulation of β2-adrenergic receptor maturation and anterograde trafficking by an interaction with Rab geranylgeranyltransferase: modulation of Rab geranylgeranylation by the receptor. J Biol Chem 2011; 286:40802-13. [PMID: 21990357 DOI: 10.1074/jbc.m111.267815] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Previous reports by us and others demonstrated that G protein-coupled receptors interact functionally with Rab GTPases. Here, we show that the β(2)-adrenergic receptor (β(2)AR) interacts with the Rab geranylgeranyltransferase α-subunit (RGGTA). Confocal microscopy showed that β(2)AR co-localizes with RGGTA in intracellular compartments and at the plasma membrane. Site-directed mutagenesis revealed that RGGTA binds to the L(339)L(340) motif in the β(2)AR C terminus known to be involved in the transport of the receptor from the endoplasmic reticulum to the cell surface. Modulation of the cellular levels of RGGTA protein by overexpression or siRNA-mediated knockdown of the endogenous protein demonstrated that RGGTA has a positive role in the maturation and anterograde trafficking of the β(2)AR, which requires the interaction of RGGTA with the β(2)AR L(339)L(340) motif. Furthermore, the β(2)AR modulates the geranylgeranylation of Rab6a, Rab8a, and Rab11a, but not of other Rab proteins tested in this study. Regulation of Rab geranylgeranylation by the β(2)AR was dependent on the RGGTA-interacting L(339)L(340) motif. Interestingly, a RGGTA-Y107F mutant was unable to regulate Rab geranylgeranylation but still promoted β(2)AR maturation, suggesting that RGGTA may have functions independent of Rab geranylgeranylation. We demonstrate for the first time an interaction between a transmembrane receptor and RGGTA which regulates the maturation and anterograde transport of the receptor, as well as geranylgeranylation of Rab GTPases.
Collapse
Affiliation(s)
- Véronik Lachance
- Service de Rhumatologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, the Centre de Recherche Clinique Étienne-Le Bel, and the Institut de Pharmacologie de Sherbrooke, Sherbrooke, Québec, Canada J1H 5N4
| | | | | | | | | | | | | |
Collapse
|
321
|
Cartier A, Parent A, Labrecque P, Laroche G, Parent JL. WDR36 acts as a scaffold protein tethering a G-protein-coupled receptor, Gαq and phospholipase Cβ in a signalling complex. J Cell Sci 2011; 124:3292-304. [DOI: 10.1242/jcs.085795] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We identified the WD-repeat-containing protein, WDR36, as an interacting partner of the β isoform of thromboxane A2 receptor (TPβ) by yeast two-hybrid screening. We demonstrated that WDR36 directly interacts with the C-terminus and the first intracellular loop of TPβ by in vitro GST-pulldown assays. The interaction in a cellular context was observed by co-immunoprecipitation, which was positively affected by TPβ stimulation. TPβ–WDR36 colocalization was detected by confocal microscopy at the plasma membrane in non-stimulated HEK293 cells but the complex translocated to intracellular vesicles following receptor stimulation. Coexpression of WDR36 and its siRNA-mediated knockdown, respectively, increased and inhibited TPβ-induced Gαq signalling. Interestingly, WDR36 co-immunoprecipitated with Gαq, and promoted TPβ–Gαq interaction. WDR36 also associated with phospholipase Cβ (PLCβ) and increased the interaction between Gαq and PLCβ, but prevented sequestration of activated Gαq by GRK2. In addition, the presence of TPβ in PLCβ immunoprecipitates was augmented by expression of WDR36. Finally, disease-associated variants of WDR36 affected its ability to modulate Gαq-mediated signalling by TPβ. We report that WDR36 acts as a new scaffold protein tethering a G-protein-coupled receptor, Gαq and PLCβ in a signalling complex.
Collapse
Affiliation(s)
- Andréane Cartier
- Service de Rhumatologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Institut de Pharmacologie de Sherbrooke and Centre de Recherche Clinique Etienne-Lebel, Sherbrooke, QC J1H 5N4, Canada
| | - Audrey Parent
- Service de Rhumatologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Institut de Pharmacologie de Sherbrooke and Centre de Recherche Clinique Etienne-Lebel, Sherbrooke, QC J1H 5N4, Canada
| | - Pascale Labrecque
- Service de Rhumatologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Institut de Pharmacologie de Sherbrooke and Centre de Recherche Clinique Etienne-Lebel, Sherbrooke, QC J1H 5N4, Canada
| | - Geneviève Laroche
- Service de Rhumatologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Institut de Pharmacologie de Sherbrooke and Centre de Recherche Clinique Etienne-Lebel, Sherbrooke, QC J1H 5N4, Canada
| | - Jean-Luc Parent
- Service de Rhumatologie, Département de Médecine, Faculté de Médecine et des Sciences de la Santé, Université de Sherbrooke, Institut de Pharmacologie de Sherbrooke and Centre de Recherche Clinique Etienne-Lebel, Sherbrooke, QC J1H 5N4, Canada
| |
Collapse
|
322
|
Structural insights into RAMP modification of secretin family G protein-coupled receptors: implications for drug development. Trends Pharmacol Sci 2011; 32:591-600. [DOI: 10.1016/j.tips.2011.05.007] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 05/25/2011] [Accepted: 05/26/2011] [Indexed: 11/18/2022]
|
323
|
Allostery in GPCRs: 'MWC' revisited. Trends Biochem Sci 2011; 36:663-72. [PMID: 21920759 DOI: 10.1016/j.tibs.2011.08.005] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2011] [Revised: 08/16/2011] [Accepted: 08/16/2011] [Indexed: 01/12/2023]
Abstract
G protein-coupled receptors (GPCRs) constitute the largest family of receptors in the genome and are the targets for at least 30% of current medicines. In recent years, there has been a dramatic increase in the discovery of allosteric modulators of GPCR activity and a growing appreciation of the diverse modes by which GPCRs can be regulated by both orthosteric and allosteric ligands. Interestingly, some of the contemporary views of GPCR function reflect characteristics that are shared by prototypical allosteric proteins, as encompassed in the classic Monod-Wyman-Changeux (MWC) model initially proposed for enzymes and subsequently extended to other protein families. In this review, we revisit the MWC model in the context of emerging structural, functional and operational data on GPCR allostery.
