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Pardridge WM. Kinetics of Blood-Brain Barrier Transport of Monoclonal Antibodies Targeting the Insulin Receptor and the Transferrin Receptor. Pharmaceuticals (Basel) 2021; 15:3. [PMID: 35056060 PMCID: PMC8778919 DOI: 10.3390/ph15010003] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Revised: 12/10/2021] [Accepted: 12/18/2021] [Indexed: 12/21/2022] Open
Abstract
Biologic drugs are large molecule pharmaceuticals that do not cross the blood-brain barrier (BBB), which is formed by the brain capillary endothelium. Biologics can be re-engineered for BBB transport as IgG fusion proteins, where the IgG domain is a monoclonal antibody (MAb) that targets an endogenous BBB transporter, such as the insulin receptor (IR) or transferrin receptor (TfR). The IR and TfR at the BBB transport the receptor-specific MAb in parallel with the transport of the endogenous ligand, insulin or transferrin. The kinetics of BBB transport of insulin or transferrin, or an IRMAb or TfRMAb, can be quantified with separate mathematical models. Mathematical models to estimate the half-time of receptor endocytosis, MAb or ligand exocytosis into brain extracellular space, or receptor recycling back to the endothelial luminal membrane were fit to the brain uptake of a TfRMAb or a IRMAb fusion protein in the Rhesus monkey. Model fits to the data also allow for estimates of the rates of association of the MAb in plasma with the IR or TfR that is embedded within the endothelial luminal membrane in vivo. The parameters generated from the model fits can be used to estimate the brain concentration profile of the MAb over time, and this brain exposure is shown to be a function of the rate of clearance of the antibody fusion protein from the plasma compartment.
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Brierley GV, Webber H, Rasijeff E, Grocott S, Siddle K, Semple RK. Anti-Insulin Receptor Antibodies Improve Hyperglycemia in a Mouse Model of Human Insulin Receptoropathy. Diabetes 2020; 69:2481-2489. [PMID: 32816962 PMCID: PMC7576564 DOI: 10.2337/db20-0345] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Accepted: 08/11/2020] [Indexed: 02/07/2023]
Abstract
Loss-of-function mutations in both alleles of the human insulin receptor gene (INSR) cause extreme insulin resistance (IR) and usually death in childhood, with few effective therapeutic options. Bivalent antireceptor antibodies can elicit insulin-like signaling by mutant INSR in cultured cells, but whether this translates into meaningful metabolic benefits in vivo, wherein the dynamics of insulin signaling and receptor recycling are more complex, is unknown. To address this, we adopted a strategy to model human insulin receptoropathy in mice, using Cre recombinase delivered by adeno-associated virus to knockout endogenous hepatic Insr acutely in floxed Insr mice (liver insulin receptor knockout [L-IRKO] + GFP), before adenovirus-mediated add back of wild-type (WT) or mutant human INSR Two murine anti-INSR monoclonal antibodies, previously shown to be surrogate agonists for mutant INSR, were then tested by intraperitoneal injections. As expected, L-IRKO + GFP mice showed glucose intolerance and severe hyperinsulinemia. This was fully corrected by add back of WT but not with either D734A or S350L mutant INSR. Antibody injection improved glucose tolerance in D734A INSR-expressing mice and reduced hyperinsulinemia in both S350L and D734A INSR-expressing animals. It did not cause hypoglycemia in WT INSR-expressing mice. Antibody treatment also downregulated both WT and mutant INSR protein, attenuating its beneficial metabolic effects. Anti-INSR antibodies thus improve IR in an acute model of insulin receptoropathy, but these findings imply a narrow therapeutic window determined by competing effects of antibodies to stimulate receptors and induce their downregulation.
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Affiliation(s)
- Gemma V Brierley
- The University of Cambridge Metabolic Research Laboratories, Wellcome-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, U.K.
| | - Hannah Webber
- MRC Disease Model Core, Metabolic Research Laboratories, Wellcome-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, U.K
| | - Eerika Rasijeff
- MRC Disease Model Core, Metabolic Research Laboratories, Wellcome-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, U.K
| | - Sarah Grocott
- MRC Disease Model Core, Metabolic Research Laboratories, Wellcome-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, U.K
| | - Kenneth Siddle
- The University of Cambridge Metabolic Research Laboratories, Wellcome-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, U.K
| | - Robert K Semple
- The University of Cambridge Metabolic Research Laboratories, Wellcome-MRC Institute of Metabolic Science, Addenbrooke's Hospital, Cambridge, U.K.
- University of Edinburgh Centre for Cardiovascular Science, Queen's Medical Research Institute, Edinburgh, U.K
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3
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Pardridge WM, Boado RJ, Giugliani R, Schmidt M. Plasma Pharmacokinetics of Valanafusp Alpha, a Human Insulin Receptor Antibody-Iduronidase Fusion Protein, in Patients with Mucopolysaccharidosis Type I. BioDrugs 2018; 32:169-176. [PMID: 29442294 DOI: 10.1007/s40259-018-0264-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
BACKGROUND Mucopolysaccharidosis type I (MPSI) is caused by mutations in the gene encoding the α-L-iduronidase (IDUA) lysosomal enzyme and the majority of MPSI patients have severe central nervous system (CNS) involvement. Enzyme replacement therapy (ERT) with recombinant IDUA does not treat the CNS, due to the lack of transport of the enzyme across the blood-brain barrier (BBB). Human IDUA has been re-engineered as an IgG-IDUA fusion protein, valanafusp alpha, where the IgG domain is a monoclonal antibody (MAb) against the human insulin receptor (HIR). The HIRMAb domain binds the endogenous insulin receptor on the human BBB to trigger receptor-mediated transport across the BBB, and acts as a molecular Trojan horse to ferry the fused IDUA into the brain of patients with MPSI. METHODS The present investigation describes the initial dosing, plasma pharmacokinetics, and plasma glucose response to the intravenous infusion of doses of valanafusp alpha ranging from 0.3 to 3 mg/kg in five adults and from 1 to 6 mg/kg in 13 pediatric subjects with MPSI. RESULTS Valanafusp alpha plasma clearance is increased four-fold in children, and shows a linear pharmacokinetic response over the dose range of 0.3-3 mg/kg with a stable plasma elimination half-life (t½). The plasma pharmacokinetic parameters for valanafusp alpha overlapped with the same parameters previously reported for recombinant human IDUA (laronidase). The majority of the tested subjects had been receiving laronidase ERT for years, and some showed high levels of anti-drug antibodies (ADAs). However, the presence of these ADAs did not generally alter the rate of plasma clearance of valanafusp alpha in MPSI. The infusion of 0.3-6 mg/kg doses of valanafusp alpha had no effect on plasma glucose for up to 24 h after the drug infusion. CONCLUSION The plasma clearance of valanafusp alpha is increased four-fold in children with MPSI compared with adult subjects at a dose of 1-3 mg/kg. The plasma pharmacokinetic profile of valanafusp alpha, at a dose of 1-3 mg/kg, is comparable to that of laronidase in children with MPSI.
