301
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Abstract
Ligand binding to receptor tyrosine kinases and G-protein-coupled receptors initiates signal transduction events and induces receptor endocytosis via clathrin-coated pits and vesicles. While receptor-mediated endocytosis has been traditionally considered an effective mechanism to attenuate ligand-activated responses, more recent studies demonstrate that signaling continues on the endocytic pathway. In fact, certain signaling events, such as the activation of the extracellular signal-regulated kinases, appear to require endocytosis. Protein components of signal transduction cascades can assemble at clathrin coated pits and remain associated with endocytic vesicles following their dynamin-dependent release from the plasma membrane. Thus, endocytic vesicles can function as a signaling compartment distinct from the plasma membrane. These observations demonstrate that endocytosis plays an important role in the activation and propagation of signaling pathways.
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Affiliation(s)
- P S McPherson
- Department of Neurology and Neurosurgery, Montreal Neurological Institute, McGill University, Montreal, Quebec, H3A 2B4, Canada.
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302
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Miggin SM, Kinsella BT. Thromboxane A(2) receptor mediated activation of the mitogen activated protein kinase cascades in human uterine smooth muscle cells. BIOCHIMICA ET BIOPHYSICA ACTA 2001; 1539:147-62. [PMID: 11389977 DOI: 10.1016/s0167-4889(01)00103-3] [Citation(s) in RCA: 61] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Both thromboxane (TX) A(2) and 8-epi prostaglandin (PG) F(2alpha) have been reported to stimulate mitogenesis of vascular smooth muscle (SM) in a number of species. However, TXA(2) and 8-epiPGF(2alpha) mediated mitogenic signalling has not been studied in detail in human vascular SM. Thus, using the human uterine ULTR cell line as a model, we investigated TXA(2) receptor (TP) mediated mitogenic signalling in cultured human vascular SMCs. Both the TP agonist U46619 and 8-epiPGF(2alpha) elicited time and concentration dependent activation of the extracellular signal regulated kinase (ERK)s and c-Jun N-terminal kinase (JNK)s in ULTR cells. Whereas the TP antagonist SQ29548 abolished U46619 mediated signalling, it only partially inhibited 8-epiPGF(2alpha) mediated ERK and JNK activation in ULTR cells. Both U46619 and 8-epiPGF(2alpha) induced ERK activations were inhibited by the protein kinase (PK) C, PKA and phosphoinositide 3-kinase inhibitors GF109203X, H-89 and wortmannin, respectively, but were unaffected by pertussis toxin. In addition, U46619 mediated ERK activation in ULTR cells involves transactivation of the epidermal growth factor (EGF) receptor. In humans, TXA(2) signals through two distinct TP isoforms. In investigating the involvement of the TP isoforms in mitogenic signalling, both TPalpha and TPbeta independently directed U46619 and 8-epiPGF(2alpha) mediated ERK and JNK activation in human embryonic kidney (HEK) 293 cells over-expressing the individual TP isoforms. However, in contrast to that which occurred in ULTR cells, SQ29548 abolished 8-epiPGF(2alpha) mediated ERK and JNK activation through both TPalpha and TPbeta in HEK 293 cells providing further evidence that 8-epiPGF(2alpha) may signal through alternative receptors, in addition to the TPs, in human uterine ULTR cells.
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Affiliation(s)
- S M Miggin
- Department of Biochemistry, Conway Institute of Biomolecular and Biomedical Research, Merville House, University College Dublin, Belfield, 4, Dublin, Ireland
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303
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Lee HJ, Chun M, Kandror KV. Tip60 and HDAC7 interact with the endothelin receptor a and may be involved in downstream signaling. J Biol Chem 2001; 276:16597-600. [PMID: 11262386 DOI: 10.1074/jbc.c000909200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Endothelins exert their biological effects through G protein-coupled receptors. However, the precise mechanism of downstream signaling and trafficking of the receptors is largely unknown. Here we report that the histone acetyltransferase Tip60 and the histone deacetylase HDAC7 interact with one of the ET receptors, ETA, as determined by yeast two-hybrid analysis, glutathione S-transferase pull-down assays, and co-immunoprecipitation from transfected COS-7 cells. In the absence of ET-1, Tip60 and HDAC7 were localized mainly in the cell nucleus while ETA was predominantly confined to the plasma membrane. Stimulation with ET-1 resulted in the internalization of ETA to the perinuclear compartment and simultaneously in the efflux of Tip60 and HDAC7 from the nucleus to the same perinuclear compartment where each protein co-localized with the receptor. Upon co-transfection with ETA into COS-7 cells, Tip60 strongly increased ET-1-induced ERK1/2 phosphorylation, whereas HDAC7 had no significant effect. We thus suggest that protein acetylase and deacetylase interact with ETA in a ligand-dependent fashion and may participate in ET signal transduction.
