IndraLab
Statements
IRS1 is inactive.
59
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"These results indicate that activation of protein kinase c stimulates a kinase which can phosphorylate insulin receptor substrate-1 at serine 612, resulting in an inhibition of insulin signaling in the cell these data suggest that: 1) activation of pkctheta contributes to ikk and jnk activation by ffas;2) ikk and jnk mediate pkctheta signals for irs-1 serine phosphorylation and degradation; ser-302 phosphorylation is dependent on pi 3-kinase/mtor, whereas ser-307 depends on c-jun nh2-terminal kinase to inhibit irs1 tyrosine phosphorylation. Ser-636 is located around the pi 3-kinase binding site and, therefore, thought to inhibit pi 3-kinase signaling."
"Nevertheless, s6k1-deficient mice remain sensitive to insulin owing to the apparent loss of a negative feedback loop from s6k1 to insulin receptor substrate 1 (irs1), which blunts s307 and s636/s639 phosphorylation; thus under conditions of nutrient satiation s6k1 negatively regulatesinsulin."
"Insulin also activates jnk, erk, pkc and mtor, which induce the phosphorylation of irs1 on serine residues 307, 612 and 632 and inhibit its functions. Our results indicate that the insulin-stimulated degradation of irs-1 via the phosphatidylinositol 3-kinase pathway is in part dependent upon the ser(312) phosphorylation of irs-1."
"Insulin also activates jnk, erk, pkc and mtor, which induce the phosphorylation of irs1 on serine residues 307, 612 and 632 and inhibit its functions. Our results indicate that the insulin-stimulated degradation of irs-1 via the phosphatidylinositol 3-kinase pathway is in part dependent upon the ser(312) phosphorylation of irs-1."
"Modulation of insulin-stimulated degradation of human insulin receptor substrate-1 by Serine 312 phosphorylationOne of the specific Ser phosphorylation sites in IRS-1 that has been proposed to negatively modulate the insulin signal is Ser312 (numbered according to the human sequence). Prior studies have demonstrated that IRS-1 associates with and is phosphorylated by JNK in vitro on Ser312"
"Modulation of insulin-stimulated degradation of human insulin receptor substrate-1 by Serine 312 phosphorylationOne of the specific Ser phosphorylation sites in IRS-1 that has been proposed to negatively modulate the insulin signal is Ser312 (numbered according to the human sequence). Prior studies have demonstrated that IRS-1 associates with and is phosphorylated by JNK in vitro on Ser312"
"Insulin also activates jnk, erk, pkc and mtor, which induce the phosphorylation of irs1 on serine residues 307, 612 and 632 and inhibit its functions. Our results indicate that the insulin-stimulated degradation of irs-1 via the phosphatidylinositol 3-kinase pathway is in part dependent upon the ser(312) phosphorylation of irs-1."
"Tyrosine phosphorylation of IRS-1 initiates insulin signaling, whereas serine/threonine phosphorylation alters the ability of IRS-1 to transduce the insulin signalInsulin increased the phosphorylation of Ser312, Ser616, Ser636, Ser892, Ser1101, and Ser1223 Ser312 can be phosphorylated by kinases, such as c-jun NH2-terminal kinase and inhibitor of _B kinase"
"Rin beta-cells exposed to high glucose exhibited increased c-jun n-terminal kinase (jnk) and erk1/2 activity, which was associated with increased irs-1 phosphorylation at serine (ser)(307) and ser(612), respectively, that inhibits coupling of irs-1 to the insulin receptor and is upstream of the inhibition of irs-1 tyrosine phosphorylation."
"These results indicate that activation of protein kinase c stimulates a kinase which can phosphorylate insulin receptor substrate-1 at serine 612, resulting in an inhibition of insulin signaling in the cell these data suggest that: 1) activation of pkctheta contributes to ikk and jnk activation by ffas;2) ikk and jnk mediate pkctheta signals for irs-1 serine phosphorylation and degradation; ser-302 phosphorylation is dependent on pi 3-kinase/mtor, whereas ser-307 depends on c-jun nh2-terminal kinase to inhibit irs1 tyrosine phosphorylation. Ser-636 is located around the pi 3-kinase binding site and, therefore, thought to inhibit pi 3-kinase signaling."
"Rin beta-cells exposed to high glucose exhibited increased c-jun n-terminal kinase (jnk) and erk1/2 activity, which was associated with increased irs-1 phosphorylation at serine (ser)(307) and ser(612), respectively, that inhibits coupling of irs-1 to the insulin receptor and is upstream of the inhibition of irs-1 tyrosine phosphorylation."