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Affiliation(s)
| | | | - Roberto Giugliani
- Department of Genetics, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.,Medical Genetics Service, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil
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Ong SC, Belgi A, van Lierop B, Delaine C, Andrikopoulos S, MacRaild CA, Norton RS, Haworth NL, Robinson AJ, Forbes BE. Probing the correlation between insulin activity and structural stability through introduction of the rigid A6-A11 bond. J Biol Chem 2018; 293:11928-11943. [PMID: 29899115 DOI: 10.1074/jbc.ra118.002486] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2018] [Revised: 06/10/2018] [Indexed: 11/06/2022] Open
Abstract
The development of fast-acting and highly stable insulin analogues is challenging. Insulin undergoes structural transitions essential for binding and activation of the insulin receptor (IR), but these conformational changes can also affect insulin stability. Previously, we substituted the insulin A6-A11 cystine with a rigid, non-reducible C=C linkage ("dicarba" linkage). A cis-alkene permitted the conformational flexibility of the A-chain N-terminal helix necessary for high-affinity IR binding, resulting in surprisingly rapid activity in vivo Here, we show that, unlike the rapidly acting LysB28ProB29 insulin analogue (KP insulin), cis-dicarba insulin is not inherently monomeric. We also show that cis-dicarba KP insulin lowers blood glucose levels even more rapidly than KP insulin, suggesting that an inability to oligomerize is not responsible for the observed rapid activity onset of cis-dicarba analogues. Although rapid-acting, neither dicarba species is stable, as assessed by fibrillation and thermodynamics assays. MALDI analyses and molecular dynamics simulations of cis-dicarba insulin revealed a previously unidentified role of the A6-A11 linkage in insulin conformational dynamics. By controlling the conformational flexibility of the insulin B-chain helix, this linkage affects overall insulin structural stability. This effect is independent of its regulation of the A-chain N-terminal helix flexibility necessary for IR engagement. We conclude that high-affinity IR binding, rapid in vivo activity, and insulin stability can be regulated by the specific conformational arrangement of the A6-A11 linkage. This detailed understanding of insulin's structural dynamics may aid in the future design of rapid-acting insulin analogues with improved stability.
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Affiliation(s)
- Shee Chee Ong
- From the College of Medicine and Public Health, Flinders University of South Australia, Bedford Park, South Australia 5042, Australia
| | - Alessia Belgi
- the School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Bianca van Lierop
- the School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Carlie Delaine
- From the College of Medicine and Public Health, Flinders University of South Australia, Bedford Park, South Australia 5042, Australia
| | - Sofianos Andrikopoulos
- the Department of Medicine, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Christopher A MacRaild
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Raymond S Norton
- Medicinal Chemistry, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Naomi L Haworth
- the School of Chemistry, Monash University, Clayton, Victoria 3800, Australia.,the Research School of Chemistry, Australian National University, Acton, Australian Capital Territory 2601, Australia, and.,the School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria 3216, Australia
| | - Andrea J Robinson
- the School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
| | - Briony E Forbes
- From the College of Medicine and Public Health, Flinders University of South Australia, Bedford Park, South Australia 5042, Australia,
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Brierley GV, Siddle K, Semple RK. Evaluation of anti-insulin receptor antibodies as potential novel therapies for human insulin receptoropathy using cell culture models. Diabetologia 2018; 61:1662-1675. [PMID: 29700562 PMCID: PMC6445487 DOI: 10.1007/s00125-018-4606-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Accepted: 03/06/2018] [Indexed: 12/28/2022]
Abstract
AIMS/HYPOTHESIS Bi-allelic loss-of-function mutations in the INSR gene (encoding the insulin receptor [INSR]) commonly cause extreme insulin resistance and early mortality. Therapeutic options are limited, but anti-INSR antibodies have been shown to activate two mutant receptors, S323L and F382V. This study evaluates four well-characterised murine anti-INSR monoclonal antibodies recognising distinct epitopes (83-7, 83-14, 18-44, 18-146) as surrogate agonists for potential targeted treatment of severe insulin resistance arising from insulin receptoropathies. METHODS Ten naturally occurring mutant human INSRs with defects affecting different aspects of receptor function were modelled and assessed for response to insulin and anti-INSR antibodies. A novel 3T3-L1 adipocyte model of insulin receptoropathy was generated, permitting conditional knockdown of endogenous mouse Insr by lentiviral expression of species-specific short hairpin (sh)RNAs with simultaneous expression of human mutant INSR transgenes. RESULTS All expressed mutant INSR bound to all antibodies tested. Eight mutants showed antibody-induced autophosphorylation, while co-treatment with antibody and insulin increased maximal phosphorylation compared with insulin alone. After knockdown of mouse Insr and expression of mutant INSR in 3T3-L1 adipocytes, two antibodies (83-7 and 83-14) activated signalling via protein kinase B (Akt) preferentially over signalling via extracellular signal-regulated kinase 1/2 (ERK1/2) for seven mutants. These antibodies stimulated glucose uptake via P193L, S323L, F382V and D707A mutant INSRs, with antibody response greater than insulin response for D707A. CONCLUSIONS/INTERPRETATION Anti-INSR monoclonal antibodies can activate selected naturally occurring mutant human insulin receptors, bringing closer the prospect of novel therapy for severe insulin resistance caused by recessive mutations.
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Affiliation(s)
- Gemma V Brierley
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
- National Institute for Health Research Cambridge Biomedical Research Centre, Addenbrooke's Hospital, Cambridge, UK
| | - Kenneth Siddle
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK
- National Institute for Health Research Cambridge Biomedical Research Centre, Addenbrooke's Hospital, Cambridge, UK
| | - Robert K Semple
- University of Cambridge Metabolic Research Laboratories, Wellcome Trust-MRC Institute of Metabolic Science, Cambridge, UK.
- National Institute for Health Research Cambridge Biomedical Research Centre, Addenbrooke's Hospital, Cambridge, UK.
- University of Edinburgh Centre for Cardiovascular Science, Queen's Medical Research Institute, Little France Crescent, Edinburgh, EH16 4TJ, UK.
