Osmotic Loading of Neutralizing Antibodies Demonstrates a Role for Protein-tyrosine Phosphatase 1B in Negative Regulation of the Insulin Action Pathway

Ahmad, Faiyaz; Li, Pei-Ming; Meyerovitch, Joseph; Goldstein, Barry J.

doi:10.1074/jbc.270.35.20503

Cited by 229 publications

(151 citation statements)

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“…Immunoblotting Studies and Adaptor Protein Overlay BlottingSamples were separated by electrophoresis on 7.5% polyacrylamide gels containing SDS and then transferred to nitrocellulose as described previously (3). Following transfer, membranes were blocked with 2% (w/v) bovine serum albumin in TBST buffer (150 mM NaCl, 0.5% (v/v) Tween 20, 0.2% (w/v) sodium azide in 250 mM Tris-HCl, pH 7.5).…”

Section: Methodsmentioning

confidence: 99%

“…Much of the available evidence characterizing the role of PTPases in insulin signaling has focused on the regulation of the activation state of the insulin receptor itself, where several PTPases, in particular the intracellular enzyme PTP1B and the transmembrane homologs LAR and LRP (RPTP-␣), have been postulated to have a regulatory function (3)(4)(5)(6). However, the identity of PTPase(s) that regulate the tyrosine phosphorylation state of substrates of the insulin receptor kinase, such as IRS-1, has not been determined.…”

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confidence: 99%

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Tyrosine Dephosphorylation and Deactivation of Insulin Receptor Substrate-1 by Protein-tyrosine Phosphatase 1B

Goldstein

Bittner-Kowalczyk

White

et al. 2000

Journal of Biological Chemistry

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Regulation of the steady-state tyrosine phosphorylation of the insulin receptor and its postreceptor substrates are essential determinants of insulin signal transduction. However, little is known regarding the molecular interactions that influence the balance of these processes, especially the phosphorylation state of postinsulin receptor substrates, such as insulin receptor substrate-1 (IRS-1). The specific activity of four candidate protein-tyrosine phosphatases (protein-tyrosine phosphatase 1B (PTP1B), SH2 domain-containing PTPase-2 (SHP-2), leukocyte common antigen-related (LAR), and leukocyte antigen-related phosphatase) (LRP) toward IRS-1 dephosphorylation was studied using recombinant proteins in vitro. PTP1B exhibited the highest specific activity (percentage dephosphorylated per g per min), and the enzyme activities varied over a range of 5.5 ؋ 10 3 . When evaluated as a ratio of activity versus IRS-1 to that versus p-nitrophenyl phosphate, PTP1B remained significantly more active by 3.1-293-fold, respectively. Overlay blots with recombinant Src homology 2 domains of IRS-1 adaptor proteins showed that the loss of IRS-1 binding of Crk, GRB2, SHP-2, and the p85 subunit of phosphatidylinositol 3-kinase paralleled the rate of overall IRS-1 dephosphorylation. Further studies revealed that the adaptor protein GRB2 strongly promoted the formation of a stable protein complex between tyrosine-phosphorylated IRS-1 and catalytically inactive PTP1B, increasing their co-immunoprecipitation from an equimolar solution by 13.5 ؎ 3.3-fold (n ‫؍‬ 7; p < 0.01). Inclusion of GRB2 in a reaction mixture of IRS-1 and active PTP1B also increased the overall rate of IRS-1 tyrosine dephosphorylation by 2.7-3.9-fold (p < 0.01). These results provide new insight into novel molecular interactions involving PTP1B and GRB2 that may influence the steady-state capacity of IRS-1 to function as a phosphotyrosine scaffold and possibly affect the balance of postreceptor insulin signaling. Cellular protein-tyrosine phosphatases (PTPases)1 play a crucial role in maintaining the steady-state phosphotyrosine content of proteins in the insulin action pathway (1, 2). Much of the available evidence characterizing the role of PTPases in insulin signaling has focused on the regulation of the activation state of the insulin receptor itself, where several PTPases, in particular the intracellular enzyme PTP1B and the transmembrane homologs LAR and LRP (RPTP-␣), have been postulated to have a regulatory function (3-6). However, the identity of PTPase(s) that regulate the tyrosine phosphorylation state of substrates of the insulin receptor kinase, such as IRS-1, has not been determined. IRS-1 is phosphorylated on multiple tyrosine residues by the activated insulin receptor kinase and serves as a docking site or scaffold for a series of adaptor proteins that possess Src homology 2 (SH2) domains (7). These proteins bind to specific phosphotyrosine sites on IRS-1, become activated, and transmit the downstream signal from the insulin receptor to various met...