"Insulin also activates jnk, erk, pkc and mtor, which induce the phosphorylation of irs1 on serine residues 307, 612 and 632 and inhibit its functions. Our results indicate that the insulin-stimulated degradation of irs-1 via the phosphatidylinositol 3-kinase pathway is in part dependent upon the ser(312) phosphorylation of irs-1."
"Insulin also activates jnk, erk, pkc and mtor, which induce the phosphorylation of irs1 on serine residues 307, 612 and 632 and inhibit its functions. Our results indicate that the insulin-stimulated degradation of irs-1 via the phosphatidylinositol 3-kinase pathway is in part dependent upon the ser(312) phosphorylation of irs-1."
"Insulin also activates jnk, erk, pkc and mtor, which induce the phosphorylation of irs1 on serine residues 307, 612 and 632 and inhibit its functions. Our results indicate that the insulin-stimulated degradation of irs-1 via the phosphatidylinositol 3-kinase pathway is in part dependent upon the ser(312) phosphorylation of irs-1."
"Nevertheless, s6k1-deficient mice remain sensitive to insulin owing to the apparent loss of a negative feedback loop from s6k1 to insulin receptor substrate 1 (irs1), which blunts s307 and s636/s639 phosphorylation; thus under conditions of nutrient satiation s6k1 negatively regulatesinsulin."
"In this report, we identified insulin receptor substrate 1 (IRS-1), a critical mediator of the insulin/insulin-like growth factor 1 signaling, as a proteolytic target of the CUL7 E3 ligase in a manner that depends on mammalian target of rapamycin and the p70 S6 kinase activities.Elimination of phosphorylation at S307/S312/S527/S636/S639 renders V5-IRS-1 partially resistant to degradation by Fbw8"
"Insulin also activates jnk, erk, pkc and mtor, which induce the phosphorylation of irs1 on serine residues 307, 612 and 632 and inhibit its functions. Our results indicate that the insulin-stimulated degradation of irs-1 via the phosphatidylinositol 3-kinase pathway is in part dependent upon the ser(312) phosphorylation of irs-1."
"Insulin also activates jnk, erk, pkc and mtor, which induce the phosphorylation of irs1 on serine residues 307, 612 and 632 and inhibit its functions. Our results indicate that the insulin-stimulated degradation of irs-1 via the phosphatidylinositol 3-kinase pathway is in part dependent upon the ser(312) phosphorylation of irs-1."
"These results indicate that activation of protein kinase c stimulates a kinase which can phosphorylate insulin receptor substrate-1 at serine 612, resulting in an inhibition of insulin signaling in the cell these data suggest that: 1) activation of pkctheta contributes to ikk and jnk activation by ffas;2) ikk and jnk mediate pkctheta signals for irs-1 serine phosphorylation and degradation; ser-302 phosphorylation is dependent on pi 3-kinase/mtor, whereas ser-307 depends on c-jun nh2-terminal kinase to inhibit irs1 tyrosine phosphorylation. Ser-636 is located around the pi 3-kinase binding site and, therefore, thought to inhibit pi 3-kinase signaling."
"Insulin also activates jnk, erk, pkc and mtor, which induce the phosphorylation of irs1 on serine residues 307, 612 and 632 and inhibit its functions. Our results indicate that the insulin-stimulated degradation of irs-1 via the phosphatidylinositol 3-kinase pathway is in part dependent upon the ser(312) phosphorylation of irs-1."
"In this report, we identified insulin receptor substrate 1 (IRS-1), a critical mediator of the insulin/insulin-like growth factor 1 signaling, as a proteolytic target of the CUL7 E3 ligase in a manner that depends on mammalian target of rapamycin and the p70 S6 kinase activities.Elimination of phosphorylation at S307/S312/S527/S636/S639 renders V5-IRS-1 partially resistant to degradation by Fbw8"
"Here we show in various cell models that the adipose hormone leptin, a putative mediator in obesity-related insulin resistance, promotes phosphorylation of ser-318 in irs1 by a janus kinase 2, irs2, and pkc-dependent pathway. we observed that insulin stimulates phosphorylation of ser(318) in irs-1, which is mediated, at least partially, by pkc-zeta."
"Here we show in various cell models that the adipose hormone leptin, a putative mediator in obesity-related insulin resistance, promotes phosphorylation of ser-318 in irs1 by a janus kinase 2, irs2, and pkc-dependent pathway. we observed that insulin stimulates phosphorylation of ser(318) in irs-1, which is mediated, at least partially, by pkc-zeta."
"Nevertheless, s6k1-deficient mice remain sensitive to insulin owing to the apparent loss of a negative feedback loop from s6k1 to insulin receptor substrate 1 (irs1), which blunts s307 and s636/s639 phosphorylation; thus under conditions of nutrient satiation s6k1 negatively regulates insulin."
