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Comeo E, Goulding J, Lin CY, Groenen M, Woolard J, Kindon ND, Harwood CR, Platt S, Briddon SJ, Kilpatrick LE, Scammells PJ, Hill SJ, Kellam B. Ligand-Directed Labeling of the Adenosine A 1 Receptor in Living Cells. J Med Chem 2024; 67:12099-12117. [PMID: 38994645 DOI: 10.1021/acs.jmedchem.4c00835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/13/2024]
Abstract
The study of protein function and dynamics in their native cellular environment is essential for progressing fundamental science. To overcome the requirement of genetic modification of the protein or the limitations of dissociable fluorescent ligands, ligand-directed (LD) chemistry has most recently emerged as a complementary, bioorthogonal approach for labeling native proteins. Here, we describe the rational design, development, and application of the first ligand-directed chemistry approach for labeling the A1AR in living cells. We pharmacologically demonstrate covalent labeling of A1AR expressed in living cells while the orthosteric binding site remains available. The probes were imaged using confocal microscopy and fluorescence correlation spectroscopy to study A1AR localization and dynamics in living cells. Additionally, the probes allowed visualization of the specific localization of A1ARs endogenously expressed in dorsal root ganglion (DRG) neurons. LD probes developed here hold promise for illuminating ligand-binding, receptor signaling, and trafficking of the A1AR in more physiologically relevant environments.
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Affiliation(s)
- Eleonora Comeo
- Division of Biomolecular Sciences and Medicinal Chemistry, School of Pharmacy, Biodiscovery Institute, University of Nottingham, Nottingham NG7 2RD, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Joëlle Goulding
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Chia-Yang Lin
- Division of Biomolecular Sciences and Medicinal Chemistry, School of Pharmacy, Biodiscovery Institute, University of Nottingham, Nottingham NG7 2RD, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Marleen Groenen
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Jeanette Woolard
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Nicholas D Kindon
- Division of Biomolecular Sciences and Medicinal Chemistry, School of Pharmacy, Biodiscovery Institute, University of Nottingham, Nottingham NG7 2RD, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Clare R Harwood
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Simon Platt
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Stephen J Briddon
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Laura E Kilpatrick
- Division of Biomolecular Sciences and Medicinal Chemistry, School of Pharmacy, Biodiscovery Institute, University of Nottingham, Nottingham NG7 2RD, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Peter J Scammells
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Stephen J Hill
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, Queens Medical Centre, University of Nottingham, Nottingham NG7 2UH, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
| | - Barrie Kellam
- Division of Biomolecular Sciences and Medicinal Chemistry, School of Pharmacy, Biodiscovery Institute, University of Nottingham, Nottingham NG7 2RD, U.K
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands NG7 2UH, U.K
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Wall MJ, Hill E, Huckstepp R, Barkan K, Deganutti G, Leuenberger M, Preti B, Winfield I, Carvalho S, Suchankova A, Wei H, Safitri D, Huang X, Imlach W, La Mache C, Dean E, Hume C, Hayward S, Oliver J, Zhao FY, Spanswick D, Reynolds CA, Lochner M, Ladds G, Frenguelli BG. Selective activation of Gαob by an adenosine A 1 receptor agonist elicits analgesia without cardiorespiratory depression. Nat Commun 2022; 13:4150. [PMID: 35851064 PMCID: PMC9293909 DOI: 10.1038/s41467-022-31652-2] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2020] [Accepted: 06/23/2022] [Indexed: 02/06/2023] Open
Abstract
The development of therapeutic agonists for G protein-coupled receptors (GPCRs) is hampered by the propensity of GPCRs to couple to multiple intracellular signalling pathways. This promiscuous coupling leads to numerous downstream cellular effects, some of which are therapeutically undesirable. This is especially the case for adenosine A1 receptors (A1Rs) whose clinical potential is undermined by the sedation and cardiorespiratory depression caused by conventional agonists. We have discovered that the A1R-selective agonist, benzyloxy-cyclopentyladenosine (BnOCPA), is a potent and powerful analgesic but does not cause sedation, bradycardia, hypotension or respiratory depression. This unprecedented discrimination between native A1Rs arises from BnOCPA's unique and exquisitely selective activation of Gob among the six Gαi/o subtypes, and in the absence of β-arrestin recruitment. BnOCPA thus demonstrates a highly-specific Gα-selective activation of the native A1R, sheds new light on GPCR signalling, and reveals new possibilities for the development of novel therapeutics based on the far-reaching concept of selective Gα agonism.
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Affiliation(s)
- Mark J Wall
- School of Life Sciences, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL, UK.
| | - Emily Hill
- School of Life Sciences, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL, UK
| | - Robert Huckstepp
- School of Life Sciences, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL, UK
| | - Kerry Barkan
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
| | - Giuseppe Deganutti
- Centre for Sport, Exercise and Life Sciences (CSELS), Faculty of Health and Life Sciences, Coventry University, Coventry, CV1 2DS, UK
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
| | - Michele Leuenberger
- Institute of Biochemistry and Molecular Medicine, University of Bern, 3012, Bern, Switzerland
| | - Barbara Preti
- Institute of Biochemistry and Molecular Medicine, University of Bern, 3012, Bern, Switzerland
| | - Ian Winfield
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
| | - Sabrina Carvalho
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
| | - Anna Suchankova
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
| | | | - Dewi Safitri
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
- Pharmacology and Clinical Pharmacy Research Group, School of Pharmacy, Bandung Institute of Technology, Bandung, 40132, Indonesia
| | - Xianglin Huang
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK
| | - Wendy Imlach
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Innovation Walk, Clayton, VIC, 3800, Australia
| | - Circe La Mache
- School of Life Sciences, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL, UK
| | - Eve Dean
- School of Life Sciences, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL, UK
| | - Cherise Hume
- School of Life Sciences, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL, UK
| | - Stephanie Hayward
- School of Life Sciences, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL, UK
| | - Jess Oliver
- School of Life Sciences, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL, UK
| | | | - David Spanswick
- NeuroSolutions Ltd, Coventry, UK
- Department of Physiology, Monash Biomedicine Discovery Institute, Monash University, Innovation Walk, Clayton, VIC, 3800, Australia
- Warwick Medical School, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL, UK
| | - Christopher A Reynolds
- Centre for Sport, Exercise and Life Sciences (CSELS), Faculty of Health and Life Sciences, Coventry University, Coventry, CV1 2DS, UK
- School of Biological Sciences, University of Essex, Wivenhoe Park, Colchester, CO4 3SQ, UK
| | - Martin Lochner
- Institute of Biochemistry and Molecular Medicine, University of Bern, 3012, Bern, Switzerland
| | - Graham Ladds
- Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1PD, UK.
| | - Bruno G Frenguelli
- School of Life Sciences, University of Warwick, Gibbet Hill Rd, Coventry, CV4 7AL, UK.
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Zuo S, Wang B, Liu J, Kong D, Cui H, Jia Y, Wang C, Xu X, Chen G, Wang Y, Yang L, Zhang K, Ai D, Du J, Shen Y, Yu Y. ER-anchored CRTH2 antagonizes collagen biosynthesis and organ fibrosis via binding LARP6. EMBO J 2021; 40:e107403. [PMID: 34223653 PMCID: PMC8365266 DOI: 10.15252/embj.2020107403] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2020] [Revised: 05/11/2021] [Accepted: 05/20/2021] [Indexed: 02/06/2023] Open
Abstract
Excessive deposition of extracellular matrix, mainly collagen protein, is the hallmark of organ fibrosis. The molecular mechanisms regulating fibrotic protein biosynthesis are unclear. Here, we find that chemoattractant receptor homologous molecule expressed on TH2 cells (CRTH2), a plasma membrane receptor for prostaglandin D2, is trafficked to the endoplasmic reticulum (ER) membrane in fibroblasts in a caveolin-1-dependent manner. ER-anchored CRTH2 binds the collagen mRNA recognition motif of La ribonucleoprotein domain family member 6 (LARP6) and promotes the degradation of collagen mRNA in these cells. In line, CRTH2 deficiency increases collagen biosynthesis in fibroblasts and exacerbates injury-induced organ fibrosis in mice, which can be rescued by LARP6 depletion. Administration of CRTH2 N-terminal peptide reduces collagen production by binding to LARP6. Similar to CRTH2, bumetanide binds the LARP6 mRNA recognition motif, suppresses collagen biosynthesis, and alleviates bleomycin-triggered pulmonary fibrosis in vivo. These findings reveal a novel anti-fibrotic function of CRTH2 in the ER membrane via the interaction with LARP6, which may represent a therapeutic target for fibrotic diseases.
