1
|
Walker V. The Intricacies of Renal Phosphate Reabsorption-An Overview. Int J Mol Sci 2024; 25:4684. [PMID: 38731904 PMCID: PMC11083860 DOI: 10.3390/ijms25094684] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2024] [Revised: 04/17/2024] [Accepted: 04/19/2024] [Indexed: 05/13/2024] Open
Abstract
To maintain an optimal body content of phosphorus throughout postnatal life, variable phosphate absorption from food must be finely matched with urinary excretion. This amazing feat is accomplished through synchronised phosphate transport by myriads of ciliated cells lining the renal proximal tubules. These respond in real time to changes in phosphate and composition of the renal filtrate and to hormonal instructions. How they do this has stimulated decades of research. New analytical techniques, coupled with incredible advances in computer technology, have opened new avenues for investigation at a sub-cellular level. There has been a surge of research into different aspects of the process. These have verified long-held beliefs and are also dramatically extending our vision of the intense, integrated, intracellular activity which mediates phosphate absorption. Already, some have indicated new approaches for pharmacological intervention to regulate phosphate in common conditions, including chronic renal failure and osteoporosis, as well as rare inherited biochemical disorders. It is a rapidly evolving field. The aim here is to provide an overview of our current knowledge, to show where it is leading, and where there are uncertainties. Hopefully, this will raise questions and stimulate new ideas for further research.
Collapse
Affiliation(s)
- Valerie Walker
- Department of Clinical Biochemistry, University Hospital Southampton NHS Foundation Trust, Southampton General Hospital, Southampton S016 6YD, UK
| |
Collapse
|
2
|
Abstract
G protein–coupled receptors (GPCRs) constitute the largest and pharmacologically most important family of cell-surface receptors. Some GPCRs interact specifically with receptor-activity-modifying proteins (RAMPs), but the consequences of this interaction for the receptor activation mechanism are not well understood. Using a set of fluorescent biosensors for the parathyroid hormone 1 receptor (PTH1R) and its downstream signaling partners, we show here that RAMP2 induces a unique, preactivated receptor state that shows faster activation and altered downstream signaling. This type of GPCR modulation may open new methods of drug design. Receptor-activity-modifying proteins (RAMPs) are ubiquitously expressed membrane proteins that associate with different G protein–coupled receptors (GPCRs), including the parathyroid hormone 1 receptor (PTH1R), a class B GPCR and an important modulator of mineral ion homeostasis and bone metabolism. However, it is unknown whether and how RAMP proteins may affect PTH1R function. Using different optical biosensors to measure the activation of PTH1R and its downstream signaling, we describe here that RAMP2 acts as a specific allosteric modulator of PTH1R, shifting PTH1R to a unique preactivated state that permits faster activation in a ligand-specific manner. Moreover, RAMP2 modulates PTH1R downstream signaling in an agonist-dependent manner, most notably increasing the PTH-mediated Gi3 signaling sensitivity. Additionally, RAMP2 increases both PTH- and PTHrP-triggered β-arrestin2 recruitment to PTH1R. Employing homology modeling, we describe the putative structural molecular basis underlying our functional findings. These data uncover a critical role of RAMPs in the activation and signaling of a GPCR that may provide a new venue for highly specific modulation of GPCR function and advanced drug design.
Collapse
|
3
|
Liu Y, Chen LY, Zeng H, Ward R, Wu N, Ma L, Mu X, Li QL, Yang Y, An S, Guo XX, Hao Q, Xu TR. Assessing the real-time activation of the cannabinoid CB1 receptor and the associated structural changes using a FRET biosensor. Int J Biochem Cell Biol 2018; 99:114-124. [PMID: 29626639 DOI: 10.1016/j.biocel.2018.04.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 03/25/2018] [Accepted: 04/04/2018] [Indexed: 11/18/2022]
Abstract
The cannabinoid receptor 1 (CB1) is mainly expressed in the nervous system and regulates learning, memory processes, pain and energy metabolism. However, there is no way to directly measure its activation. In this study, we constructed a CB1 intramolecular fluorescence resonance energy transfer (FRET) sensor, which could measure CB1 activation by monitoring structural changes between the third intracellular loop and the C-terminal tail. CB1 agonists induced a time- and concentration-dependent increase in the FRET signal, corresponding to a reduction in the distance between the third intracellular loop and the C-terminal tail. This, in turn, mobilized intracellular Ca2+, inhibited cAMP accumulation, and increased phosphorylation of the ERK1/2 MAP kinases. The activation kinetics detected using this method were consistent with those from previous reports. Moreover, the increased FRET signal was markedly inhibited by the CB1 antagonist rimonabant, which also reduced phosphorylation of the ERK1/2 MAP kinases. We mutated a single cysteine residue in the sensor (at position 257 or 264) to alanine. Both mutation reduced the agonist-induced increase in FRET signal and structural changes in the CB1 receptor, which attenuated phosphorylation of the ERK1/2 MAP kinases. In summary, our sensor directly assesses the kinetics of CB1 activation in real-time and can be used to monitor CB1 structure and function.