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Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

Tyrosine Dephosphorylation and Deactivation of Insulin Receptor Substrate-1 by Protein-tyrosine Phosphatase 1B

Goldstein

Bittner-Kowalczyk

White

et al. 2000

Journal of Biological Chemistry

Self Cite

384

221

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“…For example, tyrosine phosphorylation is a key reaction in the initiation and propagation of insulin action (Myers and White, 1996;White and Kahn, 1994). Thus, PTP1B (Ahmad et al, 1995;Kenner et al, 1996;Kole et al, 1996), LAR (Kulas et al, 1995;Zhang et al, 1996) and PTBa (Lammers et al, 1997;Moller et al, 1995) have been implicated as negative regulators of insulin receptor signaling. Consequently, protein phosphatase inhibitors may have use in the treatment of diabetes and obesity.…”

Section: Introductionmentioning

confidence: 99%

Small molecule inhibitors of dual specificity protein phosphatases

et al. 2000

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“…Early studies suggest that PTP1B blocks insulininduced S6 peptide phosphorylation and inhibits insulin-induced maturation of Xenopus oocytes (10,41). Intracellular delivery of neutralizing antibodies against PTP1B augments IR and IRS-1 phosphorylation and, conversely, overexpression of PTP1B in transfected cells inhibits IR and IRS-1 phosphorylation (4,24). Recent studies show that PTP1B-deficient mice exhibit hypersensitivity to insulin, suggesting that PTP1B is the major tyrosine phosphatase that regulates IR sensitivity (18,28).…”

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Protein-tyrosine-phosphatase 1B activation is regulated developmentally in muscle of neonatal pigs

Suryawan

Davis

2003

American Journal of Physiology-Endocrinology and Metabolism

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Suryawan, Agus, and Teresa A. Davis. Protein-tyrosine-phosphatase 1B activation is regulated developmentally in muscle of neonatal pigs. Am J Physiol Endocrinol Metab 284: E47-E54, 2003. First published September 11, 2002 10.1152/ajpendo.00210.2002The high activity of the insulin-signaling pathway contributes to the enhanced feeding-induced stimulation of translation initiation in skeletal muscle of neonatal pigs. Protein-tyrosine-phosphatase 1B (PTP1B) is a negative regulator of the tyrosine phosphorylation of the insulin receptor (IR) and insulin receptor substrate 1 (IRS-1). The activity of PTP1B is determined mainly by its association with IR and Grb2. We examined the level of PTP1B activity, PTP1B protein abundance, PTP1B tyrosine phosphorylation, and the association of PTP1B with IR and Grb2 in skeletal muscle and liver of fasted and fed 7-and 26-day-old pigs. PTP1B activity in skeletal muscle was lower (P Ͻ 0.05) in 7-compared with 26-day-old pigs but in liver was similar in the two age groups. PTP1B abundances were similar in muscle but lower (P Ͻ 0.05) in liver of 7-compared with 26-day-old pigs. PTP1B tyrosine phosphorylation in muscle was lower (P Ͻ 0.05) in 7-than in 26-day-old pigs. The associations of PTP1B with IR and with Grb2 were lower (P Ͻ 0.05) at 7 than at 26 days of age in muscle, but there were no age effects in liver. Finally, in both age groups, fasting did not have any effect on these parameters. These results indicate that basal PTP1B activation is developmentally regulated in skeletal muscle of neonatal pigs, consistent with the developmental changes in the activation of the insulin-signaling pathway reported previously. Reduced PTP1B activation in neonatal muscle likely contributes to the enhanced insulin sensitivity of skeletal muscle in neonatal pigs.neonate; insulin signaling; insulin sensitivity; protein synthesis THE ENHANCED ACTIVATION of the insulin-signaling pathway leading to translation initiation in skeletal muscle of the neonate after food consumption has an important role in the enhanced responsiveness of muscle protein synthesis to feeding in the neonate (13,16,26,27,37). We have shown that the feeding-induced activation of the insulin receptor (IR), insulin receptor substrate-1 (IRS-1), and phosphatidylinositol 3-kinase (PI 3-kinase), as well as the abundance of the IR, is enhanced in skeletal muscle of the neonatal pig and decreases markedly with development. This developmental decline in the feeding-induced activation of early insulin-signaling components parallels the developmental decline in the feeding-induced activation of downstream signaling proteins, leading to the stimulation of protein synthesis in skeletal muscle and the developmental decrease in the ability of insulin to stimulate muscle protein synthesis. However, the molecular mechanism that regulates the developmental decline in the insulin sensitivity of skeletal muscle in neonatal pigs has not been elucidated.When insulin binds to its receptor, it induces autophosphorylation of the receptor on its ty...

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Osmotic Loading of Neutralizing Antibodies Demonstrates a Role for Protein-tyrosine Phosphatase 1B in Negative Regulation of the Insulin Action Pathway

Cited by 229 publications

References 48 publications

Tyrosine Dephosphorylation and Deactivation of Insulin Receptor Substrate-1 by Protein-tyrosine Phosphatase 1B

Tyrosine Dephosphorylation and Deactivation of Insulin Receptor Substrate-1 by Protein-tyrosine Phosphatase 1B

Small molecule inhibitors of dual specificity protein phosphatases

Protein-tyrosine-phosphatase 1B activation is regulated developmentally in muscle of neonatal pigs

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