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Affiliation(s)
- Shengkai Zuo
- Tianjin Key Laboratory of Inflammatory BiologyCenter for Cardiovascular DiseasesKey Laboratory of Immune Microenvironment and Disease (Ministry of Education)Department of PharmacologyThe Province and Ministry Co‐sponsored Collaborative Innovation Center for Medical EpigeneticsSchool of Basic Medical SciencesTianjin Medical UniversityTianjinChina
| | - Bei Wang
- Tianjin Key Laboratory of Inflammatory BiologyCenter for Cardiovascular DiseasesKey Laboratory of Immune Microenvironment and Disease (Ministry of Education)Department of PharmacologyThe Province and Ministry Co‐sponsored Collaborative Innovation Center for Medical EpigeneticsSchool of Basic Medical SciencesTianjin Medical UniversityTianjinChina
| | - Jiao Liu
- Tianjin Key Laboratory of Inflammatory BiologyCenter for Cardiovascular DiseasesKey Laboratory of Immune Microenvironment and Disease (Ministry of Education)Department of PharmacologyThe Province and Ministry Co‐sponsored Collaborative Innovation Center for Medical EpigeneticsSchool of Basic Medical SciencesTianjin Medical UniversityTianjinChina
| | - Deping Kong
- Tianjin Key Laboratory of Inflammatory BiologyCenter for Cardiovascular DiseasesKey Laboratory of Immune Microenvironment and Disease (Ministry of Education)Department of PharmacologyThe Province and Ministry Co‐sponsored Collaborative Innovation Center for Medical EpigeneticsSchool of Basic Medical SciencesTianjin Medical UniversityTianjinChina
| | - Hui Cui
- School of Life Science and TechnologyShanghai Tech UniversityShanghaiChina
| | - Yaonan Jia
- School of Pharmaceutical SciencesZhengzhou UniversityZhengzhouChina
| | - Chenyao Wang
- Department of Inflammation and ImmunityLerner Research InstituteCleveland ClinicClevelandOHUSA
| | - Xin Xu
- Tianjin Key Laboratory of Inflammatory BiologyCenter for Cardiovascular DiseasesKey Laboratory of Immune Microenvironment and Disease (Ministry of Education)Department of PharmacologyThe Province and Ministry Co‐sponsored Collaborative Innovation Center for Medical EpigeneticsSchool of Basic Medical SciencesTianjin Medical UniversityTianjinChina
| | - Guilin Chen
- Tianjin Key Laboratory of Inflammatory BiologyCenter for Cardiovascular DiseasesKey Laboratory of Immune Microenvironment and Disease (Ministry of Education)Department of PharmacologyThe Province and Ministry Co‐sponsored Collaborative Innovation Center for Medical EpigeneticsSchool of Basic Medical SciencesTianjin Medical UniversityTianjinChina
| | - Yuanyang Wang
- Tianjin Key Laboratory of Inflammatory BiologyCenter for Cardiovascular DiseasesKey Laboratory of Immune Microenvironment and Disease (Ministry of Education)Department of PharmacologyThe Province and Ministry Co‐sponsored Collaborative Innovation Center for Medical EpigeneticsSchool of Basic Medical SciencesTianjin Medical UniversityTianjinChina
| | - Linlin Yang
- Department of PharmacologySchool of Basic Medical SciencesZhengzhou UniversityZhengzhouChina
| | - Kai Zhang
- Department of Biochemistry and Molecular BiologySchool of Basic Medical SciencesTianjin Medical UniversityTianjinChina
| | - Ding Ai
- Department of Physiology and PathophysiologySchool of Basic Medical SciencesTianjin Medical UniversityTianjinChina
| | - Jie Du
- Beijing Anzhen Hospital of Capital Medical University and Beijing Institute of Heart Lung and Blood Vessel DiseasesBeijingChina
| | - Yujun Shen
- Tianjin Key Laboratory of Inflammatory BiologyCenter for Cardiovascular DiseasesKey Laboratory of Immune Microenvironment and Disease (Ministry of Education)Department of PharmacologyThe Province and Ministry Co‐sponsored Collaborative Innovation Center for Medical EpigeneticsSchool of Basic Medical SciencesTianjin Medical UniversityTianjinChina
| | - Ying Yu
- Tianjin Key Laboratory of Inflammatory BiologyCenter for Cardiovascular DiseasesKey Laboratory of Immune Microenvironment and Disease (Ministry of Education)Department of PharmacologyThe Province and Ministry Co‐sponsored Collaborative Innovation Center for Medical EpigeneticsSchool of Basic Medical SciencesTianjin Medical UniversityTianjinChina
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4
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Gao X, Xue Y, Zhu Z, Chen J, Liu Y, Cheng X, Zhang X, Wang J, Pei X, Wan Q. Nanoscale Zeolitic Imidazolate Framework-8 Activator of Canonical MAPK Signaling for Bone Repair. ACS APPLIED MATERIALS & INTERFACES 2021; 13:97-111. [PMID: 33354968 DOI: 10.1021/acsami.0c15945] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Zeolitic imidazolate framework-8 (ZIF-8) is an important type of metal organic framework and has found numerous applications in the biomedical field. Our previous studies have demonstrated that nano ZIF-8-based titanium implants could promote osseointegration; however, its osteogenic capacity and the related mechanisms in bone regeneration have not been fully clarified. Presented here is a nanoscale ZIF-8 that could drive rat bone mesenchymal stem cell (rBMSC) differentiation into osteoblasts both in vitro and in vivo, and interestingly, nano ZIF-8 exhibited a better osteogenic effect compared with ionic conditions of Zn at the same concentration of Zn2+. Moreover, the cellular uptake mechanisms of the nanoparticles were thoroughly clarified. Specifically, nano ZIF-8 could enter the rBMSC cytoplasm probably via caveolae-mediated endocytosis and macropinocytosis. The intracellular and extracellular Zn2+ released from nano ZIF-8 and the receptors involved in the endocytosis may play a role in inducing activation of key osteogenic pathways. Furthermore, through transcriptome sequencing, multiple osteogenic pathways were found to be upregulated, among which nano ZIF-8 primarily phosphorylated ERK, thus activating the canonical mitogen-activated protein kinase pathway and promoting the osteogenesis of rBMSCs. Taken together, this study helps to elucidate the mechanism by which nano ZIF-8 regulates osteogenesis and suggests it to be a potential biomaterial for constructing multifunctional composites in bone tissue engineering.
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Affiliation(s)
- Xiaomeng Gao
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, PR China
| | - Yiyuan Xue
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, PR China
| | - Zhou Zhu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, PR China
| | - Junyu Chen
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, PR China
| | - Yanhua Liu
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, PR China
| | - Xinting Cheng
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, PR China
| | - Xin Zhang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, PR China
| | - Jian Wang
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, PR China
| | - Xibo Pei
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, PR China
| | - Qianbing Wan
- State Key Laboratory of Oral Diseases, National Clinical Research Center for Oral Diseases, Department of Prosthodontics, West China Hospital of Stomatology, Sichuan University, Chengdu 610041, PR China
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Functional Complexes of Angiotensin-Converting Enzyme 2 and Renin-Angiotensin System Receptors: Expression in Adult but Not Fetal Lung Tissue. Int J Mol Sci 2020; 21:ijms21249602. [PMID: 33339432 PMCID: PMC7766085 DOI: 10.3390/ijms21249602] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 12/04/2020] [Accepted: 12/11/2020] [Indexed: 12/17/2022] Open
Abstract
Angiotensin-converting enzyme 2 (ACE2) is a membrane peptidase and a component of the renin-angiotensin system (RAS) that has been found in cells of all organs, including the lungs. While ACE2 has been identified as the receptor for severe acute respiratory syndrome (SARS) coronaviruses, the mechanism underlying cell entry remains unknown. Human immunodeficiency virus infects target cells via CXC chemokine receptor 4 (CXCR4)-mediated endocytosis. Furthermore, CXCR4 interacts with dipeptidyl peptidase-4 (CD26/DPPIV), an enzyme that cleaves CXCL12/SDF-1, which is the chemokine that activates this receptor. By analogy, we hypothesized that ACE2 might also be capable of interactions with RAS-associated G-protein coupled receptors. Using resonance energy transfer and cAMP and mitogen-activated protein kinase signaling assays, we found that human ACE2 interacts with RAS-related receptors, namely the angiotensin II type 1 receptor (AT1R), the angiotensin II type 2 receptor (AT2R), and the MAS1 oncogene receptor (MasR). Although these interactions lead to minor alterations of signal transduction, ligand binding to AT1R and AT2R, but not to MasR, resulted in the upregulation of ACE2 cell surface expression. Proximity ligation assays performed in situ revealed macromolecular complexes containing ACE2 and AT1R, AT2R or MasR in adult but not fetal mouse lung tissue. These findings highlight the relevance of RAS in SARS-CoV-2 infection and the role of ACE2-containing complexes as potential therapeutic targets.
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Buwa N, Mazumdar D, Balasubramanian N. Caveolin1 Tyrosine-14 Phosphorylation: Role in Cellular Responsiveness to Mechanical Cues. J Membr Biol 2020; 253:509-534. [PMID: 33089394 DOI: 10.1007/s00232-020-00143-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Accepted: 10/05/2020] [Indexed: 02/07/2023]
Abstract
The plasma membrane is a dynamic lipid bilayer that engages with the extracellular microenvironment and intracellular cytoskeleton. Caveolae are distinct plasma membrane invaginations lined by integral membrane proteins Caveolin1, 2, and 3. Caveolae formation and stability is further supported by additional proteins including Cavin1, EHD2, Pacsin2 and ROR1. The lipid composition of caveolar membranes, rich in cholesterol and phosphatidylserine, actively contributes to caveolae formation and function. Post-translational modifications of Cav1, including its phosphorylation of the tyrosine-14 residue (pY14Cav1) are vital to its function in and out of caveolae. Cells that experience significant mechanical stress are seen to have abundant caveolae. They play a vital role in regulating cellular signaling and endocytosis, which could further affect the abundance and distribution of caveolae at the PM, contributing to sensing and/or buffering mechanical stress. Changes in membrane tension in cells responding to multiple mechanical stimuli affects the organization and function of caveolae. These mechanical cues regulate pY14Cav1 levels and function in caveolae and focal adhesions. This review, along with looking at the mechanosensitive nature of caveolae, focuses on the role of pY14Cav1 in regulating cellular mechanotransduction.
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Affiliation(s)
- Natasha Buwa
- Indian Institute of Science Education and Research, Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India
| | - Debasmita Mazumdar
- Indian Institute of Science Education and Research, Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India
| | - Nagaraj Balasubramanian
- Indian Institute of Science Education and Research, Pune, Dr. Homi Bhabha Road, Pashan, Pune, 411008, India.
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Soave M, Kellam B, Woolard J, Briddon SJ, Hill SJ. NanoBiT Complementation to Monitor Agonist-Induced Adenosine A 1 Receptor Internalization. SLAS DISCOVERY 2019; 25:186-194. [PMID: 31583945 PMCID: PMC6974774 DOI: 10.1177/2472555219880475] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Receptor internalization in response to prolonged agonist treatment is an
important regulator of G protein–coupled receptor (GPCR) function. The adenosine
A1 receptor (A1AR) is one of the adenosine receptor
family of GPCRs, and evidence for its agonist-induced internalization is
equivocal. The recently developed NanoBiT technology uses split NanoLuc
Luciferase to monitor changes in protein interactions. We have modified the
human A1AR on the N-terminus with the small high-affinity HiBiT tag.
In the presence of the large NanoLuc subunit (LgBiT), complementation occurs,
reconstituting a full-length functional NanoLuc Luciferase. Here, we have used
complemented luminescence to monitor the internalization of the A1AR
in living HEK293 cells. Agonist treatment resulted in a robust decrease in
cell-surface luminescence, indicating an increase in A1AR
internalization. These responses were inhibited by the A1AR-selective
antagonist 1,3-dipropyl-8-cyclopentylxanthine (DPCPX), with an antagonist
affinity that closely matched that measured using ligand binding with a
fluorescent A1 receptor antagonist (CA200645). The agonist potencies
for inducing A1AR internalization were very similar to the affinities
previously determined by ligand binding, suggesting little or no amplification
of the internalization response. By complementing the HiBiT tag to exogenous
purified LgBiT, it was also possible to perform NanoBRET ligand-binding
experiments using HiBiT–A1AR. This study demonstrates the use of
NanoBiT technology to monitor internalization of the A1AR and offers
the potential to combine these experiments with NanoBRET ligand-binding
assays.