Collapse
Affiliation(s)
- Ying Liu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Lu-Yao Chen
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Hong Zeng
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Richard Ward
- Center for Translational Pharmacology, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, Scotland, United Kingdom
| | - Nan Wu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Li Ma
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Xi Mu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Qiu-Lan Li
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Yang Yang
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Su An
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Xiao-Xi Guo
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Qian Hao
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China
| | - Tian-Rui Xu
- Faculty of Life Science and Technology, Kunming University of Science and Technology, Kunming, Yunnan, 650500, China.
| |
Collapse
|
4
|
McLain DE, Rea AC, Widegren MB, Dore TM. Photoactivatable, biologically-relevant phenols with sensitivity toward 2-photon excitation. Photochem Photobiol Sci 2016; 14:2151-8. [PMID: 26467796 DOI: 10.1039/c5pp00334b] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Spatio-temporal release of biologically relevant small molecules provides exquisite control over the activation of receptors and signaling pathways. This can be accomplished via a photochemical reaction that releases the desired small molecule in response to irradiation with light. A series of biologically-relevant signaling molecules (serotonin, octopamine, capsaicin, N-vanillyl-nonanoylamide, estradiol, and tyrosine) that contain a phenol moiety were conjugated to the 8-bromo-7-hydroxyquinolinyl (BHQ) or 8-cyano-7-hydroxyquinolinyl (CyHQ) photoremovable protecting groups (PPGs). The CyHQ caged compounds proved sensitive toward 1PE and 2PE processes with quantum efficiencies of 0.2-0.4 upon irradiation at 365 nm and two-photon action cross sections of 0.15-0.31 GM when irradiated at 740 nm. All but one BHQ caged compound, BHQ-estradiol, were found to be sensitive to photolysis through 1PE and 2PE with quantum efficiencies of 0.30-0.40 and two photon cross sections of 0.40-0.60 GM. Instead of releasing estradiol, BHQ-estradiol underwent debromination.
Collapse
Affiliation(s)
- Duncan E McLain
- New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates. and Department of Chemistry, University of Georgia, Athens, Georgia30602, USA
| | - Adam C Rea
- Department of Chemistry, University of Georgia, Athens, Georgia30602, USA
| | - Magnus B Widegren
- New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates.
| | - Timothy M Dore
- New York University Abu Dhabi, PO Box 129188, Abu Dhabi, United Arab Emirates. and Department of Chemistry, University of Georgia, Athens, Georgia30602, USA
| |
Collapse
|
5
|
Pancreatic Beta Cell G-Protein Coupled Receptors and Second Messenger Interactions: A Systems Biology Computational Analysis. PLoS One 2016; 11:e0152869. [PMID: 27138453 PMCID: PMC4854486 DOI: 10.1371/journal.pone.0152869] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Accepted: 03/21/2016] [Indexed: 12/17/2022] Open
Abstract
Insulin secretory in pancreatic beta-cells responses to nutrient stimuli and hormonal modulators include multiple messengers and signaling pathways with complex interdependencies. Here we present a computational model that incorporates recent data on glucose metabolism, plasma membrane potential, G-protein-coupled-receptors (GPCR), cytoplasmic and endoplasmic reticulum calcium dynamics, cAMP and phospholipase C pathways that regulate interactions between second messengers in pancreatic beta-cells. The values of key model parameters were inferred from published experimental data. The model gives a reasonable fit to important aspects of experimentally measured metabolic and second messenger concentrations and provides a framework for analyzing the role of metabolic, hormones and neurotransmitters changes on insulin secretion. Our analysis of the dynamic data provides support for the hypothesis that activation of Ca2+-dependent adenylyl cyclases play a critical role in modulating the effects of glucagon-like peptide 1 (GLP-1), glucose-dependent insulinotropic polypeptide (GIP) and catecholamines. The regulatory properties of adenylyl cyclase isoforms determine fluctuations in cytoplasmic cAMP concentration and reveal a synergistic action of glucose, GLP-1 and GIP on insulin secretion. On the other hand, the regulatory properties of phospholipase C isoforms determine the interaction of glucose, acetylcholine and free fatty acids (FFA) (that act through the FFA receptors) on insulin secretion. We found that a combination of GPCR agonists activating different messenger pathways can stimulate insulin secretion more effectively than a combination of GPCR agonists for a single pathway. This analysis also suggests that the activators of GLP-1, GIP and FFA receptors may have a relatively low risk of hypoglycemia in fasting conditions whereas an activator of muscarinic receptors can increase this risk. This computational analysis demonstrates that study of second messenger pathway interactions will improve understanding of critical regulatory sites, how different GPCRs interact and pharmacological targets for modulating insulin secretion in type 2 diabetes.
