GTK Tyrosine Kinase-induced Alteration of IRS-protein Signalling in Insulin Producing Cells
Authors:
Open Access
- 1 November 2002
- journal article
- research article
- Published by Springer Nature in Molecular Medicine
- Vol. 8 (11) , 705-713
Abstract
Insulin receptor substrate proteins (IRS) mediate various effects of insulin, including regulation of glucose homeostasis, cell growth and survival. To understand the underlying mechanisms explaining the effects of the Src-related tyrosine kinase GTK on β-cell proliferation and survival, insulin-signalling pathways involving IRS-1 and IRS-2 were studied in islet cells and RINm5F cells overexpressing wild-type and two different mutants of the SRC-related tyrosine kinase GTK. Islets isolated from transgenic mice and RINm5F cells overexpressing wild-type and mutant GTK were analysed for IRS-1, IRS-2, SHB, AKT and ERK phosphorylation/activity by Western blot analysis. RINm5F cells expressing the kinase active mutant Y504F-GTK and islet cells from GTKY504F-transgenic mice exhibited reduced insulin-induced tyrosine phosphorylation of IRS-1 and IRS-2. In RINm5F cells, the diminished IRS-phosphorylation was accompanied by a reduced insulin-stimulated activation of phosphatidylinositol 3-kinase (PI3K), AKT and Extracellular SignalRegulated Kinase, partly due to an increased basal activity. In addition, increased tyrosine phosphorylation of the SHB SH2 domain-adaptor protein and its association with IRS-2, IRS-1 and focal adhesion kinase was observed in these cells. RINm5F cells overexpressing wild-type GTK also exhibited reduced activation of IRS-2, PI3K and AKT, whereas cells expressing a GTK mutant with lower kinase activity (GTKY394F) exhibited insignificantly altered responses to insulin compared to the mock transfected cells. Moreover, GTK was shown to associate with and phosphorylate SHB in transiently transfected COS-7 cells, indicating that SHB is a specific substrate for GTK. The results suggest that GTK signals via SHB to modulate insulin-stimulated pathways in β cells and this may explain previous results showing an increased β-cell mass in GTK-transgenic mice.Keywords
This publication has 26 references indexed in Scilit:
- Protein Kinase C-ζ Phosphorylates Insulin Receptor Substrate-1 and Impairs Its Ability to Activate Phosphatidylinositol 3-Kinase in Response to InsulinJournal of Biological Chemistry, 2001
- Shf, a Shb-like Adapter Protein, Is Involved in PDGF-α-Receptor Regulation of ApoptosisBiochemical and Biophysical Research Communications, 2000
- GTK, a Src-related Tyrosine Kinase, Induces Nerve Growth Factor-independent Neurite Outgrowth in PC12 Cells through Activation of the Rap1 PathwayJournal of Biological Chemistry, 2000
- Insights into insulin resistance and type 2 diabetes from knockout mouse modelsJournal of Clinical Investigation, 2000
- A Molecular Model of Inducible Costimulator Protein and Three-Dimensional Analysis of its Relation to the CD28 Family of T Cell-Specific Costimulatory ReceptorsJournal of Molecular Modeling, 1999
- Tissue-Specific Knockout of the Insulin Receptor in Pancreatic β Cells Creates an Insulin Secretory Defect Similar to that in Type 2 DiabetesCell, 1999
- The IRS‐signalling system during insulin and cytokine actionBioEssays, 1997
- Alternative pathway of insulin signalling in mice with targeted disruption of the IRS-1 geneNature, 1994
- Insulin resistance and growth retardation in mice lacking insulin receptor substrate-1Nature, 1994
- Activation and suppression of pp60c-src transforming ability by mutation of its primary sites of tyrosine phosphorylationCell, 1987