1
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Cabral-Dias R, Lucarelli S, Zak K, Rahmani S, Judge G, Abousawan J, DiGiovanni LF, Vural D, Anderson KE, Sugiyama MG, Genc G, Hong W, Botelho RJ, Fairn GD, Kim PK, Antonescu CN. Fyn and TOM1L1 are recruited to clathrin-coated pits and regulate Akt signaling. J Cell Biol 2022; 221:213045. [PMID: 35238864 PMCID: PMC8899389 DOI: 10.1083/jcb.201808181] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Revised: 12/15/2021] [Accepted: 01/24/2022] [Indexed: 12/24/2022] Open
Abstract
The epidermal growth factor (EGF) receptor (EGFR) controls many aspects of cell physiology. EGF binding to EGFR elicits the membrane recruitment and activation of phosphatidylinositol-3-kinase, leading to Akt phosphorylation and activation. Concomitantly, EGFR is recruited to clathrin-coated pits (CCPs), eventually leading to receptor endocytosis. Previous work uncovered that clathrin, but not receptor endocytosis, is required for EGF-stimulated Akt activation, and that some EGFR signals are enriched in CCPs. Here, we examine how CCPs control EGFR signaling. The signaling adaptor TOM1L1 and the Src-family kinase Fyn are enriched within a subset of CCPs with unique lifetimes and protein composition. Perturbation of TOM1L1 or Fyn impairs EGF-stimulated phosphorylation of Akt2 but not Akt1. EGF stimulation also triggered the TOM1L1- and Fyn-dependent recruitment of the phosphoinositide 5-phosphatase SHIP2 to CCPs. Thus, the recruitment of TOM1L1 and Fyn to a subset of CCPs underlies a role for these structures in the support of EGFR signaling leading to Akt activation.
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Affiliation(s)
- Rebecca Cabral-Dias
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada.,Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
| | - Stefanie Lucarelli
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada.,Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
| | - Karolina Zak
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada.,Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
| | - Sadia Rahmani
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada.,Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
| | - Gurjeet Judge
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada.,Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
| | - John Abousawan
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada.,Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
| | - Laura F DiGiovanni
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.,Program in Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Dafne Vural
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada.,Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
| | - Karen E Anderson
- Signalling Programme, Babraham Institute, Babraham Research Campus, Cambridge, UK
| | - Michael G Sugiyama
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
| | - Gizem Genc
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada
| | - Wanjin Hong
- Institute of Molecular and Cell Biology, A*STAR, Singapore
| | - Roberto J Botelho
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada.,Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada
| | - Gregory D Fairn
- Department of Pathology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - Peter K Kim
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada.,Program in Cell Biology, The Hospital for Sick Children, Toronto, Ontario, Canada
| | - Costin N Antonescu
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario, Canada.,Graduate Program in Molecular Science, Ryerson University, Toronto, Ontario, Canada.,Keenan Research Centre for Biomedical Science of St. Michael's Hospital, Toronto, Ontario, Canada
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2
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Pasireotide protects mammalian cochlear hair cells from gentamicin ototoxicity by activating the PI3K-Akt pathway. Cell Death Dis 2019; 10:110. [PMID: 30728348 PMCID: PMC6365508 DOI: 10.1038/s41419-019-1386-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2018] [Revised: 12/18/2018] [Accepted: 01/15/2019] [Indexed: 01/07/2023]
Abstract
Gentamicin is a widely used antibiotic for the treatment of gram-negative bacterial infections; however, its use often results in significant and permanent hearing loss. Hearing loss resulting from hair cell (HC) degeneration affects millions of people worldwide, and one major cause is the loss of sensory HCs in the inner ear due to aminoglycoside exposure. Strategies to overcome the apparently irreversible loss of HCs in mammals are crucial for hearing protection. Here, we report that the somatostatin analog pasireotide protects mouse cochlear HCs from gentamicin damage using a well-established in vitro gentamicin-induced HC loss model and that the otoprotective effects of pasireotide are due to Akt up-regulation via the PI3K–Akt signal pathway activation. We demonstrate active caspase signal in organ of Corti (OC) explants exposed to gentamicin and show that pasireotide treatment activates survival genes, reduces caspase signal, and increases HC survival. The neuropeptide somatostatin and its selective analogs have provided neuroprotection by activating five somatostatin receptor (SSTR1–SSTR5) subtypes. Pasireotide has a high affinity for SSTR2 and SSTR5, and the addition of SSTR2- and SSTR5-specific antagonists leads to a loss of protection. The otoprotective effects of pasireotide were also observed in a gentamicin-injured animal model. In vivo studies have shown that 13 days of subcutaneous pasireotide application prevents gentamicin-induced HC death and permanent hearing loss in mice. Auditory brainstem response analysis confirmed the protective effect of pasireotide, and we found a significant threshold shift at all measured frequencies (4, 8, 16, 24, and 32 kHz). Together, these findings indicate that pasireotide is a novel otoprotective peptide acting via the PI3K–Akt pathway and may be of therapeutic value for HC protection from ototoxic insults.
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3
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Cieniewicz AM, Cooper PR, McGehee J, Lingham RB, Kihm AJ. Novel method demonstrates differential ligand activation and phosphatase-mediated deactivation of insulin receptor tyrosine-specific phosphorylation. Cell Signal 2016; 28:1037-47. [PMID: 27155325 DOI: 10.1016/j.cellsig.2016.05.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 04/14/2016] [Accepted: 05/02/2016] [Indexed: 10/21/2022]
Abstract
Insulin receptor signaling is a complex cascade leading to a multitude of intracellular functional responses. Three natural ligands, insulin, IGF1 and IGF2, are each capable of binding with different affinities to the insulin receptor, and result in variable biological responses. However, it is likely these affinity differences alone cannot completely explain the myriad of diverse cellular outcomes. Ligand binding initiates activation of a signaling cascade resulting in phosphorylation of the IR itself and other intracellular proteins. The direct catalytic activity along with the temporally coordinated assembly of signaling proteins is critical for insulin receptor signaling. We hypothesized that determining differential phosphorylation among individual tyrosine sites activated by ligand binding or dephosphorylation by phosphatases could provide valuable insight into insulin receptor signaling. Here, we present a sensitive, novel immunoassay adapted from Meso Scale Discovery technology to quantitatively measure changes in site-specific phosphorylation levels on endogenous insulin receptors from HuH7 cells. We identified insulin receptor phosphorylation patterns generated upon differential ligand activation and phosphatase-mediated deactivation. The data demonstrate that insulin, IGF1 and IGF2 elicit different insulin receptor phosphorylation kinetics and potencies that translate to downstream signaling. Furthermore, we show that insulin receptor deactivation, regulated by tyrosine phosphatases, occurs distinctively across specific tyrosine residues. In summary, we present a novel, quantitative and high-throughput assay that has uncovered differential ligand activation and site-specific deactivation of the insulin receptor. These results may help elucidate some of the insulin signaling mechanisms, discriminate ligand activity and contribute to a better understanding of insulin receptor signaling. We propose this methodology as a powerful approach to characterize agonists and antagonists of the insulin receptor and can be adapted to serve as a platform to evaluate ligands of alternate receptor systems.
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Affiliation(s)
- Anne M Cieniewicz
- Biologics Research, Janssen BioTherapeutics, Janssen R & D Spring House, PA 19477, USA.
| | - Philip R Cooper
- Biologics Research, Janssen BioTherapeutics, Janssen R & D Spring House, PA 19477, USA
| | - Jennifer McGehee
- Biologics Research, Janssen BioTherapeutics, Janssen R & D Spring House, PA 19477, USA
| | - Russell B Lingham
- Biologics Research, Janssen BioTherapeutics, Janssen R & D Spring House, PA 19477, USA
| | - Anthony J Kihm
- Biologics Research, Janssen BioTherapeutics, Janssen R & D Spring House, PA 19477, USA.
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4
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Gibbs PEM, Miralem T, Lerner-Marmarosh N, Maines MD. Nanoparticle Delivered Human Biliverdin Reductase-Based Peptide Increases Glucose Uptake by Activating IRK/Akt/GSK3 Axis: The Peptide Is Effective in the Cell and Wild-Type and Diabetic Ob/Ob Mice. J Diabetes Res 2016; 2016:4712053. [PMID: 27294151 PMCID: PMC4886063 DOI: 10.1155/2016/4712053] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/14/2016] [Accepted: 04/18/2016] [Indexed: 01/11/2023] Open
Abstract
Insulin's stimulation of glucose uptake by binding to the IRK extracellular domain is compromised in diabetes. We have recently described an unprecedented approach to stimulating glucose uptake. KYCCSRK (P2) peptide, corresponding to the C-terminal segment of hBVR, was effective in binding to and inducing conformational change in the IRK intracellular kinase domain. Although myristoylated P2, made of L-amino acids, was effective in cell culture, its use for animal studies was unsuitable. We developed a peptidase-resistant formulation of the peptide that was efficient in both mice and cell culture systems. The peptide was constructed of D-amino acids, in reverse order, and blocked at both termini. Delivery of the encapsulated peptide to HepG2 and HSKM cells was confirmed by its prolonged effect on stimulation of glucose uptake (>6 h). The peptide improved glucose clearance in both wild-type and Ob/Ob mice; it lowered blood glucose levels and suppressed glucose-stimulated insulin secretion. IRK activity was stimulated in the liver of treated mice and in cultured cells. The peptide potentiated function of IRK's downstream effector, Akt-GSK3-(α, β) axis. Thus, P2-based approach can be used for improving glucose uptake by cells. Also, it allows for screening peptides in vitro and in animal models for treatment of diabetes.
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Affiliation(s)
- Peter E. M. Gibbs
- Department of Biophysics and Biochemistry, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Tihomir Miralem
- Department of Biophysics and Biochemistry, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Nicole Lerner-Marmarosh
- Department of Biophysics and Biochemistry, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
| | - Mahin D. Maines
- Department of Biophysics and Biochemistry, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
- *Mahin D. Maines:
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5
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Aasrum M, Ødegård J, Thoresen GH, Brusevold IJ, Sandnes DL, Christoffersen T. Gab1 amplifies signaling in response to low-intensity stimulation by HGF. Cell Biol Int 2015; 39:1177-84. [PMID: 26146811 DOI: 10.1002/cbin.10511] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Accepted: 07/02/2015] [Indexed: 01/15/2023]
Abstract
The receptor tyrosine kinases EGFR and Met induce phosphorylation of the docking protein Gab1, and there is evidence that Gab1 may have a role in the signaling from these receptors. Studying hepatocytes, we previously found that although Gab1 mechanistically interacted in different ways with EGFR and Met, it was involved in mitogenic signaling induced by both EGF and HGF. It has been reported that in EGFR, Gab1 is required particularly at a low dose of EGF. Whether this also applies to HGF/Met signaling has not been investigated. We have studied the role of Gab1 in activation of the Akt and ERK pathways at low- and high-intensity stimulation with EGF and HGF in cultured hepatocytes. In cells where Gab1 was depleted by a specific Gab1-directed siRNA, the EGF-induced phosphorylation of ERK was lowered and HGF-induced phosphorylation of both ERK and Akt was substantially reduced. These effects were more marked at low-dose HGF stimulation. The inhibitory consequence of Gab1 depletion was particularly pronounced for HGF-induced Akt phosphorylation. The results suggest that Gab1 is an important signal amplifier for low-intensity stimulation by HGF.