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Differential Sensitivity of Human Hepatocellular Carcinoma Xenografts to an IGF-II Neutralizing Antibody May Involve Activated STAT3. Transl Oncol 2018; 11:971-978. [PMID: 29933129 PMCID: PMC6020079 DOI: 10.1016/j.tranon.2018.05.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Revised: 05/24/2018] [Accepted: 05/24/2018] [Indexed: 01/11/2023] Open
Abstract
Hepatocellular carcinoma (HCC) is highly refractory to current therapeutics used in the clinic. DX-2647, a recombinant human antibody, potently neutralizes the action of insulin-like growth factor-II (IGF-II), a ligand for three cell-surface receptors (IGF-IR, insulin receptor A and B isoforms, and the cation-independent mannose-6-phosphate receptor) which is overexpressed in primary human HCC. DX-2647 impaired the growth of tumor xenografts of the HCC cell line, Hep3B; however, xenografts of the HCC cell line, HepG2, were largely unresponsive to DX-2647 treatment. Analysis of a number of aspects of the IGF signaling axis in both cell lines did not reveal any significant differences between the two. However, while DX-2647 abolished phospho (p)-IGF-IR, p-IR and p-AKT signaling in both cell lines, HepG2 showed high levels of p-STAT3, which was unaffected by DX-2647 treatment and was absent from the Hep3B cell line. The driver of p-STAT3 was found to be a secreted cytokine, and treatment of HepG2 cells with a pan- JAK kinase inhibitor resulted in a loss of p-STAT3. These findings implicate the activation of STAT3 as one pathway that may mediate resistance to IGF-II-targeted therapy in HCC.
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Yunn NO, Kim J, Kim Y, Leibiger I, Berggren PO, Ryu SH. Mechanistic understanding of insulin receptor modulation: Implications for the development of anti-diabetic drugs. Pharmacol Ther 2018; 185:86-98. [DOI: 10.1016/j.pharmthera.2017.12.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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van Lierop B, Ong SC, Belgi A, Delaine C, Andrikopoulos S, Haworth NL, Menting JG, Lawrence MC, Robinson AJ, Forbes BE. Insulin in motion: The A6-A11 disulfide bond allosterically modulates structural transitions required for insulin activity. Sci Rep 2017; 7:17239. [PMID: 29222417 PMCID: PMC5722942 DOI: 10.1038/s41598-017-16876-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 11/17/2017] [Indexed: 01/10/2023] Open
Abstract
The structural transitions required for insulin to activate its receptor and initiate regulation of glucose homeostasis are only partly understood. Here, using ring-closing metathesis, we substitute the A6-A11 disulfide bond of insulin with a rigid, non-reducible dicarba linkage, yielding two distinct stereo-isomers (cis and trans). Remarkably, only the cis isomer displays full insulin potency, rapidly lowering blood glucose in mice (even under insulin-resistant conditions). It also posseses reduced mitogenic activity in vitro. Further biophysical, crystallographic and molecular-dynamics analyses reveal that the A6-A11 bond configuration directly affects the conformational flexibility of insulin A-chain N-terminal helix, dictating insulin’s ability to engage its receptor. We reveal that in native insulin, contraction of the Cα-Cα distance of the flexible A6-A11 cystine allows the A-chain N-terminal helix to unwind to a conformation that allows receptor engagement. This motion is also permitted in the cis isomer, with its shorter Cα-Cα distance, but prevented in the extended trans analogue. These findings thus illuminate for the first time the allosteric role of the A6-A11 bond in mediating the transition of the hormone to an active conformation, significantly advancing our understanding of insulin action and opening up new avenues for the design of improved therapeutic analogues.
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Affiliation(s)
- Bianca van Lierop
- School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia
| | - Shee Chee Ong
- College of Medicine & Public Health, Flinders University of South Australia, Bedford Park, 5042, Australia
| | - Alessia Belgi
- School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia
| | - Carlie Delaine
- College of Medicine & Public Health, Flinders University of South Australia, Bedford Park, 5042, Australia
| | | | - Naomi L Haworth
- School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia.,Research School of Chemistry, Australian National University, Acton, ACT 2601, Australia.,School of Life and Environmental Sciences, Deakin University, Waurn Ponds, Victoria, 3216, Australia
| | - John G Menting
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria, 3052, Australia
| | - Michael C Lawrence
- The Walter and Eliza Hall Institute of Medical Research, 1G Royal Parade, Parkville, Victoria, 3052, Australia.,Department of Medical Biology, University of Melbourne, Royal Parade, Parkville, Victoria, 3050, Australia
| | - Andrea J Robinson
- School of Chemistry, Monash University, Clayton, Victoria, 3800, Australia.
| | - Briony E Forbes
- College of Medicine & Public Health, Flinders University of South Australia, Bedford Park, 5042, Australia.
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9
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Pagesy P, Fardini Y, Nguyen TT, Lohmann M, Pierre-Eugene C, Tennagels N, Issad T. Effect of insulin analogues on phosphatidyl inositol-3 kinase/Akt signalling in INS-1 rat pancreatic derived β-cells. Arch Physiol Biochem 2016; 122:54-60. [PMID: 26707268 DOI: 10.3109/13813455.2015.1125364] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
CONTEXT Insulin analogues are largely used for the treatment of diabetic patients, but concerns have been raised about their mitogenic/anti-apoptotic potential. It is therefore important to evaluate these analogues in different cell systems. OBJECTIVE The aim of this work was to establish the pharmacological profiles of insulin analogues towards PI-3 kinase/Akt pathway in INS-1 β-pancreatic cells. METHODS Bioluminescence Resonance Energy Transfer (BRET), in cell western and caspase 3/7 assays, was used to study the effects of ligands. RESULTS Among the five analogues evaluated, only glargine stimulated PI-3 kinase/Akt pathway with higher efficiency than insulin, whereas glargine's metabolite M1 was less efficient. However, glargine did not show higher anti-apoptotic efficiency than insulin. CONCLUSION Glargine was more efficient than insulin for the activation of PI-3 kinase/Akt pathway, but not for the inhibition of caspase 3/7 activity. Moreover, glargine's metabolite M1 displayed lower efficiency than insulin towards PI-3 kinase/Akt activation and caspase 3/7 inhibition.
