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Molecular and Cellular Biology, July 2000, p. 4708-4723, Vol. 20, No. 13
Aventis Pharma Deutschland GmbH, 65926 Frankfurt am Main, Germany
Received 31 January 2000/Returned for modification 20 March
2000/Accepted 12 April 2000
Signaling molecules downstream from the insulin receptor, such as
the insulin receptor substrate protein 1 (IRS-1), are also activated by
other receptor tyrosine kinases. Here we demonstrate that the
non-receptor tyrosine kinases, focal adhesion kinase pp125FAK and Src-class kinase pp59Lyn, after
insulin-independent activation by phosphoinositolglycans (PIG), can
cross talk to metabolic insulin signaling in rat and 3T3-L1 adipocytes.
Introduction by electroporation of neutralizing antibodies against
pp59Lyn and pp125FAK into isolated rat
adipocytes blocked IRS-1 tyrosine phosphorylation in response to PIG
but not insulin. Introduction of peptides encompassing either the major
autophosphorylation site of pp125FAK, tyrosine 397, or its
regulatory loop with the twin tyrosines 576 and 577 inhibited
PIG-induced IRS-1 tyrosine phosphorylation and glucose transport.
PIG-induced pp59Lyn kinase activation and
pp125FAK tyrosine phosphorylation were impaired by the
former and latter peptide, respectively. Up-regulation of
pp125FAK by integrin clustering diminished PIG-induced
IRS-1 tyrosine phosphorylation and glucose transport in nonadherent but
not adherent adipocytes. In conclusion, PIG induced IRS-1 tyrosine
phosphorylation by causing (integrin antagonized) recruitment of IRS-1
and pp59Lyn to the common signaling platform molecule
pp125FAK, where cross talk of PIG-like structures and
extracellular matrix proteins to metabolic insulin signaling may
converge, possibly for the integration of the demands of glucose
metabolism and cell architecture.
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Copyright © 2000, American Society for Microbiology. All rights reserved.
Cross Talk of pp125FAK and
pp59Lyn Non-Receptor Tyrosine Kinases to Insulin-Mimetic
Signaling in Adipocytes
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Corresponding author. Mailing address: Aventis Pharma
Deutschland GmbH, DG Metabolic Diseases, Bldg. H825, 65926 Frankfurt am Main, Germany. Phone: 4969-305-4271. Fax: 4969-305-81767. E-mail: Guenter.Mueller{at}aventis.com.
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