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Affiliation(s)
- Mark Soave
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, UK.,Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, UK
| | - Barrie Kellam
- Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, UK.,School of Pharmacy, Centre for Biomolecular Sciences, University of Nottingham, Nottingham, UK
| | - Jeanette Woolard
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, UK.,Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, UK
| | - Stephen J Briddon
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, UK.,Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, UK
| | - Stephen J Hill
- Division of Physiology, Pharmacology and Neuroscience, School of Life Sciences, University of Nottingham Medical School, Queen's Medical Centre, Nottingham, UK.,Centre of Membrane Proteins and Receptors (COMPARE), University of Birmingham and University of Nottingham, The Midlands, UK
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8
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Filippini A, Sica G, D'Alessio A. The caveolar membrane system in endothelium: From cell signaling to vascular pathology. J Cell Biochem 2018; 119:5060-5071. [PMID: 29637636 DOI: 10.1002/jcb.26793] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Accepted: 02/16/2018] [Indexed: 12/12/2022]
Abstract
Caveolae are 50- to 100-nm cholesterol and glycosphingolipid-rich flask-shaped invaginations commonly observed in many terminally differentiated cells. These organelles have been described in many cell types and are particularly abundant in endothelial cells, where they have been involved in the regulation of certain signaling pathways. Specific scaffolding proteins termed caveolins, along with the more recently discovered members of the cavin family, represent the major protein components during caveolae biogenesis. In addition, multiple studies aimed to investigate the expression and the regulation of these proteins significantly contributed to elucidate the role of caveolae and caveolins in endothelial cell physiology and disease. The aim of this review is to survey recent evidence of the involvement of the caveolar network in endothelial cell biology and endothelial cell dysfunction.
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Affiliation(s)
- Antonio Filippini
- Department of Anatomy, Histology, Forensic Medicine and Orthopaedics, Unit of Histology and Medical Embryology, Sapienza University of Rome, Rome, Italy
| | - Gigliola Sica
- Istituto di Istologia ed Embriologia, Università Cattolica del Sacro Cuore, Rome, Italy
| | - Alessio D'Alessio
- Istituto di Istologia ed Embriologia, Università Cattolica del Sacro Cuore, Rome, Italy
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9
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Leiva A, Guzmán-Gutiérrez E, Contreras-Duarte S, Fuenzalida B, Cantin C, Carvajal L, Salsoso R, Gutiérrez J, Pardo F, Sobrevia L. Adenosine receptors: Modulators of lipid availability that are controlled by lipid levels. Mol Aspects Med 2017; 55:26-44. [DOI: 10.1016/j.mam.2017.01.007] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Revised: 01/25/2017] [Accepted: 01/25/2017] [Indexed: 12/20/2022]
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10
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Nguyen KCT, Cho KA. Versatile Functions of Caveolin-1 in Aging-related Diseases. Chonnam Med J 2017; 53:28-36. [PMID: 28184336 PMCID: PMC5299127 DOI: 10.4068/cmj.2017.53.1.28] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Revised: 10/10/2016] [Accepted: 10/11/2016] [Indexed: 12/24/2022] Open
Abstract
Caveolin-1 (Cav-1) is a trans-membrane protein that is a major component of the caveolae structure on the plasma membrane. Cav-1 is involved in the regulation of various cellular processes, including cell growth, differentiation, endocytosis, and in particular it has been implied in cellular senescence. Here we review current knowledge about Cav-1 in cellular signaling and discuss the role of Cav-1 in aging-related diseases.
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Affiliation(s)
- Kim Cuc Thi Nguyen
- Deparment of Life Science, ThaiNguyen University of Science, TanThinh Ward, ThaiNguyen, VietNam
| | - Kyung A Cho
- Department of Biochemistry, Chonnam National University Medical School, Gwangju, Korea
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11
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A1 Adenosine Receptor Activation Modulates Central Nervous System Development and Repair. Mol Neurobiol 2016; 54:8128-8139. [DOI: 10.1007/s12035-016-0292-6] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2016] [Accepted: 11/08/2016] [Indexed: 01/22/2023]
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12
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Navarro G, Borroto-Escuela DO, Fuxe K, Franco R. Potential of caveolae in the therapy of cardiovascular and neurological diseases. Front Physiol 2014; 5:370. [PMID: 25324780 PMCID: PMC4179688 DOI: 10.3389/fphys.2014.00370] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 09/08/2014] [Indexed: 12/25/2022] Open
Abstract
Caveolae are membrane micro-domains enriched in cholesterol, sphingolipids and caveolins, which are transmembrane proteins with a hairpin-like structure. Caveolae participate in receptor-mediated trafficking of cell surface receptors and receptor-mediated signaling. Furthermore, caveolae participate in clathrin-independent endocytosis of membrane receptors. On the one hand, caveolins are involved in vascular and cardiac dysfunction. Also, neurological abnormalities in caveolin-1 knockout mice and a link between caveolin-1 gene haplotypes and neurodegenerative diseases have been reported. The aim of this article is to present the rationale for considering caveolae as potential targets in cardiovascular and neurological diseases.
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Affiliation(s)
- Gemma Navarro
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona Barcelona, Spain
| | | | - Kjell Fuxe
- Department of Neuroscience, Karolinska Institutet Stockholm, Sweden
| | - Rafael Franco
- Departament de Bioquímica i Biologia Molecular, Facultat de Biologia, Universitat de Barcelona Barcelona, Spain
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13
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Franco N, Franco R. Understanding the added value of g-protein-coupled receptor heteromers. SCIENTIFICA 2014; 2014:362937. [PMID: 24864225 PMCID: PMC4017843 DOI: 10.1155/2014/362937] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 03/10/2014] [Indexed: 06/03/2023]
Abstract
G-protein-coupled receptors (GPCRs) constitute the most populated family of proteins within the human genome. Since the early sixties work on GPCRs and on GPCR-mediated signaling has led to a number of awards, the most recent being the Nobel Prize in Chemistry for 2012. The future of GPCRs research is surely based on their capacity for heteromerization. Receptor heteromers offer a series of challenges that will help in providing success in academic/basic research and translation into more effective and safer drugs.
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Affiliation(s)
- Nuria Franco
- Department Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Prevosti Building, Diagonal 645, 08028 Barcelona, Spain
| | - Rafael Franco
- Department Biochemistry and Molecular Biology, Faculty of Biology, University of Barcelona, Prevosti Building, Diagonal 645, 08028 Barcelona, Spain
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14
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Cardiovascular adenosine receptors: Expression, actions and interactions. Pharmacol Ther 2013; 140:92-111. [DOI: 10.1016/j.pharmthera.2013.06.002] [Citation(s) in RCA: 163] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2013] [Accepted: 05/28/2013] [Indexed: 12/26/2022]
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15
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Franco R, Martínez-Pinilla E, Ricobaraza A, McCormick PJ. Challenges in the development of heteromer-GPCR-based drugs. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2013; 117:143-62. [PMID: 23663968 DOI: 10.1016/b978-0-12-386931-9.00006-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
G-protein-coupled receptors are targets of a variety of diseases. Drug screening has been classically performed assuming the occurrence of monomeric receptors. As more and more receptor heteromers are identified, the challenge is now to develop screening assays to select heteromer-specific drugs. These drugs may, for instance, be able to interact preferentially with prerather than with postsynaptic receptors. Heteromer-based drug discovery opens new perspectives in both Academic pursuits and for the Pharmaceutical industry.
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Affiliation(s)
- Rafael Franco
- Applied Medical Research Center (CIMA), University of Navarra, Pamplona, Spain
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16
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Stary CM, Tsutsumi YM, Patel PM, Head BP, Patel HH, Roth DM. Caveolins: targeting pro-survival signaling in the heart and brain. Front Physiol 2012; 3:393. [PMID: 23060817 PMCID: PMC3464704 DOI: 10.3389/fphys.2012.00393] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 09/14/2012] [Indexed: 12/20/2022] Open
Abstract
The present review discusses intracellular signaling moieties specific to membrane lipid rafts (MLRs) and the scaffolding proteins caveolin and introduces current data promoting their potential role in the treatment of pathologies of the heart and brain. MLRs are discreet microdomains of the plasma membrane enriched in gylcosphingolipids and cholesterol that concentrate and localize signaling molecules. Caveolin proteins are necessary for the formation of MLRs, and are responsible for coordinating signaling events by scaffolding and enriching numerous signaling moieties in close proximity. Specifically in the heart and brain, caveolins are necessary for the cytoprotective phenomenon termed ischemic and anesthetic preconditioning. Targeted overexpression of caveolin in the heart and brain leads to induction of multiple pro-survival and pro-growth signaling pathways; thus, caveolins represent a potential novel therapeutic target for cardiac and neurological pathologies.
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Affiliation(s)
- Creed M Stary
- Department of Anesthesiology, Veterans Affairs San Diego Healthcare System, University of California San Diego, La Jolla, CA, USA
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17
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Byrne DP, Dart C, Rigden DJ. Evaluating caveolin interactions: do proteins interact with the caveolin scaffolding domain through a widespread aromatic residue-rich motif? PLoS One 2012; 7:e44879. [PMID: 23028656 PMCID: PMC3444507 DOI: 10.1371/journal.pone.0044879] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 08/09/2012] [Indexed: 01/08/2023] Open
Abstract
Caveolins are coat proteins of caveolae, small flask-shaped pits of the plasma membranes of most cells. Aside from roles in caveolae formation, caveolins recruit, retain and regulate many caveolae-associated signalling molecules. Caveolin-protein interactions are commonly considered to occur between a ∼20 amino acid region within caveolin, the caveolin scaffolding domain (CSD), and an aromatic-rich caveolin binding motif (CBM) on the binding partner (фXфXXXXф, фXXXXфXXф or фXфXXXXфXXф, where ф is an aromatic and X an unspecified amino acid). The CBM resembles a typical linear motif - a short, simple sequence independently evolved many times in different proteins for a specific function. Here we exploit recent improvements in bioinformatics tools and in our understanding of linear motifs to critically examine the role of CBMs in caveolin interactions. We find that sequences conforming to the CBM occur in 30% of human proteins, but find no evidence for their statistical enrichment in the caveolin interactome. Furthermore, sequence- and structure-based considerations suggest that CBMs do not have characteristics commonly associated with true interaction motifs. Analysis of the relative solvent accessible area of putative CBMs shows that the majority of their aromatic residues are buried within the protein and are thus unlikely to interact directly with caveolin, but may instead be important for protein structural stability. Together, these findings suggest that the canonical CBM may not be a common characteristic of caveolin-target interactions and that interfaces between caveolin and targets may be more structurally diverse than presently appreciated.