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Affiliation(s)
- H J Lee
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts 02118, USA
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304
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Dalle S, Ricketts W, Imamura T, Vollenweider P, Olefsky JM. Insulin and insulin-like growth factor I receptors utilize different G protein signaling components. J Biol Chem 2001; 276:15688-95. [PMID: 11278773 DOI: 10.1074/jbc.m010884200] [Citation(s) in RCA: 118] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
We examined the role of heterotrimeric G protein signaling components in insulin and insulin-like growth factor I (IGF-I) action. In HIRcB cells and in 3T3L1 adipocytes, treatment with the Galpha(i) inhibitor (pertussis toxin) or microinjection of the Gbetagamma inhibitor (glutathione S-transferase-betaARK) inhibited IGF-I and lysophosphatidic acid-stimulated mitogenesis but had no effect on epidermal growth factor (EGF) or insulin action. In basal state, Galpha(i) and Gbeta were associated with the IGF-I receptor (IGF-IR), and after ligand stimulation the association of IGF-IR with Galpha(i) increased concomitantly with a decrease in Gbeta association. No association of Galpha(i) was found with either the insulin or EGF receptor. Microinjection of anti-beta-arrestin-1 antibody specifically inhibited IGF-I mitogenic action but had no effect on EGF or insulin action. beta-Arrestin-1 was associated with the receptors for IGF-I, insulin, and EGF in a ligand-dependent manner. We demonstrated that Galpha(i), betagamma subunits, and beta-arrestin-1 all play a critical role in IGF-I mitogenic signaling. In contrast, neither metabolic, such as GLUT4 translocation, nor mitogenic signaling by insulin is dependent on these protein components. These results suggest that insulin receptors and IGF-IRs can function as G protein-coupled receptors and engage different G protein partners for downstream signaling.
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Affiliation(s)
- S Dalle
- Department of Medicine, Division of Endocrinology and Metabolism, University of California, San Diego, La Jolla, California 92093-0673, USA
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305
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Turner NA, Ball SG, Balmforth AJ. The mechanism of angiotensin II-induced extracellular signal-regulated kinase-1/2 activation is independent of angiotensin AT(1A) receptor internalisation. Cell Signal 2001; 13:269-77. [PMID: 11306244 DOI: 10.1016/s0898-6568(01)00135-8] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
The aim of this study was to determine whether internalisation of the angiotensin II (Ang II) AT(1A) receptor (AT(1A)R) was a prerequisite for Ang II-induced activation of the extracellular signal-regulated kinases, ERK-1/2. The human embryonic kidney (HEK293) cell line stably transfected with either the wild-type rat AT(1A)R or an internalisation-deficient C-terminal truncated mutant of the AT(1A)R (AT(1A)T318R) was used as a model for these studies. Inhibition of AT(1A)R internalisation by treatment with an inhibitor of clathrin-mediated endocytosis, Concanavalin A (Con A), did not inhibit Ang II-induced ERK-1/2 activation. Furthermore, cells transfected with the internalisation-deficient AT(1A)T318R mutant readily activated ERK-1/2 in response to Ang II. Ang II activated ERK-1/2 via two distinct signalling pathways in HEK-AT(1A)R cells. Approximately half of Ang II-induced ERK-1/2 activation was protein kinase C (PKC)-dependent, and the remainder was calcium- and c-Src-dependent and involved transactivation of the epidermal growth factor receptor (EGFR). In summary, Ang II-induced activation of ERK-1/2 occurs via two distinct pathways in HEK293 cells, neither of which requires AT(1A)R internalisation.
