scholarly journals Tyrosine Phosphorylation of Insulin Receptor Substrate-1in VivoDepends upon the Presence of Its Pleckstrin Homology Region

1995 â—½  
Vol 270 (30) â—½  
pp. 18083-18087 â—½  
Author(s):  
Hedva Voliovitch â—½  
Daniel G. Schindler â—½  
Yaron R. Hadari â—½  
Simeon I. Taylor â—½  
Domenico Accili â—½  
...  
Keyword(s):  
Insulin Receptor â—½  
Tyrosine Phosphorylation â—½  
Insulin Receptor Substrate â—½  
Pleckstrin Homology â—½  
Homology Region

scholarly journals Identification of SH2B2β as an Inhibitor for SH2B1- and SH2B2α-Promoted Janus Kinase-2 Activation and Insulin Signaling

Endocrinology â—½  
2007 â—½  
Vol 148 (4) â—½  
pp. 1615-1621 â—½  
Author(s):  
Minghua Li â—½  
Zhiqin Li â—½  
David L. Morris â—½  
Liangyou Rui
Keyword(s):  
Insulin Receptor â—½  
Tyrosine Phosphorylation â—½  
Insulin Signaling â—½  
Sh2 Domain â—½  
Janus Kinase â—½  
Pleckstrin Homology Domain â—½  
Insulin Receptor Substrate â—½  
Janus Kinase 2 â—½  
Pleckstrin Homology â—½  
Insulin Receptor Substrate 1

The SH2B family has three members (SH2B1, SH2B2, and SH2B3) that contain conserved dimerization (DD), pleckstrin homology, and SH2 domains. The DD domain mediates the formation of homo- and heterodimers between members of the SH2B family. The SH2 domain of SH2B1 (previously named SH2-B) or SH2B2 (previously named APS) binds to phosphorylated tyrosines in a variety of tyrosine kinases, including Janus kinase-2 (JAK2) and the insulin receptor, thereby promoting the activation of JAK2 or the insulin receptor, respectively. JAK2 binds to various members of the cytokine receptor family, including receptors for GH and leptin, to mediate cytokine responses. In mice, SH2B1 regulates energy and glucose homeostasis by enhancing leptin and insulin sensitivity. In this work, we identify SH2B2β as a new isoform of SH2B2 (designated as SH2B2α) derived from the SH2B2 gene by alternative mRNA splicing. SH2B2β has a DD and pleckstrin homology domain but lacks a SH2 domain. SH2B2β bound to both SH2B1 and SH2B2α, as demonstrated by both the interaction of glutathione S-transferase-SH2B2β fusion protein with SH2B1 or SH2B2α in vitro and coimmunoprecipitation of SH2B2β with SH2B1 or SH2B2α in intact cells. SH2B2β markedly attenuated the ability of SH2B1 to promote JAK2 activation and subsequent tyrosine phosphorylation of insulin receptor substrate-1 by JAK2. SH2B2β also significantly inhibited SH2B1- or SH2B2α-promoted insulin signaling, including insulin-stimulated tyrosine phosphorylation of insulin receptor substrate-1. These data suggest that SH2B2β is an endogenous inhibitor of SH2B1 and/or SH2B2α, negatively regulating insulin signaling and/or JAK2-mediated cellular responses.

scholarly journals The Pleckstrin Homology and Phosphotyrosine Binding Domains of Insulin Receptor Substrate 1 Mediate Inhibition of Apoptosis by Insulin

1998 â—½  
Vol 18 (11) â—½  
pp. 6784-6794 â—½  
Author(s):  
Lynne Yenush â—½  
Christine Zanella â—½  
Tohru Uchida â—½  
Dolores Bernal â—½  
Morris F. White
Keyword(s):  
Insulin Receptor â—½  
Tyrosine Phosphorylation â—½  
Insulin Receptors â—½  
Insulin Receptor Substrate â—½  
Phosphorylation Sites â—½  
Pleckstrin Homology â—½  
Insulin Stimulation â—½  
Kinase Cascade â—½  
Irs Proteins â—½  
Ptb Domains