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Affiliation(s)
- Patrick Pagesy
- a Inserm, U1016, Institut Cochin , Paris , France
- b CNRS, UMR8104 , Paris , France
- c Université Paris Descartes, Sorbonne Paris Cité , Paris , France , and
| | - Yann Fardini
- a Inserm, U1016, Institut Cochin , Paris , France
- b CNRS, UMR8104 , Paris , France
- c Université Paris Descartes, Sorbonne Paris Cité , Paris , France , and
| | - Tuyet Thu Nguyen
- a Inserm, U1016, Institut Cochin , Paris , France
- b CNRS, UMR8104 , Paris , France
- c Université Paris Descartes, Sorbonne Paris Cité , Paris , France , and
| | | | - Cécile Pierre-Eugene
- a Inserm, U1016, Institut Cochin , Paris , France
- b CNRS, UMR8104 , Paris , France
- c Université Paris Descartes, Sorbonne Paris Cité , Paris , France , and
| | | | - Tarik Issad
- a Inserm, U1016, Institut Cochin , Paris , France
- b CNRS, UMR8104 , Paris , France
- c Université Paris Descartes, Sorbonne Paris Cité , Paris , France , and
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Rajapaksha H, Forbes BE. Ligand-Binding Affinity at the Insulin Receptor Isoform-A and Subsequent IR-A Tyrosine Phosphorylation Kinetics are Important Determinants of Mitogenic Biological Outcomes. Front Endocrinol (Lausanne) 2015; 6:107. [PMID: 26217307 PMCID: PMC4493403 DOI: 10.3389/fendo.2015.00107] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
The insulin receptor (IR) is a tyrosine kinase receptor that can mediate both metabolic and mitogenic biological actions. The IR isoform-A (IR-A) arises from alternative splicing of exon 11 and has different ligand binding and signaling properties compared to the IR isoform-B. The IR-A not only binds insulin but also insulin-like growth factor-II (IGF-II) with high affinity. IGF-II acting through the IR-A promotes cancer cell proliferation, survival, and migration by activating some unique signaling molecules compared to those activated by insulin. This observation led us to investigate whether the different IR-A signaling outcomes in response to IGF-II and insulin could be attributed to phosphorylation of a different subset of IR-A tyrosine residues or to the phosphorylation kinetics. We correlated IR-A phosphorylation to activation of molecules involved in mitogenic and metabolic signaling (MAPK and Akt) and receptor internalization rates (related to mitogenic signaling). We also extended this study to incorporate two ligands that are known to promote predominantly mitogenic [(His(4), Tyr(15), Thr(49), Ile(51)) IGF-I, qIGF-I] or metabolic (S597 peptide) biological actions, to see if common mechanisms can be used to define mitogenic or metabolic signaling through the IR-A. The threefold lower mitogenic action of IGF-II compared to insulin was associated with a decreased potency in activation of Y960, Y1146, Y1150, Y1151, Y1316, and Y1322, in MAPK phosphorylation and in IR-A internalization. With the poorly mitogenic S597 peptide, it was a decreased rate of tyrosine phosphorylation rather than potency that was associated with a low mitogenic potential. We conclude that both decreased affinity of IR-A binding and kinetics of IR-A phosphorylation can independently lead to a lower mitogenic activity. None of the studied parameters could account for the lower metabolic activity of qIGF-I.
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Affiliation(s)
- Harinda Rajapaksha
- School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
| | - Briony E. Forbes
- School of Biological Sciences, University of Adelaide, Adelaide, SA, Australia
- Department of Medical Biochemistry, School of Medicine, Flinders University of South Australia, Bedford Park, SA, Australia
- *Correspondence: Briony E. Forbes, Department of Medical Biochemistry, Flinders University of South Australia, C/O Flinders Medical Centre, Flinders Drive, Bedford Park, SA 5042, Australia,
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Levetan CS, Pierce SM. Distinctions between the islets of mice and men: implications for new therapies for type 1 and 2 diabetes. Endocr Pract 2013. [PMID: 23186955 DOI: 10.4158/ep12138.ra] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
OBJECTIVE To elucidate why diabetes is so difficult to treat despite the present tools and pharmacologic armamentarium and to provide insights into emerging therapies by describing human and rodent data that demonstrates the ability to transform progenitor cells within the adult pancreas into new islets. METHODS A literature review focused on the distinctions between human and rodent islets. RESULTS We are beginning to elucidate important differences between the architecture and composition of the islets of Langerhans in humans and rodents. In contrast to rodent islets, human islets are more heterogeneous in cellular composition and have more prominent intra-islet vascularity, with smooth muscle-containing blood vessels that are not present in rodent islets. Some studies report that more than 70% of human beta cells have direct physical contact with other cell types, whereas others describe that smaller human islets possess features more typical of rodents, while larger islets exhibit greater vascularity and a cellular distribution distinct from centrally clustered beta cells surrounded by a mantle of alpha and delta cells found in rodents. CONCLUSIONS The differences between the islets of mice and men may influence why treatments hailed as reversing diabetes among rodents have not been successfully translated into humans. Increased understanding of the complexities within the human islet may yield unique insights into reversing diabetes in humans.
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Affiliation(s)
- Claresa S Levetan
- Division of Diabetes, Endocrinology and Metabolism, Chestnut Hill Hospital, Philadelphia, PA 19118, USA.
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12
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Greenall SA, Bentley JD, Pearce LA, Scoble JA, Sparrow LG, Bartone NA, Xiao X, Baxter RC, Cosgrove LJ, Adams TE. Biochemical characterization of individual human glycosylated pro-insulin-like growth factor (IGF)-II and big-IGF-II isoforms associated with cancer. J Biol Chem 2012; 288:59-68. [PMID: 23166326 DOI: 10.1074/jbc.m112.432013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Insulin-like growth factor II (IGF-II) is a major embryonic growth factor belonging to the insulin-like growth factor family, which includes insulin and IGF-I. Its expression in humans is tightly controlled by maternal imprinting, a genetic restraint that is lost in many cancers, resulting in up-regulation of both mature IGF-II mRNA and protein expression. Additionally, increased expression of several longer isoforms of IGF-II, termed "pro" and "big" IGF-II, has been observed. To date, it is ambiguous as to what role these IGF-II isoforms have in initiating and sustaining tumorigenesis and whether they are bioavailable. We have expressed each individual IGF-II isoform in their proper O-glycosylated format and established that all bind to the IGF-I receptor and both insulin receptors A and B, resulting in their activation and subsequent stimulation of fibroblast proliferation. We also confirmed that all isoforms are able to be sequestered into binary complexes with several IGF-binding proteins (IGFBP-2, IGFBP-3, and IGFBP-5). In contrast to this, ternary complex formation with IGFBP-3 or IGFBP-5 and the auxillary protein, acid labile subunit, was severely diminished. Furthermore, big-IGF-II isoforms bound much more weakly to purified ectodomain of the natural IGF-II scavenging receptor, IGF-IIR. IGF-II isoforms thus possess unique biological properties that may enable them to escape normal sequestration avenues and remain bioavailable in vivo to sustain oncogenic signaling.