"In this report, we identified insulin receptor substrate 1 (IRS-1), a critical mediator of the insulin/insulin-like growth factor 1 signaling, as a proteolytic target of the CUL7 E3 ligase in a manner that depends on mammalian target of rapamycin and the p70 S6 kinase activities.Elimination of phosphorylation at S307/S312/S527/S636/S639 renders V5-IRS-1 partially resistant to degradation by Fbw8"
"Nevertheless, s6k1-deficient mice remain sensitive to insulin owing to the apparent loss of a negative feedback loop from s6k1 to insulin receptor substrate 1 (irs1), which blunts s307 and s636/s639 phosphorylation; thus under conditions of nutrient satiation s6k1 negatively regulatesinsulin."
"Phosphorylation of ser24 in the pleckstrin homology domain of insulin receptor substrate-1 by mouse pelle-like kinase/interleukin-1 receptor-associated kinaseirs-1 mutants s24d or s24e (mimicking phosphorylation at ser(24)) had impaired ability to associate with insulin receptors resulting in diminished tyrosine phosphorylation of irs-1 and impaired ability of irs-1 to bind and activate pi-3 kinase in response to insulin."
IRS1 is active.
3
37
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"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 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."
"Therefore, during insulin stimulation irs-1 undergoes tyrosine phosphorylation, and a portion of tyrosine phosphorylated irs-1 associated with the insulin receptor. The insulin receptor substrate-1 (irs-1) is rapidly phosphorylated on several tyrosine residues by the activated insulin receptor. 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)."
"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 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."
"Here we show that stimulation by insulin of freshly isolated primary adipocytes resulted in the expected rapid tyrosine phosphorylation of the insulin receptor, IRS-1 and IRS-3. Inhibition of PI 3-kinase enhanced the insulin-stimulated phosphorylation of IRS-1 on (i) Tyr(612) and Tyr(941) (p85 binding sites), concomitant with an increased association of the p85 subunit of PI 3-kinase; (ii) Tyr(896) (a Grb2 binding site); and (iii) Tyr(1229) (an SHP-2 binding site), although little or no binding of SHP-2 to IRS-1 was detectable under any conditions."
"Therefore, during insulin stimulation irs-1 undergoes tyrosine phosphorylation, and a portion of tyrosine phosphorylated irs-1 associated with the insulin receptor. The insulin receptor substrate-1 (irs-1) is rapidly phosphorylated on several tyrosine residues by the activated insulin receptor. 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)."
"All known IRS proteins contain multiple YXXM motifs that upon phosphorylation by activated insulin re- ceptors Tyr(612) and Tyr(632) in human insulin receptor substrate-1 are important for full activation of insulin-stimulated phosphatidylinositol 3-kinase activity and translocation of GLUT4 in adipose cells"
"All known IRS proteins contain multiple YXXM motifs that upon phosphorylation by activated insulin re- ceptors Tyr(612) and Tyr(632) in human insulin receptor substrate-1 are important for full activation of insulin-stimulated phosphatidylinositol 3-kinase activity and translocation of GLUT4 in adipose cells"
"Therefore, during insulin stimulation irs-1 undergoes tyrosine phosphorylation, and a portion of tyrosine phosphorylated irs-1 associated with the insulin receptor. The insulin receptor substrate-1 (irs-1) is rapidly phosphorylated on several tyrosine residues by the activated insulin receptor. 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)."
"Here we show that stimulation by insulin of freshly isolated primary adipocytes resulted in the expected rapid tyrosine phosphorylation of the insulin receptor, IRS-1 and IRS-3. Inhibition of PI 3-kinase enhanced the insulin-stimulated phosphorylation of IRS-1 on (i) Tyr(612) and Tyr(941) (p85 binding sites), concomitant with an increased association of the p85 subunit of PI 3-kinase; (ii) Tyr(896) (a Grb2 binding site); and (iii) Tyr(1229) (an SHP-2 binding site), although little or no binding of SHP-2 to IRS-1 was detectable under any conditions."
"Therefore, during insulin stimulation irs-1 undergoes tyrosine phosphorylation, and a portion of tyrosine phosphorylated irs-1 associated with the insulin receptor. The insulin receptor substrate-1 (irs-1) is rapidly phosphorylated on several tyrosine residues by the activated insulin receptor. 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)."
"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 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."
"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 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."