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Affiliation(s)
- Monica Aasrum
- Department of Pharmacology, Institute of Clinical Medicine, Oslo University Hospital, University of Oslo, P.O. Box 1057, Blindern, 0316, Oslo, Norway
| | - John Ødegård
- Department of Pharmacology, Institute of Clinical Medicine, Oslo University Hospital, University of Oslo, P.O. Box 1057, Blindern, 0316, Oslo, Norway
| | - Gunn Hege Thoresen
- Department of Pharmacology, Institute of Clinical Medicine, Oslo University Hospital, University of Oslo, P.O. Box 1057, Blindern, 0316, Oslo, Norway.,Department of Pharmaceutical Biosciences, School of Pharmacy, University of Oslo, P.O. Box 1068, Blindern, 0316, Oslo, Norway
| | - Ingvild J Brusevold
- Department of Pharmacology, Institute of Clinical Medicine, Oslo University Hospital, University of Oslo, P.O. Box 1057, Blindern, 0316, Oslo, Norway.,Department of Oral Biology, University of Oslo, P.O. Box 1052, Blindern, 0316, Oslo, Norway.,Department of Paediatric Dentistry and Behavioural Science, Faculty of Dentistry, University of Oslo, P.O. Box 1052, Blindern, 0316, Oslo, Norway
| | - Dagny L Sandnes
- Department of Pharmacology, Institute of Clinical Medicine, Oslo University Hospital, University of Oslo, P.O. Box 1057, Blindern, 0316, Oslo, Norway
| | - Thoralf Christoffersen
- Department of Pharmacology, Institute of Clinical Medicine, Oslo University Hospital, University of Oslo, P.O. Box 1057, Blindern, 0316, Oslo, Norway
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6
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Aasrum M, Ødegård J, Sandnes D, Christoffersen T. The involvement of the docking protein Gab1 in mitogenic signalling induced by EGF and HGF in rat hepatocytes. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:3286-3294. [PMID: 24126105 DOI: 10.1016/j.bbamcr.2013.10.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2013] [Revised: 10/07/2013] [Accepted: 10/07/2013] [Indexed: 12/15/2022]
Abstract
Grb2-associated binder (Gab) family proteins are docking molecules that can interact with receptor tyrosine kinases (RTKs) and cytokine receptors and bind several downstream signalling proteins. Studies in several cell types have shown that Gab1 may have a role in signalling mediated by the two RTKs epidermal growth factor (EGF) receptor (EGFR) and Met, the receptor for hepatocyte growth factor (HGF), but the involvement of Gab1 in EGFR and Met signalling has not been directly compared in the same cell. We have studied mechanisms of activation and role in mitogenic signalling of Gab1 in response to EGF and HGF in cultured rat hepatocytes. Gab1, but not Gab2, was expressed in the hepatocytes and was phosphorylated upon stimulation with EGF or HGF. Depletion of Gab1, using siRNA, decreased the ERK and Akt activation, cyclin D1 expression, and DNA synthesis in response to both EGF and HGF. Studies of mechanisms of recruitment to the receptors showed that HGF induced co-precipitation of Gab1 and Met while EGF induced binding of Gab1 to Grb2 but not to EGFR. Gab1 activation in response to both EGF and HGF was dependent on PI3K. While EGF activated Gab1 and Shc equally, within the same concentration range, HGF very potently and almost exclusively activated Gab1, having only a minimal effect on Shc. Collectively, our results strongly suggest that although Gab1 interacts differently with EGFR and Met, it is involved in mitogenic signalling mediated by both these growth factor receptors in hepatocytes.
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Affiliation(s)
- Monica Aasrum
- Department of Pharmacology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, P.O. Box 1057, Blindern, 0316 Oslo, Norway.
| | - John Ødegård
- Department of Pharmacology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, P.O. Box 1057, Blindern, 0316 Oslo, Norway
| | - Dagny Sandnes
- Department of Pharmacology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, P.O. Box 1057, Blindern, 0316 Oslo, Norway
| | - Thoralf Christoffersen
- Department of Pharmacology, Institute of Clinical Medicine, University of Oslo and Oslo University Hospital, P.O. Box 1057, Blindern, 0316 Oslo, Norway
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7
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Ramalingam L, Oh E, Thurmond DC. Novel roles for insulin receptor (IR) in adipocytes and skeletal muscle cells via new and unexpected substrates. Cell Mol Life Sci 2013; 70:2815-34. [PMID: 23052216 PMCID: PMC3556358 DOI: 10.1007/s00018-012-1176-1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 08/21/2012] [Accepted: 09/18/2012] [Indexed: 01/30/2023]
Abstract
The insulin signaling pathway regulates whole-body glucose homeostasis by transducing extracellular signals from the insulin receptor (IR) to downstream intracellular targets, thus coordinating a multitude of biological functions. Dysregulation of IR or its signal transduction is associated with insulin resistance, which may culminate in type 2 diabetes. Following initial stimulation of IR, insulin signaling diverges into different pathways, activating multiple substrates that have roles in various metabolic and cellular processes. The integration of multiple pathways arising from IR activation continues to expand as new IR substrates are identified and characterized. Accordingly, our review will focus on roles for IR substrates as they pertain to three primary areas: metabolism/glucose uptake, mitogenesis/growth, and aging/longevity. While IR functions in a seemingly pleiotropic manner in many cell types, through these three main roles in fat and skeletal muscle cells, IR multi-tasks to regulate whole-body glucose homeostasis to impact healthspan and lifespan.
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Affiliation(s)
- Latha Ramalingam
- Department of Biochemistry and Molecular Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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8
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Rajala A, Dilly AK, Rajala RV. Protein tyrosine phosphatase-1B regulates the tyrosine phosphorylation of the adapter Grb2-associated binder 1 (Gab1) in the retina. Cell Commun Signal 2013; 11:20. [PMID: 23521888 PMCID: PMC3637500 DOI: 10.1186/1478-811x-11-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2013] [Accepted: 03/19/2013] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Gab1 (Grb2-associated binder 1) is a key coordinator that belongs to the insulin receptor substrate-1 like family of adaptor molecules and is tyrosine phosphorylated in response to various growth factors, cytokines, and numerous other molecules. Tyrosine phosphorylated Gab1 is able to recruit a number of signaling effectors including PI3K, SHP2 and PLC-γ. In this study, we characterized the localization and regulation of tyrosine phosphorylation of Gab1 in the retina. RESULTS Our immuno localization studies suggest that Gab1 is expressed in rod photoreceptor inner segments. We found that hydrogen peroxide activates the tyrosine phosphorylation of Gab1 ex vivo and hydrogen peroxide has been shown to inhibit the protein tyrosine phosphatase PTP1B activity. We found a stable association between the D181A substrate trap mutant of PTP1B and Gab1. Our studies suggest that PTP1B interacts with Gab1 through Tyrosine 83 and this residue may be the major PTP1B target residue on Gab1. We also found that Gab1 undergoes a light-dependent tyrosine phosphorylation and PTP1B regulates the phosphorylation state of Gab1. Consistent with these observations, we found an enhanced Gab1 tyrosine phosphorylation in PTP1B deficient mice and also in retinas treated ex vivo with a PTP1B specific allosteric inhibitor. CONCLUSIONS Our laboratory has previously reported that retinas deficient of PTP1B are resistant to light damage compared to wild type mice. Since Gab1 is negatively regulated by PTP1B, a part of the retinal neuroprotective effect we have observed previously in PTP1B deficient mice could be contributed by Gab1 as well. In summary, our data suggest that PTP1B regulates the phosphorylation state of retinal Gab1 in vivo.
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Affiliation(s)
- Ammaji Rajala
- Departments of Ophthalmology, University of Oklahoma Health Sciences Center, Oklahoma City, OK, 73104, USA.
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9
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Abstract
Ninety-one years ago insulin was discovered, which was one of the most important medical discoveries in the past century, transforming the lives of millions of diabetic patients. Initially insulin was considered only important for rapid control of blood glucose by its action on a restricted number of tissues; however, it has now become clear that this hormone controls an array of cellular processes in many different tissues. The present review will focus on the role of insulin in the kidney in health and disease.
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10
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Siddle K. Molecular basis of signaling specificity of insulin and IGF receptors: neglected corners and recent advances. Front Endocrinol (Lausanne) 2012; 3:34. [PMID: 22649417 PMCID: PMC3355962 DOI: 10.3389/fendo.2012.00034] [Citation(s) in RCA: 106] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2011] [Accepted: 02/13/2012] [Indexed: 12/15/2022] Open
Abstract
Insulin and insulin-like growth factor (IGF) receptors utilize common phosphoinositide 3-kinase/Akt and Ras/extracellular signal-regulated kinase signaling pathways to mediate a broad spectrum of "metabolic" and "mitogenic" responses. Specificity of insulin and IGF action in vivo must in part reflect expression of receptors and responsive pathways in different tissues but it is widely assumed that it is also determined by the ligand binding and signaling mechanisms of the receptors. This review focuses on receptor-proximal events in insulin/IGF signaling and examines their contribution to specificity of downstream responses. Insulin and IGF receptors may differ subtly in the efficiency with which they recruit their major substrates (IRS-1 and IRS-2 and Shc) and this could influence effectiveness of signaling to "metabolic" and "mitogenic" responses. Other substrates (Grb2-associated binder, downstream of kinases, SH2Bs, Crk), scaffolds (RACK1, β-arrestins, cytohesins), and pathways (non-receptor tyrosine kinases, phosphoinositide kinases, reactive oxygen species) have been less widely studied. Some of these components appear to be specifically involved in "metabolic" or "mitogenic" signaling but it has not been shown that this reflects receptor-preferential interaction. Very few receptor-specific interactions have been characterized, and their roles in signaling are unclear. Signaling specificity might also be imparted by differences in intracellular trafficking or feedback regulation of receptors, but few studies have directly addressed this possibility. Although published data are not wholly conclusive, no evidence has yet emerged for signaling mechanisms that are specifically engaged by insulin receptors but not IGF receptors or vice versa, and there is only limited evidence for differential activation of signaling mechanisms that are common to both receptors. Cellular context, rather than intrinsic receptor activity, therefore appears to be the major determinant of whether responses to insulin and IGFs are perceived as "metabolic" or "mitogenic."
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Affiliation(s)
- Kenneth Siddle
- University of Cambridge Metabolic Research Laboratories and Department of Clinical Biochemistry, Institute of Metabolic Science, Addenbrooke's Hospital Cambridge, UK.
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11
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Fritsche L, Neukamm SS, Lehmann R, Kremmer E, Hennige AM, Hunder-Gugel A, Schenk M, Häring HU, Schleicher ED, Weigert C. Insulin-induced serine phosphorylation of IRS-2 via ERK1/2 and mTOR: studies on the function of Ser675 and Ser907. Am J Physiol Endocrinol Metab 2011; 300:E824-36. [PMID: 21098738 DOI: 10.1152/ajpendo.00409.2010] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
The identity of specific serine phosphorylation residues of insulin receptor substrate (IRS)-2 and their impact on insulin signal transduction are largely unknown. Ser(675) and Ser(907) of mouse IRS-2 are adjacent to PI 3-kinase or Grb2 binding domains, respectively. Using monoclonal phosphosite-specific antibodies, we demonstrated the phosphorylation of both serines after stimulation of Fao hepatoma cells with insulin, anisomycin, or phorbol esters. Phosphorylation of both sites was a late and prolonged event during insulin treatment and was also detected in liver tissue of insulin-treated as well as refed mice. Inhibition and siRNA-mediated knockdown of ERK1/2 indicated that the insulin-induced phosphorylation of Ser(907) was ERK dependent. Phosphorylation of Ser(907) did not prevent the insulin-induced association of IRS-2 with Grb2, but phosphorylation of the adjacent Tyr(911) was proved to be crucial in HEK 293 cells expressing IRS-2 Ala mutants. The insulin-induced phosphorylation of Ser(675) was prevented by inhibition and siRNA-mediated knockdown of mTOR but not of p70(S6K1). Mutation of Ser(675) to Ala did not affect downstream insulin signaling but increased the half-life of the protein, suggesting an involvement of phospho-Ser(675) in an accelerated degradation of IRS-2. Moreover, the insulin-induced degradation of IRS-2 was blocked by inhibition of mTOR. We conclude that the two novel insulin-dependent serine phosphorylation sites of IRS-2 were not involved in the regulation of the adjacent PI 3-kinase and Grb2 binding domains but might be implicated in the ERK- and mTOR-mediated negative feedback control.
