The insulin receptor: structure, function, and signaling

1994 ◽  
Vol 266 (2) ◽  
pp. C319-C334 ◽  
Author(s):  
J. Lee ◽  
P. F. Pilch
Keyword(s):  
Insulin Receptor ◽  
Tyrosine Kinases ◽  
Intracellular Signaling ◽  
Metabolic Regulation ◽  
Receptor Tyrosine Kinases ◽  
Physiological Role ◽  
Biochemical Properties ◽  
Therapeutic Interventions ◽  
Intracellular Signaling Pathway ◽  
Effector Molecules

The insulin receptor is a member of the ligand-activated receptor and tyrosine kinase family of transmembrane signaling proteins that collectively are fundamentally important regulators of cell differentiation, growth, and metabolism. The insulin receptor has a number of unique physiological and biochemical properties that distinguish it from other members of this large well-studied receptor family. The main physiological role of the insulin receptor appears to be metabolic regulation, whereas all other receptor tyrosine kinases are engaged in regulating cell growth and/or differentiation. Receptor tyrosine kinases are allosterically regulated by their cognate ligands and function as dimers. In all cases but the insulin receptor (and 2 closely related receptors), these dimers are noncovalent, but insulin receptors are covalently maintained as functional dimers by disulfide bonds. The initial response to the ligand is receptor autophosphorylation for all receptor tyrosine kinases. In most cases, this results in receptor association of effector molecules that have unique recognition domains for phosphotyrosine residues and whose binding to these results in a biological response. For the insulin receptor, this does not occur; rather, it phosphorylates a large substrate protein that, in turn, engages effector molecules. Possible reasons for these differences are discussed in this review. The chemistry of insulin is very well characterized because of possible therapeutic interventions in diabetes using insulin derivatives. This has allowed the synthesis of many insulin derivatives, and we review our recent exploitation of one such derivative to understand the biochemistry of the interaction of this ligand with the receptor and to dissect the complicated steps of ligand-induced insulin receptor autophosphorylation. We note possible future directions in the study of the insulin receptor and its intracellular signaling pathway(s).

scholarly journals Insulin signalling: putting the G- in protein-protein interactions

2004 ◽  
Vol 380 (1) ◽  
pp. e11-e12 ◽  
Author(s):  
Craig C. MALBON
Keyword(s):  
Insulin Receptor ◽  
Cross Talk ◽  
Protein Interactions ◽  
Tyrosine Kinases ◽  
Cell Biology ◽  
Receptor Tyrosine Kinases ◽  
Insulin Signalling ◽  
Cell Signalling ◽  
Protein Protein Interactions ◽  
Proximal Point

Cell signalling via receptor tyrosine kinases, such as the insulin receptor, and via heterotrimeric G-proteins, such as Gαi, Gαs and Gαq family members, constitute two of most avidly studied paradigms in cell biology. That elements of these two populous signalling pathways must cross-talk to achieve proper signalling in the regulation of cell proliferation, differentiation and metabolism has been anticipated, but the evolution of our thinking and the analysis of such cross-talk have lagged behind the ever-expanding troupe of players and the recognition of multivalency as the rule, rather than the exception, in signalling biology. New insights have been provided by Kreuzer et al. in this issue of the Biochemical Journal, in which insulin is shown to provoke recruitment of Gαi-proteins to insulin-receptor-based complexes that can regulate the gain of insulin-receptor-catalysed autophosphorylation, a proximal point in the insulin-sensitive cascade of signalling. Understanding the convergence and cross-talk of signals from the receptor tyrosine kinases and G-protein-coupled receptor pathways in physical, spatial and temporal contexts will remain a major challenge of cell biology.