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Affiliation(s)
- Dominic P. Byrne
- Institute of Integrative Biology, The University of Liverpool, Liverpool, United Kingdom
| | - Caroline Dart
- Institute of Integrative Biology, The University of Liverpool, Liverpool, United Kingdom
| | - Daniel J. Rigden
- Institute of Integrative Biology, The University of Liverpool, Liverpool, United Kingdom
- * E-mail:
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18
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Uptake mechanisms of non-viral gene delivery. J Control Release 2012; 158:371-8. [DOI: 10.1016/j.jconrel.2011.09.093] [Citation(s) in RCA: 229] [Impact Index Per Article: 19.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Accepted: 09/23/2011] [Indexed: 01/04/2023]
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19
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Hamil NE, Cock HR, Walker MC. Acute down-regulation of adenosine A1 receptor activity in status epilepticus. Epilepsia 2011; 53:177-88. [DOI: 10.1111/j.1528-1167.2011.03340.x] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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20
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Maternal glutamate intake during gestation and lactation regulates adenosine A1 and A2A receptors in rat brain from mothers and neonates. Neuroscience 2011; 199:133-42. [DOI: 10.1016/j.neuroscience.2011.09.045] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2011] [Revised: 09/08/2011] [Accepted: 09/22/2011] [Indexed: 11/24/2022]
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21
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Desensitization of adenosine A(1) receptors in rat immature cortical neurons. Eur J Pharmacol 2011; 670:365-71. [PMID: 21946103 DOI: 10.1016/j.ejphar.2011.09.027] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2011] [Revised: 09/05/2011] [Accepted: 09/12/2011] [Indexed: 12/11/2022]
Abstract
Adenosine plays an important neuroprotective role in brain, usually mediated by the activation of adenosine A₁ receptors. Prolonged activation of a G-protein-coupled receptor generally leads to the partial loss of the responsiveness of receptor-mediated transduction pathways (desensitization). Rat immature cortical neurons were treated with 100 nM⁻N⁶-phenylisopropyladenosine (R-PIA), a selective A₁ receptor agonist, and the effect on adenosine A₁ receptor/adenylyl cyclase pathway was studied. Incubation with R-PIA for 6, 12, 24 and 48 h elicited a time-dependent decrease in adenosine A₁ receptors in plasma membranes (92, 58, 43 and 26% of control, respectively), which was associated with variations in microsomal fraction (21, 56, 124 and 233% of control, respectively), suggesting the internalization and down-regulation of adenosine A₁ receptors. Moreover, real-time PCR assays showed a significant increase in mRNA levels coding adenosine A₁ receptor after the longest treatment period (48 h). In addition, αGi₁₋₂ protein levels detected in microsomes and mRNA levels coding αGi₁ protein were increased after 48 h of treatment with R-PIA, suggesting the synthesis of new αGi₁ proteins. Finally, adenylyl cyclase inhibition elicited by 2-Chloro-N6-cyclopentyladenosine (CPA), a selective adenosine A₁ receptor agonist, was significantly reduced after 12, 24 and 48h of treatment (37, 24 and 23%, respectively) as compared to controls (54%), suggesting the desensitization of adenosine A₁ receptor/adenylyl cyclase pathway. These results suggest that adenosine A₁ receptors desensitize slowly after prolonged receptor activation in immature cortical neurons, showing mechanisms of desensitization similar to those described not only in fetal but also in adult rat brain.
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22
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Verzijl D, IJzerman AP. Functional selectivity of adenosine receptor ligands. Purinergic Signal 2011; 7:171-92. [PMID: 21544511 PMCID: PMC3146648 DOI: 10.1007/s11302-011-9232-0] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2011] [Accepted: 04/05/2011] [Indexed: 12/11/2022] Open
Abstract
Adenosine receptors are plasma membrane proteins that transduce an extracellular signal into the interior of the cell. Basically every mammalian cell expresses at least one of the four adenosine receptor subtypes. Recent insight in signal transduction cascades teaches us that the current classification of receptor ligands into agonists, antagonists, and inverse agonists relies very much on the experimental setup that was used. Upon activation of the receptors by the ubiquitous endogenous ligand adenosine they engage classical G protein-mediated pathways, resulting in production of second messengers and activation of kinases. Besides this well-described G protein-mediated signaling pathway, adenosine receptors activate scaffold proteins such as β-arrestins. Using innovative and sensitive experimental tools, it has been possible to detect ligands that preferentially stimulate the β-arrestin pathway over the G protein-mediated signal transduction route, or vice versa. This phenomenon is referred to as functional selectivity or biased signaling and implies that an antagonist for one pathway may be a full agonist for the other signaling route. Functional selectivity makes it necessary to redefine the functional properties of currently used adenosine receptor ligands and opens possibilities for new and more selective ligands. This review focuses on the current knowledge of functionally selective adenosine receptor ligands and on G protein-independent signaling of adenosine receptors through scaffold proteins.
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Affiliation(s)
- Dennis Verzijl
- Division of Medicinal Chemistry, Leiden/Amsterdam Center for Drug Research, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands
| | - Ad P. IJzerman
- Division of Medicinal Chemistry, Leiden/Amsterdam Center for Drug Research, Leiden University, PO Box 9502, 2300 RA Leiden, The Netherlands
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23
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Baines AE, Corrêa SAL, Irving AJ, Frenguelli BG. Differential trafficking of adenosine receptors in hippocampal neurons monitored using GFP- and super-ecliptic pHluorin-tagged receptors. Neuropharmacology 2011; 61:1-11. [PMID: 21315741 DOI: 10.1016/j.neuropharm.2011.02.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 01/28/2011] [Accepted: 02/02/2011] [Indexed: 01/18/2023]
Abstract
Adenosine receptors (ARs) modulate many cellular and systems-level processes in the mammalian CNS. However, little is known about the trafficking of ARs in neurons, despite their importance in controlling seizure activity and in neuroprotection in cerebral ischaemia. To address this we examined the agonist-dependent internalisation of C-terminal GFP-tagged A(1)Rs, A(2A)Rs and A(3)Rs in primary hippocampal neurons. Furthermore, we developed a novel super-ecliptic pHluorin (SEP)-tagged A(1)R which, via the N-terminal SEP tag, reports the cell-surface expression and trafficking of A(1)Rs in real-time. We demonstrate the differential trafficking of ARs in neurons: A(3)Rs internalise more rapidly than A1Rs, with little evidence of appreciable A(2A)R trafficking over the time-course of the experiments. Furthermore, the novel SEP-A(1)R construct revealed the time-course of internalisation and recovery of cell-surface expression to occur within minutes of agonist exposure and removal, respectively. These observations highlight the labile nature of A(1)R and A(3)Rs when expressed at the neuronal plasma membrane. Given the high levels of adenosine in the brain during ischaemia and seizures, internalisation of the inhibitory A(1)R may result in hyperexcitability, increased brain damage and the development of chronic epileptic states.
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Affiliation(s)
- A E Baines
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
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24
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Amadio S, Apolloni S, D'Ambrosi N, Volonté C. Purinergic signalling at the plasma membrane: a multipurpose and multidirectional mode to deal with amyotrophic lateral sclerosis and multiple sclerosis. J Neurochem 2011; 116:796-805. [PMID: 21214557 DOI: 10.1111/j.1471-4159.2010.07025.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
ATP is a widespread and multipurpose signalling molecule copiously released in the extracellular environment of the whole nervous system upon cell activation, stress, or damage. Extracellular ATP is also a multidirectional information molecule, given the concurrent presence at the plasma membrane of various targets for ATP. These include ectonucleotidases (metabolizing ATP down to adenosine), ATP/adenosine transporters, P2 receptors for purine/pyrimidine nucleotides (ligand-gated ion channels P2X receptors and G-protein-coupled P2Y receptors), in addition to metabotropic P1 receptors for nucleosides. All these targets rarely operate as single units, rather they associate with each other at the plasma membrane as multi-protein complexes. Altogether, they control the duration, magnitude and/or direction of the signals triggered and propagated by purine/pyrimidine ligands, and the impact that each single ligand has on a variety of short- and long-term functions. A strict control system allows assorted, even divergent, biological outcomes. Among these, we enumerate cell-to-cell communication, tropic, trophic, but also noxious actions causing the insurgence/progression of pathological conditions. Here, we show that purinergic signalling in the nervous system can be instrumental for instance to neurodegenerative and neuroinflammatory diseases such as amyotrophic lateral sclerosis and multiple sclerosis.
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Affiliation(s)
- Susanna Amadio
- CNR, Institute of Neurobiology and Molecular Medicine/Santa Lucia Foundation, Rome, Italy
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25
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Feiner EC, Chung P, Jasmin JF, Zhang J, Whitaker-Menezes D, Myers V, Song J, Feldman EW, Funakoshi H, Degeorge BR, Yelamarty RV, Koch WJ, Lisanti MP, McTiernan CF, Cheung JY, Bristow MR, Chan TO, Feldman AM. Left ventricular dysfunction in murine models of heart failure and in failing human heart is associated with a selective decrease in the expression of caveolin-3. J Card Fail 2010; 17:253-63. [PMID: 21362533 DOI: 10.1016/j.cardfail.2010.10.008] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Revised: 10/07/2010] [Accepted: 10/25/2010] [Indexed: 01/03/2023]
Abstract
BACKGROUND Caveolins are scaffolding proteins that are integral components of caveolae, flask-shaped invaginations in the membranes of all mammalian cells. Caveolin-1 and -2 are expressed ubiquitously, whereas caveolin-3 is found only in muscle. The role of caveolin-3 in heart muscle disease is controversial. METHODS AND RESULTS The present study was undertaken to assess the effects of left ventricular dysfunction on the expression of caveolin proteins using 2 well characterized models of murine heart failure and failing human heart. Transgenic mice with constitutive overexpression of A(1)-adenosine receptor (A(1)-TG) demonstrated cardiac dilatation and decreased left ventricular function at 10 weeks of age. This was accompanied by a marked decrease in caveolin-3 mRNA and protein levels compared with non-TG control mice. The change in caveolin-3 expression was selective, because levels of caveolin-1 and -2 did not change. Confocal imaging of myocytes isolated from A(1)-TG mice demonstrated a loss of the plate-like appearance of T tubules. Caveolin-3 levels were also reduced in hearts from mice overexpressing tumor necrosis factor α. There was a direct relationship between caveolin-3 expression and fractional shortening in all mice that were studied (r = 0.65; P < .001). Although we could not demonstrate a significant decrease in caveolin-3 levels in failing human heart, we did find a direct correlation (r = 0.7; P < .05) between levels of caveolin-3 protein and Ca(2+)-adenosine triphosphatase, a marker of the heart failure phenotype. CONCLUSIONS These results suggest a relationship between left ventricular dysfunction and caveolin-3 levels and suggest that caveolin-3 may provide a novel target for heart failure therapy.