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Affiliation(s)
- Louise Fritsche
- Dept. of Internal Medicine, Div. of Pathobiochemistry and Clinical Chemistry, Univ. of Tuebingen, Otfried-Mueller-Straße 10, 72076 Tuebingen, Germany
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12
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Rahib L, Sriram G, Harada MK, Liao JC, Dipple KM. Transcriptomic and network component analysis of glycerol kinase in skeletal muscle using a mouse model of glycerol kinase deficiency. Mol Genet Metab 2009; 96:106-12. [PMID: 19121967 PMCID: PMC2702540 DOI: 10.1016/j.ymgme.2008.11.163] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/18/2008] [Revised: 11/16/2008] [Accepted: 11/16/2008] [Indexed: 11/25/2022]
Abstract
Glycerol kinase (GK) is at the interface of fat and carbohydrate metabolism and has been linked to obesity and type 2 diabetes mellitus (T2DM). The purpose of this study was to investigate the role of GK in fat metabolism and insulin signaling in skeletal muscle (an important end organ tissue in T2DM). Microarray analysis determined that there were 525 genes that were differentially expressed (1.2-fold, p value<0.05) between knockout (KO) and wild-type (WT) mice. Quantitative PCR (qPCR) confirmed the differential expression of genes including glycerol kinase (Gyk), phosphatidylinositol 3-kinase regulatory subunit, polypeptide 1 (p85 alpha) (Pik3r1), insulin-like growth factor 1 (Igf1), and growth factor receptor bound protein 2-associated protein 1 (Gab1). Network component analysis demonstrated that transcription factor activities of myogenic differentiation 1 (MYOD), myogenic regulatory factor 5 (MYF5), myogenin (MYOG), nuclear receptor subfamily 4, group A, member 1 (NUR77) are decreased in the Gyk KO whereas the activity of paired box 3 (PAX3) is increased. The activity of MYOD was confirmed using a DNA binding assay. In addition, myoblasts from Gyk KO had less ability to differentiate into myotubes compared to WT myoblasts. These findings support our previous studies in brown adipose tissue and demonstrate that the role of Gyk in muscle is due in part to its non-metabolic (moonlighting) activities.
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MESH Headings
- Animals
- Cell Differentiation
- Cells, Cultured
- Diabetes Mellitus, Type 2/enzymology
- Diabetes Mellitus, Type 2/genetics
- Diabetes Mellitus, Type 2/metabolism
- Disease Models, Animal
- Female
- Gene Expression Profiling
- Gene Regulatory Networks
- Glycerol Kinase/deficiency
- Glycerol Kinase/genetics
- Humans
- Male
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/enzymology
- Muscle Fibers, Skeletal/metabolism
- Muscle, Skeletal/enzymology
- Muscle, Skeletal/metabolism
- Protein Binding
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Affiliation(s)
- Lola Rahib
- Biomedical Engineering Interdepartmental Program, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, USA
| | - Ganesh Sriram
- Department of Human Genetics, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA, USA
| | - Melissa K. Harada
- Department of Human Genetics, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA
| | - James C. Liao
- Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, CA, USA
| | - Katrina M. Dipple
- Biomedical Engineering Interdepartmental Program, Henry Samueli School of Engineering and Applied Science, University of California, Los Angeles, CA, USA
- Department of Human Genetics, David Geffen School of Medicine at UCLA, University of California, Los Angeles, CA, USA
- Department of Pediatrics, David Geffen School of Medicine at UCLA, Mattel Children’s Hospital at UCLA, University of California, Los Angeles, CA, USA
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13
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Abstract
In the diabetic eye, the increased accumulation of sorbitol in the retina has been implicated in the pathogenesis of diabetic retinopathy (DR). Neurodegeneration is an important component of DR as demonstrated by increased neural apoptosis in the retina during experimental and human diabetes. Insulin receptor (IR) activation has been shown to rescue retinal neurons from apoptosis through a phosphoinositide 3-kinase and protein kinase B (Akt) survival cascade. In this study, we examined the IR signaling in sorbitol-induced hyperosmotic stressed retinas.
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14
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Wang Z, Ge L, Wang M, Carr BI. Grb2-associated binder-1 plays a central role in the hepatocyte growth factor enhancement of hepatoma growth inhibition by K vitamin analog compound 5. Hepatology 2007; 46:2003-13. [PMID: 18046719 DOI: 10.1002/hep.21900] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
UNLABELLED Compound 5 (Cpd 5), a K vitamin analog, has been shown to inhibit Hep3B human hepatoma cell growth in cultures and rat hepatoma growth in vivo through prolonged epidermal growth factor receptor (EGFR)-extracellular response kinase (ERK) phosphorylation, and hepatocyte growth factor (HGF) synergizes with Cpd 5 to enhance the inhibition of Hep3B cell and rat hepatoma growth. To explore the mechanisms mediating the HGF/Cpd 5 synergy, we examined the possible involvement of the Grb2-associated binder-1 (Gab1) docking protein because it interacts with both EGFR and HGF receptor c-Met pathways. We found that HGF enhanced Cpd 5-induced c-Met phosphorylation at Tyr-1349, a binding site for Gab1, resulting in increased c-Met binding to Gab1, and induced strong and prolonged Gab1 tyrosine phosphorylation. Prolonged Gab1 phosphorylation by HGF/Cpd 5 in turn enhanced the ability of Gab1 to bind to protein tyrosine phosphatase SHP2 and enhanced the activation of its downstream mitogen-activated protein kinase pathway. In contrast, this same HGF/Cpd 5 treatment inhibited Gab1 binding to phosphatidylinositol 3-kinase (PI3K), leading to the inactivation of the PI3K-Akt pathway. The inhibition of Akt phosphorylation by HGF/Cpd 5 further activated the Raf-MEK-ERK signaling cascade via an Akt-Raf1 interaction, leading to strong and prolonged ERK phosphorylation. The transfection of Hep3B cells with mutated Gab1 (Gab1 Y627F), which had lost its ability to bind SHP2, antagonized HGF/Cpd 5-induced ERK phosphorylation, whereas the transfection of Hep3B cells with mutated Gab1 3YF, which lost its ability to bind PI3K, further enhanced HGF/Cpd 5-induced ERK phosphorylation and cell growth inhibition. CONCLUSION Gab1 plays a central role in regulating HGF/Cpd 5 synergy in their actions on Hep3B cell growth inhibition.
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Affiliation(s)
- Ziqiu Wang
- Kimmel Cancer Center, Thomas Jefferson University, Philadelphia, PA 19107, USA
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15
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Meng S, Chen Z, Munoz-Antonia T, Wu J. Participation of both Gab1 and Gab2 in the activation of the ERK/MAPK pathway by epidermal growth factor. Biochem J 2006; 391:143-51. [PMID: 15952937 PMCID: PMC1237148 DOI: 10.1042/bj20050229] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Three members of Gab family docking proteins, Gab1, Gab2 and Gab3, have been identified in humans. Previous studies have found that the hepatocyte growth factor preferentially utilizes Gab1 for signalling, whereas Bcr-Abl selectively signals through Gab2. Gab1-SHP2 interaction has been shown to mediate ERK (extracellular-signal-regulated kinase) activation by EGF (epidermal growth factor). However, it was unclear whether EGF selectively utilizes Gab1 for signalling to ERK and whether Gab2 is dispensable in cells where Gab1 and Gab2 are co-expressed. Using T47D and MCF-7 human breast carcinoma cells that express endogenous Gab1 and Gab2, we examined the role of these docking proteins in EGF-induced ERK activation. It was found that EGF induced a similar amount of SHP2-Gab1 and SHP2-Gab2 complexes. Expression of either SHP2-binding defective Gab1 or Gab2 mutant blocked EGF-induced ERK activation. Down-regulation of either Gab1 or Gab2 by siRNAs (small interfering RNAs) effectively inhibited the EGF-stimulated ERK activation pathway and cell migration. Interestingly, the inhibitory effect of Gab1 siRNA could be rescued not only by expression of an exogenous mouse Gab1 but also by an exogenous human Gab2 and vice versa, but not by IRS1 (insulin receptor substrate 1). These results reveal that Gab2 plays a pivotal role in the EGF-induced ERK activation pathway and that it can complement the function of Gab1 in the EGF signalling pathway. Furthermore, Gab1 and Gab2 are critical signalling threshold proteins for ERK activation by EGF.
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Affiliation(s)
- Songshu Meng
- *Molecular Oncology Program, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612, U.S.A
- †Department of Interdisciplinary Oncology, University of South Florida College of Medicine, Tampa, FL 33612, U.S.A
| | - Zhengming Chen
- *Molecular Oncology Program, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612, U.S.A
- †Department of Interdisciplinary Oncology, University of South Florida College of Medicine, Tampa, FL 33612, U.S.A
| | - Teresita Munoz-Antonia
- *Molecular Oncology Program, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612, U.S.A
- †Department of Interdisciplinary Oncology, University of South Florida College of Medicine, Tampa, FL 33612, U.S.A
| | - Jie Wu
- *Molecular Oncology Program, H. Lee Moffitt Cancer Center and Research Institute, 12902 Magnolia Drive, Tampa, FL 33612, U.S.A
- †Department of Interdisciplinary Oncology, University of South Florida College of Medicine, Tampa, FL 33612, U.S.A
- ‡Department of Medical Microbiology and Immunology, University of South Florida College of Medicine, Tampa, FL 33612, U.S.A
- To whom correspondence should be addressed, at Molecular Oncology Program, SRB-3, H. Lee Moffitt Cancer Center and Research Institute (email )
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16
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Bolanos-Garcia VM. MET meet adaptors: functional and structural implications in downstream signalling mediated by the Met receptor. Mol Cell Biochem 2006; 276:149-57. [PMID: 16132696 DOI: 10.1007/s11010-005-3696-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2005] [Accepted: 03/14/2005] [Indexed: 01/12/2023]
Abstract
The tyrosin kinase Met receptor regulates multiple cellular events, ranging from cell motility and angiogenesis to morphological differentiation and tissue regeneration. To conduce these activities, the cytoplasmic C-terminal region of this receptor acts as a docking site for multiple protein substrates, including Grb 2, Gab 1, STAT 3, Shc, SHIP-1 and Src. These substrates are characterised by the presence of multiple domains, including the PH, PTB, SH 2 and SH 3 domains, which directly interact with the multisubstrate C-terminal region of Met. How this receptor recognises and binds a specific substrate in a space-temporal mode is a central question in cell signalling. The recently solved crystal structure of the tyrosine kinase domain of the Met receptor and that of domains of diverse Met substrates provides the molecular framework to understand Met substrate specificity. This structural information also gives new insights on the plasticity of Met signalling and the implications of Met deregulation in tumorigenic processes. In the light of these advances, the present work discusses the molecular basis of Met-substrate recognition and its functional implications in signalling events mediated by this pleiotropic receptor.
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17
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Lerner-Marmarosh N, Shen J, Torno MD, Kravets A, Hu Z, Maines MD. Human biliverdin reductase: a member of the insulin receptor substrate family with serine/threonine/tyrosine kinase activity. Proc Natl Acad Sci U S A 2005; 102:7109-14. [PMID: 15870194 PMCID: PMC1088173 DOI: 10.1073/pnas.0502173102] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2004] [Indexed: 01/06/2023] Open
Abstract
We describe here the tyrosine kinase activity of human biliverdin reductase (BVR) and its potential role in the insulin-signaling pathway. BVR is both a substrate for insulin receptor (IR) tyrosine kinase (IRK) activity and a kinase for serine phosphorylation of IR substrate 1 (IRS-1). Our previous studies have revealed serine/threonine kinase activity of BVR. Y198, in the YMKM motif found in the C-terminal domain of BVR, is shown to be a substrate for insulin-activated IRK. This motif in IRS proteins provides a docking site for proteins that contain a Src homology 2 domain. Additionally, Y228 in the YLSF sequence and Y291 are IRK substrates; the former sequence provides optimum recognition motif in the tyrosine phosphatase, SHP-1, and for SHC (Src homology 2 domain containing transfroming protein 1). BVR autophosphorylates N-terminal tyrosines Y72 and Y83. Serine residues in IRS-1 are targets for BVR phosphorylation, and point mutation of serine residues in the kinase domain of the reductase inhibits phosphotransferase activity. Because tyrosine phosphorylation of IRS-1 activates the insulin signaling pathway and serine phosphorylation of IRS-1 blocks insulin action, our findings that insulin increases BVR tyrosine phosphorylation and that there is an increase in glucose uptake in response to insulin when expression of BVR is "knocked down" by small interfering RNA suggest a potential role for BVR in the insulin signaling pathway.