Gas6-Induced Tissue Factor Expression in Endothelial Cells Is Mediated Through Caveolin-1-Enriched Domains

Blood ◽  
2012 ◽  
Vol 120 (21) ◽  
pp. 3308-3308
Author(s):  
Sandrine Laurance ◽  
Catherine A Lemarie ◽  
Mark D Blostein
Keyword(s):  
Endothelial Cells ◽  
Tissue Factor ◽  
Tyrosine Kinases ◽  
Intracellular Signaling ◽  
Receptor Tyrosine Kinases ◽  
Tissue Factor Expression ◽  
Caveolin 1 ◽  
Intracellular Signaling Pathways ◽  
Factor Expression ◽  
Cell Fractions

Abstract Abstract 3308 Gas6 is the ligand for the TAM family of receptors, which are composed of three members namely Tyro3, Axl and Mer. These receptors belong to the large family of type I transmembrane receptor tyrosine kinases. Our laboratory has identified important intracellular signaling pathways important in gas6-Axl mediated protection of endothelial cells from apoptosis. However, as both gas6 and Axl null mice are protected from lethal thromboembolism, we sought to explore novel gas6-Axl intracellular signaling pathways regulating thrombosis. Caveolae have been shown to play a crucial role in the activation of signaling cascades following ligand binding to receptor tyrosine kinases. Caveolae are formed from lipid rafts by polymerization of caveolins. Caveolin-1 is the most abundant protein found in caveolae. Caveolin-1-enriched microdomains are well known to play a role as a docking platform for receptor tyrosine kinases and intracellular adaptor signaling proteins. Axl association with these highly specialized domains of the plasma membrane has not been previously elucidated. In the present study, we investigated the role of caveolin-1-enriched microdomains in gas6/Axl signaling in endothelial cells. First, we demonstrated that gas6-induced Akt and Erk1/2 phosphorylation required the presence of a functional Axl receptor as shown by Axl siRNA knockdown experiments in human umbilical vein endothelial cells. Then, caveolin-1 fractions, enriched by a detergent-free cell lysis followed by sucrose gradient ultra centrifugation, were studied by western blot analysis. After 5 and 10 min of gas6 treatment, Axl colocalized with caveolin-1 suggesting Axl recruitment into caveolin-1-enriched cell fractions. We found that c-Src, a signaling molecule known to behave as a transient docking platform in lipid rafts, also moved in caveolin-1-enriched cell fractions after gas6 stimulation. Caveolin-1 siRNA abolished gas6-induced Akt, Erk1/2 and c-Src phosphorylation suggesting that caveolin-1 enriched fractions are required for gas6-Axl signaling. Interestingly, we have shown that gas6-induced Akt phosphorylation required c-Src activation using c-Src siRNA and the pharmacological inhibitor (PP2). However, gas6-induced Erk1/2 phosphorylation was independent of c-Src. Finally, we found that gas6 increased tissue factor expression through the Axl-c-Src-Akt signaling cascade. Taken together, our results demonstrate that caveolin-1-enriched domains are required for gas6-Axl signaling and lead to the upregulation of tissue factor expression by gas6 in endothelial cells. These results highlight new insights of gas6-Axl signaling and function in endothelial cells. Disclosures: No relevant conflicts of interest to declare.

scholarly journals Class III Receptor Tyrosine Kinases in Acute Leukemia – Biological Functions and Modern Laboratory Analysis

2015 ◽  
Vol 10s3 ◽  
pp. BMI.S22433 ◽  
Author(s):  
Rimma Berenstein
Keyword(s):  
Tyrosine Kinases ◽  
Complex Disease ◽  
Receptor Tyrosine Kinases ◽  
Physiological Role ◽  
Leukemic Cells ◽  
World Health ◽  
Laboratory Diagnostics ◽  
Screening Methods ◽  
Class Iii ◽  
Short Period