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Affiliation(s)
- Ellina Cheskis Feiner
- Department of Medicine, Center for Translational Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA
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26
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Lasley RD. Adenosine receptors and membrane microdomains. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:1284-9. [PMID: 20888790 DOI: 10.1016/j.bbamem.2010.09.019] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2010] [Revised: 09/20/2010] [Accepted: 09/25/2010] [Indexed: 11/16/2022]
Abstract
Adenosine receptors are a member of the large family of seven transmembrane spanning G protein coupled receptors. The four adenosine receptor subtypes-A(1), A(2a), A(2b), A(3)-exert their effects via the activation of one or more heterotrimeric G proteins resulting in the modulation of intracellular signaling. Numerous studies over the past decade have documented the complexity of G protein coupled receptor signaling at the level of protein-protein interactions as well as through signaling cross talk. With respect to adenosine receptors, the activation of one receptor subtype can have profound direct effects in one cell type but little or no effect in other cells. There is significant evidence that the compartmentation of subcellular signaling plays a physiological role in the fidelity of G protein coupled receptor signaling. This compartmentation is evident at the level of the plasma membrane in the form of membrane microdomains such as caveolae and lipid rafts. This review will summarize and critically assess our current understanding of the role of membrane microdomains in regulating adenosine receptor signaling.
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Affiliation(s)
- Robert D Lasley
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA.
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27
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Castillo CA, León D, Ruiz MA, Albasanz JL, Martín M. Modulation of adenosine A1 and A2A receptors in C6 glioma cells during hypoxia: involvement of endogenous adenosine. J Neurochem 2010; 105:2315-29. [PMID: 18315561 DOI: 10.1111/j.1471-4159.2008.05314.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
During hypoxia, extracellular adenosine levels are increased to prevent cell damage, playing a neuroprotective role mainly through adenosine A(1) receptors. The aim of the present study was to analyze the effect of hypoxia in both adenosine A(1) and A(2A) receptors endogenously expressed in C6 glioma cells. Two hours of hypoxia (5% O(2)) caused a significant decrease in adenosine A(1) receptors. The same effect was observed at 6 h and 24 h of hypoxia. However, adenosine A(2A) receptors were significantly increased at the same times. These effects were not due to hypoxia-induced alterations in cells number or viability. Changes in receptor density were not associated with variations in the rate of gene expression. Furthermore, hypoxia did not alter HIF-1alpha expression in C6 cells. However, HIF-3alpha, CREB and CREM were decreased. Adenosine A(1) and A(2A) receptor density in normoxic C6 cells treated with adenosine for 2, 6 and 24 h was similar to that observed in cells after oxygen deprivation. When C6 cells were subjected to hypoxia in the presence of adenosine deaminase, the density of receptors was not significantly modulated. Moreover, DPCPX, an A(1) receptor antagonist, blocked the effects of hypoxia on these receptors, while ZM241385, an A(2A) receptor antagonist, was unable to prevent these changes. These results suggest that moderate hypoxia modulates adenosine receptors and cAMP response elements in glial cells, through a mechanism in which endogenous adenosine and tonic A(1) receptor activation is involved.
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Affiliation(s)
- Carlos A Castillo
- Departamento de Química Inorgánica, Orgánica y Bioquímica, Facultad de Químicas, Centro Regional de Investigaciones Biomédicas, Universidad de Castilla-La Mancha, Ciudad Real, Spain
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28
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Mundell S, Kelly E. Adenosine receptor desensitization and trafficking. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2010; 1808:1319-28. [PMID: 20550943 DOI: 10.1016/j.bbamem.2010.06.007] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Revised: 05/28/2010] [Accepted: 06/06/2010] [Indexed: 11/26/2022]
Abstract
As with the majority of G-protein-coupled receptors, all four of the adenosine receptor subtypes are known to undergo agonist-induced regulation in the form of desensitization and trafficking. These processes can limit the ability of adenosine receptors to couple to intracellular signalling pathways and thus reduce the ability of adenosine receptor agonists as well as endogenous adenosine to produce cellular responses. In addition, since adenosine receptors couple to multiple signalling pathways, these pathways may desensitize differentially, while the desensitization of one pathway could even trigger signalling via another. Thus, the overall picture of adenosine receptor regulation can be complex. For all adenosine receptor subtypes, there is evidence to implicate arrestins in agonist-induced desensitization and trafficking, but there is also evidence for other possible forms of regulation, including second messenger-dependent kinase regulation, heterologous effects involving G proteins, and the involvement of non-clathrin trafficking pathways such as caveolae. In this review, the evidence implicating these mechanisms is summarized for each adenosine receptor subtype, and we also discuss those issues of adenosine receptor regulation that remain to be resolved as well as likely directions for future research in this field.
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Affiliation(s)
- Stuart Mundell
- Department of Physiology and Pharmacology, University of Bristol, Bristol, UK
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29
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Singh RD, Marks DL, Holicky EL, Wheatley CL, Kaptzan T, Sato SB, Kobayashi T, Ling K, Pagano RE. Gangliosides and beta1-integrin are required for caveolae and membrane domains. Traffic 2009; 11:348-60. [PMID: 20051050 DOI: 10.1111/j.1600-0854.2009.01022.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Caveolae are plasma membrane domains involved in the uptake of certain pathogens and toxins. Internalization of some cell surface integrins occurs via caveolae suggesting caveolae may play a crucial role in modulating integrin-mediated adhesion and cell migration. Here we demonstrate a critical role for gangliosides (sialo-glycosphingolipids) in regulating caveolar endocytosis in human skin fibroblasts. Pretreatment of cells with endoglycoceramidase (cleaves glycosphingolipids) or sialidase (modifies cell surface gangliosides and glycoproteins) selectively inhibited caveolar endocytosis by >70%, inhibited the formation of plasma membrane domains enriched in sphingolipids and cholesterol ('lipid rafts'), reduced caveolae and caveolin-1 at the plasma membrane by approximately 80%, and blunted activation of beta1-integrin, a protein required for caveolar endocytosis in these cells. These effects could be reversed by a brief incubation with gangliosides (but not with asialo-gangliosides or other sphingolipids) at 10 degrees C, suggesting that sialo-lipids are critical in supporting caveolar endocytosis. Endoglycoceramidase treatment also caused a redistribution of focal adhesion kinase, paxillin, talin, and PIP Kinase Igamma away from focal adhesions. The effects of sialidase or endoglycoceramidase on membrane domains and the distribution of caveolin-1 could be recapitulated by beta1-integrin knockdown. These results suggest that both gangliosides and beta1-integrin are required for maintenance of caveolae and plasma membrane domains.
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Affiliation(s)
- Raman Deep Singh
- Departments of Medicine, Biochemistry and Molecular Biology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA
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Lorenzo A, León D, Castillo C, Ruiz M, Albasanz J, Martín M. Maternal caffeine intake during gestation and lactation down-regulates adenosine A1receptor in rat brain from mothers and neonates. J Neurosci Res 2009; 88:1252-61. [DOI: 10.1002/jnr.22287] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Ciruela F, Albergaria C, Soriano A, Cuffí L, Carbonell L, Sánchez S, Gandía J, Fernández-Dueñas V. Adenosine receptors interacting proteins (ARIPs): Behind the biology of adenosine signaling. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2009; 1798:9-20. [PMID: 19883624 DOI: 10.1016/j.bbamem.2009.10.016] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2009] [Revised: 09/26/2009] [Accepted: 10/27/2009] [Indexed: 01/18/2023]
Abstract
Adenosine is a well known neuromodulator in the central nervous system. As a consequence, adenosine can be beneficial in certain disorders and adenosine receptors will be potential targets for therapy in a variety of diseases. Adenosine receptors are G protein-coupled receptors, and are also expressed in a large variety of cells and tissues. Using these receptors as a paradigm of G protein-coupled receptors, the present review focus on how protein-protein interactions might contribute to neurotransmitter/neuromodulator regulation, based on the fact that accessory proteins impinge on the receptor/G protein interaction and therefore modulate receptor functioning. Besides affecting receptor signaling, these accessory components also play a key role in receptor trafficking, internalization and desensitization, as it will be reviewed here. In conclusion, the finding of an increasing number of adenosine receptors interacting proteins, and specially the molecular and functional integration of these accessory proteins into receptorsomes, will open new perspectives in the understanding of particular disorders where these receptors have been proved to be involved.
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Affiliation(s)
- Francisco Ciruela
- Unitat de Farmacologia, Departament de Patologia i Terapèutica Experimental, Facultat de Medicina-Bellvitge, Pavelló de Govern, Universitat de Barcelona, 08907 L'Hospitalet del Llobregat, Barcelona, Spain.
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Reduced expression and desensitization of adenosine A1 receptor/adenylyl cyclase pathway after chronic (−)N6-phenylisopropyladenosine intake during pregnancy. Neuroscience 2009; 163:524-32. [DOI: 10.1016/j.neuroscience.2009.06.050] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Revised: 06/22/2009] [Accepted: 06/22/2009] [Indexed: 02/07/2023]
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Garlid KD, Costa ADT, Quinlan CL, Pierre SV, Dos Santos P. Cardioprotective signaling to mitochondria. J Mol Cell Cardiol 2008; 46:858-66. [PMID: 19118560 DOI: 10.1016/j.yjmcc.2008.11.019] [Citation(s) in RCA: 156] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/14/2008] [Revised: 11/07/2008] [Accepted: 11/26/2008] [Indexed: 01/05/2023]
Abstract
Mitochondria are central players in the pathophysiology of ischemia-reperfusion. Activation of plasma membrane G-coupled receptors or the Na,K-ATPase triggers cytosolic signaling pathways that result in cardioprotection. Our working hypothesis is that the occupied receptors migrate to caveolae, where signaling enzymes are scaffolded into signalosomes that bud off the plasma membrane and migrate to mitochondria. The signalosome-mitochondria interaction then initiates intramitochondrial signaling by opening the mitochondrial ATP-sensitive K(+) channel (mitoK(ATP)). MitoK(ATP) opening causes an increase in ROS production, which activates mitochondrial protein kinase C epsilon (PKCvarepsilon), which inhibits the mitochondrial permeability transition (MPT), thus decreasing cell death. We review the experimental findings that bear on these hypotheses and other modes of protection involving mitochondria.