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Affiliation(s)
- N A Turner
- Integrated Molecular Cardiology Group, Institute for Cardiovascular Research, Worsley Building, University of Leeds, LS2 9JT, Leeds, UK
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306
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Pierce KL, Luttrell LM, Lefkowitz RJ. New mechanisms in heptahelical receptor signaling to mitogen activated protein kinase cascades. Oncogene 2001; 20:1532-9. [PMID: 11313899 DOI: 10.1038/sj.onc.1204184] [Citation(s) in RCA: 331] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Activation of classical second messenger cascades cannot fully explain the recently appreciated roles of heptahelical, or G-protein coupled receptors (GPCRs), in stimulation of mitogen activated protein kinase (MAPK) cascades. Rather, several distinct signaling mechanisms appear to contribute to GPCR-mediated MAPK activation. These include transactivation of the Epidermal Growth Factor Receptor (EGFR) via the autocrine/paracrine release of EGF-like ligands at the cell surface and scaffolding of MAPK cascades. A significant advance in the understanding of how GPCRs activate MAPK cascades is the discovery that beta-arrestin, a protein well known for its roles in both receptor desensitization and internalization, serves as a scaffolding protein for at least two GPCR stimulated MAPK cascades, the extracellular signal regulated kinase (ERK) cascade and the c-jun N-terminal kinase 3 (JNK3) cascade. Together, these novel mechanisms of GPCR-mediated MAPK regulation may permit GPCRs in specific situations to control the temporal and spatial activity of MAPKs and thereby determine the consequences of GPCR stimulation with respect to transcriptional activation, cell proliferation and apoptosis.
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Affiliation(s)
- K L Pierce
- The Howard Hughes Medical Institute, Box 3821, Duke University Medical Center, Durham, North Carolina, NC 27710, USA
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307
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Gschwind A, Zwick E, Prenzel N, Leserer M, Ullrich A. Cell communication networks: epidermal growth factor receptor transactivation as the paradigm for interreceptor signal transmission. Oncogene 2001; 20:1594-600. [PMID: 11313906 DOI: 10.1038/sj.onc.1204192] [Citation(s) in RCA: 355] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Communication between different cellular signaling systems has emerged as a common principle that enables cells to integrate a multitude of signals from its environment. Transactivation of the epidermal growth factor receptor (EGFR) represents the paradigm for cross-talk between G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs). The recent identification of Zn2+-dependent metalloproteinases and transmembrane growth factor precursors as critical elements in GPCR-induced EGFR transactivation pathways has defined new components of a cellular communication network of rapidly increasing complexity. Further elucidation of the molecular details of the EGFR transactivation mechanism will provide new understanding of its relevance for normal physiological processes and their pathophysiological deviations.
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Affiliation(s)
- A Gschwind
- Max-Planck-Institut für Biochemie, Am Klopferspitz 18A, 82152 Martinsried, Germany
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308
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Novak U, Walker F, Kaye A. Expression of EGFR-family proteins in the brain: role in development, health and disease. J Clin Neurosci 2001; 8:106-11. [PMID: 11243764 DOI: 10.1054/jocn.2000.0799] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
- U Novak
- Dept. of Surgery, Royal Melbourne Hospital, University of Melbourne, Parkville, 3050, Australia.
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309
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Feldman RD. Adrenergic receptor polymorphisms and cardiac function (and dysfunction): a failure to communicate? Circulation 2001; 103:1042-3. [PMID: 11222462 DOI: 10.1161/01.cir.103.8.1042] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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310
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Abstract
Over the last year the combinations of G-protein-coupled receptors that are known to form heterodimeric complexes has rapidly increased. For example, dopamine receptors can dimerize with both somatostatin and adenosine receptors. These studies have been aided by improved technologies to monitor protein/protein interactions in living cells. Crosstalk at the level of the receptors might explain some of the known physiological interactions of these neurotransmitter systems and also provide new approaches for therapeutic intervention.