ABSTRACT Insulin and insulin-like growth factor 1 (IGF-1) evoke diverse biological effects through receptor-mediated tyrosine phosphorylation of insulin receptor substrate (IRS) proteins. We investigated the elements of IRS-1 signaling that inhibit apoptosis of interleukin 3 (IL-3)-deprived 32D myeloid progenitor cells. 32D cells have few insulin receptors and no IRS proteins; therefore, insulin failed to inhibit apoptosis during IL-3 withdrawal. Insulin stimulated mitogen-activated protein kinase in 32D cells expressing insulin receptors (32DIR) but failed to activate the phosphatidylinositol 3 (PI 3)-kinase cascade or to inhibit apoptosis. By contrast, insulin stimulated the PI 3-kinase cascade, inhibited apoptosis, and promoted replication of 32DIR cells expressing IRS-1. As expected, insulin did not stimulate PI 3-kinase in 32DIR cells, which expressed a truncated IRS-1 protein lacking the tail of tyrosine phosphorylation sites. However, this truncated IRS-1 protein, which retained the NH2-terminal pleckstrin homology (PH) and phosphotyrosine binding (PTB) domains, mediated phosphorylation of PKB/akt, inhibition of apoptosis, and replication of 32DIR cells during insulin stimulation. These results suggest that a phosphotyrosine-independent mechanism mediated by the PH and PTB domains promoted antiapoptotic and growth actions of insulin. Although PI 3-kinase was not activated, its phospholipid products were required, since LY294002 inhibited these responses. Without IRS-1, a chimeric insulin receptor containing a tail of tyrosine phosphorylation sites derived from IRS-1 activated the PI 3-kinase cascade but failed to inhibit apoptosis. Thus, phosphotyrosine-independent IRS-1-linked pathways may be critical for survival and growth of IL-3-deprived 32D cells during insulin stimulation.

scholarly journals Insulin and Metabolic Stress Stimulate Multisite Serine/Threonine Phosphorylation of Insulin Receptor Substrate 1 and Inhibit Tyrosine Phosphorylation

2014 â—½  
Vol 289 (18) â—½  
pp. 12467-12484 â—½  
Author(s):  
Nancy J. Hançer â—½  
Wei Qiu â—½  
Christine Cherella â—½  
Yedan Li â—½  
Kyle D. Copps â—½  
...  
Keyword(s):  
Insulin Receptor â—½  
Tyrosine Phosphorylation â—½  
Metabolic Stress â—½  
Insulin Receptor Substrate â—½  
Insulin Receptor Substrate 1

scholarly journals Insulin receptor substrate 1 rescues insulin action in CHO cells expressing mutant insulin receptors that lack a juxtamembrane NPXY motif.

1995 â—½  
Vol 15 (9) â—½  
pp. 4711-4717 â—½  
Author(s):  
D Chen â—½  
D J Van Horn â—½  
M F White â—½  
J M Backer
Keyword(s):  
Insulin Receptor â—½  
Tyrosine Phosphorylation â—½  
Cho Cells â—½  
Glycogen Synthesis â—½  
Insulin Receptors â—½  
Insulin Receptor Substrate â—½  
Insulin Stimulation â—½  
Insulin Receptor Substrate 1 â—½  
Npxy Motif â—½  
Stimulation Of