Collapse
|
324
|
PKA phosphorylation couples hepatic inositol-requiring enzyme 1alpha to glucagon signaling in glucose metabolism. Proc Natl Acad Sci U S A 2011; 108:15852-7. [PMID: 21911379 DOI: 10.1073/pnas.1107394108] [Citation(s) in RCA: 72] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The endoplasmic reticulum (ER)-resident protein kinase/endoribonuclease inositol-requiring enzyme 1 (IRE1) is activated through transautophosphorylation in response to protein folding overload in the ER lumen and maintains ER homeostasis by triggering a key branch of the unfolded protein response. Here we show that mammalian IRE1α in liver cells is also phosphorylated by a kinase other than itself in response to metabolic stimuli. Glucagon-stimulated protein kinase PKA, which in turn phosphorylated IRE1α at Ser(724), a highly conserved site within the kinase activation domain. Blocking Ser(724) phosphorylation impaired the ability of IRE1α to augment the up-regulation by glucagon signaling of the expression of gluconeogenic genes. Moreover, hepatic IRE1α was highly phosphorylated at Ser(724) by PKA in mice with obesity, and silencing hepatic IRE1α markedly reduced hyperglycemia and glucose intolerance. Hence, these results suggest that IRE1α integrates signals from both the ER lumen and the cytoplasm in the liver and is coupled to the glucagon signaling in the regulation of glucose metabolism.
Collapse
|
325
|
Detection and characterization of receptor interactions with PDZ domains. Methods Mol Biol 2011. [PMID: 21870238 DOI: 10.1007/978-1-61779-160-4_21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
Abstract
Many transmembrane receptors are regulated by associations with scaffold proteins containing PDZ domains, which interact with receptor carboxyl-termini to control receptor signaling, trafficking, and localization. We describe here approaches for detecting and characterizing interactions between receptors and PDZ scaffolds. These approaches include the construction and screening of proteomic arrays, blot overlays using fusion proteins, and co-immunoprecipitation studies to assess interactions in cells.
Collapse
|
326
|
Lyssand JS, Lee KS, DeFino M, Adams ME, Hague C. Syntrophin isoforms play specific functional roles in the α1D-adrenergic receptor/DAPC signalosome. Biochem Biophys Res Commun 2011; 412:596-601. [PMID: 21846462 DOI: 10.1016/j.bbrc.2011.08.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 08/02/2011] [Indexed: 12/28/2022]
Abstract
α(1D)-Adrenergic receptors, key regulators of cardiovascular system function, are organized as a multi-protein complex in the plasma membrane. Using a Type-I PDZ-binding motif in their distal C-terminal domain, α(1D)-ARs associate with syntrophins and dystrophin-associated protein complex (DAPC) members utrophin, dystrobrevin and α-catulin. Three of the five syntrophin isoforms (α, β(1) and β(2)) interact with α(1D)-ARs and our previous studies suggest multiple isoforms are required for proper α(1D)-AR function in vivo. This study determined the contribution of each specific syntrophin isoform to α(1D)-AR function. Radioligand binding experiments reveal α-syntrophin enhances α(1D)-AR binding site density, while phosphoinositol and ERK1/2 signaling assays indicate β(2)-syntrophin augments full and partial agonist efficacy for coupling to downstream signaling mechanisms. The results of this study provide clear evidence that the cytosolic components within the α(1D)-AR/DAPC signalosome significantly alter the pharmacological properties of α(1)-AR ligands in vitro.
Collapse
Affiliation(s)
- John S Lyssand
- Department of Pharmacology, University of Washington, Seattle, WA 98195, USA
| | | | | | | | | |
Collapse
|
327
|
Mikhaylova M, Hradsky J, Kreutz MR. Between promiscuity and specificity: novel roles of EF-hand calcium sensors in neuronal Ca2+ signalling. J Neurochem 2011; 118:695-713. [PMID: 21722133 DOI: 10.1111/j.1471-4159.2011.07372.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In recent years, substantial progress has been made towards an understanding of the physiological function of EF-hand calcium sensor proteins of the Calmodulin (CaM) superfamily in neurons. This deeper appreciation is based on the identification of novel target interactions, structural studies and the discovery of novel signalling mechanisms in protein trafficking and synaptic plasticity, in which CaM-like sensor proteins appear to play a role. However, not all interactions are of plausible physiological relevance and in many cases it is not yet clear how the CaM signaling network relates to the proposed function of other EF-hand sensors. In this review, we will summarize these findings and address some of the open questions on the functional role of EF-hand calcium binding proteins in neurons.
Collapse
Affiliation(s)
- Marina Mikhaylova
- PG Neuroplasticity, Leibniz-Institute for Neurobiology, Magdeburg, Germany
| | | | | |
Collapse
|
328
|
Kukkonen JP. A ménage à trois made in heaven: G-protein-coupled receptors, lipids and TRP channels. Cell Calcium 2011; 50:9-26. [DOI: 10.1016/j.ceca.2011.04.005] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 04/21/2011] [Accepted: 04/22/2011] [Indexed: 12/15/2022]
|
329
|
Maurice P, Kamal M, Jockers R. Asymmetry of GPCR oligomers supports their functional relevance. Trends Pharmacol Sci 2011; 32:514-20. [PMID: 21715028 DOI: 10.1016/j.tips.2011.05.006] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Revised: 05/19/2011] [Accepted: 05/20/2011] [Indexed: 01/29/2023]
Abstract
G protein-coupled receptors (GPCRs) can exist as dimers or as larger oligomeric clusters that enable intercommunication between different receptor protomers within the same complex. This phenomenon is observed at three distinct levels: (i) at the level of ligand binding where the activation of one protomer can allosterically inhibit or facilitate ligand binding to the second protomer; (ii) at the level of ligand-induced conformational switches, which occur between transmembrane domains of the two protomers; and (iii) within GPCR-associated protein complexes, either directly at the level of GPCR-interacting proteins or at further downstream levels of the complex. Intercommunication at these different levels introduces asymmetry within GPCR dimers wherein each protomer fulfills its specific task. In this review, we discuss how the asymmetric behavior of GPCRs highlights the advantage of oligomeric receptor organization and supports the functional relevance of GPCR dimerization.