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Affiliation(s)
- F H Marshall
- Molecular Pharmacology Department, GlaxoWellcome Research and Development, Stevenage, Hertfordshire, UK.
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311
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Liebmann C. Bradykinin signalling to MAP kinase: cell-specific connections versus principle mitogenic pathways. Biol Chem 2001; 382:49-55. [PMID: 11258671 DOI: 10.1515/bc.2001.008] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Mitogenic signalling pathways from G protein-coupled receptors (GPCRs) to the mitogen-activated protein kinase (MAPK) cascade may involve alpha- or betagamma-subunits of heterotrimeric G proteins, receptor or non-receptor tyrosine kinases, adaptor molecules, phosphoinositide 3-kinases, protein kinase C, and probably other proteins. The majority of models describing the connection of different signalling proteins within a mitogenic pathway are based on experimental data obtained by co- and overexpression of epitope-tagged MAPK together with the respective GPCR and other signalling proteins of interest in transfectable cell lines. Here the link of the bradykinin B2 receptor (B2R) to MAPK in the COS-7 cell expression system is compared with mitogenic signalling pathways of bradykinin in various tumour cell lines. It becomes evident that in natural or tumour cells expressing individual amounts and different isoforms of signalling proteins completely other relations between B2R and MAPK may exist than in COS-7 cells, suggesting a high degree of cellular specificity in mitogenic signalling.
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Affiliation(s)
- C Liebmann
- Institute of Biochemistry and Biophysics, Biological and Pharmaceutical Faculty, Friedrich-Schiller-University, Jena, Germany
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312
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Saito Y, Berk BC. Transactivation: a novel signaling pathway from angiotensin II to tyrosine kinase receptors. J Mol Cell Cardiol 2001; 33:3-7. [PMID: 11133218 DOI: 10.1006/jmcc.2000.1272] [Citation(s) in RCA: 135] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Angiotensin II (Ang II), an octapeptide pressor hormone, activates cellular events that may contribute to the pathogenesis of cardiovascular disease. The physiological actions of Ang II are mediated via the Ang II type 1 receptor (AT1R) and type 2 receptor (AT2R), which are G protein-coupled receptors (GPCR). GPCR share a common basic structure of seven transmembrane helices connected by alternating cytoplasmic and extracellular loops. GPCR lack intrinsic kinase activity possessed by receptor tyrosine kinases (RTK) such as platelet-derived growth factor receptor (PDGFR) or epidermal growth factor receptor (EGFR). Nonetheless, the signal transduction events activated by the AT1R mimic those of RTKs. Recently, cross-talk between GPCR and RTK has been observed. There is accumulating evidence that GPCR take advantage of signaling pathways downstream of RTK to exert its effect on the cells. In this context, RTK may be considered as one of signaling molecules downstream of GPCR.
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MESH Headings
- Angiotensin II/physiology
- Animals
- Blood Pressure/physiology
- Calcium/physiology
- Cell Survival
- ErbB Receptors/chemistry
- ErbB Receptors/physiology
- Free Radical Scavengers/pharmacology
- GTP-Binding Proteins/physiology
- Humans
- Models, Biological
- Models, Molecular
- Oxidation-Reduction
- Phosphorylation
- Protein Processing, Post-Translational/physiology
- Protein Structure, Tertiary
- Reactive Oxygen Species
- Receptor Cross-Talk/physiology
- Receptor Protein-Tyrosine Kinases/physiology
- Receptor, Angiotensin, Type 1
- Receptor, Angiotensin, Type 2
- Receptors, Angiotensin/chemistry
- Receptors, Angiotensin/drug effects
- Receptors, Angiotensin/physiology
- Receptors, Platelet-Derived Growth Factor/chemistry
- Receptors, Platelet-Derived Growth Factor/drug effects
- Receptors, Platelet-Derived Growth Factor/physiology
- Signal Transduction/physiology
- Structure-Activity Relationship
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Affiliation(s)