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Affiliation(s)
- Keith D Garlid
- Department of Biology, Portland State University, Portland, OR 97201-0751, USA.
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Quinlan CL, Costa ADT, Costa CL, Pierre SV, Dos Santos P, Garlid KD. Conditioning the heart induces formation of signalosomes that interact with mitochondria to open mitoKATP channels. Am J Physiol Heart Circ Physiol 2008; 295:H953-H961. [PMID: 18621853 DOI: 10.1152/ajpheart.00520.2008] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Perfusion of the heart with bradykinin triggers cellular signaling events that ultimately cause opening of mitochondrial ATP-sensitive K+ (mitoKATP) channels, increased H2O2 production, inhibition of the mitochondrial permeability transition (MPT), and cardioprotection. We hypothesized that the interaction of bradykinin with its receptor induces the assembly of a caveolar signaling platform (signalosome) that contains the enzymes of the signaling pathway and that migrates to mitochondria to induce mitoKATP channel opening. We developed a novel method for isolating and purifying signalosomes from Langendorff-perfused rat hearts treated with bradykinin. Fractions containing the signalosomes were found to open mitoKATP channels in mitochondria isolated from untreated hearts via the activation of mitochondrial PKC-epsilon. mitoKATP channel opening required signalosome-dependent phosphorylation of an outer membrane protein. Immunodetection analysis revealed the presence of the bradykinin B2 receptor only in the fraction isolated from bradykinin-treated hearts. Immunodetection and immunogold labeling of caveolin-3, as well as sensitivity to cholesterol depletion and resistance to Triton X-100, attested to the caveolar nature of the signalosomes. Ischemic preconditioning, ischemic postconditioning, and perfusion with ouabain also led to active signalosome fractions that opened mitoKATP channels in mitochondria from untreated hearts. These results provide initial support for a novel mechanism for signal transmission from a plasma membrane receptor to mitoKATP channels.
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Affiliation(s)
- Casey L Quinlan
- Department of Biology, Portland State University, PO Box 751, Portland, OR 97201-0751, USA
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Gandía J, Lluís C, Ferré S, Franco R, Ciruela F. Light resonance energy transfer-based methods in the study of G protein-coupled receptor oligomerization. Bioessays 2008; 30:82-9. [PMID: 18081019 DOI: 10.1002/bies.20682] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Since most of the functions in cells are mediated by multimeric protein complexes, the determination of protein-protein interactions is an important step in the study of cellular mechanisms. Traditionally, after screening for possible target interactors by means of a yeast two-hybrid screen, several methods are used to validate the initial result before carrying out functional experiments. Nowadays, non-invasive fluorescence-based methods like Bioluminescence Resonance Energy Transfer (BRET) and Fluorescence Resonance Energy Transfer (FRET) are widely used in the study of protein-protein interactions in living cells. In the present review, we address the individual strengths and weaknesses of both RET approaches, providing information on their possible future use in the study of G protein-coupled receptor oligomerization.
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Affiliation(s)
- Jorge Gandía
- Unitat de Farmacologia, Departament de Patologia i Terapèutica Experimental, Facultat de Medicina, Universitat de Barcelona, Spain
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Aoki T, Hagiwara H, Matsuzaki T, Suzuki T, Takata K. Internalization of caveolae and their relationship with endosomes in cultured human and mouse endothelial cells. Anat Sci Int 2008; 82:82-97. [PMID: 17585564 DOI: 10.1111/j.1447-073x.2006.00160.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Treatment of cells with pervanadate or vanadate induces the phosphorylation of caveolin-1 and its internalization from the cell surface, but the intracellular fate of caveolae has not been fully elucidated. In the present study, we examined the fate of endocytosed caveolae in human umbilical vein endothelial cells and mouse endothelial KOP2.16 cells. The localization of internalized caveolae and their relationship with the endosomes were examined by immunofluorescence microscopy as well as by immunoprecipitation and chasing of biotinylated transferrin. In untreated cells, caveolin-1 was mostly confined to the cell surface. When cells were treated with either pervanadate for 30 min or vanadate for 3 h, many caveolin-1-labeled vesicles were formed inside the cells, some of which were colocalized with Rab5 or Rab4. The internalized caveolin-1 was colocalized with the endocytosed transferrin in the Rab5-, Rab4- or early endosome antigen-1-labeled compartment where caveolin-1 was phosphorylated. It then moved to the Rabl 1-associated compartment. Immunogold electron microscopy revealed that internalized caveolin-1 colocalized with Rab5 or Rab4 in vesicles larger than caveolae. These results suggest that the internalized caveolae interact with early endosomes.
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Affiliation(s)
- Takeo Aoki
- Department of Anatomy and Cell Biology, Gunma University Graduate School of Medicine, Gunma, Japan.
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Internalization and desensitization of adenosine receptors. Purinergic Signal 2007; 4:21-37. [PMID: 18368531 PMCID: PMC2245999 DOI: 10.1007/s11302-007-9086-7] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2007] [Accepted: 10/02/2007] [Indexed: 01/28/2023] Open
Abstract
Until now, more than 800 distinct G protein-coupled receptors (GPCRs) have been identified in the human genome. The four subtypes of the adenosine receptor (A1, A2A, A2B and A3 receptor) belong to this large family of GPCRs that represent the most widely targeted pharmacological protein class. Since adenosine receptors are widespread throughout the body and involved in a variety of physiological processes and diseases, there is great interest in understanding how the different subtypes are regulated, as a basis for designing therapeutic drugs that either avoid or make use of this regulation. The major GPCR regulatory pathway involves phosphorylation of activated receptors by G protein-coupled receptor kinases (GRKs), a process that is followed by binding of arrestin proteins. This prevents receptors from activating downstream heterotrimeric G protein pathways, but at the same time allows activation of arrestin-dependent signalling pathways. Upon agonist treatment, adenosine receptor subtypes are differently regulated. For instance, the A1Rs are not (readily) phosphorylated and internalize slowly, showing a typical half-life of several hours, whereas the A2AR and A2BR undergo much faster downregulation, usually shorter than 1 h. The A3R is subject to even faster downregulation, often a matter of minutes. The fast desensitization of the A3R after agonist exposure may be therapeutically equivalent to antagonist occupancy of the receptor. This review describes the process of desensitization and internalization of the different adenosine subtypes in cell systems, tissues and in vivo studies. In addition, molecular mechanisms involved in adenosine receptor desensitization are discussed.
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León D, Albasanz JL, Castillo CA, Martín M. Effect of glutamate intake during gestation on adenosine A(1) receptor/adenylyl cyclase pathway in both maternal and fetal rat brain. J Neurochem 2007; 104:435-45. [PMID: 17953672 DOI: 10.1111/j.1471-4159.2007.04998.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Pregnant Wistar rats were orally treated with 1 g/L l-glutamate during the entire gestational period and the status of adenosine A(1) receptor (A(1)R)/adenylyl cyclase transduction pathway from maternal and fetal brain was analyzed. Glutamate consumption, estimated from the loss of water from the drinking bottles, was 110 +/- 4.6 mg/kg/day. In mother brains glutamate intake did not significantly alter the B(max) value, although the K(d) value was significantly decreased. However in fetus brain, a significant decrease in B(max) was observed, without an alteration of K(d) value. Similar results were observed by western blot assays using specific A(1)R antibody, suggesting a down-regulation of A(1)R in fetal brain. Concerning alpha subunits of inhibitory G proteins (Gi), alphaGi(3) protein was slightly but significantly decreased in maternal brain without alterations of either Gi(1) or Gi(2). In contrast, alphaGi(1) and alphaGi(2) isoforms were increased in fetal brain. On the other hand, basal, forskolin, and forskolin plus GTPgammaS-stimulated adenylyl cyclase activity was significantly decreased in both maternal and fetal brain, and this was more prominent in fetal than in maternal brain. Finally, A(1)R functionality was significantly decreased in mother brain whereas no significant differences were detected in fetus brain. These results suggest that glutamate administered to pregnant rats modulates A(1)R signaling pathways in both tissues, showing an A(1)R down-regulation in fetal brain, and desensitization in maternal brain.
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Affiliation(s)
- David León
- Departamento de Química Inorgánica, Orgánica y Bioquímica, Facultad de Químicas, Centro Regional de Investigaciones Biomédicas, Universidad de Castilla-La Mancha, Ciudad Real, Spain
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39
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Franco R, Lluis C, Canela EI, Mallol J, Agnati L, Casadó V, Ciruela F, Ferré S, Fuxe K. Receptor-receptor interactions involving adenosine A1 or dopamine D1 receptors and accessory proteins. J Neural Transm (Vienna) 2006; 114:93-104. [PMID: 17024327 DOI: 10.1007/s00702-006-0566-7] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Accepted: 07/13/2006] [Indexed: 11/24/2022]
Abstract
The molecular basis for the known intramembrane receptor-receptor interactions among heptahelical receptors (G protein coupled receptors, GPCR) was postulated to be heteromerization based on receptor subtype specific interactions between different types of homomers of GPCR. Adenosine and dopamine receptors in the basal ganglia have been fundamental to demonstrate the existence of receptor heteromers and the functional consequences of such molecular interactions. The heterodimer is only one type of heteromeric complex and the evidence is equally compatible with the existence of higher order heteromeric complexes, where also adapter proteins such as homer proteins and scaffolding proteins can exist, assisting in the process of linking the GPCR and ion channel receptors together in a receptor mosaic that may have special integrative value and may constitute the molecular basis for learning and memory. Heteromerization of D(2) dopamine and A(2A) adenosine receptors is reviewed by Fuxe in another article in this special issue. Here, heteromerization between D(1) dopamine and A(1) adenosine receptors is reviewed. Heteromers formed by dopamine D(1) and D(2) receptors and by adenosine A(1) and A(2A) receptors also occur in striatal cells and open new perspectives to understand why two receptors with apparently opposite effects are expressed in the same neuron and in the nerve terminals. The role of accessory proteins also capable of interacting with receptor-receptor heteromers in regulating the traffic and the molecular physiology of these receptors is also discussed. Overall, the knowledge of the reason why such complex networks of receptor-receptor and receptor-protein interactions occur in striatal cells is crucial to develop new strategies to combat neurological and neuropsychiatric diseases.