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Affiliation(s)
- Nicole Lerner-Marmarosh
- Department of Biochemistry and Biophysics, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, NY 14624, USA
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18
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Bard-Chapeau EA, Hevener AL, Long S, Zhang EE, Olefsky JM, Feng GS. Deletion of Gab1 in the liver leads to enhanced glucose tolerance and improved hepatic insulin action. Nat Med 2005; 11:567-71. [PMID: 15821749 DOI: 10.1038/nm1227] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2005] [Accepted: 03/02/2005] [Indexed: 11/08/2022]
Abstract
Insulin receptor substrate-1 (IRS-1) and IRS-2 are known to transduce and amplify signals emanating from the insulin receptor. Here we show that Grb2-associated binder 1 (Gab1), despite its structural similarity to IRS proteins, is a negative modulator of hepatic insulin action. Liver-specific Gab1 knockout (LGKO) mice showed enhanced hepatic insulin sensitivity with reduced glycemia and improved glucose tolerance. In LGKO liver, basal and insulin-stimulated tyrosine phosphorylation of IRS-1 and IRS-2 was elevated, accompanied by enhanced Akt/PKB activation. Conversely, Erk activation by insulin was suppressed in LGKO liver, leading to defective IRS-1 Ser612 phosphorylation. Thus, Gab1 acts to attenuate, through promotion of the Erk pathway, insulin-elicited signals flowing through IRS and Akt proteins, which represents a novel balancing mechanism for control of insulin signal strength in the liver.
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Affiliation(s)
- Emilie A Bard-Chapeau
- Signal Transduction Program, The Burnham Institute, 10901 North Torrey Pines Road, La Jolla, California 92037, USA
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19
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Hayashi K, Shibata K, Morita T, Iwasaki K, Watanabe M, Sobue K. Insulin Receptor Substrate-1/SHP-2 Interaction, a Phenotype-dependent Switching Machinery of Insulin-like Growth Factor-I Signaling in Vascular Smooth Muscle Cells. J Biol Chem 2004; 279:40807-18. [PMID: 15272025 DOI: 10.1074/jbc.m405100200] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Insulin-like growth factor-I (IGF-I) plays a role in mutually exclusive processes such as proliferation and differentiation in a variety of cell types. IGF-I is a potent mitogen and motogen for dedifferentiated vascular smooth muscle cells (VSMCs) in vivo and in vitro. However, in differentiated VSMCs, IGF-I is only required for maintaining the differentiated phenotype. Here we investigated the VSMC phenotype-dependent signaling and biological processes triggered by IGF-I. In differentiated VSMCs, IGF-I activated a protein-tyrosine phosphatase, SHP-2, recruited by insulin receptor substrate-1 (IRS-1). The activated SHP-2 then dephosphorylated IRS-1 Tyr(P)-895, resulting in blockade of the pathways from IRS-1/Grb2/Sos to the ERK and p38 MAPK. Conversely, such negative regulation was silent in dedifferentiated VSMCs, where IGF-I activated both MAPKs via IRS-1/Grb2/Sos interaction-linked Ras activation, leading to proliferation and migration. Thus, our present results demonstrate that the IRS-1/SHP-2 interaction acts as a switch controlling VSMC phenotype-dependent IGF-I-induced signaling pathways and biological processes, and this mechanism is likely to be applicable to other cells.
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Affiliation(s)
- Ken'ichiro Hayashi
- Department of Neuroscience (D13), Osaka University Graduate School of Medicine, Yamadaoka 2-2, Suita, Osaka 565-0871, Japan
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20
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Arnaud M, Mzali R, Gesbert F, Crouin C, Guenzi C, Vermot-Desroches C, Wijdenes J, Courtois G, Bernard O, Bertoglio J. Interaction of the tyrosine phosphatase SHP-2 with Gab2 regulates Rho-dependent activation of the c-fos serum response element by interleukin-2. Biochem J 2004; 382:545-56. [PMID: 15170389 PMCID: PMC1133811 DOI: 10.1042/bj20040103] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2004] [Revised: 05/17/2004] [Accepted: 06/01/2004] [Indexed: 12/27/2022]
Abstract
Gab2 (Grb2-associated binder-2), a member of the IRS (insulin receptor substrate)/Gab family of adapter proteins, undergoes tyrosine phosphorylation in response to cytokine or growth factor stimulation and serves as a docking platform for many signal transduction effectors, including the tyrosine phosphatase SHP-2 [SH2 (Src homology 2)-domain-containing tyrosine phosphatase]. Here, we report that, following IL-2 (interleukin-2) stimulation of human T lymphocytes, SHP-2 binds tyrosine residues 614 and 643 of human Gab2 through its N- and C-terminal SH2 domains respectively. However, the sole mutation of Tyr-614 into phenylalanine is sufficient to prevent Gab2 from recruiting SHP-2. Expression of the Gab2 Tyr-614-->Phe (Y614F) mutant, defective in SHP-2 association, prevents ERK (extracellular-signal-regulated kinase) activation and expression of a luciferase reporter plasmid driven by the c-fos SRE (serum response element), indicating that interaction of SHP-2 with Gab2 is required for ERK activation in response to IL-2. Further investigation of IL-2-dependent induction of SRE showed that expression of a constitutively active mutant of the RhoA GTPase synergizes with IL-2 for SRE-driven transcription, whereas a dominant-negative mutant reduces the IL-2 response. Thus, in response to IL-2, full induction of the SRE requires ERK-dependent as well as Rho-dependent signals that target the Ets-box and the CArG-box respectively. We also report that the synergy between Gab2/SHP-2 and RhoA for IL-2-dependent CArG-box-driven transcription depends upon MEK (mitogen-activated protein kinase/ERK kinase) activation, and is likely to involve regulation of the serum response factor co-activator MAL. Our studies thus provide new insights into the role of Gab2 and SHP-2 in IL-2 signal transduction.
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Key Words
- c-fos
- grb2-associated binder 2 (gab2)
- interleukin 2 (il-2)
- mitogen-activated protein (map) kinase
- rho gtpase
- serum response element (sre)
- sh2-domain-containing tyrosine phosphatase (shp-2)
- ecl, enhanced chemiluminescence
- erk, extracellular-signal-regulated kinase
- gab2, grb2-associated binder-2
- gst, glutathione s-transferase
- ha, haemagglutinin
- il, interleukin
- iptg, isopropyl β-d-thiogalactoside
- irs, insulin receptor substrate
- jak, janus kinase
- mapk, mitogen-activated protein kinase
- mek, mapk/erk kinase
- pdgf-r, platelet-derived growth factor receptor
- pi3k, phosphoinositide 3-kinase
- sre, serum response element
- srf, serum response factor
- sh2, src homology 2
- shp-2, sh2-domain-containing tyrosine phosphatase
- stat, signal transduction and activators of transcription
- tcf, ternary complex factor
- y614f, etc., a mutant bearing a replacement of tyr-614 with phenylalanine, etc
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Affiliation(s)
- Mary Arnaud
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
| | - Rym Mzali
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
| | - Franck Gesbert
- †Unité de Biologie des Interactions Cellulaires, Institut Pasteur, 25 rue du docteur Roux, 75015 Paris, France
| | - Catherine Crouin
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
| | - Christine Guenzi
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
| | | | - John Wijdenes
- ‡Diaclone, 1 Boulevard A. Fleming, 25020 Besançon, France
| | - Geneviève Courtois
- §Inserm EMI0210, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75015 Paris, France
| | - Olivier Bernard
- §Inserm EMI0210, Faculté de Médecine Necker-Enfants Malades, 156 rue de Vaugirard, 75015 Paris, France
| | - Jacques Bertoglio
- *Inserm U461, Faculté de Pharmacie Paris-XI, 5 rue Jean-Baptiste Clément, 92290 Chatenay-Malabry, France
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21
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Holgado-Madruga M, Wong AJ. Role of the Grb2-associated binder 1/SHP-2 interaction in cell growth and transformation. Cancer Res 2004; 64:2007-15. [PMID: 15026337 DOI: 10.1158/0008-5472.can-03-2886] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Grb2-associated binder 1 (Gab1) is a docking protein that is tyrosine phosphorylated following the activation of multiple cytokine receptors and receptor tyrosine kinases. Its function then is to recruit and activate multiple signaling molecules. In our previous work, we showed that Gab1 enhances cell growth and induces the transformed phenotype in NIH3T3 cells downstream of the epidermal growth factor (EGF) receptor. In this report, we analyze how it produces these effects. Because SHP-2 is the major binding partner of Gab1, we mutated its binding site in the Gab1 cDNA (Gab1/DeltaSHP-2). This construct was stably overexpressed in NIH3T3 cells (3T3-Gab1/DeltaSHP-2) and in the wild-type Gab1 cDNA (3T3-Gab1) or an empty expression vector (3T3-CTR). Our findings show that after EGF stimulation, Gab1/DeltaSHP-2 has a higher level of tyrosine phosphorylation at early time points than Gab1. Gab1/DeltaSHP-2 recruits more phosphatidylinositol 3'-kinase than Gab1 after EGF triggering, which accounts for a higher and more sustained AKT activation in 3T3-Gab1/DeltaSHP-2 cells relative to 3T3-Gab1 fibroblasts. Moreover, 3T3-Gab1/DeltaSHP-2 cells demonstrate a higher level of extracellular-regulated kinase 1 activation at early time points of EGF stimulation. However, there was an unexpected decrease in c-fos promoter induction in 3T3-Gab1/DeltaSHP-2 cells when compared with 3T3-Gab1 cells. Additionally, the 3T3-Gab1/DeltaSHP-2 cells show a reversion of the transformed phenotype, including fewer morphologic changes, an increase in stress fiber cytoskeletal organization, and a decrease in cell proliferation and anchorage independent growth. These results reveal that the Gab1/SHP-2 interaction is essential for cell growth and transformation but that this must occur through a novel pathway that is independent of extracellular-regulated kinase or AKT. On the basis of its role in growth and transformation, the Gab1/SHP-2 interaction may become an attractive target for the pharmacologic intervention of malignant cell growth.
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Affiliation(s)
- Marina Holgado-Madruga
- Department of Microbiology and Immunology, The Kimmel Cancer Institute, Thomas Jefferson University, 233 South 10th Street, 1002 BLSB, Philadelphia, PA 19107, USA.
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22
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Ibarrola N, Molina H, Iwahori A, Pandey A. A Novel Proteomic Approach for Specific Identification of Tyrosine Kinase Substrates Using [13C]Tyrosine. J Biol Chem 2004; 279:15805-13. [PMID: 14739304 DOI: 10.1074/jbc.m311714200] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Proteomic studies to find substrates of tyrosine kinases generally rely on identification of protein bands that are "pulled down" by antiphosphotyrosine antibodies from ligand-stimulated samples. One can obtain erroneous results from such experiments because of two major reasons. First, some proteins might be basally phosphorylated on tyrosine residues in the absence of ligand stimulation. Second, proteins can bind non-specifically to the antibodies or the affinity matrix. Induction of phosphorylation of proteins by ligand must therefore be confirmed by a different approach, which is not always feasible. We have developed a novel proteomic approach to identify substrates of tyrosine kinases in signaling pathways studies based on in vivo labeling of proteins with "light" (12C-labeled) or "heavy" (13C-labeled) tyrosine. This stable isotope labeling in cell culture method enables the unequivocal identification of tyrosine kinase substrates, as peptides derived from true substrates give rise to a unique signature in a mass spectrometry experiment. By using this approach, from a single experiment, we have successfully identified several known substrates of insulin signaling pathway and a novel substrate, polymerase I and transcript release factor, a protein that is implicated in the control of RNA metabolism and regulation of type I collagen promoters. This approach is amenable to high throughput global studies as it simplifies the specific identification of substrates of tyrosine kinases as well as serine/threonine kinases using mass spectrometry.