- Y Saito
- Center for Cardiovascular Research, University of Rochester, Rochester, NY, USA
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313
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Zheng M, Zhang SJ, Zhu WZ, Ziman B, Kobilka BK, Xiao RP. beta 2-adrenergic receptor-induced p38 MAPK activation is mediated by protein kinase A rather than by Gi or gbeta gamma in adult mouse cardiomyocytes. J Biol Chem 2000; 275:40635-40. [PMID: 11018034 DOI: 10.1074/jbc.m006325200] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Increasing evidence shows that stimulation of beta-adrenergic receptor (AR) activates mitogen-activated protein kinases (MAPKs), in addition to the classical G(s)-adenylyl cyclase-cAMP-dependent protein kinase (PKA) signaling cascade. In the present study, we demonstrate a novel beta(2)-AR-mediated cross-talk between PKA and p38 MAPK in adult mouse cardiac myocytes expressing beta(2)-AR, with a null background of beta(1)beta(2)-AR double knockout. beta(2)-AR stimulation by isoproterenol increased p38 MAPK activity in a time- and dose-dependent manner. Inhibiting G(i) with pertussis toxin or scavenging Gbetagamma with betaARK-ct overexpression could not prevent beta(2)-AR-induced p38 MAPK activation. In contrast, a specific peptide inhibitor of PKA, PKI (5 microm), completely abolished the stimulatory effect of beta(2)-AR, suggesting that beta(2)-AR-induced p38 MAPK activation is mediated via a PKA-dependent mechanism, rather than by G(i) or Gbetagamma. This conclusion was further supported by the ability of forskolin (10 microm), an adenylyl cyclase activator, to elevate p38 MAPK activity in a PKI-sensitive manner. Furthermore, inhibition of p38 MAPK with SB203580 (10 microm) markedly enhanced the beta(2)-AR-mediated contractile response, without altering base-line contractility. These results provide the first evidence that cardiac beta(2)-AR activates p38 MAPK via a PKA-dependent signaling pathway, rather than by G(i) or Gbetagamma, and reveal a novel role of p38 MAPK in regulating cardiac contractility.
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Affiliation(s)
- M Zheng
- Laboratory of Cardiovascular Science, Gerontology Research Center, NIA, National Institutes of Health, Baltimore, Maryland 21224, USA
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314
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Cao W, Luttrell LM, Medvedev AV, Pierce KL, Daniel KW, Dixon TM, Lefkowitz RJ, Collins S. Direct binding of activated c-Src to the beta 3-adrenergic receptor is required for MAP kinase activation. J Biol Chem 2000; 275:38131-4. [PMID: 11013230 DOI: 10.1074/jbc.c000592200] [Citation(s) in RCA: 159] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Both beta(2)- and beta(3)-adrenergic receptors (ARs) are able to activate the extracellular signal-regulated kinase (ERK) pathway. We previously showed that c-Src is required for ERK activation by beta(2)AR and that it is recruited to activated beta(2)AR through binding of the Src homology 3 (SH3) domain to proline-rich regions of the adapter protein beta-arrestin1. Despite the absence of sites for phosphorylation and beta-arrestin binding, ERK activation by beta(3)AR still requires c-Src. Agonist activation of beta(2)AR, but not beta(3)AR, led to redistribution of green fluorescent protein-tagged beta-arrestin to the plasma membrane. In beta-arrestin-deficient COS-7 cells, beta-agonist-dependent co-precipitation of c-Src with the beta(2)AR required exogenous beta-arrestin, but activated beta(3)AR co-precipitated c-Src in the absence or presence of beta-arrestin. ERK activation and Src co-precipitation with beta(3)AR also occurred in adipocytes in an agonist-dependent and pertussis toxin-sensitive manner. Protein interaction studies show that the beta(3)AR interacts directly with the SH3 domain of Src through proline-rich motifs (PXXP) in the third intracellular loop and the carboxyl terminus. ERK activation and Src co-precipitation were abolished in cells expressing point mutations in these PXXP motifs. Together, these data describe a novel mechanism of ERK activation by a G protein-coupled receptor in which the intracellular domains directly recruit c-Src.