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Affiliation(s)
- Sameer A Greenall
- Division of Materials Science and Engineering, Commonwealth Scientific and Industrial Research Organisation, Parkville, Victoria 3052, Australia
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Pierre-Eugene C, Pagesy P, Nguyen TT, Neuillé M, Tschank G, Tennagels N, Hampe C, Issad T. Effect of insulin analogues on insulin/IGF1 hybrid receptors: increased activation by glargine but not by its metabolites M1 and M2. PLoS One 2012; 7:e41992. [PMID: 22848683 PMCID: PMC3406060 DOI: 10.1371/journal.pone.0041992] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Accepted: 06/28/2012] [Indexed: 12/28/2022] Open
Abstract
Background In diabetic patients, the pharmacokinetics of injected human insulin does not permit optimal control of glycemia. Fast and slow acting insulin analogues have been developed, but they may have adverse properties, such as increased mitogenic or anti-apoptotic signaling. Insulin/IGF1 hybrid receptors (IR/IGF1R), present in most tissues, have been proposed to transmit biological effects close to those of IGF1R. However, the study of hybrid receptors is difficult because of the presence of IR and IGF1R homodimers. Our objective was to perform the first study on the pharmacological properties of the five marketed insulin analogues towards IR/IGF1R hybrids. Methodology To study the effect of insulin analogues on IR/IGF1R hybrids, we used our previously developed Bioluminescence Resonance Energy Transfer (BRET) assay that permits specific analysis of the pharmacological properties of hybrid receptors. Moreover, we have developed a new, highly sensitive BRET-based assay to monitor phophatidylinositol-3 phosphate (PIP3) production in living cells. Using this assay, we performed a detailed pharmacological analysis of PIP3 production induced by IGF1, insulin and insulin analogues in living breast cancer-derived MCF-7 and MDA-MB231 cells. Results Among the five insulin analogues tested, only glargine stimulated IR/IGF1R hybrids with an EC50 that was significantly lower than insulin and close to that of IGF1. Glargine more efficiently stimulated PIP3 production in MCF-7 cells but not in MDA-MB231 cells as compared to insulin. In contrast, glargine metabolites M1 and M2 showed lower potency for hybrid receptors stimulation, PIP3 production, Akt and Erk1/2 phosphorylation and DNA synthesis in MCF-7 cells, compared to insulin. Conclusion Glargine, possibly acting through IR/IGF1R hybrids, displays higher potency, whereas its metabolites M1 and M2 display lower potency than insulin for the stimulation of proliferative/anti-apoptotic pathways in MCF-7 cells.
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Affiliation(s)
- Cécile Pierre-Eugene
- Institut Cochin, Université Paris Descartes, CNRS (UMR8104), Paris, France
- INSERM, U1016, Paris, France
| | - Patrick Pagesy
- Institut Cochin, Université Paris Descartes, CNRS (UMR8104), Paris, France
- INSERM, U1016, Paris, France
| | - Tuyet Thu Nguyen
- Institut Cochin, Université Paris Descartes, CNRS (UMR8104), Paris, France
- INSERM, U1016, Paris, France
| | - Marion Neuillé
- Institut Cochin, Université Paris Descartes, CNRS (UMR8104), Paris, France
- INSERM, U1016, Paris, France
| | | | | | - Cornelia Hampe
- Institut Cochin, Université Paris Descartes, CNRS (UMR8104), Paris, France
- INSERM, U1016, Paris, France
| | - Tarik Issad
- Institut Cochin, Université Paris Descartes, CNRS (UMR8104), Paris, France
- INSERM, U1016, Paris, France
- * E-mail:
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14
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Kirk J, Porter KM, Parker V, Barroso I, O’Rahilly S, Hendriksz C, Semple RK. Loss of NPC1 function in a patient with a co-inherited novel insulin receptor mutation does not grossly modify the severity of the associated insulin resistance. J Inherit Metab Dis 2010; 33 Suppl 3:S227-32. [PMID: 20521171 PMCID: PMC3757264 DOI: 10.1007/s10545-010-9107-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/20/2010] [Revised: 03/31/2010] [Accepted: 04/12/2010] [Indexed: 11/24/2022]
Abstract
In Npc1 null mice, a model for Niemann Pick Disease Type C1, it has been reported that hepatocyte insulin receptor function is significantly impaired, consistent with growing evidence that membrane fluidity and microdomain structure have an important role in insulin signal transduction. However, whether insulin receptor function is also compromised in human Niemann Pick disease Type C1 is unclear. We now report a girl who developed progressive dementia, ataxia and opthalmoplegia from 9 years old, followed by severe acanthosis nigricans, hirsutism and acne at 11 years old. She was diagnosed with Niemann Pick Disease type C1 (OMIM#257220) based on positive filipin staining and reduced cholesterol-esterifying activity in dermal fibroblasts, and homozygosity for the p.Ile1061Thr NPC1 mutation. Further analysis revealed her also to be heterozygous for a novel trinucleotide deletion (c.3659 + 1_3659 + 3delGTG) at the end of exon 20 of INSR, encoding the insulin receptor, leading to deletion of Trp1193 in the intracellular tyrosine kinase domain. INSR mRNA and protein levels were normal in dermal fibroblasts, consistent with a primary signal transduction defect in the mutant receptor. Although the proband was significantly more insulin resistant than her father, who carried the INSR mutation but was only heterozygous for the NPC1 variant, their respective degrees of IR were very similar to those previously reported in a father-daughter pair with the closely related p.Trp1193Leu INSR mutation. This suggests that loss of NPC1 function, with attendant changes in membrane cholesterol composition, does not significantly modify the IR phenotype, even in the context of severely impaired INSR function.
