scholarly journals Cellular effects of phosphotyrosine-binding domain inhibitors on insulin receptor signaling and trafficking.

1997 ◽  
Vol 17 (3) ◽  
pp. 1180-1188 ◽  
Author(s):  
S Giorgetti-Peraldi ◽  
E Ottinger ◽  
G Wolf ◽  
B Ye ◽  
T R Burke ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Insulin Receptors ◽  
Mitogen Activated Protein Kinase ◽  
Sh2 Domains ◽  
Cellular Effects ◽  
Mitogen Activated Protein ◽  
Insulin Receptor Signaling ◽  
Cellular Inhibitors ◽  
Phosphotyrosine Binding Domain ◽  
Ptb Domain

Shc and insulin receptor substrate 1 (IRS-1) are cytoplasmic substrates of tyrosine kinase receptors that engage, localize, and activate downstream SH2 enzymes. Each contains a phosphotyrosine-binding (PTB) domain that is structurally unrelated to SH2 domains. We have designed high-affinity, cellular inhibitors of the Shc PTB domain by incorporating nonnatural, phosphatase-resistant amino acids into short peptides. None of the inhibitors bind the IRS-1 PTB domain, consistent with distinct specificities for domains. The best inhibitor of the Shc domain was introduced by electroporation into Rat1 fibroblasts that express human insulin receptors. Insulin-stimulated phosphorylation of Shc was inhibited, with no effect on IRS-1, and downstream effects on mitogen-activated protein kinase and DNA synthesis were both inhibited. The PTB domain inhibitor had less influence on epidermal growth factor-induced effects and essentially no impact on serum- or phorbol ester-induced effects. The inhibitor did not affect insulin internalization and its degradation. We conclude that the PTB domain of Shc is critical for its phosphorylation by the insulin receptor, that Shc is an important mediator of insulin's mitogenic effects, and that Shc is not central to insulin receptor cycling in these cells. PTB domains can be inhibited selectively in cells and represent potential targets for drug discovery.

scholarly journals The Insulin Receptor: A Potential Target of Amarogentin Isolated from Gentiana rigescens Franch That Induces Neurogenesis in PC12 Cells

Biomedicines ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 581
Author(s):  
Lihong Cheng ◽  
Hiroyuki Osada ◽  
Tianyan Xing ◽  
Minoru Yoshida ◽  
Lan Xiang ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Insulin Receptor ◽  
Signaling Pathways ◽  
Neurite Outgrowth ◽  
Pc12 Cells ◽  
Mitogen Activated Protein Kinase ◽  
Potential Target ◽  
Extracellular Signal ◽  
Mitogen Activated Protein ◽  
Gentiana Rigescens

Amarogentin (AMA) is a secoiridoid glycoside isolated from the traditional Chinese medicine, Gentiana rigescens Franch. AMA exhibits nerve growth factor (NGF)-mimicking and NGF-enhancing activities in PC12 cells and in primary cortical neuron cells. In this study, a possible mechanism was found showing the remarkable induction of phosphorylation of the insulin receptor (INSR) and protein kinase B (AKT). The potential target of AMA was predicted by using a small-interfering RNA (siRNA) and the cellular thermal shift assay (CETSA). The AMA-induced neurite outgrowth was reduced by the siRNA against the INSR and the results of the CETSA suggested that the INSR showed a significant thermal stability-shifted effect upon AMA treatment. Other neurotrophic signaling pathways in PC12 cells were investigated using specific inhibitors, Western blotting and PC12(rasN17) and PC12(mtGAP) mutants. The inhibitors of the glucocorticoid receptor (GR), phospholipase C (PLC) and protein kinase C (PKC), Ras, Raf and mitogen-activated protein kinase (MEK) significantly reduced the neurite outgrowth induced by AMA in PC12 cells. Furthermore, the phosphorylation reactions of GR, PLC, PKC and an extracellular signal-regulated kinase (ERK) were significantly increased after inducing AMA and markedly decreased after treatment with the corresponding inhibitors. Collectively, these results suggested that AMA-induced neuritogenic activity in PC12 cells potentially depended on targeting the INSR and activating the downstream Ras/Raf/ERK and PI3K/AKT signaling pathways. In addition, the GR/PLC/PKC signaling pathway was found to be involved in the neurogenesis effect of AMA.