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Affiliation(s)
- W Cao
- Departments of Psychiatry and Behavioral Sciences, Pharmacology, and Medicine and the Howard Hughes Medical Institute, Duke University Medical Center, Durham, North Carolina 27710, USA
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315
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McDonald PH, Chow CW, Miller WE, Laporte SA, Field ME, Lin FT, Davis RJ, Lefkowitz RJ. Beta-arrestin 2: a receptor-regulated MAPK scaffold for the activation of JNK3. Science 2000; 290:1574-7. [PMID: 11090355 DOI: 10.1126/science.290.5496.1574] [Citation(s) in RCA: 653] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
beta-Arrestins, originally discovered in the context of heterotrimeric guanine nucleotide binding protein-coupled receptor (GPCR) desensitization, also function in internalization and signaling of these receptors. We identified c-Jun amino-terminal kinase 3 (JNK3) as a binding partner of beta-arrestin 2 using a yeast two-hybrid screen and by coimmunoprecipitation from mouse brain extracts or cotransfected COS-7 cells. The upstream JNK activators apoptosis signal-regulating kinase 1 (ASK1) and mitogen-activated protein kinase (MAPK) kinase 4 were also found in complex with beta-arrestin 2. Cellular transfection of beta-arrestin 2 caused cytosolic retention of JNK3 and enhanced JNK3 phosphorylation stimulated by ASK1. Moreover, stimulation of the angiotensin II type 1A receptor activated JNK3 and triggered the colocalization of beta-arrestin 2 and active JNK3 to intracellular vesicles. Thus, beta-arrestin 2 acts as a scaffold protein, which brings the spatial distribution and activity of this MAPK module under the control of a GPCR.
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Affiliation(s)
- P H McDonald
- Howard Hughes Medical Institute and Department of Medicine, Duke University Medical Center, Box 3821, Durham, NC 27710, USA
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316
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York RD, Molliver DC, Grewal SS, Stenberg PE, McCleskey EW, Stork PJ. Role of phosphoinositide 3-kinase and endocytosis in nerve growth factor-induced extracellular signal-regulated kinase activation via Ras and Rap1. Mol Cell Biol 2000; 20:8069-83. [PMID: 11027277 PMCID: PMC86417 DOI: 10.1128/mcb.20.21.8069-8083.2000] [Citation(s) in RCA: 191] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Neurotrophins promote multiple actions on neuronal cells including cell survival and differentiation. The best-studied neurotrophin, nerve growth factor (NGF), is a major survival factor in sympathetic and sensory neurons and promotes differentiation in a well-studied model system, PC12 cells. To mediate these actions, NGF binds to the TrkA receptor to trigger intracellular signaling cascades. Two kinases whose activities mediate these processes include the mitogen-activated protein (MAP) kinase (or extracellular signal-regulated kinase [ERK]) and phosphoinositide 3-kinase (PI3-K). To examine potential interactions between the ERK and PI3-K pathways, we studied the requirement of PI3-K for NGF activation of the ERK signaling cascade in dorsal root ganglion cells and PC12 cells. We show that PI3-K is required for TrkA internalization and participates in NGF signaling to ERKs via distinct actions on the small G proteins Ras and Rap1. In PC12 cells, NGF activates Ras and Rap1 to elicit the rapid and sustained activation of ERKs respectively. We show here that Rap1 activation requires both TrkA internalization and PI3-K, whereas Ras activation requires neither TrkA internalization nor PI3-K. Both inhibitors of PI3-K and inhibitors of endocytosis prevent GTP loading of Rap1 and block sustained ERK activation by NGF. PI3-K and endocytosis may also regulate ERK signaling at a second site downstream of Ras, since both rapid ERK activation and the Ras-dependent activation of the MAP kinase kinase kinase B-Raf are blocked by inhibition of either PI3-K or endocytosis. The results of this study suggest that PI3-K may be required for the signals initiated by TrkA internalization and demonstrate that specific endocytic events may distinguish ERK signaling via Rap1 and Ras.