Collapse
Affiliation(s)
- Pascal Maurice
- Inserm, U1016, Institut Cochin, 22 rue Méchain, 75014 Paris, France
| | | | | |
Collapse
|
330
|
Abstract
Over the past 20 years, naturally occurring mutations that affect G protein-coupled receptors (GPCRs) have been identified, mainly in patients with endocrine diseases. The study of loss-of-function or gain-of-function mutations has contributed to our understanding of the pathophysiology of several diseases with classic hypophenotypes or hyperphenotypes of the target endocrine organs, respectively. Simultaneously, study of the mutant receptors ex vivo was instrumental in delineating the relationships between the structure and function of these important physiological and pharmacological molecules. Now that access to the crystallographic structure of a few GPCRs is available, the mechanics of these receptors can be studied at the atomic level. Progress in the fields of cell biology, molecular pharmacology and proteomics has also widened our view of GPCR functions. Initially considered simply as guanine nucleotide exchange factors capable of activating G protein-dependent regulatory cascades, GPCRs are now known to display several additional characteristics, each susceptible to alterations by disease-causing mutations. These characteristics include functionally important basal activity of the receptor; differential activation of various G proteins; differential activation of G protein-dependent and independent effects (biased agonism); interaction with proteins that modify receptor function; dimerization-dependent effects; and interaction with allosteric modulators. This Review attempts to illustrate how natural mutations of GPCR could contribute to our understanding of these novel facets of GPCR biology.
Collapse
Affiliation(s)
- Gilbert Vassart
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Faculty of Medicine, Université Libre de Bruxelles, 808 Route de Lennik, 1070 Brussels, Belgium.
| | | |
Collapse
|
331
|
Djannatian MS, Galinski S, Fischer TM, Rossner MJ. Studying G protein-coupled receptor activation using split-tobacco etch virus assays. Anal Biochem 2011; 412:141-52. [PMID: 21295005 DOI: 10.1016/j.ab.2011.01.042] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2010] [Revised: 01/21/2011] [Accepted: 01/28/2011] [Indexed: 11/26/2022]
Abstract
G protein-coupled receptors (GPCRs) constitute the largest receptor family in mammals and represent important drug targets. Signaling through GPCRs mediates physiological effects that are strongly dependent on the cellular context. Therefore, the availability of assays monitoring GPCR activation applicable in different cell types could help to better understand GPCR functions and to realize the potential of known substances as well as novel ones. Here we introduce a split-TEV (tobacco etch virus) assay to monitor GPCR activation through the stimulation-dependent recruitment of β-arrestin 2. Inactive N- and C-terminal fragments of the TEV protease are coupled to a GPCR and β-arrestin 2, respectively. Ligand-dependent interaction of the two fusion proteins leads to functional complementation of the TEV protease, followed by the cleavage of an artificial transcription factor and successive reporter gene activation. The presented split-TEV assay system is highly sensitive and was successfully applied in heterologous cell lines as well as in primary cultured neuronal and glial cells. We show that assay performance strongly depends on the endogenous properties of different cell types. The sensitivity and flexibility make split-TEV assays a valuable tool to analyze GPCR activation in different cell types in a rapid and cost-effective way.
Collapse
|
332
|
Damera G, Panettieri RA. Does airway smooth muscle express an inflammatory phenotype in asthma? Br J Pharmacol 2011; 163:68-80. [PMID: 21175578 PMCID: PMC3085869 DOI: 10.1111/j.1476-5381.2010.01165.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2010] [Indexed: 01/12/2023] Open
Abstract
In addition to hyperresponsiveness in asthma, airway smooth muscle (ASM) also manifests an inflammatory phenotype characterized by augmented expression of mediators that enhance inflammation, contribute to tissue remodelling and augment leucocyte trafficking and activity. Our present review summarizes contemporary understanding of ASM-derived mediators and their paracrine and autocrine actions in airway diseases.
Collapse
Affiliation(s)
- Gautam Damera
- Airways Biology Initiative, Pulmonary, Allergy and Critical Care Division, Department of Medicine, University of PennsylvaniaPhiladelphia, PA, USA
| | - Reynold A Panettieri
- Airways Biology Initiative, Pulmonary, Allergy and Critical Care Division, Department of Medicine, University of PennsylvaniaPhiladelphia, PA, USA
- Center of Excellence in Environmental Toxicology, University of PennsylvaniaPhiladelphia, PA, USA
| |
Collapse
|
333
|
Björk K, Svenningsson P. Modulation of monoamine receptors by adaptor proteins and lipid rafts: role in some effects of centrally acting drugs and therapeutic agents. Annu Rev Pharmacol Toxicol 2011; 51:211-42. [PMID: 20887195 DOI: 10.1146/annurev-pharmtox-010510-100520] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The monoamines and their cognate receptors are widespread in the central nervous system and are vital for normal brain function. Dysfunction in these systems underlies several psychiatric and neurological disease states, and consequently monoamines are targets of a host of pharmacotherapies. This review provides an overview on how monoamine receptors are regulated by adaptor proteins and lipid rafts with emphasis on interactions in nerve cells. Monoamine receptors have prominent intracellular loops that provide binding sites for adaptor proteins. Receptor function is further modulated by cholesterol and submembranous microdomains termed lipid rafts. These interactions determine several facets of G protein-coupled receptor (GPCR) function including trafficking, localization, and signaling. Possible roles of adaptor proteins and lipid rafts in disease states and in mediating actions of drugs and therapeutic agents are also discussed.