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Affiliation(s)
- Nieves Ibarrola
- McKusick-Nathans Institute for Genetic Medicine and the Department of Biological Chemistry, The Johns Hopkins University, Baltimore, Maryland 21205, USA
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23
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Audette M, Larouche L, Lussier I, Fugère N. Stimulation of theICAM-1gene transcription by the peroxovanadium compound [bpV(Pic)] involves STAT-1 but not NF-κB activation in 293 cells. ACTA ACUST UNITED AC 2003. [DOI: 10.1046/j.1432-1327.2001.02054.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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24
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Rezzonico R, Cayatte C, Bourget-Ponzio I, Romey G, Belhacene N, Loubat A, Rocchi S, Van Obberghen E, Girault JA, Rossi B, Schmid-Antomarchi H. Focal adhesion kinase pp125FAK interacts with the large conductance calcium-activated hSlo potassium channel in human osteoblasts: potential role in mechanotransduction. J Bone Miner Res 2003; 18:1863-71. [PMID: 14584897 DOI: 10.1359/jbmr.2003.18.10.1863] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
UNLABELLED Molecular events of mechanotransduction in osteoblasts are poorly defined. We show that the mechanosensitive BK channels open and recruit the focal adhesion kinase FAK in osteoblasts on hypotonic shock. This could convert mechanical signals in biochemical events, leading to osteoblast activation. INTRODUCTION Mechanical strains applied to the skeleton influence bone remodeling and architecture mainly through the osteoblast lineage. The molecular mechanisms involved in osteoblastic mechanotransduction include opening of mechanosensitive cation channels and the activation of protein tyrosine kinases, notably FAK, but their interplay remains poorly characterized. The large conductance K+ channel (BK) seems likely as a bone mechanoreceptor candidate because of its high expression in osteoblasts and its ability to open in response to membrane stretch or hypotonic shock. Propagation of the signals issued from the mechanosensitivity of BK channels inside the cell likely implies complex interactions with molecular partners involved in mechanotransduction, notably FAK. METHODS Interaction of FAK with the C terminus of the hSlo alpha-subunit of BK was investigated using the yeast two-hybrid system as well as immunofluorescence microscopy and coimmunoprecipitation experiments with a rabbit anti-hslo antibody on MG63 and CAL72 human osteosarcoma cell lines and on normal human osteoblasts. Mapping of the FAK region interacting with hSlo was approached by testing the ability of hSlo to recruit mutated ot truncated FAK proteins. RESULTS To the best of our knowledge, we provide the first evidence of the physical association of FAK with the intracellular part of hslo. We show that FAK/hSlo interaction likely takes place through the Pro-1-rich domain situated in the C-terminal region of the kinase. FAK/hSlo association occurs constitutively at a low, but appreciable, level in human osteosarcoma cells and normal human osteoblasts that express endogenous FAK and hSlo. In addition, we found that application of an hypo-osmotic shock to these cells induced a sustained activation of BK channels associated to a marked increase in the recruitment of FAK on hSlo. CONCLUSIONS Based on these data, we propose that BK channels might play a triggering role in the signaling cascade induced by mechanical strains in osteoblasts.
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25
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Lock LS, Frigault MM, Saucier C, Park M. Grb2-independent recruitment of Gab1 requires the C-terminal lobe and structural integrity of the Met receptor kinase domain. J Biol Chem 2003; 278:30083-90. [PMID: 12766170 DOI: 10.1074/jbc.m302675200] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The Gab1 docking protein forms a platform for the assembly of a multiprotein signaling complex downstream from receptor tyrosine kinases. In general, recruitment of Gab1 occurs indirectly, via the adapter protein Grb2. In addition, Gab1 interacts with the Met/hepatocyte growth factor receptor in a Grb2-independent manner. This interaction requires a Met binding domain (MBD) in Gab1 and is essential for Met-mediated epithelial morphogenesis. The Gab1 MBD has been proposed to act as a phosphotyrosine binding domain that binds Tyr-1349 in the Met receptor. We show that a 16-amino acid motif within the Gab1 MBD is sufficient for interaction with the Met receptor, suggesting that it is unlikely that the Gab1 MBD forms a structured domain. Alternatively, the structural integrity of the Met receptor, and residues upstream of Tyr-1349 located in the C-terminal lobe of the kinase domain, are required for Grb2-independent interaction with the Gab1 MBD. Moreover, the substitution of Tyr-1349 with an acidic residue allows for the recruitment of the Gab1 MBD and for phosphorylation of Gab1. We propose that Gab1 and the Met receptor interact in a novel manner, such that the activated kinase domain of Met and the negative charge of phosphotyrosine 1349 engage the Gab1 MBD as an extended peptide ligand.
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Affiliation(s)
- Lisa S Lock
- Department of Biochemistry, Molecular Oncology Group, McGill University Health Centre, Montreal, Quebec H3A 1A1, Canada
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26
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Lock LS, Maroun CR, Naujokas MA, Park M. Distinct recruitment and function of Gab1 and Gab2 in Met receptor-mediated epithelial morphogenesis. Mol Biol Cell 2002. [PMID: 12058075 DOI: 10.1091/mbc.02-02-0031.] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The Gab family of docking proteins (Gab1 and Gab2) are phosphorylated in response to various cytokines and growth factors. Gab1 acts to diversify the signal downstream from the Met receptor tyrosine kinase through the recruitment of multiple signaling proteins, and is essential for epithelial morphogenesis. To determine whether Gab1 and Gab2 are functionally redundant, we have examined the role of Gab2 in epithelial cells. Both Gab1 and Gab2 are expressed in epithelial cells and localize to cell-cell junctions. However, whereas overexpression of Gab1 promotes a morphogenic response, the overexpression of Gab2 fails to induce this response. We show that Gab2 recruitment to the Met receptor is dependent on the Grb2 adapter protein. In contrast, Gab1 recruitment to Met is both Grb2 dependent and Grb2 independent. The latter requires a novel amino acid sequence present in the Met-binding domain of Gab1 but not Gab2. Mutation of these residues in Gab1 impairs both association with the Met receptor and the ability of Gab1 to promote a morphogenic response, whereas their insertion into Gab2 increases Gab2 association with Met, but does not confer on Gab2 the ability to promote epithelial morphogenesis. We propose that the Grb2-independent recruitment of Gab proteins to Met is necessary but not sufficient to promote epithelial morphogenesis.
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Affiliation(s)
- Lisa S Lock
- Department of Biochemistry, Molecular Oncology Group, McGill University Health Centre, Montreal, Quebec, Canada H3A 1A1
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Lock LS, Maroun CR, Naujokas MA, Park M. Distinct recruitment and function of Gab1 and Gab2 in Met receptor-mediated epithelial morphogenesis. Mol Biol Cell 2002; 13:2132-46. [PMID: 12058075 PMCID: PMC117630 DOI: 10.1091/mbc.02-02-0031] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The Gab family of docking proteins (Gab1 and Gab2) are phosphorylated in response to various cytokines and growth factors. Gab1 acts to diversify the signal downstream from the Met receptor tyrosine kinase through the recruitment of multiple signaling proteins, and is essential for epithelial morphogenesis. To determine whether Gab1 and Gab2 are functionally redundant, we have examined the role of Gab2 in epithelial cells. Both Gab1 and Gab2 are expressed in epithelial cells and localize to cell-cell junctions. However, whereas overexpression of Gab1 promotes a morphogenic response, the overexpression of Gab2 fails to induce this response. We show that Gab2 recruitment to the Met receptor is dependent on the Grb2 adapter protein. In contrast, Gab1 recruitment to Met is both Grb2 dependent and Grb2 independent. The latter requires a novel amino acid sequence present in the Met-binding domain of Gab1 but not Gab2. Mutation of these residues in Gab1 impairs both association with the Met receptor and the ability of Gab1 to promote a morphogenic response, whereas their insertion into Gab2 increases Gab2 association with Met, but does not confer on Gab2 the ability to promote epithelial morphogenesis. We propose that the Grb2-independent recruitment of Gab proteins to Met is necessary but not sufficient to promote epithelial morphogenesis.
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Affiliation(s)
- Lisa S Lock
- Department of Biochemistry, Molecular Oncology Group, McGill University Health Centre, Montreal, Quebec, Canada H3A 1A1
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Almind K, Delahaye L, Hansen T, Van Obberghen E, Pedersen O, Kahn CR. Characterization of the Met326Ile variant of phosphatidylinositol 3-kinase p85alpha. Proc Natl Acad Sci U S A 2002; 99:2124-8. [PMID: 11842213 PMCID: PMC122329 DOI: 10.1073/pnas.042688799] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/20/2001] [Indexed: 11/18/2022] Open
Abstract
Phosphatidylinositol 3-kinase is a key step in the metabolic actions of insulin. Two amino acid substitutions have been identified in the gene for the regulatory subunit of human p85alpha, Met-326Ile, and Asn-330Asp, and the former has been associated with alterations in glucose/insulin homeostasis. When the four human p85alpha proteins were expressed in yeast, a 27% decrease occurred in the level of protein expression of p85alpha(Ile/Asp) (P = 0.03) and a 43% decrease in p85alpha(Ile/Asn) (P = 0.08) as compared with p85alpha(Met/Asp). Both p85alpha(Ile/Asp) and p85alpha(Ile/Asn) also exhibited increased binding to phospho-insulin receptor substrate-1 by 41% and 83%, respectively (P < 0.001), as compared with p85alpha(Met/Asp). The expression of p85alpha(Ile) was also slightly decreased and the binding to insulin receptor substrate-1 slightly increased in brown preadipocytes derived from p85alpha knockout mice. Both p85alpha(Met) and p85alpha(Ile) had similar effects on AKT activity and were able to reconstitute differentiation of the preadipocytes, although the triglyceride concentration in fully differentiated adipocytes and insulin-stimulated 2-deoxyglucose uptake were slightly lower than in adipocytes expressing p85alpha(Met). Thus, the Met-326Ile variant of p85alpha is functional for intracellular signaling and adipocyte differentiation but has small alterations in protein expression and activity that could play a role in modifying insulin action.
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Affiliation(s)
- Katrine Almind
- Research Division, Joslin Diabetes Center and Department of Medicine, Harvard Medical School, Boston, MA 02215, USA
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29
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Nicholson PR, Empereur S, Glover HR, Dilworth SM. ShcA tyrosine phosphorylation sites can replace ShcA binding in signalling by middle T-antigen. EMBO J 2001; 20:6337-46. [PMID: 11707405 PMCID: PMC125738 DOI: 10.1093/emboj/20.22.6337] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
ShcA and Grb2 are crucial components in signalling by most tyrosine kinase-associated receptors. How ever, it is not clear whether Grb2 bound directly to the receptor is equivalent to Grb2 associated via ShcA. We have used signalling stimulated by the middle T-antigen (MT) of polyoma virus to address this question. The two known Grb2-binding sites from murine ShcA, 313Y and 239/240YY, could functionally replace the MT ShcA-interacting region in transformation assays using Rat2 fibroblasts. This demonstrates that signal output from membrane-bound ShcA requires only these two sequences and the ShcA-binding site in MT does not recruit other signalling molecules. Two standard Grb2-interacting sequences, either from the EGF receptor or the ShcA 313Y region, could not replace the requirement for ShcA binding to MT, indicating an enhanced role for the ShcA 239/240YY motif. Sos1 and the docking protein Gab1 are brought into the MT complex through Grb2 association and this may be more effective using the 239/240YY sequence.
