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Title: Insulin receptor substrates 1 and 2 but not Shc can activate the insulin receptor independent of insulin and induce proliferation in CHO-IR cells

Abstract

Ligand-activated insulin receptor (IR) attracts and phosphorylates various substrates such as insulin receptor substrates 1-4 (IRS) and Shc. To investigate how binding affinity for substrate affects signalling we generated chimeric receptors with the {beta}-chain of the insulin receptor containing NPXY motives with different affinities for receptor substrates. We found that the extent of receptor tyrosine phosphorylation positively correlates with binding affinity towards IRS1/2 but not towards Shc. Moreover, overexpression of IRS1 or IRS2 but not of Shc increased IR tyrosine phosphorylation in a dose-dependent manner, also independent of insulin. Molecular truncations of IRS1 revealed that neither the isolated PH and PTB domains nor the C-terminus with the tyrosine phosphorylation sites alone are sufficient for substrate-dependent receptor activation. Overexpression of IRS1 and IRS2 impaired insulin-induced internalization of the IR in a dose-dependent manner suggesting that IRS proteins prevent endosome-associated receptor dephosphorylation/inactivation. IRS1 and IRS2 could therefore target the activated IR to different cellular compartments. Overexpression of IRS1 and IRS2 inhibited insulin-stimulated activation of the MAP kinases Erk1/2 while it increased/induced activation of Akt/PKB. Finally, overexpression of IRS1 and IRS2 but not of Shc induced DNA synthesis in starved CHO-IR cells independent of exogenous growth factors. Our results demonstrate that variations inmore » cellular IRS1 and IRS2 concentration affect insulin signalling both upstream and downstream and that IRS proteins could play instructive rather than just permissive roles in signal transmission.« less

Authors:
 [1];  [2];  [2];  [3];  [2];  [2];  [3];  [4]
  1. Department of Endocrinology and Diabetes, University Hospital Zurich, Ramistrasse 100, 8091 Zurich (Switzerland) and Competence Center for Systems Physiology and Metabolic Diseases, ETH Honggerberg, Schafmattstr. 18, 8093 Zurich (Switzerland). E-mail: markus.niessen@usz.ch
  2. Department of Endocrinology and Diabetes, University Hospital Zurich, Ramistrasse 100, 8091 Zurich (Switzerland)
  3. (Switzerland)
  4. Zentrale Dienste der Universitaet, Ausruestung und Logistik, Y10 G 22, Winterthurerstrasse 190, 8057 Zurich (Switzerland)
Publication Date:
OSTI Identifier:
20972124
Resource Type:
Journal Article
Resource Relation:
Journal Name: Experimental Cell Research; Journal Volume: 313; Journal Issue: 4; Other Information: DOI: 10.1016/j.yexcr.2006.11.015; PII: S0014-4827(06)00488-5; Copyright (c) 2006 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
60 APPLIED LIFE SCIENCES; CELL PROLIFERATION; GROWTH FACTORS; INSULIN; PHOSPHORYLATION; PHOSPHOTRANSFERASES; RECEPTORS; SUBSTRATES; TYROSINE

Citation Formats

Niessen, Markus, Jaschinski, Frank, Item, Flurin, Institute of Human Movement Sciences and Sport, ETH Zurich, Winterthurerstrasse 190, 8057 Zurich, McNamara, Morgan P., Spinas, Giatgen A., Competence Center for Systems Physiology and Metabolic Diseases, ETH Honggerberg, Schafmattstr. 18, 8093 Zurich, and Trueb, Thomas. Insulin receptor substrates 1 and 2 but not Shc can activate the insulin receptor independent of insulin and induce proliferation in CHO-IR cells. United States: N. p., 2007. Web. doi:10.1016/j.yexcr.2006.11.015.
Niessen, Markus, Jaschinski, Frank, Item, Flurin, Institute of Human Movement Sciences and Sport, ETH Zurich, Winterthurerstrasse 190, 8057 Zurich, McNamara, Morgan P., Spinas, Giatgen A., Competence Center for Systems Physiology and Metabolic Diseases, ETH Honggerberg, Schafmattstr. 18, 8093 Zurich, & Trueb, Thomas. Insulin receptor substrates 1 and 2 but not Shc can activate the insulin receptor independent of insulin and induce proliferation in CHO-IR cells. United States. doi:10.1016/j.yexcr.2006.11.015.
Niessen, Markus, Jaschinski, Frank, Item, Flurin, Institute of Human Movement Sciences and Sport, ETH Zurich, Winterthurerstrasse 190, 8057 Zurich, McNamara, Morgan P., Spinas, Giatgen A., Competence Center for Systems Physiology and Metabolic Diseases, ETH Honggerberg, Schafmattstr. 18, 8093 Zurich, and Trueb, Thomas. Thu . "Insulin receptor substrates 1 and 2 but not Shc can activate the insulin receptor independent of insulin and induce proliferation in CHO-IR cells". United States. doi:10.1016/j.yexcr.2006.11.015.
@article{osti_20972124,
title = {Insulin receptor substrates 1 and 2 but not Shc can activate the insulin receptor independent of insulin and induce proliferation in CHO-IR cells},
author = {Niessen, Markus and Jaschinski, Frank and Item, Flurin and Institute of Human Movement Sciences and Sport, ETH Zurich, Winterthurerstrasse 190, 8057 Zurich and McNamara, Morgan P. and Spinas, Giatgen A. and Competence Center for Systems Physiology and Metabolic Diseases, ETH Honggerberg, Schafmattstr. 18, 8093 Zurich and Trueb, Thomas},
abstractNote = {Ligand-activated insulin receptor (IR) attracts and phosphorylates various substrates such as insulin receptor substrates 1-4 (IRS) and Shc. To investigate how binding affinity for substrate affects signalling we generated chimeric receptors with the {beta}-chain of the insulin receptor containing NPXY motives with different affinities for receptor substrates. We found that the extent of receptor tyrosine phosphorylation positively correlates with binding affinity towards IRS1/2 but not towards Shc. Moreover, overexpression of IRS1 or IRS2 but not of Shc increased IR tyrosine phosphorylation in a dose-dependent manner, also independent of insulin. Molecular truncations of IRS1 revealed that neither the isolated PH and PTB domains nor the C-terminus with the tyrosine phosphorylation sites alone are sufficient for substrate-dependent receptor activation. Overexpression of IRS1 and IRS2 impaired insulin-induced internalization of the IR in a dose-dependent manner suggesting that IRS proteins prevent endosome-associated receptor dephosphorylation/inactivation. IRS1 and IRS2 could therefore target the activated IR to different cellular compartments. Overexpression of IRS1 and IRS2 inhibited insulin-stimulated activation of the MAP kinases Erk1/2 while it increased/induced activation of Akt/PKB. Finally, overexpression of IRS1 and IRS2 but not of Shc induced DNA synthesis in starved CHO-IR cells independent of exogenous growth factors. Our results demonstrate that variations in cellular IRS1 and IRS2 concentration affect insulin signalling both upstream and downstream and that IRS proteins could play instructive rather than just permissive roles in signal transmission.},
doi = {10.1016/j.yexcr.2006.11.015},
journal = {Experimental Cell Research},
number = 4,
volume = 313,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}