Collapse
Affiliation(s)
- Karl Björk
- Center for Molecular Medicine, Karolinska Institutet, Stockholm, Sweden
| | | |
Collapse
|
334
|
Ganguly S, Saxena R, Chattopadhyay A. Reorganization of the actin cytoskeleton upon G-protein coupled receptor signaling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1921-9. [PMID: 21501584 DOI: 10.1016/j.bbamem.2011.04.001] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2011] [Revised: 03/29/2011] [Accepted: 04/01/2011] [Indexed: 12/28/2022]
Abstract
The actin cytoskeleton is involved in a multitude of cellular responses besides providing structural support. While the role of the actin cytoskeleton in cellular processes such as trafficking and motility has been extensively studied, reorganization of the actin cytoskeleton upon signaling by G-protein coupled receptors (GPCRs) represents a relatively unexplored area. The G-protein coupled receptor superfamily is an important protein family in mammals, involved in signal transduction across membranes. G-protein coupled receptors act as major signaling hubs and drug targets. The serotonin(1A) receptor is a representative member of the G-protein coupled receptor superfamily and plays a crucial role in the generation and modulation of various cognitive, developmental and behavioral functions. In order to monitor the changes in the actin cytoskeleton upon serotonin(1A) receptor signaling in a quantitative manner, we developed an approach based on high magnification imaging of F-actin in cells, followed by image reconstruction. Our results suggest that the actin cytoskeleton is reorganized in response to serotonin(1A) receptor signaling. In addition, we show that reorganization of the actin cytoskeleton is strongly dependent on adenosine 3',5'-cyclic monophosphate level, and is mediated by the activation of protein kinase A. Our results are consistent with the possibility of a feedback mechanism involving the actin cytoskeleton, adenosine 3',5'-cyclic monophosphate level and the serotonin(1A) receptor.
Collapse
Affiliation(s)
- Sourav Ganguly
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Hyderabad, India
| | | | | |
Collapse
|
335
|
Martin C, Balasubramanian R, Dwyer AA, Au MG, Sidis Y, Kaiser UB, Seminara SB, Pitteloud N, Zhou QY, Crowley WF. The role of the prokineticin 2 pathway in human reproduction: evidence from the study of human and murine gene mutations. Endocr Rev 2011; 32:225-46. [PMID: 21037178 PMCID: PMC3365793 DOI: 10.1210/er.2010-0007] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
A widely dispersed network of hypothalamic GnRH neurons controls the reproductive axis in mammals. Genetic investigation of the human disease model of isolated GnRH deficiency has revealed several key genes crucial for GnRH neuronal ontogeny and GnRH secretion. Among these genes, prokineticin 2 (PROK2), and PROK2 receptor (PROKR2) have recently emerged as critical regulators of reproduction in both mice and humans. Both prok2- and prokr2-deficient mice recapitulate the human Kallmann syndrome phenotype. Additionally, PROK2 and PROKR2 mutations are seen in humans with Kallmann syndrome, thus implicating this pathway in GnRH neuronal migration. However, PROK2/PROKR2 mutations are also seen in normosmic GnRH deficiency, suggesting a role for the prokineticin signaling system in GnRH biology that is beyond neuronal migration. This observation is particularly surprising because mature GnRH neurons do not express PROKR2. Moreover, mutations in both PROK2 and PROKR2 are predominantly detected in the heterozygous state with incomplete penetrance or variable expressivity frequently seen within and across pedigrees. In some of these pedigrees, a "second hit" or oligogenicity has been documented. Besides reproduction, a pleiotropic physiological role for PROK2 is now recognized, including regulation of pain perception, circadian rhythms, hematopoiesis, and immune response. Therefore, further detailed clinical studies of patients with PROK2/PROKR2 mutations will help to map the broader biological role of the PROK2/PROKR2 pathway and identify other interacting genes/proteins that mediate its molecular effects in humans.
Collapse
Affiliation(s)
- Cecilia Martin
- Harvard Center for Reproductive Endocrine Sciences, Reproductive Endocrine Unit, Department of Medicine, Massachusetts General Hospital, Boston, 02114, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
336
|
Bianco SDC, Vandepas L, Correa-Medina M, Gereben B, Mukherjee A, Kuohung W, Carroll R, Teles MG, Latronico AC, Kaiser UB. KISS1R intracellular trafficking and degradation: effect of the Arg386Pro disease-associated mutation. Endocrinology 2011; 152:1616-26. [PMID: 21285314 PMCID: PMC3060635 DOI: 10.1210/en.2010-0903] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The goal of this study was to investigate how the Arg386Pro mutation prolongs KiSS-1 receptor (KISS1R) responsiveness to kisspeptin, contributing to human central precocious puberty. Confocal imaging showed colocalization of wild-type (WT) KISS1R with a membrane marker, which persisted for up to 5 h of stimulation. Conversely, no colocalization with a lysosome marker was detected. Also, overnight treatment with a lysosome inhibitor did not affect WT KISS1R protein, whereas overnight treatment with a proteasome inhibitor increased protein levels by 24-fold. WT and Arg386Pro KISS1R showed time-dependent internalization upon stimulation. However, both receptors were recycled back to the membrane. The Arg386Pro mutation did not affect the relative distribution of KISS1R in membrane and internalized fractions when compared to WT KISS1R for up to 120 min of stimulation, demonstrating that this mutation does not affect KISS1R trafficking rate. Nonetheless, total Arg386Pro KISS1R was substantially increased compared with WT after 120 min of kisspeptin stimulation. This net increase was eliminated by blockade of detection of recycled receptors, demonstrating that recycled receptors account for the increased responsiveness of this mutant to kisspeptin. We therefore conclude the following: 1) WT KISS1R is degraded by proteasomes rather than lysosomes; 2) WT and Arg386Pro KISS1R are internalized upon stimulation, but most of the internalized receptors are recycled back to the membrane rather than degraded; 3) the Arg386Pro mutation does not affect the rate of KISS1R trafficking--instead, it prolongs responsiveness to kisspeptin by decreasing KISS1R degradation, resulting in the net increase on mutant receptor recycled back to the plasma membrane.