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Affiliation(s)
| | | | | | - Stephen M. Dilworth
- Department of Metabolic Medicine, Imperial College School of Medicine, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK
Corresponding author e-mail:
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30
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Van Obberghen E, Baron V, Delahaye L, Emanuelli B, Filippa N, Giorgetti-Peraldi S, Lebrun P, Mothe-Satney I, Peraldi P, Rocchi S, Sawka-Verhelle D, Tartare-Deckert S, Giudicelli J. Surfing the insulin signaling web. Eur J Clin Invest 2001; 31:966-77. [PMID: 11737239 DOI: 10.1046/j.1365-2362.2001.00896.x] [Citation(s) in RCA: 65] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The diverse biological actions of insulin and insulin-like growth factor I (IGF-I) are initiated by binding of the polypeptides to their respective cell surface tyrosine kinase receptors. These activated receptors phosphorylate a series of endogenous substrates on tyrosine, amongst which the insulin receptor substrate (IRS) proteins are the best characterized. Their phosphotyrosine-containing motifs become binding sites for Src homology 2 (SH2) domains on proteins such as SH2 domain-containing protein-tyrosine-phosphatase (SHP)-2/Syp, growth factor receptor bound-2 protein, (Grb-2), and phosphatidyl inositol 3 kinase (PI3 kinase), which participate in activation of specific signaling cascades. However, the IRS molecules are not only platforms for signaling molecules, they also orchestrate the generation of signal specificity, integration of signals induced by several extracellular stimuli, and signal termination and modulation. An extensive review is beyond the scope of the present article, which will be centered on our own contribution and reflect our biases.
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Affiliation(s)
- E Van Obberghen
- Inserm U 145, IFR 50, Faculté de Médecine, Avenue de Valombrose, Nice Cedex, France.
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31
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Yu CF, Roshan B, Liu ZX, Cantley LG. ERK regulates the hepatocyte growth factor-mediated interaction of Gab1 and the phosphatidylinositol 3-kinase. J Biol Chem 2001; 276:32552-8. [PMID: 11445578 DOI: 10.1074/jbc.m104493200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Based on our previous observations that active ERK associates with and phosphorylates Gab1 in response to HGF, and the prediction that the ERK phosphorylation site is adjacent to one of the phosphatidylinositol 3-kinase (PI3K) SH2 binding motifs, we examined the possibility that ERK phosphorylation can regulate the Gab1/PI3K association. The HGF-mediated association of Gab1 with either full-length GST-p85 or its isolated N- or C-terminal SH2 domains was inhibited by approximately 50% in the setting of ERK inhibition, a result confirmed by co-immunoprecipitation of the native proteins. A 14-amino acid peptide encoding (472)YVPMTP(477) (one of the major p85 binding sites in Gab1 and the predicted ERK phosphorylation site) was synthesized with either phosphotyrosine alone (pY), or phosphotyrosine + phosphothreonine (pYT). In both pull-down assays and competition assays, pYT demonstrated a higher affinity for p85 than did pY alone. Finally, examination of the phosphorylation state of Akt after HGF stimulation revealed that ERK inhibition resulted in a decrease in Akt activation at both 5 and 10 min. These results suggest that activated ERK can phosphorylate Gab1 in response to HGF stimulation and thereby potentiate the Gab1/PI3K association and subsequent PI3K activation.
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Affiliation(s)
- C F Yu
- Department of Internal Medicine, Section of Nephrology, Yale University School of Medicine, New Haven, Connecticut 06520-8062, USA.
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32
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Fan S, Ma YX, Gao M, Yuan RQ, Meng Q, Goldberg ID, Rosen EM. The multisubstrate adapter Gab1 regulates hepatocyte growth factor (scatter factor)-c-Met signaling for cell survival and DNA repair. Mol Cell Biol 2001; 21:4968-84. [PMID: 11438654 PMCID: PMC87224 DOI: 10.1128/mcb.21.15.4968-4984.2001] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Hepatocyte growth factor (scatter factor) (HGF/SF) is a pleiotrophic mediator of epithelial cell motility, morphogenesis, angiogenesis, and tumorigenesis. HGF/SF protects cells against DNA damage by a pathway from its receptor c-Met to phosphatidylinositol 3-kinase (PI3K) to c-Akt, resulting in enhanced DNA repair and decreased apoptosis. We now show that protection against the DNA-damaging agent adriamycin (ADR; topoisomerase IIalpha inhibitor) requires the Grb2-binding site of c-Met, and overexpression of the Grb2-associated binder Gab1 (a multisubstrate adapter required for epithelial morphogenesis) inhibits the ability of HGF/SF to protect MDCK epithelial cells against ADR. In contrast to Gab1 and its homolog Gab2, overexpression of c-Cb1, another multisubstrate adapter that associates with c-Met, did not affect protection. Gab1 blocked the ability of HGF/SF to cause the sustained activation of c-Akt and c-Akt signaling (FKHR phosphorylation). The Gab1 inhibition of sustained c-Akt activation and of cell protection did not require the Gab1 pleckstrin homology or SHP2 phosphatase-binding domain but did require the PI3K-binding domain. HGF/SF protection of parental MDCK cells was blocked by wortmannin, expression of PTEN, and dominant negative mutants of p85 (regulatory subunit of PI3K), Akt, and Pak1; the protection of cells overexpressing Gab1 was restored by wild-type or activated mutants of p85, Akt, and Pak1. These findings suggest that the adapter Gab1 may redirect c-Met signaling through PI3K away from a c-Akt/Pak1 cell survival pathway.
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Affiliation(s)
- S Fan
- Department of Radiation Oncology, Long Island Jewish Medical Center, The Long Island Campus for the Albert Einstein College of Medicine, New Hyde Park, New York 11040, USA
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33
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Peraldi P, Filloux C, Emanuelli B, Hilton DJ, Van Obberghen E. Insulin induces suppressor of cytokine signaling-3 tyrosine phosphorylation through janus-activated kinase. J Biol Chem 2001; 276:24614-20. [PMID: 11325969 DOI: 10.1074/jbc.m102209200] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Suppressor of cytokine signaling (SOCS) proteins were originally described as cytokine-induced molecules involved in negative feedback loops. We have shown that SOCS-3 is also a component of the insulin signaling network (). Indeed, insulin leads to SOCS-3 expression in 3T3-L1 adipocytes. Once produced, SOCS-3 binds to phosphorylated tyrosine 960 of the insulin receptor and inhibits insulin signaling. Now we show that in 3T3-L1 adipocytes and in transfected COS-7 cells insulin leads to SOCS-3 tyrosine phosphorylation. This phosphorylation takes place on Tyr(204) and is dependent upon a functional SOCS-3 SH2 domain. Purified insulin receptor directly phosphorylates SOCS-3. However, in intact cells, a mutant of the insulin receptor, IRY960F, unable to bind SOCS-3, was as efficient as the wild type insulin receptor to phosphorylate SOCS-3. Importantly, IRY960F is as potent as the wild type insulin receptor to activate janus-activated kinase (Jak) 1 and Jak2. Furthermore, expression of a dominant negative form of Jak2 inhibits insulin-induced SOCS-3 tyrosine phosphorylation. As transfected Jaks have been shown to cause SOCS-3 phosphorylation, we propose that insulin induces SOCS-3 phosphorylation through Jak activation. Our data indicate that SOCS-3 belongs to a class of tyrosine-phosphorylated insulin signaling molecules, the phosphorylation of which is not dependent upon a direct coupling with the insulin receptor but relies on the Jaks.
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Affiliation(s)
- P Peraldi
- INSERM U145, IFR-50, Faculté de Médecine, 06107 Nice Cédex 2, France.
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34
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Koncz G, Tóth GK, Bökönyi G, Kéri G, Pecht I, Medgyesi D, Gergely J, Sármay G. Co-clustering of Fcgamma and B cell receptors induces dephosphorylation of the Grb2-associated binder 1 docking protein. EUROPEAN JOURNAL OF BIOCHEMISTRY 2001; 268:3898-906. [PMID: 11453982 DOI: 10.1046/j.1432-1327.2001.02295.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The immunoreceptor tyrosine-based inhibitory motif (ITIM) of human type IIb Fcgamma receptor (FcgammaRIIb) is phosphorylated on its tyrosine upon co-clustering with the B cell receptor (BCR). The phosphorylated ITIM (p-ITIM) binds to the SH2 domains of polyphosphoinositol 5-phosphatase (SHIP) and the tyrosine phosphatase, SHP-2. We investigated the involvement of the molecular complex composed of the phosphorylated SHIP and FcgammaRIIb in the activation of SHP-2. As a model compound, we synthesized a bisphosphopeptide, combining the sequences of p-ITIM and the N-terminal tyrosine phosphorylated motif of SHIP with a flexible spacer. This compound bound to the recombinant SH2 domains of SHP-2 with high affinity and activated the phosphatase in an in vitro assay. These data suggest that the phosphorylated FcgammaRII-SHIP complexes formed in the intact cells may also activate SHP-2. Grb2-associated binder 1 (Gab1) is a multisite docking protein, which becomes tyrosine-phosphorylated in response to various types of signaling, including BCR. In turn it binds to the SH2 domains of SHP-2, SHIP and the p85 subunit of phosphatidyl inositol 3-kinase (PtdIns3-K) and may regulate their activity. Gab1 is a potential substrate of SHP-2, thus its binding to FcgammaRIIb may modify the Gab1-bound signaling complex. We show here that Gab1 is part of the multiprotein complex assembled by FcgammaRIIb upon its co-clustering with BCR. Gab1 may recruit SH2 domain-containing molecules to the phosphorylated FcgammaRIIb. SHP-2, activated upon the binding to FcgammaRIIb-SHIP complex, partially dephosphorylates Gab1, resulting in the release of PtdIns3-K and ultimately in the inhibition of downstream activation pathways in BCR/FcgammaRIIb co-aggregated cells.
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MESH Headings
- Adaptor Proteins, Signal Transducing
- Adaptor Proteins, Vesicular Transport
- Amino Acid Motifs
- Antigens, CD/metabolism
- Intracellular Signaling Peptides and Proteins
- Phosphatidylinositol 3-Kinases/metabolism
- Phosphatidylinositol-3,4,5-Trisphosphate 5-Phosphatases
- Phosphopeptides/metabolism
- Phosphoproteins/metabolism
- Phosphoric Monoester Hydrolases/metabolism
- Protein Binding
- Protein Tyrosine Phosphatase, Non-Receptor Type 11
- Protein Tyrosine Phosphatase, Non-Receptor Type 6
- Protein Tyrosine Phosphatases/metabolism
- Proteins/metabolism
- Receptors, Antigen, B-Cell/metabolism
- Receptors, IgG/metabolism
- SH2 Domain-Containing Protein Tyrosine Phosphatases
- Shc Signaling Adaptor Proteins
- Signal Transduction
- Src Homology 2 Domain-Containing, Transforming Protein 1
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Affiliation(s)
- G Koncz
- Research Group of the Hungarian Academy of Science at the Department of Immunology, Loránd Eötvös University, Göd, Hungary
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35
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Cunnick JM, Mei L, Doupnik CA, Wu J. Phosphotyrosines 627 and 659 of Gab1 constitute a bisphosphoryl tyrosine-based activation motif (BTAM) conferring binding and activation of SHP2. J Biol Chem 2001; 276:24380-7. [PMID: 11323411 DOI: 10.1074/jbc.m010275200] [Citation(s) in RCA: 132] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
A major Grb2-associated binder-1 (Gab1) binding partner in epidermal growth factor (EGF)-stimulated cells is protein-tyrosine phosphatase (PTPase) SHP2, which contains tandem SH2 domains. The SHP2 PTPase activity is required for activation of the extracellular signal-regulated kinase (ERK) subfamily of mitogen-activated protein (MAP) kinase by EGF. To investigate the mechanism by which Gab1 and SHP2 mediate ERK activation, we characterized the Gab1-SHP2 interaction. We found that both Tyr-627 and Tyr-659 of Gab1 were required for SHP2 binding to Gab1 and for ERK2 activation by EGF. Far Western blot analysis suggested that the tandem SH2 domains of SHP2 bind to Gab1 in a specific orientation, in which the N-SH2 domain binds to phosphotyrosine (Tyr(P))-627 and the C-SH2 domain binds to Tyr(P)-659. When assayed with peptide substrates, SHP2 PTPase was activated by a bisphosphopeptide containing both Tyr(P)-627 and Tyr(P)-659, but not by monophosphopeptides containing Tyr(P)-627 or Tyr(P)-659 or a mixture of these monophosphopeptides. These results suggest that Tyr(P)-627 and Tyr(P)-659 of Gab1 constitute a bisphosphoryl tyrosine-based activation motif (BTAM) that binds and activates SHP2. Remarkably, while a constitutively active SHP2 (SHP2DeltaN) could not rescue the defect of a SHP2-binding defective Gab1 (Gab1FF) in ERK2 activation, expression of a Gab1FF-SHP2DeltaN chimera resulted in constitutive activation of ERK2 in transfected cells. Thus, physical association of activated SHP2 with Gab1 is necessary and sufficient to mediate the ERK mitogen-activated protein kinase activation. Phosphopeptides derived from Gab1 were dephosphorylated by active SHP2 in vitro. Consistently, substrate-trapping experiments with a SHP2 catalytic inactive mutant suggested that Gab1 was a SHP2 PTPase substrate in the cells. Therefore, Gab1 not only is a SHP2 activator but also is a target of its PTPase.