Role of IRS-1-GRB-2 complexes in insulin signaling

1994 ◽  
Vol 14 (6) ◽  
pp. 3577-3587
Author(s):  
M G Myers ◽  
L M Wang ◽  
X J Sun ◽  
Y Zhang ◽  
L Yenush ◽  
...  
Keyword(s):  
Map Kinase ◽  
Insulin Receptor ◽  
Insulin Receptors ◽  
Growth Factor Signaling ◽  
Insulin Stimulation ◽  
Mitogen Activated Protein ◽  
D Cells ◽  
Stimulation Of

GRB-2 is a small SH2- and SH3 domain-containing adapter protein that associates with the mammalian SOS homolog to regulate p21ras during growth factor signaling. During insulin stimulation, GRB-2 binds to the phosphorylated Y895VNI motif of IRS-1. Substitution of Tyr-895 with phenylalanine (IRS-1F-895) prevented the IRS-1-GRB-2 association in vivo and in vitro. The myeloid progenitor cell line, 32-D, is insensitive to insulin because it contains few insulin receptors and no IRS-1. Coexpression of IRS-1 or IRS-1F-895 with the insulin receptor was required for insulin-stimulated mitogenesis in 32-D cells, while expression of the insulin receptor alone was sufficient to mediate insulin-stimulated tyrosine phosphorylation of Shc and activation of p21ras and mitogen-activated protein (MAP) kinase. The Shc-GRB-2 complex formed during insulin stimulation is a possible mediator of p21ras and MAP kinase activation in IRS-1-deficient 32-D cells. Interestingly, IRS-1, but not IRS-1F-895, enhanced the stimulation of MAP kinase by insulin in 32-D cells expressing insulin receptors. Thus, IRS-1 contributes to the stimulation of MAP kinase by insulin, probably through formation of the IRS-1-GRB-2 complex at Tyr-895. Our results suggest that the Shc-GRB-2 complex and the activation of p21ras-dependent signaling pathways, including MAP kinase, are insufficient for insulin-stimulated mitogenesis and that the essential function(s) of IRS-1 in proliferative signaling is largely unrelated to IRS-1-GRB-2 complex formation.

Exercise-associated differences in an array of proteins involved in signal transduction and glucose transport

2001 ◽  
Vol 90 (1) ◽  
pp. 29-34 ◽  
Author(s):  
Mei Yu ◽  
Eva Blomstrand ◽  
Alexander V. Chibalin ◽  
Harriet Wallberg-Henriksson ◽  
Juleen R. Zierath ◽  
...  
Keyword(s):  
Signal Transduction ◽  
Protein Kinase ◽  
Insulin Receptor ◽  
Insulin Signaling ◽  
Mitogen Activated Protein Kinase ◽  
Signaling Cascade ◽  
Vastus Lateralis Muscle ◽  
Glut 4 ◽  
Mitogen Activated Protein ◽  
Kinase Expression

Vastus lateralis muscle biopsies were obtained from endurance-trained (running ∼50 km/wk) and untrained (no regular physical exercise) men, and the expression of an array of insulin-signaling intermediates was determined. Expression of insulin receptor and insulin receptor substrate-1 and -2 was decreased 44% ( P < 0.05), 57% ( P < 0.001), and 77% ( P < 0.001), respectively, in trained vs. untrained muscle. The downstream signaling target, Akt kinase, was not altered in trained subjects. Components of the mitogenic signaling cascade were also assessed. Extracellular signal-regulated kinase 1/2 mitogen-activated protein kinase expression was 190% greater ( P < 0.05), whereas p38 mitogen-activated protein kinase expression was 32% lower ( P < 0.05), in trained vs. untrained muscle. GLUT-4 protein expression was twofold higher ( P < 0.05), and the GLUT-4 vesicle-associated protein, the insulin-regulated aminopeptidase, was increased 4.7-fold ( P < 0.05) in trained muscle. In conclusion, the expression of proteins involved in signal transduction is altered in skeletal muscle from well-trained athletes. Downregulation of early components of the insulin-signaling cascade may occur in response to increased insulin sensitivity associated with endurance training.

Activation of the insulin receptor (IR) by insulin and a synthetic peptide has different effects on gene expression in IR-transfected L6 myoblasts

2008 ◽  
Vol 412 (3) ◽  
pp. 435-445 ◽  
Author(s):  
Maja Jensen ◽  
Jane Palsgaard ◽  
Rehannah Borup ◽  
Pierre de Meyts ◽  
Lauge Schäffer
Keyword(s):  
Gene Expression ◽  
Insulin Receptor ◽  
Mapk Pathway ◽  
Receptor Activation ◽  
Mitogen Activated Protein Kinase ◽  
Single Chain ◽  
Therapeutic Implications ◽  
Insulin Mimetic ◽  
Mitogen Activated Protein