Collapse
Affiliation(s)
- Suzy D C Bianco
- Department of Molecular and Cellular Pharmacology, University of Miami Miller School of Medicine, Miami, Florida 33136, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
337
|
Zhang X, Tan F, Brovkovych V, Zhang Y, Skidgel RA. Cross-talk between carboxypeptidase M and the kinin B1 receptor mediates a new mode of G protein-coupled receptor signaling. J Biol Chem 2011; 286:18547-61. [PMID: 21454694 DOI: 10.1074/jbc.m110.214940] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptor (GPCR) signaling is affected by formation of GPCR homo- or heterodimers, but GPCR regulation by other cell surface proteins is not well understood. We reported that the kinin B1 receptor (B1R) heterodimerizes with membrane carboxypeptidase M (CPM), facilitating receptor signaling via CPM-mediated conversion of bradykinin or kallidin to des-Arg kinin B1R agonists. Here, we found that a catalytically inactive CPM mutant that still binds substrate (CPM-E264Q) also facilitates efficient B1R signaling by B2 receptor agonists bradykinin or kallidin. This response required co-expression of B1R and CPM-E264Q in the same cell, was disrupted by antibody that dissociates CPM from B1R, and was not found with a CPM-E264Q-B1R fusion protein. An additional mutation that reduced the affinity of CPM for C-terminal Arg and increased the affinity for C-terminal Lys inhibited the B1R response to bradykinin (with C-terminal Arg) but generated a response to Lys(9)-bradykinin. CPM-E264Q-mediated activation of B1Rs by bradykinin resulted in increased intramolecular fluorescence resonance energy transfer (FRET) in a B1R FRET construct, similar to that generated directly by a B1R agonist. In cytokine-treated human lung microvascular endothelial cells, disruption of B1R-CPM heterodimers inhibited B1R-dependent NO production stimulated by bradykinin and blocked the increased endothelial permeability caused by treatment with bradykinin and pyrogallol (a superoxide generator). Thus, CPM and B1Rs on cell membranes form a critical complex that potentiates B1R signaling. Kinin peptide binding to CPM causes a conformational change in the B1R leading to intracellular signaling and reveals a new mode of GPCR activation by a cell surface peptidase.
Collapse
Affiliation(s)
- Xianming Zhang
- Department of Pharmacology, University of Illinois College of Medicine, Chicago, Illinois 60612, USA
| | | | | | | | | |
Collapse
|
338
|
Massarsky A, Trudeau VL, Moon TW. β-blockers as endocrine disruptors: the potential effects of human β-blockers on aquatic organisms. ACTA ACUST UNITED AC 2011; 315:251-65. [DOI: 10.1002/jez.672] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2010] [Revised: 12/15/2010] [Accepted: 02/01/2011] [Indexed: 12/12/2022]
|
339
|
Lee SJ, Ritter SL, Zhang H, Shim H, Hall RA, Yun CC. MAGI-3 competes with NHERF-2 to negatively regulate LPA2 receptor signaling in colon cancer cells. Gastroenterology 2011; 140:924-34. [PMID: 21134377 PMCID: PMC3057353 DOI: 10.1053/j.gastro.2010.11.054] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2010] [Revised: 11/03/2010] [Accepted: 11/24/2010] [Indexed: 12/25/2022]
Abstract
BACKGROUND & AIMS Lysophosphatidic acid (LPA) is a potent inducer of colon cancer and LPA receptor type 2 (LPA(2)) is overexpressed in colon tumors. LPA(2) interacts with membrane-associated guanylate kinase with inverted orientation-3 (MAGI-3) and the Na+/H+ exchanger regulatory factor 2 (NHERF-2), but the biological effects of these interactions are unknown. We investigated the roles of MAGI-3 and NHERF-2 in LPA(2)-mediated signaling in human colon cancer cells. METHODS We overexpressed or knocked down MAGI-3 in HCT116 and SW480 cells. The effects of MAGI-3 and NHERF-2 in LPA-induced cell migration, invasion, inositol phosphate generation, and nuclear factor-κB activation were determined. Expression of MAGI-3 and NHERF-2 in human colon tumor tissues was analyzed using tissue microarray analysis. RESULTS NHERF-2 promoted migration and invasion of colon cancer cells, whereas MAGI-3 inhibited these processes. MAGI-3 competed with NHERF-2 for binding to LPA(2) and phospholipase C-β3. However, NHERF-2 and MAGI-3 reciprocally regulated LPA(2)-induced phospholipase C activity. MAGI-3 increased the interaction of LPA(2) with Gα(12), whereas NHERF-2 preferentially promoted interaction between LPA(2) and Gα(q). MAGI-3 decreased the tumorigenic capacity of LPA(2) by attenuating the activities of nuclear factor-κB and c-Jun N-terminal kinase. MAGI-3 and NHERF-2 were expressed differentially in colon adenocarcinomas, consistent with their opposing effects. CONCLUSIONS LPA(2) is dynamically regulated by 2 distinct PDZ proteins via modulation of G-protein coupling and receptor signaling. MAGI-3 is a negative regulator of LPA(2) signaling.