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Affiliation(s)
- J. Kirk
- />Department of Endocrinology, Birmingham Children’s Hospital, Steelhouse Lane, Birmingham, B4 6NH United Kingdom
| | - K. M. Porter
- />Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge, Cambridge, CB2 0QQ UK
| | - V. Parker
- />Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge, Cambridge, CB2 0QQ UK
| | - I. Barroso
- />The Wellcome Trust Sanger Institute, Wellcome Trust Genome Campus, Hinxton, Cambridge, CB10 1SA United Kingdom
| | - S. O’Rahilly
- />Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge, Cambridge, CB2 0QQ UK
| | - C. Hendriksz
- />Clinical Inherited Metabolic Disorders, Birmingham Children’s Hospital, Steelhouse Lane, Birmingham, B4 6NH United Kingdom
| | - R. K. Semple
- />Metabolic Research Laboratories, Institute of Metabolic Science, Addenbrooke’s Hospital, University of Cambridge, Cambridge, CB2 0QQ UK
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15
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Zhang M, Riedel H. Insulin receptor kinase-independent signaling via tyrosine phosphorylation of phosphatase PHLPP1. J Cell Biochem 2009; 107:65-75. [PMID: 19277985 DOI: 10.1002/jcb.22095] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Most insulin responses correlate well with insulin receptor (IR) Tyr kinase activation; however, critical exceptions to this concept have been presented. Specific IR mutants and stimulatory IR antibodies demonstrate a lack of correlation between IR kinase activity and specific insulin responses in numerous independent studies. IR conformation changes in response to insulin observed with various IR antibodies define an IR kinase-independent signal that alters the C-terminus. IR-related receptors in lower eukaryotes that lack a Tyr kinase point to an alternative mechanism of IR signaling earlier in evolution. However, the implied IR kinase-independent signaling mechanism remained obscure at the molecular level. Here we begin to define the molecular basis of an IR-dependent but IR kinase-independent insulin signal that is equally transmitted by a kinase-inactive mutant IR. This insulin signal results in Tyr phosphorylation and catalytic activation of phosphatase PHLPP1 via a PI 3-kinase-independent, wortmannin-insensitive signaling pathway. Dimerized SH2B1/PSM is a critical activator of the IR kinase and the resulting established insulin signal. In contrast it is an inhibitor of the IR kinase-independent insulin signal and disruption of SH2B1/PSM dimer binding to IR potentiates this signal. Dephosphorylation of Akt2 by PHLPP1 provides an alternative, SH2B1/PSM-regulated insulin-signaling pathway from IR to Akt2 of opposite polarity and distinct from the established PI 3-kinase-dependent signaling pathway via IRS proteins. In combination, both pathways should allow the opposing regulation of Akt2 activity at two phosphorylation sites to specifically define the insulin signal in the background of interfering Akt-regulating signals, such as those controlling cell proliferation and survival.
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Affiliation(s)
- Manchao Zhang
- Department of Biochemistry and Mary Babb Randolph Cancer Center, West Virginia University School of Medicine, Morgantown, West Virginia 26506-9142, USA
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16
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Alvino CL, McNeil KA, Ong SC, Delaine C, Booker GW, Wallace JC, Whittaker J, Forbes BE. A novel approach to identify two distinct receptor binding surfaces of insulin-like growth factor II. J Biol Chem 2009; 284:7656-64. [PMID: 19139090 DOI: 10.1074/jbc.m808061200] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Very little is known about the residues important for the interaction of insulin-like growth factor II (IGF-II) with the type 1 IGF receptor (IGF-1R) and the insulin receptor (IR). Insulin, to which IGF-II is homologous, is proposed to cross-link opposite halves of the IR dimer through two receptor binding surfaces, site 1 and site 2. In the present study we have analyzed the contribution of IGF-II residues equivalent to insulin's two binding surfaces toward the interaction of IGF-II with the IGF-1R and IR. Four "site 1" and six "site 2" analogues were produced and analyzed in terms of IGF-1R and IR binding and activation. The results show that Val(43), Phe(28), and Val(14) (equivalent to site 1) are critical to IGF-1R and IR binding, whereas mutation to alanine of Gln(18) affects only IGF-1R and not IR binding. Alanine substitutions at Glu(12), Asp(15), Phe(19), Leu(53), and Glu(57) analogues resulted in significant (>2-fold) decreases in affinity for both the IGF-1R and IR. Furthermore, taking a novel approach using a monomeric, single-chain minimized IGF-1R we have defined a distinct second binding surface formed by Glu(12), Phe(19), Leu(53), and Glu(57) that potentially engages the IGF-1R at one or more of the FnIII domains.
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Affiliation(s)
- Clair L Alvino
- School of Molecular and Biomedical Science, The University of Adelaide, Gate 8, Victoria Drive, Adelaide, South Australia 5005, Australia
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17
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Motegi A, Fujimoto J, Kotani M, Sakuraba H, Yamamoto T. ALK receptor tyrosine kinase promotes cell growth and neurite outgrowth. J Cell Sci 2005; 117:3319-29. [PMID: 15226403 DOI: 10.1242/jcs.01183] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Anaplastic lymphoma kinase (ALK) is a receptor-type protein tyrosine kinase that is expressed preferentially in neurons of the central and peripheral nervous systems at late embryonic stages. To elucidate the role of ALK in neurons, we developed an agonist monoclonal antibody (mAb) against the extracellular domain of ALK. Here we show that mAb16-39 elicits tyrosine phosphorylation of endogenously expressed ALK in human neuroblastoma (SK-N-SH) cells. Stimulation of these cells with mAb16-39 markedly induces the tyrosine phosphorylation of insulin receptor substrate-1 (IRS-1), Shc, and c-Cbl and also their interaction with ALK and activation of ERK1/2. Furthermore, we show that continuous incubation with mAb16-39 induces the cell growth and neurite outgrowth of SK-N-SH cells. These responses are completely blocked by MEK inhibitor PD98059 but not by the phosphatidylinositol 3-kinase (PI 3-kinase) inhibitor wortmannin, indicating an essential role of the mitogen-activated protein kinase (MAP kinase) signaling cascade in ALK-mediated growth and differentiation of neurons.
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Affiliation(s)
- Akira Motegi
- Division of Oncology, Institute of Medical Science, University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, 108-8639, Japan
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18
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Denley A, Wang CC, McNeil KA, Walenkamp MJE, van Duyvenvoorde H, Wit JM, Wallace JC, Norton RS, Karperien M, Forbes BE. Structural and functional characteristics of the Val44Met insulin-like growth factor I missense mutation: correlation with effects on growth and development. Mol Endocrinol 2004; 19:711-21. [PMID: 15576456 DOI: 10.1210/me.2004-0409] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We have previously described the phenotype resulting from a missense mutation in the IGF-I gene, which leads to expression of IGF-I with a methionine instead of a valine at position 44 (Val44Met IGF-I). This mutation caused severe growth and mental retardation as well as deafness evident at birth and growth retardation in childhood, but is relatively well tolerated in adulthood. We have conducted a biochemical and structural analysis of Val44Met IGF-I to provide a molecular basis for the phenotype observed. Val44Met IGF-I exhibits a 90-fold decrease in type 1 IGF receptor (IGF-1R) binding compared with wild-type human IGF-I and only poorly stimulates autophosphorylation of the IGF-1R. The ability of Val44Met IGF-I to signal via the extracellular signal-regulated kinase 1/2 and Akt/protein kinase B pathways and to stimulate DNA synthesis is correspondingly poorer. Binding or activation of both insulin receptor isoforms is not detectable even at micromolar concentrations. However, Val44Met IGF-I binds IGF-binding protein-2 (IGFBP-2), IGFBP-3, and IGFBP-6 with equal affinity to IGF-I, suggesting the maintenance of overall structure, particularly in the IGFBP binding domain. Structural analysis by nuclear magnetic resonance confirms retention of near-native structure with only local side-chain disruptions despite the significant loss of function. To our knowledge, our results provide the first structural study of a naturally occurring mutant human IGF-I associated with growth and developmental abnormalities and identifies Val44 as an essential residue involved in the IGF-IGF-1R interaction.