Acute myeloid leukemia (AML) is a complex disease caused by deregulation of multiple signaling pathways. Mutations in class III receptor tyrosine kinases (RTKs) have been implicated in alteration of cell signals concerning the growth and differentiation of leukemic cells. Point mutations, insertions, or deletions of RTKs as well as chromosomal translocations induce constitutive activation of the receptor, leading to uncontrolled proliferation of undifferentiated myeloid blasts. Aberrations can occur in all domains of RTKs causing either the ligand-independent activation or mimicking the activated conformation. The World Health Organization recommended including RTK mutations in the AML classification since their detection in routine laboratory diagnostics is a major factor for prognostic stratification of patients. Polymerase chain reaction (PCR)–based methods are well-validated for the detection of fms-related tyrosine kinase 3 ( FLT3) mutations and can easily be applied for other RTKs. However, when methodological limitations are reached, accessory techniques can be applied. For a higher resolution and more quantitative approach compared to agarose gel electrophoresis, PCR fragments can be separated by capillary electrophoresis. Furthermore, high-resolution melting and denaturing high-pressure liquid chromatography are reliable presequencing screening methods that reduce the sample amount for Sanger sequencing. Because traditional DNA sequencing is time-consuming, next-generation sequencing (NGS) is an innovative modern possibility to analyze a high amount of samples simultaneously in a short period of time. At present, standardized procedures for NGS are not established, but when this barrier is resolved, it will provide a new platform for rapid and reliable laboratory diagnostic of RTK mutations in patients with AML. In this article, the biological and physiological role of RTK mutations in AML as well as possible laboratory methods for their detection will be reviewed.

scholarly journals Intrasteric Inhibition of ATP Binding Is Not Required To Prevent Unregulated Autophosphorylation or Signaling by the Insulin Receptor

2001 ◽  
Vol 21 (13) ◽  
pp. 4197-4207 ◽  
Author(s):  
Mark Frankel ◽  
Ararat J. Ablooglu ◽  
Joseph W. Leone ◽  
Elena Rusinova ◽  
J. B. Alexander Ross ◽  
...  
Keyword(s):  
Insulin Receptor ◽  
Conformational Changes ◽  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
Kinase Domain ◽  
Atp Binding ◽  
Activation Loop ◽  
Wild Type ◽  
Solution Studies ◽  
Activated State

ABSTRACT Receptor tyrosine kinases may use intrasteric inhibition to suppress autophosphorylation prior to growth factor stimulation. To test this hypothesis we made an Asp1161Ala mutant in the activation loop that relieved intrasteric inhibition of the unphosphorylated insulin receptor (IR) and its recombinant cytoplasmic kinase domain (IRKD) without affecting the activated state. Solution studies with the unphosphorylated mutant IRKD demonstrated conformational changes and greater catalytic efficiency from a 10-fold increase ink cat and a 15-fold-lowerK m ATP althoughK m peptide was unchanged. Kinetic parameters of the autophosphorylated mutant and wild-type kinase domains were virtually identical. The Asp1161Ala mutation increased the rate of in vitro autophosphorylation of the IRKD or IR at low ATP concentrations and in the absence of insulin. However, saturation with ATP (for the IRKD) or the presence of insulin (for the IR) yielded equivalent rates of autophosphorylation for mutant versus wild-type kinases. Despite a biochemically more active kinase domain, the mutant IR expressed in C2C12 myoblasts was not constitutively autophosphorylated. However, it displayed a 2.5-fold-lower 50% effective concentration for insulin stimulation of autophosphorylation and was dephosphorylated more slowly following withdrawal of insulin than wild-type IR. In tests of the regulation of the unphosphorylated basal state, these results demonstrate that neither intrasteric inhibition against ATP binding nor suppression of kinase activity is required to prevent premature autophosphorylation of the IR. Finally, the lower rate of dephosphorylation suggests invariant residues of the activation loop such as Asp1161 may function at multiple junctures in cellular regulation of receptor tyrosine kinases.

scholarly journals Association and phosphorylation-dependent dissociation of proteins in the insulin receptor complex

1993 ◽  
Vol 90 (23) ◽  
pp. 11317-11321 ◽  
Author(s):  
W Zhang ◽  
J D Johnson ◽  
W J Rutter
Keyword(s):  
Insulin Receptor ◽  
Tyrosine Kinases ◽  
Receptor Tyrosine Kinases ◽  
Receptor Complex ◽  
Phosphatidylinositol 3 Kinase ◽  
Gtpase Activating Protein ◽  
Tyrosine Residues ◽  
Mild Conditions ◽  
Ras Gtpase ◽  
Rapid Purification