Collapse
|
6
|
Tahimic CGT, Long RK, Kubota T, Sun MY, Elalieh H, Fong C, Menendez AT, Wang Y, Vilardaga JP, Bikle DD. Regulation of Ligand and Shear Stress-induced Insulin-like Growth Factor 1 (IGF1) Signaling by the Integrin Pathway. J Biol Chem 2016; 291:8140-9. [PMID: 26865633 DOI: 10.1074/jbc.m115.693598] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Indexed: 01/30/2023] Open
Abstract
Mechanical loading of the skeleton, as achieved during daily movement and exercise, preserves bone mass and stimulates bone formation, whereas skeletal unloading from prolonged immobilization leads to bone loss. A functional interplay between the insulin-like growth factor 1 receptor (IGF1R), a major player in skeletal development, and integrins, mechanosensors, is thought to regulate the anabolic response of osteogenic cells to mechanical load. The mechanistic basis for this cross-talk is unclear. Here we report that integrin signaling regulates activation of IGF1R and downstream targets in response to both IGF1 and a mechanical stimulus. In addition, integrins potentiate responsiveness of IGF1R to IGF1 and mechanical forces. We demonstrate that integrin-associated kinases, Rous sarcoma oncogene (SRC) and focal adhesion kinase (FAK), display distinct actions on IGF1 signaling; FAK regulates IGF1R activation and its downstream effectors, AKT and ERK, whereas SRC controls signaling downstream of IGF1R. These findings linked to our observation that IGF1 assembles the formation of a heterocomplex between IGF1R and integrin β3 subunit indicate that the regulation of IGF1 signaling by integrins proceeds by direct receptor-receptor interaction as a possible means to translate biomechanical forces into osteoanabolic signals.
Collapse
Affiliation(s)
- Candice G T Tahimic
- From the Endocrine Research Unit, Veterans Affairs Medical Center, San Francisco, California 94121, University of California, San Francisco, California 94158
| | - Roger K Long
- Department of Pediatrics, University of California, San Francisco, California 94143
| | - Takuo Kubota
- Department of Pediatrics, Osaka University, Osaka, Japan 565-0871, and
| | - Maggie Yige Sun
- From the Endocrine Research Unit, Veterans Affairs Medical Center, San Francisco, California 94121, University of California, San Francisco, California 94158
| | - Hashem Elalieh
- From the Endocrine Research Unit, Veterans Affairs Medical Center, San Francisco, California 94121, University of California, San Francisco, California 94158
| | - Chak Fong
- From the Endocrine Research Unit, Veterans Affairs Medical Center, San Francisco, California 94121, University of California, San Francisco, California 94158
| | - Alicia T Menendez
- From the Endocrine Research Unit, Veterans Affairs Medical Center, San Francisco, California 94121, University of California, San Francisco, California 94158
| | - Yongmei Wang
- From the Endocrine Research Unit, Veterans Affairs Medical Center, San Francisco, California 94121, University of California, San Francisco, California 94158
| | - Jean-Pierre Vilardaga
- Laboratory for GPCR Biology, Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213
| | - Daniel D Bikle
- From the Endocrine Research Unit, Veterans Affairs Medical Center, San Francisco, California 94121, University of California, San Francisco, California 94158,
| |
Collapse
|
7
|
Gidon A, Feinstein TN, Xiao K, Vilardaga JP. Studying the regulation of endosomal cAMP production in GPCR signaling. Methods Cell Biol 2015; 132:109-26. [PMID: 26928541 DOI: 10.1016/bs.mcb.2015.10.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We describe methods based on live cell fluorescent microscopy and mass spectrometry to characterize the mechanism of endosomal cAMP production and its regulation using the parathyroid hormone (PTH) type 1 receptor as a prime example. These methods permit to measure rapid changes of cAMP levels in response to PTH, kinetics of endosomal ligand-receptor interaction, pH changes associated with receptor trafficking, and to identify the endosomal receptor interactome.