Collapse
Affiliation(s)
- Sei-Jung Lee
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Stefanie L. Ritter
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Huanchun Zhang
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Hyunsuk Shim
- Department of Radiology, Emory University School of Medicine, Atlanta, Georgia, USA, Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia, USA
| | - Randy A. Hall
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia, USA
| | - C. Chris Yun
- Division of Digestive Diseases, Department of Medicine, Emory University School of Medicine, Atlanta, Georgia, USA, Winship Cancer Institute, Emory University School of Medicine, Atlanta, Georgia, USA, Department of Physiology, Emory University School of Medicine, Atlanta, Georgia, USA
| |
Collapse
|
340
|
Turner EC, Kavanagh DJ, Mulvaney EP, McLean C, Wikström K, Reid HM, Kinsella BT. Identification of an interaction between the TPalpha and TPbeta isoforms of the human thromboxane A2 receptor with protein kinase C-related kinase (PRK) 1: implications for prostate cancer. J Biol Chem 2011; 286:15440-57. [PMID: 21357687 DOI: 10.1074/jbc.m110.181180] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In humans, thromboxane (TX) A(2) signals through the TPα and TPβ isoforms of the TXA(2) receptor or TP. Here, the RhoA effector protein kinase C-related kinase (PRK) 1 was identified as an interactant of both TPα and ΤPβ involving common and unique sequences within their respective C-terminal (C)-tail domains and the kinase domain of PRK1 (PRK1(640-942)). Although the interaction with PRK1 is constitutive, agonist activation of TPα/TPβ did not regulate the complex per se but enhanced PRK1 activation leading to phosphorylation of its general substrate histone H1 in vitro. Altered PRK1 and TP expression and signaling are increasingly implicated in certain neoplasms, particularly in androgen-associated prostate carcinomas. Agonist activation of TPα/TPβ led to phosphorylation of histone H3 at Thr(11) (H3 Thr(11)), a previously recognized specific marker of androgen-induced chromatin remodeling, in the prostate LNCaP and PC-3 cell lines but not in primary vascular smooth muscle or endothelial cells. Moreover, this effect was augmented by dihydrotestosterone in androgen-responsive LNCaP but not in nonresponsive PC-3 cells. Furthermore, PRK1 was confirmed to constitutively interact with TPα/TPβ in both LNCaP and PC-3 cells, and targeted disruption of PRK1 impaired TPα/TPβ-mediated H3 Thr(11) phosphorylation in, and cell migration of, both prostate cell types. Collectively, considering the role of TXA(2) as a potent mediator of RhoA signaling, the identification of PRK1 as a bona fide interactant of TPα/TPβ, and leading to H3 Thr(11) phosphorylation to regulate cell migration, has broad functional significance such as within the vasculature and in neoplasms in which both PRK1 and the TPs are increasingly implicated.
Collapse
Affiliation(s)
- Elizebeth C Turner
- School of Biomolecular and Biomedical Sciences, Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland
| | | | | | | | | | | | | |
Collapse
|
341
|
Adams MN, Ramachandran R, Yau MK, Suen JY, Fairlie DP, Hollenberg MD, Hooper JD. Structure, function and pathophysiology of protease activated receptors. Pharmacol Ther 2011; 130:248-82. [PMID: 21277892 DOI: 10.1016/j.pharmthera.2011.01.003] [Citation(s) in RCA: 267] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2011] [Accepted: 01/03/2011] [Indexed: 12/18/2022]
Abstract
Discovered in the 1990s, protease activated receptors(1) (PARs) are membrane-spanning cell surface proteins that belong to the G protein coupled receptor (GPCR) family. A defining feature of these receptors is their irreversible activation by proteases; mainly serine. Proteolytic agonists remove the PAR extracellular amino terminal pro-domain to expose a new amino terminus, or tethered ligand, that binds intramolecularly to induce intracellular signal transduction via a number of molecular pathways that regulate a variety of cellular responses. By these mechanisms PARs function as cell surface sensors of extracellular and cell surface associated proteases, contributing extensively to regulation of homeostasis, as well as to dysfunctional responses required for progression of a number of diseases. This review examines common and distinguishing structural features of PARs, mechanisms of receptor activation, trafficking and signal termination, and discusses the physiological and pathological roles of these receptors and emerging approaches for modulating PAR-mediated signaling in disease.
Collapse
Affiliation(s)
- Mark N Adams
- Mater Medical Research Institute, Aubigny Place, Raymond Terrace, South Brisbane Qld 4101, Australia
| | | | | | | | | | | | | |
Collapse
|
342
|
Liebmann C. EGF receptor activation by GPCRs: an universal pathway reveals different versions. Mol Cell Endocrinol 2011; 331:222-31. [PMID: 20398727 DOI: 10.1016/j.mce.2010.04.008] [Citation(s) in RCA: 115] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/19/2010] [Accepted: 04/01/2010] [Indexed: 11/20/2022]
Abstract
About one decade ago has been demonstrated that G protein-coupled receptors (GPCRs) are able to utilize the epidermal growth factor (EGF) receptor (EGFR) as signalling intermediate. Thereby GPCRs are enabled to regulate cell growth, differentiation, and migration. A molecular mechanism for this process has been proposed that involves the activation of a distinct set of metalloproteases and the subsequent generation and release of particular members of the EGF peptide family which in turn activate the EGFR in an autocrine/paracrine manner. This model that allows GPCRs direct access to the signalling network of the EGFR family has emerged as a valid concept in a variety of cell types including cancer cells. The present review briefly summarizes the current knowledge but will be focussed on the ligand-dependency of EGFR transactivation. Several alternative mechanisms and novel aspects will be introduced. Using the example of head and neck squamous carcinoma, the potency of EGFR transactivation as a therapeutical target will be discussed.
Collapse
Affiliation(s)
- Claus Liebmann
- Center of Molecular Biomedicine (CMB), Institute of Biochemistry and Biophysics, Friedrich-Schiller-University Jena, Hans-Knöll-Str. 2, D-07745 Jena, Germany.
| |
Collapse
|
343
|
Donnellan PD, Kimbembe CC, Reid HM, Kinsella BT. Identification of a novel endoplasmic reticulum export motif within the eighth α-helical domain (α-H8) of the human prostacyclin receptor. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:1202-18. [PMID: 21223948 DOI: 10.1016/j.bbamem.2011.01.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 12/20/2010] [Accepted: 01/03/2011] [Indexed: 01/20/2023]
Abstract
The human prostacyclin receptor (hIP) undergoes agonist-dependent trafficking involving a direct interaction with Rab11a GTPase. The region of interaction was localised to a 14 residue Rab11a binding domain (RBD) within the proximal carboxyl-terminal (C)-tail domain of the hIP, consisting of Val(299)-Val(307) within the eighth helical domain (α-H8) adjacent to the palmitoylated residues at Cys(308)-Cys(311). However, the factors determining the anterograde transport of the newly synthesised hIP from the endoplasmic reticulum (ER) to the plasma membrane (PM) have not been identified. The aim of the current study was to identify the major ER export motif(s) within the hIP initially by investigating the role of Lys residues in its maturation and processing. Through site-directed and Ala-scanning mutational studies in combination with analyses of protein expression and maturation, functional analyses of ligand binding, agonist-induced intracellular signalling and confocal image analyses, it was determined that Lys(297), Arg(302) and Lys(304) located within α-H8 represent the critical determinants of a novel ER export motif of the hIP. Furthermore, while substitution of those critical residues significantly impaired maturation and processing of the hIP, replacement of the positively charged Lys with Arg residues, and vice versa, was functionally permissible. Hence, this study has identified a novel 8 residue ER export motif within the functionally important α-H8 of the hIP. This ER export motif, defined by "K/R(X)(4)K/R(X)K/R," has a strict requirement for positively charged, basic Lys/Arg residues at the 1st, 6th and 8th positions and appears to be evolutionarily conserved within IP sequences from mouse to man.