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Affiliation(s)
- R Franco
- Molecular Neurobiology Unit, Department of Biochemistry and Molecular Biology, IDIBAPS (Institut d'Investigacions Biomèdiques August Pi i Sunyer), Universitat de Barcelona, Barcelona, Spain.
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40
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Rodríguez A, Martín M, Albasanz JL, Barrachina M, Espinosa JC, Torres JM, Ferrer I. Adenosine A1 Receptor Protein Levels and Activity Is Increased in the Cerebral Cortex in Creutzfeldt-Jakob Disease and in Bovine Spongiform Encephalopathy-Infected Bovine-PrP Mice. J Neuropathol Exp Neurol 2006; 65:964-75. [PMID: 17021401 DOI: 10.1097/01.jnen.0000235120.59935.f5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
Prion diseases are characterized by neuronal loss, astrocytic gliosis, spongiform change, and abnormal protease-resistant prion protein (PrP) deposition. Creutzfeldt-Jakob disease (CJD) is the most prevalent human prion disease, whereas scrapie and bovine spongiform encephalopathy (BSE) are the most common animal prion diseases. Several candidates have been proposed as mediators of degeneration in prion diseases, one of them glutamate. Recent studies have shown reduced metabotropic glutamate receptor/phospholipase C signaling in the cerebral cortex in CJD, suggesting that this important neuromodulator and neuroprotector pathway is attenuated in CJD. Adenosine is involved in the regulation of different metabolic processes under physiological and pathologic conditions. Adenosine function is mediated by adenosine receptors, which are categorized into 4 types: A1, A2A, A2B, and A3. A1Rs are G-protein-coupled receptors that induce the inhibition of adenylyl cyclase activity. The most dramatic inhibitory actions of adenosine receptors are on the glutamatergic system. For these reasons, we examined the levels of A1Rs in the frontal cortex of 12 patients with CJD and 6 age-matched controls and in BSE-infected bovine-PrP transgenic mice (BoPrP-Tg110 mice) at different postincubation times to address modifications in A1Rs with disease progression. A significant increase in the protein levels of A1Rs was found in the cerebral cortex in CJD and in the murine BSE model at advanced stages of the disease and coincidental with the appearance of PrP expression. In addition, the activity of A1Rs was analyzed by in vitro assays with isolated membranes of the frontal cortex in CJD. Increased activity of the receptor, as revealed by the decreased forskolin-stimulated cAMP production in response to the A1R agonists cyclohexyl adenosine and cyclopentyl adenosine, was observed in CJD cases when compared with controls. Finally, mRNA A1R levels were similar in CJD and control cases, thus suggesting abnormal A1R turnover or dysregulation of raft-associated signaling pathways in CJD. These results show, for the first time, sensitization of A1Rs in prion diseases.
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Affiliation(s)
- Agustín Rodríguez
- Institut de Neuropatologia, Servei Anatomia Patològica, IDIBELL-Hospital Universitari de Bellvitge, Universitat de Barcelona, 08907 Hospitalet de Llobregat, Spain
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41
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Lu TL, Kuo FT, Lu TJ, Hsu CY, Fu HW. Negative regulation of protease-activated receptor 1-induced Src kinase activity by the association of phosphocaveolin-1 with Csk. Cell Signal 2006; 18:1977-87. [PMID: 16678999 DOI: 10.1016/j.cellsig.2006.03.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2006] [Revised: 03/05/2006] [Accepted: 03/06/2006] [Indexed: 11/18/2022]
Abstract
Protease-activated receptor 1 (PAR1), a G protein-coupled receptor (GPCR) for thrombin, has been correlated with cell proliferation. PAR1 is activated by the irreversibly proteolytic cleavage, internalized via clathrin-coated pits, and then sorted to lysosomes for degradation. Caveolae play important roles in both signaling transduction and internalization of several GPCRs. However, the role of caveolae in cellular signaling and trafficking of PAR1 is still unclear. In this study, we show that PAR1 was partially localized in caveolae. Disruption of caveolae by cholesterol depletion did not inhibit PAR1 internalization, indicating that internalization of PAR1 was not via caveolae. Of interest, activation of PAR1 resulted in the phosphorylation of caveolin-1, a principal component of caveolae, on tyrosine 14 by a Gi-linked Src kinase pathway and p38 mitogen-activated protein kinase. Analysis of immunoprecipitates from cells stimulated by PAR1 showed that phosphocaveolin-1 but not caveolin-1 with mutation at tyrosine 14 could bind to Csk. In addition, phosphocaveolin-1 could not bind to CskS109C mutant with the defective SH2 domain. These results indicated that phosphocaveolin-1 was associated with the SH2 domain of Csk in response to PAR1 activation. The association further resulted in a rapid decrease in Src kinase activity. Thus, PAR1-induced Src activation is negatively regulated by recruiting Csk through phosphocaveolin-1. Our results also reveal that phosphocaveolin-1 represents a novel effector of PAR1 to downregulate Src kinase activity. The downregulation of PAR1-induced Src activation mediated by phosphocaveolin-1 provides an additional mechanism for the termination of PAR1 signaling at its downstream molecules.
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Affiliation(s)
- Te-Ling Lu
- Department of Life Science, National Tsing Hua University, 101 Section 2 Kuang Fu Road, Hsinchu 30013, Taiwan, ROC
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42
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León-Sicairos N, Reyes-López M, Canizalez-Román A, Bermúdez-Cruz RM, Serrano-Luna J, Arroyo R, de la Garza M. Human hololactoferrin: endocytosis and use as an iron source by the parasite Entamoeba histolytica. MICROBIOLOGY-SGM 2006; 151:3859-3871. [PMID: 16339932 DOI: 10.1099/mic.0.28121-0] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Entamoeba histolytica is an enteric protozoan that exclusively infects human beings. This parasite requires iron for its metabolic functions. Lactoferrin is a mammalian glycoprotein that chelates extracellular iron on mucosal surfaces, including the surface of the large intestine, where E. histolytica initiates infection. This work examined the interaction in vitro of E. histolytica trophozoites with human hololactoferrin (iron-saturated lactoferrin). A minimum concentration of 50 microM Fe from hololactoferrin supported growth of the amoeba. Amoebic binding sites for hololactoferrin were different from those for human apolactoferrin, holotransferrin and haemoglobin. One amoebic hololactoferrrin-binding polypeptide of 90 kDa was found, which was not observed after treatment of trophozoites with trypsin. Hololactoferrin-binding-protein levels increased in amoebas starved of iron, or grown in hololactoferrin. Internalization of hololactoferrin was inhibited by filipin. Endocytosed hololactoferrin colocalized with an anti-chick embryo caveolin mAb in amoebic vesicles, and lactoferrin was further detected in acidic vesicles; amoebic caveolin of 22 kDa was detected by Western blotting using this antibody. Cysteine proteases from amoebic extracts were able to cleave hololactoferrin. Together, these data indicate that E. histolytica trophozoites bind to hololactoferrin through specific membrane lactoferrin-binding proteins. This ferric protein might be internalized via caveolae-like microdomains, then used as an iron source, and degraded.
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Affiliation(s)
- Nidia León-Sicairos
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN, Apdo. 14-740, México, D F 07000, Mexico
| | - Magda Reyes-López
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN, Apdo. 14-740, México, D F 07000, Mexico
| | - Adrián Canizalez-Román
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN, Apdo. 14-740, México, D F 07000, Mexico
| | - Rosa María Bermúdez-Cruz
- Departamento de Genética y Biología Molecular, Centro de Investigación y de Estudios Avanzados del IPN, Apdo. 14-740, México, D F 07000, Mexico
| | - Jesús Serrano-Luna
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN, Apdo. 14-740, México, D F 07000, Mexico
| | - Rossana Arroyo
- Departamento de Patología Experimental, Centro de Investigación y de Estudios Avanzados del IPN, Apdo. 14-740, México, D F 07000, Mexico
| | - Mireya de la Garza
- Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN, Apdo. 14-740, México, D F 07000, Mexico
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Franco R, Ciruela F, Casadó V, Cortes A, Canela EI, Mallol J, Agnati LF, Ferré S, Fuxe K, Lluis C. Partners for adenosine A1 receptors. J Mol Neurosci 2005; 26:221-32. [PMID: 16012195 DOI: 10.1385/jmn:26:2-3:221] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
G protein-coupled receptors (GPCRs) are targets for therapy in a variety of neurological diseases. Using adenosine A1 receptors (A1Rs) as paradigm of GPCRs, this review focuses on how protein-protein interactions, from monomers to heteromers, can contribute to hormone/neurotransmitter/neuromodulator regulation. The interaction of A1Rs with other membrane receptors, enzymes, and adaptor and scaffolding proteins is relevant for receptor traffic, internalization, and desensitization, and A1Rs are extremely important in driving signaling through different intracellular pathways. There is even the possibility of linking together GPCR heteromeric complexes with ion channel receptors in a receptor mosaic that might have special integrative value and might constitute the molecular basis for learning and memory.
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Affiliation(s)
- Rafael Franco
- Department of Biochemistry and Molecular Biology, University of Barcelona, Barcelona, Spain.
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44
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Klaasse EC, van den Hout G, Roerink SF, de Grip WJ, Ijzerman AP, Beukers MW. Allosteric modulators affect the internalization of human adenosine A1 receptors. Eur J Pharmacol 2005; 522:1-8. [PMID: 16214128 DOI: 10.1016/j.ejphar.2005.08.052] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2005] [Accepted: 08/10/2005] [Indexed: 10/25/2022]
Abstract
To study the effect of allosteric modulators on the internalization of human adenosine A(1) receptors, the receptor was equipped with a C-terminal yellow fluorescent protein tag. The introduction of this tag did not affect the radioligand binding properties of the receptor. CHO cells stably expressing this receptor were subjected during 16 h to varying concentrations of the agonist N(6)-cyclopentyladenosine (CPA) in the absence or presence of 10 microM of the allosteric enhancer PD 81,723 ((2-amino-4,5-dimethyl-3-thienyl)-[3-(trifluoromethyl)phenyl]methanone) or the allosteric inhibitor SCH-202676 (N-(2,3-diphenyl-1,2,4-thiadiazol-5(2H)-ylidene)methanamine). CPA itself was able to internalize 25% and 40% of the receptors at a concentration of 400 nM or 4 muM, respectively. Addition of either PD 81,723 or SCH-202676 alone had no effect on internalization. However, with PD 81,723 a slight amount of internalization was obtained already at 40 nM of CPA and at 400 nM CPA 59% of the receptors internalized. SCH-202676 on the other hand effectively prevented CPA-induced internalization of the receptor.