Insulin signals are mediated through tyrosine phosphorylation of specific proteins such as insulin receptor substrate 1 (IRS-1) and Shc by the activated insulin receptor (IR). Phosphorylation of both proteins is nearly abolished by an alanine substitution at Tyr-960 (A960) in the beta-subunit of the receptor. However, overexpression of IRS-1 in CHO cells expressing the mutant receptor (A960 cells) restored sufficient tyrosine phosphorylation of IRS-1 to rescue IRS-1/Grb-2 binding and phosphatidylinositol 3' kinase activation during insulin stimulation. Shc tyrosine phosphorylation and its binding to Grb-2 were impaired in the A960 cells and were unaffected by overexpression of IRS-1. Although overexpression of IRS-1 increased IRS-1 binding to Grb-2, ERK-1/ERK-2 activation was not rescued. These data suggest that signaling molecules other than IRS-1, perhaps including Shc, are critical for insulin stimulation of p21ras. Interestingly, overexpression of IRS-1 in the A960 cells restored insulin-stimulated mitogenesis and partially restored insulin stimulation of glycogen synthesis. Thus, IRS-1 tyrosine phosphorylation is sufficient to increase the mitogenic response to insulin, whereas insulin stimulation of glycogen synthesis appears to involve other factors. Moreover, IRS-1 phosphorylation is either not sufficient or not involved in insulin stimulation of ERK.

Molecular and functional resistance to insulin in hypothalamus of rats exposed to cold

2003 â—½  
Vol 285 (1) â—½  
pp. E216-E223 â—½  
Author(s):  
Márcio A. Torsoni â—½  
José B. Carvalheira â—½  
Márcio Pereira-Da-Silva â—½  
Marco A. de Carvalho-Filho â—½  
Mário J. A. Saad â—½  
...  
Keyword(s):  
Insulin Receptor â—½  
Tyrosine Phosphorylation â—½  
Insulin Signaling â—½  
Room Temperature â—½  
Arcuate Nucleus â—½  
Insulin Receptor Substrate â—½  
Food Ingestion â—½  
Phosphatidylinositol 3 Kinase â—½  
Resistance To Insulin â—½  
Low Levels

Insulin and leptin act in the hypothalamus, providing robust anorexigenic signals. The exposure of homeothermic animals to a cold environment leads to increased feeding, accompanied by sustained low levels of insulin and leptin. In the present study, the initial and intermediate steps of the insulin-signaling cascade were evaluated in the hypothalamus of cold-exposed Wistar rats. By immunohistochemistry, most insulin receptor (IR) and insulin receptor substrate-2 (IRS-2) immunoreactivity localized to the arcuate nucleus. Basal levels of tyrosine phosphorylation of IR and IRS-2 were increased in cold-exposed rats compared with rats maintained at room temperature. However, after an acute, peripheral infusion of exogenous insulin, significantly lower increases of IR and IRS-2 tyrosine phosphorylation were detected in the hypothalamus of cold-exposed rats. Insulin-induced association of p85/phosphatidylinositol 3-kinase with IRS-2, Ser473 phosphorylation of Akt, and tyrosine phosphorylation of ERK was significantly reduced in the hypothalamus of cold-exposed rats. To test the hypothesis of functional impairment of insulin signaling in the hypothalamus, intracerebroventricularly cannulated rats were acutely treated with insulin, and food ingestion was measured over a period of 12 h. Cold-exposed animals presented a significantly lower insulin-induced reduction in food consumption compared with animals maintained at room temperature. Hence, the present studies reveal that animals exposed to cold are resistant, both at the molecular and the functional level, to the actions of insulin in the hypothalamus.

Protein Kinase C Modulation of Insulin Receptor Substrate-1 Tyrosine Phosphorylation Requires Serine 612†

Biochemistry â—½  
10.1021/bi971157f â—½  
1997 â—½  
Vol 36 (42) â—½  
pp. 12939-12947 â—½  
Author(s):  
Kathryn De Fea â—½  
Richard A. Roth
Keyword(s):  
Protein Kinase C â—½  
Protein Kinase â—½  
Insulin Receptor â—½  
Tyrosine Phosphorylation â—½  
Insulin Receptor Substrate â—½  
Insulin Receptor Substrate 1 â—½  
Kinase C

scholarly journals Insulin Receptor Substrate 3 (IRS-3) and IRS-4 Impair IRS-1- and IRS-2-Mediated Signaling