Receptor tyrosine kinases have been found to interact with a variety of specific signaling molecules. To detect molecules that interact with the insulin receptor, we have produced a modified insulin receptor with an additional epitope allowing rapid purification under mild conditions of the insulin receptor complex. By this method we have found multiple proteins (including the p85 subunit of phosphatidylinositol 3'-kinase and the ras GTPase-activating protein) that specifically associate with the activated (phosphorylated) insulin receptor (insulin receptor complex proteins) but are released from the complex after they are phosphorylated on tyrosine residues. We have also shown that tyrosine phosphorylation of p85 by the activated insulin receptor blocks binding to the activated receptor. These results suggest that association of proteins with the insulin receptor complex is controlled by phosphorylation of the receptor, while dissociation of insulin receptor complex proteins is controlled in turn by phosphorylation of the proteins in the insulin receptor complex. This process results in the dispersion of phosphorylated insulin receptor complex proteins into the cell.

scholarly journals Invadopodia, a Kingdom of Non-Receptor Tyrosine Kinases

Cells ◽  
2021 ◽  
Vol 10 (8) ◽  
pp. 2037
Author(s):  
Trishna Saha ◽  
Hava Gil-Henn
Keyword(s):  
Primary Tumor ◽  
Tyrosine Kinases ◽  
Intracellular Signaling ◽  
Molecular Mechanisms ◽  
Cancer Metastasis ◽  
Receptor Tyrosine Kinases ◽  
General Belief ◽  
Human Disorders ◽  
Cell Invasiveness ◽  
And Function

Non-receptor tyrosine kinases (NRTKs) are crucial mediators of intracellular signaling and control a wide variety of processes such as cell division, morphogenesis, and motility. Aberrant NRTK-mediated tyrosine phosphorylation has been linked to various human disorders and diseases, among them cancer metastasis, to which no treatment presently exists. Invasive cancer cells leaving the primary tumor use invadopodia, feet-like structures which facilitate extracellular matrix (ECM) degradation and intravasation, to escape the primary tumor and disseminate into distant tissues and organs during metastasis. A major challenge in metastasis research is to elucidate the molecular mechanisms and signaling pathways underlying invadopodia regulation, as the general belief is that targeting these structures can potentially lead to the eradication of cancer metastasis. Non-receptor tyrosine kinases (NRTKs) play a central role in regulating invadopodia formation and function, but how they coordinate the signaling leading to these processes was not clear until recently. Here, we describe the major NRTKs that rule invadopodia and how they work in concert while keeping an accurate hierarchy to control tumor cell invasiveness and dissemination.

scholarly journals Growth hormone and erythropoietin differentially activate DNA-binding proteins by tyrosine phosphorylation.

1994 ◽  
Vol 14 (3) ◽  
pp. 2113-2118 ◽  
Author(s):  
D S Finbloom ◽  
E F Petricoin ◽  
R H Hackett ◽  
M David ◽  
G M Feldman ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Dna Binding ◽  
Tyrosine Phosphorylation ◽  
Tyrosine Kinases ◽  
Intracellular Signaling ◽  
Protein Complexes ◽  
Early Response ◽  
Receptor Clustering ◽  
Intracellular Signaling Pathway ◽  
Transcription Complexes

Binding of growth hormone (GH) and erythropoietin (EPO) to their respective receptors results in receptor clustering and activation of tyrosine kinases that initiate a cascade of events resulting not only in the rapid tyrosine phosphorylation of several proteins but also in the induction of early-response genes. In this report, we show that GH and EPO induce the tyrosine phosphorylation of cellular proteins with molecular masses of 93 kDa and of 91 and 84 kDa, respectively, and that these proteins form DNA-binding complexes which recognize an enhancer that has features in common with several rapidly induced genes such as c-fos. Assembly of the protein complexes required tyrosine phosphorylation, which occurred within minutes after addition of ligand. The activated complexes translocated from the cytoplasm to the nucleus. The protein activated by GH is antigenically similar to p91, a protein common to several transcription complexes that are activated by interferons and other cytokines. In contrast, the proteins activated by EPO are distinct from p91. These findings establish the outlines for a cytokine-induced intracellular signaling pathway, which begins with ligand-induced receptor clustering that activates one or more tyrosine kinases. These data are the first to demonstrate that GH- and EPO-activated tyrosine-phosphorylated proteins can specifically recognize a well-defined enhancer and therefore provide a mechanism for rapidly transducing signals from the membrane to the nucleus.

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