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Affiliation(s)
- J M Cunnick
- Molecular Oncology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612, USA
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36
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Crouin C, Arnaud M, Gesbert F, Camonis J, Bertoglio J. A yeast two-hybrid study of human p97/Gab2 interactions with its SH2 domain-containing binding partners. FEBS Lett 2001; 495:148-53. [PMID: 11334882 DOI: 10.1016/s0014-5793(01)02373-0] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
p97/Gab2 is a recently characterized member of a large family of scaffold proteins that play essential roles in signal transduction. Gab2 becomes tyrosine-phosphorylated in response to a variety of growth factors and forms multimolecular complexes with SH2 domain-containing signaling molecules such as the p85-regulatory subunit of the phosphoinositide-3-kinase (p85-PI3K), the tyrosine phosphatase SHP-2 and the adapter protein CrkL. To characterize the interactions between Gab2 and its SH2-containing binding partners, we designed a modified yeast two-hybrid system in which the Lyn tyrosine kinase is expressed in a regulated manner in yeast. Using this assay, we demonstrated that p97/Gab2 specifically interacts with the SH2 domains of PI3K, SHP-2 and CrkL. Interaction with p85-PI3K is mediated by tyrosine residues Y452, Y476 and Y584 of Gab2, while interaction with SHP-2 depends exclusively on tyrosine Y614. CrkL interaction is mediated by its SH2 domain recognizing Y266 and Y293, despite the latter being in a non-consensus (YTFK) environment.
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Affiliation(s)
- C Crouin
- Inserm Unit 461, Faculté de Pharmacie Paris-XI, Châtenay-Malabry, france
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37
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Ingham RJ, Santos L, Dang-Lawson M, Holgado-Madruga M, Dudek P, Maroun CR, Wong AJ, Matsuuchi L, Gold MR. The Gab1 docking protein links the b cell antigen receptor to the phosphatidylinositol 3-kinase/Akt signaling pathway and to the SHP2 tyrosine phosphatase. J Biol Chem 2001; 276:12257-65. [PMID: 11278704 DOI: 10.1074/jbc.m010590200] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
B cell antigen receptor (BCR) signaling causes tyrosine phosphorylation of the Gab1 docking protein. This allows phosphatidylinositol 3-kinase (PI3K) and the SHP2 tyrosine phosphatase to bind to Gab1. In this report, we tested the hypothesis that Gab1 acts as an amplifier of PI3K- and SHP2-dependent signaling in B lymphocytes. By overexpressing Gab1 in the WEHI-231 B cell line, we found that Gab1 can potentiate BCR-induced phosphorylation of Akt, a PI3K-dependent response. Gab1 expression also increased BCR-induced tyrosine phosphorylation of SHP2 as well as the binding of Grb2 to SHP2. We show that the pleckstrin homology (PH) domain of Gab1 is required for BCR-induced phosphorylation of Gab1 and for Gab1 participation in BCR signaling. Moreover, using confocal microscopy, we show that BCR ligation can induce the translocation of Gab1 from the cytosol to the plasma membrane and that this requires the Gab1 PH domain as well as PI3K activity. These findings are consistent with a model in which the binding of the Gab1 PH domain to PI3K-derived lipids brings Gab1 to the plasma membrane, where it can be tyrosine-phosphorylated and then act as an amplifier of BCR signaling.
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Affiliation(s)
- R J Ingham
- Departments of Microbiology and Immunology and Zoology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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38
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Abstract
Insulin resistance is thought to be the primary defect in the pathophysiology of type 2 diabetes. Thus, understanding the cellular mechanisms of insulin action may contribute significantly to developing new treatments for this disease. Although the effects of insulin on glucose and lipid metabolism are well documented, gaps remain in our understanding of the precise molecular mechanisms of signal transduction for the hormone. One potential clue to understanding the unique cellular effects of insulin may lie in the compartmentalization of signaling molecules and metabolic enzymes. We review this evidence, and speculate on how PI-3 kinase-independent and -dependent signaling pathways both diverge from the insulin receptor and converge at discrete targets to insure the specificity of insulin action.
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Affiliation(s)
- C A Baumann
- Department of Cell Biology, Parke-Davis Pharmaceutical Research and the Department of Physiology, University of Michigan, Ann Arbor, USA
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39
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Ali S, Ali S. Recruitment of the protein-tyrosine phosphatase SHP-2 to the C-terminal tyrosine of the prolactin receptor and to the adaptor protein Gab2. J Biol Chem 2000; 275:39073-80. [PMID: 10991949 DOI: 10.1074/jbc.m007478200] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The protein-tyrosine phosphatase SHP-2 modulates signaling events through receptor tyrosine kinases and cytokine receptors including the receptor for prolactin (PRLR). Here we investigated mechanisms of SHP-2 recruitment within the PRLR signaling complex. Using SHP-2 and PRLR immunoprecipitation studies in 293 cells and in the mouse mammary epithelial cell line HC11, we found that SHP-2 co-immunoprecipitates with the PRLR and that the C-terminal tyrosine of the PRLR plays a regulatory role in both the tyrosine phosphorylation and the recruitment of SHP-2. Our results further indicate that SHP-2 association to the PRLR occurs via the C-terminal SH2 domain of the phosphatase. In addition, we determined that the newly identified adaptor protein Gab2, but not Gab1, is specifically tyrosine phosphorylated and is able to recruit SHP-2 and phosphatidyinositol 3-kinase in response to PRLR activation. Together, these studies suggest the presence of dual recruitment sites for SHP-2; the first is to the C-terminal tyrosine of the PRLR and the second is to the adaptor protein Gab2.
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Affiliation(s)
- S Ali
- Department of Medicine, Division of Hematology and Molecular Oncology Group, Royal Victoria Hospital, McGill University, Montreal, Quebec H3A 1A1, Canada
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40
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Janez A, Worrall DS, Imamura T, Sharma PM, Olefsky JM. The Osmotic Shock-induced Glucose Transport Pathway in 3T3-L1 Adipocytes Is Mediated by Gab-1 and Requires Gab-1-associated Phosphatidylinositol 3-Kinase Activity for Full Activation. J Biol Chem 2000. [DOI: 10.1016/s0021-9258(19)61455-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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41
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Schaeper U, Gehring NH, Fuchs KP, Sachs M, Kempkes B, Birchmeier W. Coupling of Gab1 to c-Met, Grb2, and Shp2 mediates biological responses. J Cell Biol 2000; 149:1419-32. [PMID: 10871282 PMCID: PMC2175135 DOI: 10.1083/jcb.149.7.1419] [Citation(s) in RCA: 275] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Gab1 is a substrate of the receptor tyrosine kinase c-Met and involved in c-Met-specific branching morphogenesis. It associates directly with c-Met via the c-Met-binding domain, which is not related to known phosphotyrosine-binding domains. In addition, Gab1 is engaged in a constitutive complex with the adaptor protein Grb2. We have now mapped the c-Met and Grb2 interaction sites using reverse yeast two-hybrid technology. The c-Met-binding site is localized to a 13-amino acid region unique to Gab1. Insertion of this site into the Gab1-related protein p97/Gab2 was sufficient to confer c-Met-binding activity. Association with Grb2 was mapped to two sites: a classical SH3-binding site (PXXP) and a novel Grb2 SH3 consensus-binding motif (PX(V/I)(D/N)RXXKP). To detect phosphorylation-dependent interactions of Gab1 with downstream substrates, we developed a modified yeast two-hybrid assay and identified PI(3)K, Shc, Shp2, and CRKL as interaction partners of Gab1. In a trk-met-Gab1-specific branching morphogenesis assay, association of Gab1 with Shp2, but not PI(3)K, CRKL, or Shc was essential to induce a biological response in MDCK cells. Overexpression of a Gab1 mutant deficient in Shp2 interaction could also block HGF/SF-induced activation of the MAPK pathway, suggesting that Shp2 is critical for c-Met/Gab1-specific signaling.
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Affiliation(s)
- U Schaeper
- Max Delbrück Center for Molecular Medicine, 13092 Berlin, Germany.
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42
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Cunnick JM, Dorsey JF, Munoz-Antonia T, Mei L, Wu J. Requirement of SHP2 binding to Grb2-associated binder-1 for mitogen-activated protein kinase activation in response to lysophosphatidic acid and epidermal growth factor. J Biol Chem 2000; 275:13842-8. [PMID: 10788507 DOI: 10.1074/jbc.275.18.13842] [Citation(s) in RCA: 116] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Grb2-associated binder-1 (Gab1) is a multisite docking protein containing a pleckstrin homology (PH) domain, multiple potential tyrosine phosphorylation sites, and several proline-rich sequences. Gab1 becomes tyrosine-phosphorylated in cells stimulated with growth factors, cytokines, and ligands for G protein-coupled receptors. A major Gab1-binding protein detected in cells treated with extracellular stimuli is the tyrosine phosphatase, SHP2. Although the role of SHP2-Gab1 interaction in cell signaling has not yet been characterized, SHP2 is known to mediate mitogen-activated protein (MAP) kinase activation induced by the epidermal growth factor (EGF). However, the mechanism by which the SHP2 phosphatase exerts a positive signaling role remains obscure. In this study, we prepared Gab1 mutants lacking the SHP2 binding site (Gab1Y627F), the phosphatidylinositol 3-kinase (PI3K) binding sites (Gab1DeltaPI3K), and the PH domain (Gab1DeltaPH). Expression of Gab1Y627F blocked the extracellular signal-regulated kinase-2 (ERK2) activation by lysophosphatidic acid (LPA) and EGF. Conversely, expression of the wild-type Gab1 in HEK293 cells augmented the LPA receptor Edg2-mediated ERK2 activation. Whereas the PH domain was required for Gab1 mediation of ERK2 activation by LPA, it was not essential for EGF-induced ERK2 activation. Expression of Gab1DeltaPI3K had no apparent effect on ERK2 activation by LPA and EGF in the cells that we have examined. These results establish a role for Gab1 in the LPA-induced MAP kinase pathway and clearly demonstrate that Gab1-SHP2 interaction is essential for ERK2 activation by LPA and EGF. These findings also suggest that the positive role of SHP2 in the MAP kinase pathway depends on its interaction with Gab1.