Single-chain peptides have been recently produced that display either mimetic or antagonistic properties against the insulin and IGF-1 (insulin-like growth factor 1) receptors. We have shown previously that the insulin mimetic peptide S597 leads to significant differences in receptor activation and initiation of downstream signalling cascades despite similar binding affinity and in vivo hypoglycaemic potency. It is still unclear how two ligands can initiate different signalling responses through the IR (insulin receptor). To investigate further how the activation of the IR by insulin and S597 differentially activates post-receptor signalling, we studied the gene expression profile in response to IR activation by either insulin or S597 using microarray technology. We found striking differences between the patterns induced by these two ligands. Most remarkable was that almost half of the genes differentially regulated by insulin and S597 were involved in cell proliferation and growth. Insulin either selectively regulated the expression of these genes or was a more potent regulator. Furthermore, we found that half of the differentially regulated genes interact with the genes involved with the MAPK (mitogen-activated protein kinase) pathway. These findings support our signalling results obtained previously and confirm that the main difference between S597 and insulin stimulation resides in the activation of the MAPK pathway. In conclusion, we show that insulin and S597 acting via the same receptor differentially affect gene expression in cells, resulting in a different mitogenicity of the two ligands, a finding which has critical therapeutic implications.

scholarly journals Molecular Mechanisms of Liver Injury and Hepatocarcinogenesis: Focusing on the Role of Stress-Activated MAPK

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Hayato Nakagawa ◽  
Shin Maeda
Keyword(s):  
Liver Injury ◽  
Molecular Mechanisms ◽  
Mapk Pathway ◽  
Mitogen Activated Protein Kinase ◽  
Cellular Effects ◽  
Wide Range ◽  
Mitogen Activated Protein ◽  
Compensatory Proliferation

Hepatocellular carcinoma (HCC) is the third most common cause of cancer mortality. Short-term prognosis of patients with HCC has improved recently due to advances in early diagnosis and treatment, but long-term prognosis is still unsatisfactory. Therefore, obtaining a further understanding of the molecular carcinogenic mechanisms and the unique pathogenic biology of HCC is important. The most characteristic process in hepatocarcinogenesis is underlying chronic liver injury, which leads to repeated cycles of hepatocyte death, inflammation, and compensatory proliferation and subsequently provides a mitogenic and mutagenic environment leading to the development of HCC. Recent in vivo studies have shown that the stress-activated mitogen-activated protein kinase (MAPK) cascade converging on c-Jun NH2-terminal kinase (JNK) and p38 plays a central role in these processes, and it has attracted considerable attention as a therapeutic target. However, JNK and p38 have complex functions and a wide range of cellular effects. In addition, crosstalk with each other and the nuclear factor-kappaB pathway further complicate these functions. A full understanding is essential to bring these observations into clinical settings. In this paper, we discuss the latest findings regarding the mechanisms of liver injury and hepatocarcinogenesis focusing on the role of the stress-activated MAPK pathway.

scholarly journals Caveolin-1 Interacts with the Insulin Receptor and Can Differentially Modulate Insulin Signaling in Transfected Cos-7 Cells and Rat Adipose Cells

1999 ◽  
Vol 13 (12) ◽  
pp. 2013-2024 ◽  
Author(s):  
Fredrik H. Nystrom ◽  
Hui Chen ◽  
Li-Na Cong ◽  
Yunhua Li ◽  
Michael J. Quon
Keyword(s):  
Insulin Receptor ◽  
Insulin Signaling ◽  
Kinase Domain ◽  
Mitogen Activated Protein Kinase ◽  
Binding Motif ◽  
Intact Cells ◽  
Caveolin 1 ◽  
Mitogen Activated Protein ◽  
Adipose Cells

Abstract Caveolae may function as microdomains for signaling that help to determine specific biological actions mediated by the insulin receptor (IR). Caveolin-1, a major component of caveolae, contains a scaffolding domain (SD) that binds to a caveolin-1 binding motif in the kinase domain of the IR in vitro. To investigate the potential role of caveolin-1 in insulin signaling we overexpressed wild-type (Cav-WT) or mutant (Cav-Mut; F92A/V94A in SD) caveolin-1 in either Cos-7 cells cotransfected with IR or rat adipose cells (low and high levels of endogenous caveolin-1, respectively). Cav-WT coimmunoprecipitated with the IR to a much greater extent than Cav-Mut, suggesting that the SD is important for interactions between caveolin-1 and the IR in intact cells. We also constructed several IR mutants with a disrupted caveolin-1 binding motif and found that these mutants were poorly expressed and did not undergo autophosphorylation. Interestingly, overexpression of Cav-WT in Cos-7 cells significantly enhanced insulin-stimulated phosphorylation of Elk-1 (a mitogen-activated protein kinase-dependent pathway) while overexpression of Cav-Mut was without effect. In contrast, in adipose cells, overexpression of either Cav-WT or Cav-Mut did not affect insulin-stimulated phosphorylation of a cotransfected ERK2 (but did significantly inhibit basal phosphorylation of ERK2). Furthermore, we also observed a small inhibition of insulin-stimulated translocation of GLUT4 when either Cav-WT or Cav-Mut was overexpressed in adipose cells. Thus, interaction of caveolin-1 with IRs may differentially modulate insulin signaling to enhance insulin action in Cos-7 cells but inhibit insulin’s effects in adipose cells.

Sign in / Sign up

Export Citation Format

Share Document