Collapse
MESH Headings
- Amino Acid Motifs
- Amino Acid Sequence
- Arginine/chemistry
- Arginine/genetics
- Arginine/metabolism
- Binding Sites
- Blotting, Western
- Calcium/metabolism
- Calnexin/metabolism
- Computational Biology
- Endoplasmic Reticulum/metabolism
- HEK293 Cells
- Humans
- Lysine/chemistry
- Lysine/genetics
- Lysine/metabolism
- Microscopy, Confocal
- Models, Molecular
- Molecular Sequence Data
- Mutagenesis, Site-Directed
- Mutation
- Protein Binding
- Protein Structure, Secondary
- Protein Structure, Tertiary
- Protein Transport
- Radioligand Assay
- Receptors, Epoprostenol/chemistry
- Receptors, Epoprostenol/genetics
- Receptors, Epoprostenol/metabolism
- Sequence Homology, Amino Acid
Collapse
Affiliation(s)
- Peter D Donnellan
- School of Biomeolecular and Biomedical Sciences, University College Dublin, Belfield, Dublin 4, Ireland
| | | | | | | |
Collapse
|
344
|
Maurice P, Guillaume JL, Benleulmi-Chaachoua A, Daulat AM, Kamal M, Jockers R. GPCR-Interacting Proteins, Major Players of GPCR Function. PHARMACOLOGY OF G PROTEIN COUPLED RECEPTORS 2011; 62:349-80. [DOI: 10.1016/b978-0-12-385952-5.00001-4] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
|
345
|
Micevych PE, Dewing P. Membrane-initiated estradiol signaling regulating sexual receptivity. Front Endocrinol (Lausanne) 2011; 2:26. [PMID: 22649369 PMCID: PMC3355897 DOI: 10.3389/fendo.2011.00026] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Accepted: 08/16/2011] [Indexed: 12/24/2022] Open
Abstract
Estradiol has profound actions on the structure and function of the nervous system. In addition to nuclear actions that directly modulate gene expression, the idea that estradiol can rapidly activate cell signaling by binding to membrane estrogen receptors (mERs) has emerged. Even the regulation of sexual receptivity, an action previously thought to be completely regulated by nuclear ERs, has been shown to have a membrane-initiated estradiol signaling (MIES) component. This highlighted the question of the nature of mERs. Several candidates have been proposed, ERα, ERβ, ER-X, GPR30 (G protein coupled estrogen receptor), and a receptor activated by a diphenylacrylamide compound, STX. Although each of these receptors has been shown to be active in specific assays, we present evidence for and against their participation in sexual receptivity by acting in the lordosis-regulating circuit. The initial MIES that activates the circuit is in the arcuate nucleus of the hypothalamus (ARH). Using both activation of μ-opioid receptors (MOR) in the medial preoptic nucleus and lordosis behavior, we document that both ERα and the STX-receptor participate in the required MIES. ERα and the STX-receptor activation of cell signaling are dependent on the transactivation of type 1 metabotropic glutamate receptors (mGluR1a) that augment progesterone synthesis in astrocytes and protein kinase C (PKC) in ARH neurons. While estradiol-induced sexual receptivity does not depend on neuroprogesterone, proceptive behaviors do. Moreover, the ERα and the STX-receptor activation of medial preoptic MORs and augmentation of lordosis were sensitive to mGluR1a blockade. These observations suggest a common mechanism through which mERs are coupled to intracellular signaling cascades, not just in regulating reproduction, but in actions throughout the neuraxis including the cortex, hippocampus, striatum, and dorsal root ganglias.
Collapse
Affiliation(s)
- Paul E. Micevych
- Laboratory of Neuroendocrinology, Department of Neurobiology, Brain Research Institute, David Geffen School of Medicine at University of California Los AngelesLos Angeles, CA, USA
- *Correspondence: Paul E Micevych, Department of Neurobiology, David Geffen School of Medicine at University of California Los Angeles, Los Angeles, CA 90095-1763, USA. e-mail:
| | - Phoebe Dewing
- Laboratory of Neuroendocrinology, Department of Neurobiology, Brain Research Institute, David Geffen School of Medicine at University of California Los AngelesLos Angeles, CA, USA
| |
Collapse
|
346
|
Historical Perspective for Understanding of Adrenergic Receptors. CURRENT TOPICS IN MEMBRANES 2011; 67:1-17. [DOI: 10.1016/b978-0-12-384921-2.00001-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
|
347
|
Filipeanu CM, de Vries R, Danser AHJ, Kapusta DR. Modulation of α(2C) adrenergic receptor temperature-sensitive trafficking by HSP90. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2010; 1813:346-57. [PMID: 21145921 DOI: 10.1016/j.bbamcr.2010.11.020] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2010] [Revised: 11/23/2010] [Accepted: 11/30/2010] [Indexed: 11/18/2022]
Abstract
Decreasing the temperature to 30°C is accompanied by significant enhancement of α(2C)-AR plasma membrane levels in several cell lines with fibroblast phenotype, as demonstrated by radioligand binding in intact cells. No changes were observed on the effects of low-temperature after blocking receptor internalization in α(2C)-AR transfected HEK293T cells. In contrast, two pharmacological chaperones, dimethyl sulfoxide and glycerol, increased the cell surface receptor levels at 37°C, but not at 30°C. Further, at 37°C α(2C)-AR is co-localized with endoplasmic reticulum markers, but not with the lysosomal markers. Treatment with three distinct HSP90 inhibitors, radicicol, macbecin and 17-DMAG significantly enhanced α(2C)-AR cell surface levels at 37°C, but these inhibitors had no effect at 30°C. Similar results were obtained after decreasing the HSP90 cellular levels using specific siRNA. Co-immunoprecipitation experiments demonstrated that α(2C)-AR interacts with HSP90 and this interaction is decreased at 30°C. The contractile response to endogenous α(2C)-AR stimulation in rat tail artery was also enhanced at reduced temperature. Similar to HEK293T cells, HSP90 inhibition increased the α(2C)-AR contractile effects only at 37°C. Moreover, exposure to low-temperature of vascular smooth muscle cells from rat tail artery decreased the cellular levels of HSP90, but did not change HSP70 levels. These data demonstrate that exposure to low-temperature augments the α(2C)-AR transport to the plasma membrane by releasing the inhibitory activity of HSP90 on the receptor traffic, findings which may have clinical relevance for the diagnostic and treatment of Raynaud Phenomenon.