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Affiliation(s)
- J M Cunnick
- Molecular Oncology Program, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida 33612, USA
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Gual P, Giordano S, Williams TA, Rocchi S, Van Obberghen E, Comoglio PM. Sustained recruitment of phospholipase C-gamma to Gab1 is required for HGF-induced branching tubulogenesis. Oncogene 2000; 19:1509-18. [PMID: 10734310 DOI: 10.1038/sj.onc.1203514] [Citation(s) in RCA: 137] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
A distinctive property of Hepatocyte Growth Factor (HGF) is its ability to induce differentiation of tubular structures from epithelial and endothelial cells (branching tubulogenesis). The HGF receptor directly activates PI3 kinase, Ras and STAT signalling pathways and phosphorylates the adaptator GRB2 Associated Binder-1 (Gab1). Gab1 is also phosphorylated in response to Epidermal Growth Factor (EGF) but is unable to induce tubule formation. Comparison of 32P-peptide maps of Gab1 from EGF- versus HGF-treated cells, demonstrates that the same sites are phosphorylated in vivo. However, while both EGF and HGF induce rapid tyrosine phosphorylation of Gab1 with a peak at 15 min, the phosphorylation persists for over 1 h, only in response to HGF. Nine tyrosines are phosphorylated by both receptors. Three of them (Y307, Y373, Y407) bind phospholipase C-gamma (PLC-gamma). Interestingly, the overexpression of a Gab1 mutant unable to bind PLC-gamma (Gab1 Y307/373/407F) did not alter HGF-stimulated cell scattering, only partially reduced the growth stimulation but completely abolished HGF-mediated tubulogenesis. It is concluded that sustained recruitment of PLCgamma to Gab1 plays an important role in branching tubulogenesis.
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Affiliation(s)
- P Gual
- Institute for Cancer Research and Treatment (IRCC), University of Torino Medical School, Str. Prov. 142, Km 3.95, 10060 Candiolo, Italy
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Abstract
Shp-2 is implicated in several tyrosine kinase receptor signaling pathways. This phosphotyrosine phosphatase is composed of a catalytic domain in its C-terminus and two SH2 domains in its N-terminus. Shp-2 becomes activated upon binding through one or both SH2 domains to tyrosine phosphorylated molecules such as Shc or insulin receptor substrates. We were interested in finding a new molecule(s), tyrosine phosphorylated by the insulin receptor (IR), that could interact with Shp-2. To do so, we screened a human placenta complementary DNA (cDNA) library with the SH2 domain-containing part of Shp-2 using a modified yeast two-hybrid system. In this system we induce or repress the expression of a constitutive active IR beta-subunit. When expressed, IR phosphorylates proteins produced from the library that can then associate with Shp-2. Using this approach, we isolated FRS2 as a potential target for tyrosine phosphorylation by the IR. After cloning the entire cDNA, we found that 1) in the yeast two-hybrid system, FRS2 interacts with Shp-2 in a fashion dependent on the presence of the IR; and 2) in the PC12/IR cell-line, insulin leads to an increase in FRS2 association with the phosphatase. We next wanted to determine whether FRS2 could be a direct substrate for IR. In an in vitro kinase assay we found that wheat-germ agglutinin-purified IR phosphorylates glutathione-S-transferase-FRS2 fusion protein. Finally, in intact cells we show that insulin stimulates tyrosine phosphorylation of endogenous FRS2. In summary, by screening a two-hybrid cDNA library, we have isolated FRS2 as a possible substrate for IR. We found that IR can directly phosphorylate FRS2. Moreover, in intact cells insulin stimulates tyrosine phosphorylation of FRS2 and its subsequent association with Shp-2. Taken together these results suggest that FRS2 could participate in insulin signaling by recruiting Shp-2 and, hence, could function as a docking molecule similar to insulin receptor substrate proteins.
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Korhonen JM, Saïd FA, Wong AJ, Kaplan DR. Gab1 mediates neurite outgrowth, DNA synthesis, and survival in PC12 cells. J Biol Chem 1999; 274:37307-14. [PMID: 10601297 DOI: 10.1074/jbc.274.52.37307] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
The Gab1-docking protein has been shown to regulate phosphatidylinositol 3-kinase PI3K activity and potentiate nerve growth factor (NGF)-induced survival in PC12 cells. Here, we investigated the potential of Gab1 to induce neurite outgrowth and DNA synthesis, two other important aspects of NGF-induced neuronal differentiation of PC12 cells and NGF-independent survival. We generated a recombinant adenovirus encoding hemagglutinin (HA)-epitope-tagged Gab1 and expressed this protein in PC12 cells. HA-Gab1 was constitutively tyrosine-phosphorylated in PC12 cells and induced the phosphorylation of Akt/protein kinase B and p44/42 mitogen-activated protein kinase. HA-Gab1-stimulated a 10-fold increase in neurite outgrowth in the absence of NGF and a 5-fold increase in NGF-induced neurite outgrowth. HA-Gab1 also stimulated DNA synthesis and caused NGF-independent survival in PC12 cells. Finally, we found that HA-Gab1-induced neuritogenesis was completely suppressed by pharmacological inhibition of mitogen-activated protein kinase kinase (MEK) activity and 50% suppressed by inhibition of PI3K activity. In contrast, HA-Gab1-stimulated cell survival was efficiently suppressed only by inhibition of both PI3K and MEK activities. These results indicate that Gab1 is capable of mediating differentiation, DNA synthesis, and cell survival and uses both PI3K and MEK signaling pathways to achieve its effects.
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Affiliation(s)
- J M Korhonen
- Montreal Neurological Institute, Brain Tumor Research Centre, Montreal, Quebec H3A 2B4, Canada
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Zozulya S, Lioubin M, Hill RJ, Abram C, Gishizky ML. Mapping signal transduction pathways by phage display. Nat Biotechnol 1999; 17:1193-8. [PMID: 10585717 DOI: 10.1038/70736] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Rapid identification of proteins that interact with a novel gene product is an important element of functional genomics. Here we describe a phage display-based technique for interaction screening of complex cDNA libraries using proteins or synthetic peptides as baits. Starting with the epidermal growth factor receptor (EGFR) cytoplasmic tail, we identified known protein interactions that link EGFR to the Ras/MAP kinase signal transduction cascade and several novel interactions. This approach can be used as a rapid and efficient tool for elucidating protein networks and mapping intracellular signal transduction pathways.
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Affiliation(s)
- S Zozulya
- Sugen, Inc., 230 East Grand Ave., South San Francisco, CA 04080, USA
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Elmendorf JS, Pessin JE. Insulin signaling regulating the trafficking and plasma membrane fusion of GLUT4-containing intracellular vesicles. Exp Cell Res 1999; 253:55-62. [PMID: 10579911 DOI: 10.1006/excr.1999.4675] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- J S Elmendorf
- Department of Physiology, University of Iowa, Iowa City, Iowa, 52242-1109, USA
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Maegawa H, Hasegawa M, Sugai S, Obata T, Ugi S, Morino K, Egawa K, Fujita T, Sakamoto T, Nishio Y, Kojima H, Haneda M, Yasuda H, Kikkawa R, Kashiwagi A. Expression of a dominant negative SHP-2 in transgenic mice induces insulin resistance. J Biol Chem 1999; 274:30236-43. [PMID: 10514516 DOI: 10.1074/jbc.274.42.30236] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
To elucidate the roles of SHP-2, we generated transgenic (Tg) mice expressing a dominant negative mutant lacking protein tyrosine phosphatase domain (DeltaPTP). On examining two lines of Tg mice identified by Southern blot, the transgene product was expressed in skeletal muscle, liver, and adipose tissues, and insulin-induced association of insulin receptor substrate 1 with endogenous SHP-2 was inhibited, confirming that DeltaPTP has a dominant negative property. The intraperitoneal glucose loading test demonstrated an increase in blood glucose levels in Tg mice. Plasma insulin levels in Tg mice after 4 h fasting were 3 times greater with comparable blood glucose levels. To estimate insulin sensitivity by a constant glucose, insulin, and somatostatin infusion, steady state blood glucose levels were higher, suggesting the presence of insulin resistance. Furthermore, we observed the impairment of insulin-stimulated glucose uptake in muscle and adipocytes in the presence of physiological concentrations of insulin. Moreover, tyrosine phosphorylation of insulin receptor substrate-1 and stimulation of phosphatidylinositol 3-kinase and Akt kinase activities by insulin were attenuated in muscle and liver. These results indicate that the inhibition of endogenous SHP-2 function by the overexpression of a dominant negative mutant may lead to impaired insulin sensitivity of glucose metabolism, and thus SHP-2 may function to modulate insulin signaling in target tissues.
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Affiliation(s)
- H Maegawa
- Third Department of Medicine, Shiga University of Medical Science, Otsu, Shiga 520-2192, Japan.
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Erythropoietin Induces the Tyrosine Phosphorylation of GAB1 and Its Association With SHC, SHP2, SHIP, and Phosphatidylinositol 3-Kinase. Blood 1999. [DOI: 10.1182/blood.v93.8.2578] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
AbstractFive tyrosine-phosphorylated proteins with molecular masses of 180, 145, 116, 100, and 70 kD are associated with phosphatidylinositol 3-kinase (PI 3-kinase) in erythropoietin (Epo)-stimulated UT-7 cells. The 180- and 70-kD proteins have been previously shown to be IRS2 and the Epo receptor. In this report, we show that the 116-kD protein is the IRS2-related molecular adapter, GAB1. Indeed, Epo induced the transient tyrosine phosphorylation of GAB1 in UT-7 cells. Both kinetics and Epo dose-response experiments showed that GAB1 tyrosine phosphorylation was a direct consequence of Epo receptor activation. After tyrosine phosphorylation, GAB1 associated with the PI 3-kinase, the phosphotyrosine phosphatase SHP2, the phosphatidylinositol 3,4,5 trisphosphate 5-phosphatase SHIP, and the molecular adapter SHC. GAB1 was also associated with the molecular adapter GRB2 in unstimulated cells, and this association dramatically increased after Epo stimulation. Thus, GAB1 could be a scaffold protein able to couple the Epo receptor activation with the stimulation of several intracellular signaling pathways. Epo-induced tyrosine phosphorylation of GAB1 was also observed in normal human erythroid progenitors isolated from cord blood. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and thrombopoietin (TPO) also induced the tyrosine phosphorylation of GAB1 in UT-7 cells, indicating that this molecule participates in the signal transduction of several cytokine receptors.
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Erythropoietin Induces the Tyrosine Phosphorylation of GAB1 and Its Association With SHC, SHP2, SHIP, and Phosphatidylinositol 3-Kinase. Blood 1999. [DOI: 10.1182/blood.v93.8.2578.408k24_2578_2585] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Five tyrosine-phosphorylated proteins with molecular masses of 180, 145, 116, 100, and 70 kD are associated with phosphatidylinositol 3-kinase (PI 3-kinase) in erythropoietin (Epo)-stimulated UT-7 cells. The 180- and 70-kD proteins have been previously shown to be IRS2 and the Epo receptor. In this report, we show that the 116-kD protein is the IRS2-related molecular adapter, GAB1. Indeed, Epo induced the transient tyrosine phosphorylation of GAB1 in UT-7 cells. Both kinetics and Epo dose-response experiments showed that GAB1 tyrosine phosphorylation was a direct consequence of Epo receptor activation. After tyrosine phosphorylation, GAB1 associated with the PI 3-kinase, the phosphotyrosine phosphatase SHP2, the phosphatidylinositol 3,4,5 trisphosphate 5-phosphatase SHIP, and the molecular adapter SHC. GAB1 was also associated with the molecular adapter GRB2 in unstimulated cells, and this association dramatically increased after Epo stimulation. Thus, GAB1 could be a scaffold protein able to couple the Epo receptor activation with the stimulation of several intracellular signaling pathways. Epo-induced tyrosine phosphorylation of GAB1 was also observed in normal human erythroid progenitors isolated from cord blood. Granulocyte-macrophage colony-stimulating factor (GM-CSF) and thrombopoietin (TPO) also induced the tyrosine phosphorylation of GAB1 in UT-7 cells, indicating that this molecule participates in the signal transduction of several cytokine receptors.
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