"MAP kinases and mTOR mediate insulin-induced phosphorylation of insulin receptor substrate-1 on serine residues 307, 612 and 632.|The phosphorylation of Serine(612/632) required the activation of the MAP kinase pathway following short-term insulin stimulation and activation of the PI 3-kinase/mTOR pathway following prolonged insulin stimulation"
"MAP kinases and mTOR mediate insulin-induced phosphorylation of insulin receptor substrate-1 on serine residues 307, 612 and 632.|The phosphorylation of Serine(612/632) required the activation of the MAP kinase pathway following short-term insulin stimulation and activation of the PI 3-kinase/mTOR pathway following prolonged insulin stimulation"
"All known IRS proteins contain multiple YXXM motifs that upon phosphorylation by activated insulin receptors A previous study using phosphopeptides suggested that tyrosine-phosphorylated YXXM motifs at positions 608 and 939 in rat IRS-1 bind with high affinity to SH2 domains of p85, and motifs at positions 460 and 987 bind with lower affinity (10)."
"All known IRS proteins contain multiple YXXM motifs that upon phosphorylation by activated insulin receptors A previous study using phosphopeptides suggested that tyrosine-phosphorylated YXXM motifs at positions 608 and 939 in rat IRS-1 bind with high affinity to SH2 domains of p85, and motifs at positions 460 and 987 bind with lower affinity (10)."
"MAP kinases and mTOR mediate insulin-induced phosphorylation of insulin receptor substrate-1 on serine residues 307, 612 and 632.|The phosphorylation of Serine(612/632) required the activation of the MAP kinase pathway following short-term insulin stimulation and activation of the PI 3-kinase/mTOR pathway following prolonged insulin stimulation"
"MAP kinases and mTOR mediate insulin-induced phosphorylation of insulin receptor substrate-1 on serine residues 307, 612 and 632.|The phosphorylation of Serine(612/632) required the activation of the MAP kinase pathway following short-term insulin stimulation and activation of the PI 3-kinase/mTOR pathway following prolonged insulin stimulation"
"All known IRS proteins contain multiple YXXM motifs that upon phosphorylation by activated insulin receptors A previous study using phosphopeptides suggested that tyrosine-phosphorylated YXXM motifs at positions 608 and 939 in rat IRS-1 bind with high affinity to SH2 domains of p85, and motifs at positions 460 and 987 bind with lower affinity (10)."
"We show that pkcalpha is likely to be directly involved in ser24 phosphorylation...Using Ser24asp irs-1 mutants to mimic the phosphorylated residue, we demonstrate that the phosphorylation status of ser24 does play an important role in regulating phosphoinositide binding to, and the intracellular localization of, the irs1-ph domain, which can ultimately impinge on insulin-stimulated glucose uptake"
IRS1 is catalytically inactive.
6
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"Insulin affects cells through binding to its receptor on the surface of insulin-responsive cells. The stimulated insulin receptor phosphorylates itself and several substrates, including members of the insulin receptor substrate (IRS) family, thus initiating downstream signaling events (32, 33). The inhibition of signaling downstream of the insulin receptor is a primary mechanism through which inflammatory signaling leads to insulin resistance. Exposure of cells to TNF-a or elevated levels of free fatty acids stimulates inhibitory phosphorylation of serine residues of IRS-1"
"The 3 members of the JNK group of serine/threonine kinases, JNK-1, -2, and -3, JNK has recently emerged as a central metabolic regulator, playing an important role in the development of insulin resistance in obesity In response to stimuli such as ER stress, cytokines, and fatty acids, JNK is activated, whereupon it associates with and phosphorylates IRS-1 on Ser307, impairing insulin action"
"Here, we demonstrate that nutrients suppress phosphatidylinositol 3 (PI3)-kinase/Akt signaling via Raptor-dependent mTOR (mammalian target of rapamycin)-mediated phosphorylation of insulin receptor substrate 1 (IRS-1). Raptor directly binds to and serves as a scaffold for mTOR-mediated phosphorylation of IRS-1 on Ser636/639"
IRS1 is catalytically active.
3
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"TNF-{alpha} reduces insulin-stimulated receptor tyrosine kinase activity at low concentrations and can also decrease the expression of the insulin receptor, IRS-1 and GLUT-4 at higher concentrations (22) as well as increase the phosphorylation of serine 307 of IRS-1, thus impairing its ability to bind to the insulin receptor and initiate downstream signaling."
"Accordingly, under the cellular context of the elevated expression of IL- 6Ra on myeloma cells, it is assumed that IL-6Ra molecules are located close to IGF-I receptors at lipid rafts, and IL-6 stimulation triggers the complex formation of IL-6Ra not only with gp130 but also with IGF-I receptors, leading to autophosphorylation of IGF-I receptor b and subsequent acti- vation of PI-3 kinase-Akt pathways (Fig. 4) 79 ."