Collapse
MESH Headings
- Animals
- Arteries
- Benzoquinones/pharmacology
- Cell Membrane/metabolism
- Cells, Cultured
- Enzyme Inhibitors/pharmacology
- HSP90 Heat-Shock Proteins/physiology
- Humans
- Kidney/cytology
- Kidney/metabolism
- Lactams, Macrocyclic/pharmacology
- Macrolides/pharmacology
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Protein Transport
- Protein-Tyrosine Kinases/antagonists & inhibitors
- RNA, Small Interfering/genetics
- Rats
- Rats, Wistar
- Receptors, Adrenergic, alpha-2/genetics
- Receptors, Adrenergic, alpha-2/metabolism
- Subcellular Fractions
- Temperature
Collapse
Affiliation(s)
- Catalin M Filipeanu
- Department of Pharmacology and Experimental Therapeutics, Louisiana State University Health Sciences Center, 1901 Perdido Street, New Orleans, Louisiana, LA-70112, USA.
| | | | | | | |
Collapse
|
348
|
Kobayashi NR, Hawes SM, Crook JM, Pébay A. G-protein coupled receptors in stem cell self-renewal and differentiation. Stem Cell Rev Rep 2010; 6:351-66. [PMID: 20625855 DOI: 10.1007/s12015-010-9167-9] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Stem cells have great potential for understanding early development, treating human disease, tissue trauma and early phase drug discovery. The factors that control the regulation of stem cell survival, proliferation, migration and differentiation are still emerging. Some evidence now exists demonstrating the potent effects of various G-protein coupled receptor (GPCR) ligands on the biology of stem cells. This review aims to give an overview of the current knowledge of the regulation of embryonic and somatic stem cell maintenance and differentiation by GPCR ligands.
Collapse
|
349
|
Churcher AM, Taylor JS. The antiquity of chordate odorant receptors is revealed by the discovery of orthologs in the cnidarian Nematostella vectensis. Genome Biol Evol 2010; 3:36-43. [PMID: 21123836 PMCID: PMC3017388 DOI: 10.1093/gbe/evq079] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
In vertebrates, olfaction is mediated by several families of G protein–coupled receptors (GPCRs) including odorant receptors (ORs). In this study, we investigated the antiquity of OR genes by searching for amino acid motifs found in chordate ORs among the protein predictions from 12 nonchordate species. Our search uncovered a novel group of genes in the cnidarian Nematostella vectensis. Phylogenetic analysis that included representatives from the other major lineages of rhodopsin-like GPCRs showed that the cnidarian genes, the cephalochordate and vertebrate ORs, and a family of genes from the echinoderm, Strongylocentrotus purpuratus, form a monophyletic clade. The taxonomic distribution of these genes indicates that the formation of this clade and therefore the diversification of the rhodopsin-like GPCR family began at least 700 million years ago, prior to the divergence of cnidarians and bilaterians. ORs and other rhodopsin-like GPCRs have roles in cell migration, axon guidance, and neurite growth; therefore, duplication and divergence in this family may have played a key role in the evolution of cell type diversity (including the emergence of complex nervous systems) and in the evolution of metazoan body plan diversity.
Collapse
Affiliation(s)
- Allison M Churcher
- Department of Biology, University of Victoria, Station CSC, Victoria, British Columbia, Canada
| | | |
Collapse
|
350
|
Alpha-dystrobrevin-1 recruits alpha-catulin to the alpha1D-adrenergic receptor/dystrophin-associated protein complex signalosome. Proc Natl Acad Sci U S A 2010; 107:21854-9. [PMID: 21115837 DOI: 10.1073/pnas.1010819107] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
α(1D)-Adrenergic receptors (ARs) are key regulators of cardiovascular system function that increase blood pressure and promote vascular remodeling. Unfortunately, little information exists about the signaling pathways used by this important G protein-coupled receptor (GPCR). We recently discovered that α(1D)-ARs form a "signalosome" with multiple members of the dystrophin-associated protein complex (DAPC) to become functionally expressed at the plasma membrane and bind ligands. However, the molecular mechanism by which the DAPC imparts functionality to the α(1D)-AR signalosome remains a mystery. To test the hypothesis that previously unidentified molecules are recruited to the α(1D)-AR signalosome, we performed an extensive proteomic analysis on each member of the DAPC. Bioinformatic analysis of our proteomic data sets detected a common interacting protein of relatively unknown function, α-catulin. Coimmunoprecipitation and blot overlay assays indicate that α-catulin is directly recruited to the α(1D)-AR signalosome by the C-terminal domain of α-dystrobrevin-1 and not the closely related splice variant α-dystrobrevin-2. Proteomic and biochemical analysis revealed that α-catulin supersensitizes α(1D)-AR functional responses by recruiting effector molecules to the signalosome. Taken together, our study implicates α-catulin as a unique regulator of GPCR signaling and represents a unique expansion of the intricate and continually evolving array of GPCR signaling networks.
Collapse
|