2001 â—½  
Vol 21 (1) â—½  
pp. 26-38 â—½  
Author(s):  
Kaku Tsuruzoe â—½  
Renee Emkey â—½  
Kristina M. Kriauciunas â—½  
Kohjiro Ueki â—½  
C. Ronald Kahn
Keyword(s):  
Insulin Receptor â—½  
Tyrosine Phosphorylation â—½  
Cell Lines â—½  
Protein Level â—½  
Fibroblast Cell â—½  
Host Cells â—½  
Mitogen Activated Protein Kinase â—½  
Insulin Receptor Substrate â—½  
Akt Phosphorylation â—½  
Irs Proteins

ABSTRACT To investigate the roles of insulin receptor substrate 3 (IRS-3) and IRS-4 in the insulin-like growth factor 1 (IGF-1) signaling cascade, we introduced these proteins into 3T3 embryonic fibroblast cell lines prepared from wild-type (WT) and IRS-1 knockout (KO) mice by using a retroviral system. Following transduction of IRS-3 or IRS-4, the cells showed a significant decrease in IRS-2 mRNA and protein levels without any change in the IRS-1 protein level. In these cell lines, IGF-1 caused the rapid tyrosine phosphorylation of all four IRS proteins. However, IRS-3- or IRS-4-expressing cells also showed a marked decrease in IRS-1 and IRS-2 phosphorylation compared to the host cells. This decrease was accounted for in part by a decrease in the level of IRS-2 protein but occurred with no significant change in the IRS-1 protein level. IRS-3- or IRS-4-overexpressing cells showed an increase in basal phosphatidylinositol 3-kinase activity and basal Akt phosphorylation, while the IGF-1-stimulated levels correlated well with total tyrosine phosphorylation level of all IRS proteins in each cell line. IRS-3 expression in WT cells also caused an increase in IGF-1-induced mitogen-activated protein kinase phosphorylation and egr-1 expression (∼1.8- and ∼2.4-fold with respect to WT). In the IRS-1 KO cells, the impaired mitogenic response to IGF-1 was reconstituted with IRS-1 to supranormal levels and was returned to almost normal by IRS-2 or IRS-3 but was not improved by overexpression of IRS-4. These data suggest that IRS-3 and IRS-4 may act as negative regulators of the IGF-1 signaling pathway by suppressing the function of other IRS proteins at several steps.

scholarly journals The Drosophila insulin receptor activates multiple signaling pathways but requires insulin receptor substrate proteins for DNA synthesis.

1996 â—½  
Vol 16 (5) â—½  
pp. 2509-2517 â—½  
Author(s):  
L Yenush â—½  
R Fernandez â—½  
M G Myers â—½  
T C Grammer â—½  
X J Sun â—½  
...  
Keyword(s):  
Insulin Receptor â—½  
Tyrosine Phosphorylation â—½  
Human Insulin â—½  
Mammalian Cells â—½  
Insulin Response â—½  
Mitogen Activated Protein Kinase â—½  
Insulin Receptor Substrate â—½  
Human Insulin Receptor â—½  
Irs Proteins â—½  
Drosophila Insulin Receptor

The Drosophila insulin receptor (DIR) contains a 368-amino-acid COOH-terminal extension that contains several tyrosine phosphorylation sites in YXXM motifs. This extension is absent from the human insulin receptor but resembles a region in insulin receptor substrate (IRS) proteins which binds to the phosphatidylinositol (PI) 3-kinase and mediates mitogenesis. The function of a chimeric DIR containing the human insulin receptor binding domain (hDIR) was investigated in 32D cells, which contain few insulin receptors and no IRS proteins. Insulin stimulated tyrosine autophosphorylation of the human insulin receptor and hDIR, and both receptors mediated tyrosine phosphorylation of Shc and activated mitogen-activated protein kinase. IRS-1 was required by the human insulin receptor to activate PI 3-kinase and p70s6k, whereas hDIR associated with PI 3-kinase and activated p70s6k without IRS-1. However, both receptors required IRS-1 to mediate insulin-stimulated mitogenesis. These data demonstrate that the DIR possesses additional signaling capabilities compared with its mammalian counterpart but still requires IRS-1 for the complete insulin response in mammalian cells.

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