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Affiliation(s)
- Adam Denley
- School of Molecular and Biomedical Science, University of Adelaide, Adelaide, 5005 South Australia
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19
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Denley A, Bonython ER, Booker GW, Cosgrove LJ, Forbes BE, Ward CW, Wallace JC. Structural determinants for high-affinity binding of insulin-like growth factor II to insulin receptor (IR)-A, the exon 11 minus isoform of the IR. Mol Endocrinol 2004; 18:2502-12. [PMID: 15205474 DOI: 10.1210/me.2004-0183] [Citation(s) in RCA: 154] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
The insulin receptor (IR) lacking the alternatively spliced exon 11 (IR-A) is preferentially expressed in fetal and cancer cells. The IR-A has been identified as a high-affinity receptor for insulin and IGF-II but not IGF-I, which it binds with substantially lower affinity. Several cancer cell types that express the IR-A also overexpress IGF-II, suggesting a possible autocrine proliferative loop. To determine the regions of IGF-I and IGF-II responsible for this differential affinity, chimeras were made where the C and D domains were exchanged between IGF-I and IGF-II either singly or together. The abilities of these chimeras to bind to, and activate, the IR-A were investigated. We also investigated the ability of these chimeras to bind and activate the IR exon 11+ isoform (IR-B) and as a positive control, the IGF-I receptor (IGF-1R). We show that the C domain and, to a lesser extent, the D domains represent the principal determinants of the binding differences between IGF-I and IGF-II to IR-A. The C and D domains of IGF-II promote higher affinity binding to the IR-A than the equivalent domains of IGF-I, resulting in an affinity close to that of insulin for the IR-A. The C and D domains also regulate the IR-B binding specificity of the IGFs in a similar manner, although the level of binding for all IGF ligands to IR-B is lower than to IR-A. In contrast, the C and D domains of IGF-I allow higher affinity binding to the IGF-1R than the analogous domains of IGF-II. Activation of IGF-1R by the chimeras reflected their binding affinities whereas the phosphorylation of the two IR isoforms was more complex.
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Affiliation(s)
- Adam Denley
- School of Molecular and Biomedical Science, The University of Adelaide, Adelaide 5005, Australia
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20
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Schäffer L, Brissette RE, Spetzler JC, Pillutla RC, Østergaard S, Lennick M, Brandt J, Fletcher PW, Danielsen GM, Hsiao KC, Andersen AS, Dedova O, Ribel U, Hoeg-Jensen T, Hansen PH, Blume AJ, Markussen J, Goldstein NI. Assembly of high-affinity insulin receptor agonists and antagonists from peptide building blocks. Proc Natl Acad Sci U S A 2003; 100:4435-9. [PMID: 12684539 PMCID: PMC153573 DOI: 10.1073/pnas.0830026100] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Insulin is thought to elicit its effects by crosslinking the two extracellular alpha-subunits of its receptor, thereby inducing a conformational change in the receptor, which activates the intracellular tyrosine kinase signaling cascade. Previously we identified a series of peptides binding to two discrete hotspots on the insulin receptor. Here we show that covalent linkage of such peptides into homodimers or heterodimers results in insulin agonists or antagonists, depending on how the peptides are linked. An optimized agonist has been shown, both in vitro and in vivo, to have a potency close to that of insulin itself. The ability to construct such peptide derivatives may offer a path for developing agonists or antagonists for treatment of a wide variety of diseases.
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21
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Vyas SP. CNS-delivery via conjugation to biological carriers: physiological-based approaches. PROGRESS IN DRUG RESEARCH. FORTSCHRITTE DER ARZNEIMITTELFORSCHUNG. PROGRES DES RECHERCHES PHARMACEUTIQUES 2003; 61:189-219. [PMID: 14674613 DOI: 10.1007/978-3-0348-8049-7_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/27/2023]
Affiliation(s)
- Suresh P Vyas
- Drug Delivery Research Laboratory, Department of Pharmaceutical Sciences, Dr. Harisingh Gour University, Sagar (M.P.) 470 003, India
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22
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Issad T, Boute N, Pernet K. A homogenous assay to monitor the activity of the insulin receptor using Bioluminescence Resonance Energy Transfer. Biochem Pharmacol 2002; 64:813-7. [PMID: 12213574 DOI: 10.1016/s0006-2952(02)01143-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Insulin exerts its biological effects through a plasma membrane receptor that possesses a tyrosine kinase activity. Binding of insulin to its receptor induces a conformational change that stimulates the autophosphorylation of the receptor on tyrosine residues. This autophosphorylation stimulates the tyrosine kinase activity of the receptor toward intracellular substrates involved in the transmission of the signal. The discovery of pharmacological agents that specifically activate the tyrosine kinase activity of the insulin receptor will be of great importance for the treatment of insulin-resistant or insulin-deficient patients. We have developed a procedure based on Bioluminescence Resonance Energy Transfer (BRET) to monitor the activation state of the insulin receptor. Human insulin receptor cDNA, was fused to either Renilla luciferase or yellow fluorescent protein coding sequences. Fusion insulin receptors were partially purified by wheat-germ lectin chromatography from HEK-293 cells co-transfected with these constructs. The conformational change induced by insulin on its receptor could be detected as an energy transfer (BRET signal) between Renilla luciferase and yellow fluorescent protein. BRET signal paralleled insulin-induced autophosphorylation of the fusion receptor. Dose-dependent effects of insulin, insulin-like growth factor 1 and epidermal growth factor on BRET signal were in agreement with known pharmacological properties of these ligands. Moreover, an antibody, which activated the autophosphorylation of the receptor, had similar effects on BRET signal. This methodology allows for rapid analysis of the effects of agonists on insulin receptor activity and could, therefore, be used in high-throughput screening for the discovery of molecules with insulin-like properties.