Collapse
Affiliation(s)
- Alexandre Gidon
- Molecular Mechanisms of Mycobacterial Infection, Center for Molecular Inflammation Research, Norwegian University of Science and Technology, Trondheim, Norway
| | - Timothy N Feinstein
- Department of Developmental Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Kunhong Xiao
- Laboratory for GPCR Biology, Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Jean-Pierre Vilardaga
- Laboratory for GPCR Biology, Department of Pharmacology & Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| |
Collapse
|
8
|
Stumpf AD, Hoffmann C. Optical probes based on G protein-coupled receptors - added work or added value? Br J Pharmacol 2015; 173:255-66. [PMID: 26562218 DOI: 10.1111/bph.13382] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Revised: 09/22/2015] [Accepted: 10/26/2015] [Indexed: 12/22/2022] Open
Abstract
In 2003, the first report was published that presented proof of principle for a novel class of FRET biosensors for use in living cells. This novel sensor class was built on the base of GPCRs, which represent an integral transmembrane receptor family passing the membrane seven times and are thus also called the 7TM receptor family. As an estimated number of 30% of all marketed drugs exert their effects by modulating GPCR function, these initial reports promised the gain of novel insights into receptor function. Such FRET sensors have slowly, but progressively, made their way into the standard toolbox for GPCR research as several groups are now reporting on the generation and use of these sensors. By now, FRET sensors have been reported for 18 different GPCRs, and more are expected to be added. These particular receptor sensors have been used to investigate receptor dynamics in living cells to evaluate ligand binding and ligand efficacy in real time, to study voltage and mechanosensitivity of GPCRs or to study the influence of receptor polymorphisms on receptor function in real-time. In this review we will describe the different design principles of these GPCR-based sensors and will summarize their current biological applications in living cells.
Collapse
Affiliation(s)
- A D Stumpf
- Bio-Imaging Center, Rudolf-Virchow-Zentrum für Experimentelle Medizin, University of Würzburg, Würzburg, Germany.,Department of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
| | - C Hoffmann
- Bio-Imaging Center, Rudolf-Virchow-Zentrum für Experimentelle Medizin, University of Würzburg, Würzburg, Germany.,Department of Pharmacology and Toxicology, University of Würzburg, Würzburg, Germany
| |
Collapse
|
9
|
Molden BM, Cooney KA, West K, Van Der Ploeg LHT, Baldini G. Temporal cAMP Signaling Selectivity by Natural and Synthetic MC4R Agonists. Mol Endocrinol 2015; 29:1619-33. [PMID: 26418335 DOI: 10.1210/me.2015-1071] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The melanocortin-4 receptor (MC4R) is a G protein-coupled receptor expressed in the brain, where it controls energy balance through pathways including α-melanocyte-stimulating hormone (α-MSH)-dependent signaling. We have reported that the MC4R can exist in an active conformation that signals constitutively by increasing cAMP levels in the absence of receptor desensitization. We asked whether synthetic MC4R agonists differ in their ability to increase intracellular cAMP over time in Neuro2A cells expressing endogenous MC4R and exogenous, epitope-tagged hemagglutinin-MC4R-green fluorescent protein. By analyzing intracellular cAMP in a temporally resolved Förster resonance energy transfer assay, we show that withdrawal of α-MSH leads to a quick reversal of cAMP induction. By contrast, the synthetic agonist melanotan II (MTII) induces a cAMP signal that persists for at least 1 hour after removal of MTII from the medium and cannot be antagonized by agouti related protein. Similarly, in mHypoE-42 immortalized hypothalamic neurons, MTII, but not α-MSH, induced persistent AMP kinase signal, which occurs downstream of increased cAMP. By using a fluorescence recovery after photobleaching assay, it appears that the receptor exposed to MTII continues to signal after being internalized. Similar to MTII, the synthetic MC4R agonists, THIQ and BIM-22511, but not LY2112688, induced prolonged cAMP signaling after agonist withdrawal. However, agonist-exposed MC4R desensitized to the same extent, regardless of the ligand used and regardless of differences in receptor intracellular retention kinetics. In conclusion, α-MSH and LY2112688, when compared with MTII, THIQ, and BIM-22511, vary in the duration of the acute cAMP response, showing distinct temporal signaling selectivity, possibly linked to specific cell compartments from which cAMP signals may originate.