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Affiliation(s)
- R D York
- Vollum Institute, Oregon Health Sciences University, Portland, Oregon 97201, USA
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317
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Maudsley S, Zamah AM, Rahman N, Blitzer JT, Luttrell LM, Lefkowitz RJ, Hall RA. Platelet-derived growth factor receptor association with Na(+)/H(+) exchanger regulatory factor potentiates receptor activity. Mol Cell Biol 2000; 20:8352-63. [PMID: 11046132 PMCID: PMC102142 DOI: 10.1128/mcb.20.22.8352-8363.2000] [Citation(s) in RCA: 171] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Platelet-derived growth factor (PDGF) is a potent mitogen for many cell types. The PDGF receptor (PDGFR) is a receptor tyrosine kinase that mediates the mitogenic effects of PDGF by binding to and/or phosphorylating a variety of intracellular signaling proteins upon PDGF-induced receptor dimerization. We show here that the Na(+)/H(+) exchanger regulatory factor (NHERF; also known as EBP50), a protein not previously known to interact with the PDGFR, binds to the PDGFR carboxyl terminus (PDGFR-CT) with high affinity via a PDZ (PSD-95/Dlg/Z0-1 homology) domain-mediated interaction and potentiates PDGFR autophosphorylation and extracellular signal-regulated kinase (ERK) activation in cells. A point-mutated version of the PDGFR, with the terminal leucine changed to alanine (L1106A), cannot bind NHERF in vitro and is markedly impaired relative to the wild-type receptor with regard to PDGF-induced autophosphorylation and activation of ERK in cells. NHERF potentiation of PDGFR signaling depends on the capacity of NHERF to oligomerize. NHERF oligomerizes in vitro when bound with PDGFR-CT, and a truncated version of the first NHERF PDZ domain that can bind PDGFR-CT but which does not oligomerize reduces PDGFR tyrosine kinase activity when transiently overexpressed in cells. PDGFR activity in cells can also be regulated in a NHERF-dependent fashion by stimulation of the beta(2)-adrenergic receptor, a known cellular binding partner for NHERF. These findings reveal that NHERF can directly bind to the PDGFR and potentiate PDGFR activity, thus elucidating both a novel mechanism by which PDGFR activity can be regulated and a new cellular role for the PDZ domain-containing adapter protein NHERF.
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Affiliation(s)
- S Maudsley
- Howard Hughes Medical Institute, Departments of Medicine and Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
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318
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Rhee SG, Bae YS, Lee SR, Kwon J. Hydrogen peroxide: a key messenger that modulates protein phosphorylation through cysteine oxidation. SCIENCE'S STKE : SIGNAL TRANSDUCTION KNOWLEDGE ENVIRONMENT 2000; 2000:pe1. [PMID: 11752613 DOI: 10.1126/stke.2000.53.pe1] [Citation(s) in RCA: 344] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Ligand-receptor interactions can generate the production of hydrogen peroxide (H(2)O(2)) in cells, the implications of which are becoming appreciated. Fluctuations in H(2)O(2) levels can affect the intracellular activity of key signaling components including protein kinases and protein phosphatases. Rhee et al. discuss recent findings on the role of H(2)O(2) in signal transduction. Specifically, H(2)O(2) appears to oxidize active site cysteines in phosphatases, thereby inactivating them. H(2)O(2) also can activate protein kinases; however, although the mechanism of activation for some kinases appears to be similar to that of phosphatase inactivation (cysteine oxidation), it is unclear how H(2)O(2) promotes increased activation of other kinases. Thus, the higher levels of intracellular phosphoproteins observed in cells most likely occur because of the concomitant inhibition of protein phosphatases and activation of protein kinases.
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Affiliation(s)
- S G Rhee
- Laboratory of Cell Signaling, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
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319
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Rhee SG, Bae YS, Lee SR, Kwon J. Hydrogen Peroxide: A Key Messenger That Modulates Protein Phosphorylation Through Cysteine Oxidation. Sci Signal 2000. [DOI: 10.1126/scisignal.532000pe1] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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320
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Houslay MD, Kolch W. Cell-Type Specific Integration of Cross-Talk between Extracellular Signal-Regulated Kinase and cAMP Signaling. Mol Pharmacol 2000. [DOI: 10.1124/mol.58.4.659] [Citation(s) in RCA: 160] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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321
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Abstract
Two classes of receptors transduce neurotransmitter signals: ionotropic receptors and heptahelical metabotropic receptors. Whereas the ionotropic receptors are structurally associated with a membrane channel, a mediating mechanism is necessary to functionally link metabotropic receptors with their respective effectors. According to the accepted paradigm, the first step in the metabotropic transduction process requires the activation of heterotrimeric G-proteins. An increasing number of observations, however, point to a novel mechanism through which neurotransmitters can initiate biochemical signals and modulate neuronal excitability. According to this mechanism metabotropic receptors induce responses by activating transduction systems that do not involve G-proteins.