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Affiliation(s)
- Elisabeth C Klaasse
- Department of Medicinal Chemistry, Leiden/Amsterdam Center for Drug Research, Leiden University, The Netherlands
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45
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Kwak JO, Kim HW, Song JH, Kim MJ, Park HS, Hyun DK, Kim DS, Cha SH. Evidence for rat organic anion transporter 3 association with caveolin-1 in rat kidney. IUBMB Life 2005; 57:109-17. [PMID: 16036570 DOI: 10.1080/15216540500104750] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
The rat organic anion transporter 3 (rOAT3) has recently been identified as the third isoform of the OAT family. The mechanisms that regulate rOAT3's functions remain to be elucidated. rOAT3 contributes for moving a number of negatively charged organic compounds between cells and their extracellular milieu. Caveolin (Cav) also plays a role as a membrane transporter. To address the relationship of these two proteins, we investigated the protein-protein interaction between rOAT3 and Cav-1. The rOAT3 mRNA and protein expression were observed in the rat kidney, and the expressions of Cav-1 mRNA and protein were also detected in the kidney. Confocal microscopy of the immuno-cytochemistry experiments using primary cultured renal proximal tubular cells showed that rOAT3 and Cav-1 were co-localized at the plasma membrane. This finding was confirmed by Western blot analysis using isolated caveolae-enriched membrane fractions from the rat kidney and immuno-precipitation experimentation. When rOAT3's synthesized cRNA of rOAT3 along with the antisense oligo deoxynucleotide ofXenopusCav-1 were co-injected intoXenopusoocytes, the [(3)H] estrone sulfate uptake was significantly decreased. These findings suggest that rOAT3 and caveolin-1 share a cellular expression in the plasma membrane and Cav-1 up-regulates the organic anionic compound uptake via rOAT3 under normal physiological conditions.
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Affiliation(s)
- Jin-Oh Kwak
- Department of Pharmacology and Toxicology, Inha Research Institute for Medical Sciences, Incheon, Korea
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Sun WC, Cao Y, Jin L, Wang LZ, Meng F, Zhu XZ. Modulating effect of adenosine deaminase on function of adenosine A1 receptors. Acta Pharmacol Sin 2005; 26:160-5. [PMID: 15663892 DOI: 10.1111/j.1745-7254.2005.00524.x] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
AIM To study the modulating effect of adenosine deaminase (ADA) on the adenosine A1 receptor (A1R) in HEK293 cells stably expressing the human A1R. METHODS cDNA was amplified by RT-PCR using total RNA from human embryo brain tissue as the template. The PCR products were subcloned into the plasmid pcDNA3 and cloned into the plasmid pcDNA3.1. The cloned A1R cDNA was sequenced and stably expressed in HEK293 cells. The modulating effect of adenosine deaminase on A1R was studied by using [3H]DPCPX binding assay and an intracellular calcium assay. RESULTS HEK293 cells stably expressing human A1R were obtained. Saturation studies showed that the K(D) value and B(max) value of [3H]DPCPX were 1.6+/-0.2 nmol/L and 1.819+/-0.215 nmol/g of protein respectively, in the absence of ecto-ADA respectively, and 1.3+/-0.2 nmol/L and 1.992+/-0.130 nmol/g of protein in the presence of ecto-ADA respectively, suggesting that the K(D) value and B(max) value of [3H]DPCPX were unaffected by ecto-ADA. In the case of [3H]DPCPX competition curves obtained from intact cells or membranes, A1R agonist CCPA/[3H]DPCPX competition curve could be fitted well to a one-site model in the absence of ecto-ADA and a two-site model in the presence of ecto-ADA with a K(H) value of 0.74 (0.11+/-4.8) nmol/L (intact cells) or 1.8 (0.25+/-10) nmol/L (membrane) and a K(L) value of 0.94 (0.62+/-1.41) micromol/L (intact cells) or 0.77 (0.29+/-0.99) micromol/L (membrane). The K(L) value is not significantly different from the IC50 value of 0.84(0.57+/-1.23) micromol/L (intact cells) or 0.84 (0.63+/-1.12) micromol/L (membrane) obtained in the absence of ecto-ADA. Similar results were obtained from the CPA/[3H]DPCPX competition curve in the absence or presence of ecto-ADA on intact cells or membranes. Intracellular calcium assay demonstrated that the EC50 value of CPA were 10 (5+/-29) nmol/L and 94 (38+/-229) nmol/L in the presence or absence of ecto-ADA, respectively. CONCLUSION A1R stably expressed in the HEK293 cells display a low affinity for agonists in the absence of ADA and high and low affinities for agonists in the presence of ADA. The presence of ADA may promote the signaling through the adenosine A1 receptor in HEK293 cells.
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Affiliation(s)
- Wan-Chun Sun
- Department of Pharmacology, Shanghai Institute of Materia Medica, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 201203, China
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Claing A. Regulation of G protein-coupled receptor endocytosis by ARF6 GTP-binding proteins. Biochem Cell Biol 2004; 82:610-7. [PMID: 15674428 DOI: 10.1139/o04-113] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The function of G protein-coupled receptors is regulated by a broad variety of membrane-bound and intracellular proteins. These act in concert to activate signaling pathways that will lead to the desensitization of activated receptors and, for most receptor types, their trafficking to intracellular compartments. This review focuses mainly on the endocytic pathways used by a G protein-coupled receptor and on the proteins that play an essential role in the regulation of the internalization process, most specifically the ADP-ribosylation factors. This family of proteins has been shown to be important for vesicle trafficking between different cellular membranes. The latest findings regarding the molecular mechanisms that regulate internalization of an agonist-stimulated receptor are presented here. Finally, a perspective on how ARF6 proteins might regulate the internalization process is also proposed.Key words: G protein-coupled receptors, endocytosis, ADP-ribosylation factor.
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Affiliation(s)
- Audrey Claing
- Department of Pharmacology, School of Medicine, Université de Montréal, Montreal, QC H3C 3J7, Canada.
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Langlet C, Gaspard N, Nachtergael I, Robberecht P, Langer I. Comparative efficacy of VIP and analogs on activation and internalization of the recombinant VPAC2 receptor expressed in CHO cells. Peptides 2004; 25:2079-86. [PMID: 15572195 DOI: 10.1016/j.peptides.2004.08.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/29/2004] [Revised: 08/20/2004] [Accepted: 08/24/2004] [Indexed: 11/27/2022]
Abstract
Using a monoclonal antibody interacting with the extracellular amino-terminus of the human VPAC2 receptor but that did not interfere with ligand binding, we measured by flow cytometry receptor internalization and trafficking induced by full agonists, partial agonists and an antagonist in Chinese hamster ovary cells expressing the recombinant receptor. The agonists, but not the antagonist, induced a rapid, dose-dependent receptor internalization blocked by hypertonic sucrose that was more pronounced for the VIP analog N-hexanoyl-VIP (80%) than for VIP and Ro 25-1553 (50%) and the [A11]-VIP (20%). Re-expression of the receptors at the membrane was achieved within two hours after exposure to VIP and Ro 25-1553 was blocked by 25 microM monensin but not by 10 microg/ml cycloheximide. Re-expression was much slower after exposure to the acylated peptide and was blocked by preincubation with 25 microM monensin and 10 microg/ml cycloheximide.
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Affiliation(s)
- Christelle Langlet
- Department of Biochemistry and Nutrition, Faculty of Medicine, Université Libre de Bruxelles, Bât G/E, CP 611, 808 route de Lennik, B-1070 Bruxelles, Belgium
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Abstract
Caveolae and the caveolae coat proteins, caveolins, are putatively implicated in many cellular processes, including transcytosis of macromolecules, cholesterol transport, and signal transduction. Recent insights into the physiological and pathophysiological roles of these organelles and the caveolins from genetically modified mice suggest that they may be profoundly important for postnatal cardiovascular function, including endothelial barrier function, regulation of nitric oxide synthesis, cholesterol metabolism, and cardiac function.
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Affiliation(s)
- Jean-Philippe Gratton
- Laboratory of Endothelial Cell Biology, Institut de Recherches Cliniques de Montreal, Canada
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Estall JL, Yusta B, Drucker DJ. Lipid raft-dependent glucagon-like peptide-2 receptor trafficking occurs independently of agonist-induced desensitization. Mol Biol Cell 2004; 15:3673-87. [PMID: 15169869 PMCID: PMC491827 DOI: 10.1091/mbc.e03-11-0825] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The intestinotrophic and cytoprotective actions of glucagon-like peptide-2 (GLP-2) are mediated by the GLP-2 receptor (GLP-2R), a member of the class II glucagon-secretin G protein-coupled receptor superfamily. Although native GLP-2 exhibits a short circulating half-life, long-acting degradation-resistant GLP-2 analogues are being evaluated for therapeutic use in human subjects. Accordingly, we examined the mechanisms regulating signaling, internalization, and trafficking of the GLP-2R to identify determinants of receptor activation and desensitization. Heterologous cells expressing the transfected rat or human GLP-2R exhibited a rapid, dose-dependent, and prolonged desensitization of the GLP-2-stimulated cAMP response and a sustained GLP-2-induced decrease in levels of cell surface receptor. Surprisingly, inhibitors of clathrin-dependent endocytosis failed to significantly decrease GLP-2R internalization, whereas cholesterol sequestration inhibited ligand-induced receptor internalization and potentiated homologous desensitization. The hGLP-2R localized to both Triton X-100-soluble and -insoluble (lipid raft) cellular fractions and colocalized transiently with the lipid raft marker caveolin-1. Although GLP-2R endocytosis was dependent on lipid raft integrity, the receptor transiently associated with green fluorescent protein tagged-early endosome antigen 1-positive vesicles and inhibitors of endosomal acidification attenuated the reappearance of the GLP-2R on the cell surface. Our data demonstrate that GLP-2R desensitization and raft-dependent trafficking represent distinct and independent cellular mechanisms and provide new evidence implicating the importance of a clathrin- and dynamin-independent, lipid raft-dependent pathway for homologous G protein-coupled receptor internalization.
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Affiliation(s)
- Jennifer L Estall
- Department of Laboratory Medicine and Pathobiology, University of Toronto, The Banting and Best Diabetes Centre, Toronto General Hospital, Toronto, Canada M5G 2C4
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