Collapse
Affiliation(s)
- Brent M Molden
- Department of Biochemistry and Molecular Biology (B.M.M., K.A.C., K.W., G.B.), University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199; and Rhythm Pharmaceuticals, Inc (L.H.T.V.D.P.), Boston, Massachusetts 02116
| | - Kimberly A Cooney
- Department of Biochemistry and Molecular Biology (B.M.M., K.A.C., K.W., G.B.), University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199; and Rhythm Pharmaceuticals, Inc (L.H.T.V.D.P.), Boston, Massachusetts 02116
| | - Kirk West
- Department of Biochemistry and Molecular Biology (B.M.M., K.A.C., K.W., G.B.), University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199; and Rhythm Pharmaceuticals, Inc (L.H.T.V.D.P.), Boston, Massachusetts 02116
| | - Lex H T Van Der Ploeg
- Department of Biochemistry and Molecular Biology (B.M.M., K.A.C., K.W., G.B.), University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199; and Rhythm Pharmaceuticals, Inc (L.H.T.V.D.P.), Boston, Massachusetts 02116
| | - Giulia Baldini
- Department of Biochemistry and Molecular Biology (B.M.M., K.A.C., K.W., G.B.), University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205-7199; and Rhythm Pharmaceuticals, Inc (L.H.T.V.D.P.), Boston, Massachusetts 02116
| |
Collapse
|
10
|
Zhang R, Kavana M. Quantitative analysis of receptor allosterism and its implication for drug discovery. Expert Opin Drug Discov 2015; 10:763-80. [DOI: 10.1517/17460441.2015.1041498] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
|
11
|
Abstract
It has been widely assumed that the production of the ubiquitous second messenger cyclic AMP, which is mediated by cell surface G protein–coupled receptors (GPCRs), and its termination take place exclusively at the plasma membrane. Recent studies reveal that diverse GPCRs do not always follow this conventional paradigm. In the new model, GPCRs mediate G-protein signaling not only from the plasma membrane but also from endosomal membranes. This model proposes that following ligand binding and activation, cell surface GPCRs internalize and redistribute into early endosomes, where trimeric G protein signaling can be maintained for an extended period of time. This Perspective discusses the molecular and cellular mechanistic subtleties as well as the physiological consequences of this unexpected process, which is considerably changing how we think about GPCR signaling and regulation and how we study drugs that target this receptor family.
Collapse
|
12
|
Gidon A, Al-Bataineh MM, Jean-Alphonse FG, Stevenson H, Watanabe T, Louet C, Khatri A, Calero G, Pastor-Soler NM, Gardella TJ, Vilardaga JP. Endosomal GPCR signaling turned off by negative feedback actions of PKA and v-ATPase. Nat Chem Biol 2014; 10:707-9. [PMID: 25064832 PMCID: PMC4138287 DOI: 10.1038/nchembio.1589] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2014] [Accepted: 06/13/2014] [Indexed: 12/13/2022]
Abstract
The PTH receptor is to our knowledge one of the first G protein-coupled receptor (GPCR) found to sustain cAMP signaling after internalization of the ligand-receptor complex in endosomes. This unexpected model is adding a new dimension on how we think about GPCR signaling, but its mechanism is incompletely understood. We report here that endosomal acidification mediated by the PKA action on the v-ATPase provides a negative feedback mechanism by which endosomal receptor signaling is turned off.
Collapse
Affiliation(s)
- Alexandre Gidon
- Laboratory for GPCR Biology, Department of Pharmacology & Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15261, USA
| | - Mohammad M. Al-Bataineh
- Renal-Electrolyte Division, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15261, USA
| | - Frederic G. Jean-Alphonse
- Laboratory for GPCR Biology, Department of Pharmacology & Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15261, USA
| | - Hilary Stevenson
- Department of Structural Biology Department of Medicine, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15261, USA
| | - Tomoyuki Watanabe
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 0114, USA
| | - Claire Louet
- Laboratory for GPCR Biology, Department of Pharmacology & Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15261, USA
| | - Ashok Khatri
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 0114, USA
| | - Guillermo Calero
- Department of Structural Biology Department of Medicine, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15261, USA
| | - Núria M. Pastor-Soler
- Renal-Electrolyte Division, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15261, USA
| | - Thomas J. Gardella
- Endocrine Unit, Massachusetts General Hospital and Harvard Medical School, Boston, MA 0114, USA
| | - Jean-Pierre Vilardaga
- Laboratory for GPCR Biology, Department of Pharmacology & Chemical Biology, University of Pittsburgh, School of Medicine, Pittsburgh, PA 15261, USA
| |
Collapse
|