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Affiliation(s)
- C Heuss
- Brain Research Institute, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland
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322
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Schmitt JM, Stork PJ. beta 2-adrenergic receptor activates extracellular signal-regulated kinases (ERKs) via the small G protein rap1 and the serine/threonine kinase B-Raf. J Biol Chem 2000; 275:25342-50. [PMID: 10840035 DOI: 10.1074/jbc.m003213200] [Citation(s) in RCA: 144] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
G protein-coupled receptors can induce cellular proliferation by stimulating the mitogen-activated protein (MAP) kinase cascade. Heterotrimeric G proteins are composed of both alpha and betagamma subunits that can signal independently to diverse intracellular signaling pathways including those that activate MAP kinases. In this study, we examined the ability of isoproterenol, an agonist of the beta(2)-adrenergic receptor (beta(2)AR), to stimulate extracellular signal-regulated kinases (ERKs). Using HEK293 cells, which express endogenous beta(2)AR, we show that isoproterenol stimulates ERKs via beta(2)AR. This action of isoproterenol requires cAMP-dependent protein kinase and is insensitive to pertussis toxin, suggesting that Galpha(s) activation of cAMP-dependent protein kinase is required. Interestingly, beta(2)AR activates both the small G proteins Rap1 and Ras, but only Rap1 is capable of coupling to Raf isoforms. beta(2)AR inhibits the Ras-dependent activation of both Raf isoforms Raf-1 and B-Raf, whereas Rap1 activation by isoproterenol recruits and activates B-Raf. beta(2)AR activation of ERKs is not blocked by expression of RasN17, an interfering mutant of Ras, but is blocked by expression of either RapN17 or Rap1GAP1, both of which interfere with Rap1 signaling. We propose that isoproterenol can activate ERKs via Rap1 and B-Raf in these cells.
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Affiliation(s)
- J M Schmitt
- Vollum Institute and the Department of Cell and Developmental Biology, Oregon Health Sciences University, Portland 97201, USA
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323
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Warren JS. Intrapulmonary interleukin 1 mediates acute immune complex alveolitis in the rat. Biochem Biophys Res Commun 1991; 23:17-22. [PMID: 1826836 DOI: 10.1152/physiol.00042.2007] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Interleukin 1 alpha and beta are polypeptide cytokines that possesses a wide variety of immunologic and inflammatory activities. We have examined the role of intrapulmonary interleukin 1 in the pathogenesis of acute IgG immune complex alveolitis in the rat. Intratracheal instillation of IgG anti-bovine serum albumin accompanied by intravenous infusion of bovine albumin results in acute neutrophil and complement-dependent alveolitis. Over the course of evolving lung injury there was a 12-fold increase in bronchoalveolar lavage fluid interleukin 1 activity. Intratracheal instillation of neutralizing anti-interleukin 1 beta antibodies upon induction of lung injury resulted in a dose-dependent reduction in lung injury as assessed by measurements of pulmonary hemorrhage and vascular permeability. Morphometric analysis and measurements of myeloperoxidase activities in whole lung homogenates from rats that received anti-interleukin 1 beta revealed a pronounced reduction in neutrophil recruitment compared to positive controls. Incubation of isolated alveolar macrophages with preformed IgG immune complexes resulted in dose-dependent interleukin 1 secretion. These data suggest that intrapulmonary IL-1 activity plays a role in neutrophil recruitment and is necessary for the full development of acute IgG immune complex induced lung injury in the rat.
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Affiliation(s)
- J S Warren
- Department of Pathology, University of Michigan Medical School, Ann Arbor 48109-0602
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