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Affiliation(s)
- Tarik Issad
- Department of Cell Biology, Cochin Institute, CNRS, INSERM, University René Descartes, 22 rue Méchain, 75014 Paris, France.
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23
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Smith RA, Mosesson MW, Daniels AU, Gartner TK. Adhesion of microvascular endothelial cells to metallic implant surfaces. JOURNAL OF MATERIALS SCIENCE. MATERIALS IN MEDICINE 2000; 11:279-285. [PMID: 15348024 DOI: 10.1023/a:1008953112683] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
The objective of this study was to explore the molecular mechanisms of adhesion of endothelial cells (ECs) to implant grades of titanium alloy (Ti) and stainless steel (SS), compared to tissue culture polystyrene (PS). The idea is that promotion of EC adhesion to implant surfaces during the initial stages of healing may be critical in the formation of a capillary bed intimately associated with the implant surface. Ultimately this could be expected in turn to promote bone formation close to the surface and a more stable implant/bone interface. Surfaces were coated with either peak 1 fibrinogen gammaAgammaA, fibrinogen Fr I-9, fibrinogen fragment D1, fibronectin, vitronectin, or fetal calf serum and then post-coated with bovine serum albumin (BSA) to block non-specific cell adhesion. Surfaces with BSA alone and no other protein coating were also evaluated. Fibronectin coating maximized cell adhesion on all three surfaces, and adhesion was highest on PS. BSA blocked cell adhesion to PS (and most adhesion to SS) much better than to Ti. These results provide evidence that BSA adsorption on the metal surface is unable to effectively block the adhesion of the cells to the Ti. These data may provide a basis for understanding in vivo observations that soft tissue becomes attached to a Ti surface more rapidly and with more bone formation than to SS. Evidence is also presented that alphavbeta3 plays an important role in adhesion of ECs to the Ti surface. These experiments also provide preliminary data which may reflect some of the features of initial EC adhesion to metal implants.
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Affiliation(s)
- R A Smith
- University of Tennessee-Campbell Clinic, Department of Orthopaedic Surgery, Memphis, TN 38163, USA.
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24
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Avena R, Mitchell ME, Carmody B, Arora S, Neville RF, Sidaway AN. Insulin-like growth factor-1 receptors mediate infragenicular vascular smooth muscle cell proliferation in response to glucose and insulin not by insulin receptors. Am J Surg 1999; 178:156-61. [PMID: 10487270 DOI: 10.1016/s0002-9610(99)00150-6] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
PURPOSE Vascular smooth muscle cell (VSMC) proliferation is an early event in the pathogenesis of atherosclerosis. Insulin and glucose are known to stimulate the growth of VSMC. Cell membrane receptors play an important role in the proliferation of VSMC in response to growth factors. Insulin and insulin-like growth factor-1 (IGF-1) have demonstrated a cross reactivity for receptor binding and function. By using monoclonal antibodies directed against insulin (IRA) and IGF-1 (IGF-1RA) receptors, we attempt to further delineate the mechanism for the proliferation of VSMC in response to insulin and glucose. METHODS Human infragenicular VSMC isolated from diabetic patients undergoing below-knee amputations were used. Cells from passages 3 to 6 were grown in serum-free media with a glucose concentrations of 0.1% or 0.2%, both with and without insulin (100 ng/mL). The baseline cell density was 4,635 +/- 329 cells/mL. IRA or IGF-1RA was added to the media, with the control group receiving neither antibody. Cells were grown in 5% CO2 at 37 degrees C for 6 days. Analysis of variance was used for statistical analysis, with P <0.05 considered significant. In addition, DNA synthesis was measured using thymidine incorporation assays in the same groups of cells receiving IRA, IGF-1RA, and no antibody. RESULTS IGF-1RA prevented the proliferation of VSMC in response to insulin and glucose, while IRA had no effect on cell growth. There was no significant growth when IGF-1RA was added to the media, while the control group and the group receiving IRA demonstrated significant growth compared with the baseline concentration of 4,635 +/- 329 cells/mL at all concentrations of insulin and glucose. [3H]thymidine incorporation assays confirmed the cell count results. CONCLUSIONS These results suggest that the mitogenic effects of insulin and glucose on infragenicular VSMC are due to stimulation of the IGF-1 receptor. VSMC antiproliferative strategies employing receptor blockade should be directed against the IGF-1 receptor, not the insulin receptor.
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MESH Headings
- Analysis of Variance
- Antibodies, Monoclonal
- Arteriosclerosis/etiology
- Arteriosclerosis/pathology
- Cell Count/drug effects
- Cell Division/drug effects
- Cell Division/physiology
- Cells, Cultured
- Cross Reactions
- Culture Media, Serum-Free
- DNA/biosynthesis
- Diabetes Mellitus/pathology
- Glucose/administration & dosage
- Glucose/pharmacology
- Humans
- Insulin/administration & dosage
- Insulin/pharmacology
- Mitogens/administration & dosage
- Mitogens/pharmacology
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Radiopharmaceuticals
- Receptor, IGF Type 1/drug effects
- Receptor, IGF Type 1/physiology
- Receptor, Insulin/drug effects
- Receptor, Insulin/physiology
- Thymidine/metabolism
- Tritium
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Affiliation(s)
- R Avena
- Department of Surgery, Veterans Affairs Medical Center, Washington, DC, USA
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25
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Tulloch PA, Lawrence LJ, McKern NM, Robinson CP, Bentley JD, Cosgrove L, Ivancic N, Lovrecz GO, Siddle K, Ward CW. Single-molecule imaging of human insulin receptor ectodomain and its Fab complexes. J Struct Biol 1999; 125:11-8. [PMID: 10196112 DOI: 10.1006/jsbi.1998.4066] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The insulin receptor (IR) is a four-chain, transmembrane dimer held together by disulfide bonds. To gain information about the molecular envelope and the organization of its domains, single-molecule images of the IR ectodomain and its complexes with three Fabs have been analyzed by electron microscopy. The data indicate that the IR ectodomain resembles a U-shaped prism of approximate dimensions 90 x 80 x 120 A. The width of the cleft (assumed membrane-distal) between the two side arms is sufficient to accommodate ligand. Fab 83-7, which recognizes the cys-rich region of IR, bound halfway up one end of each side arm in a diametrically opposite manner, indicating a twofold axis of symmetry normal to the membrane surface. Fabs 83-14 and 18-44, which have been mapped respectively to the first fibronectin type III domain (residues 469-592) and residues 765-770 in the insert domain, bound near the base of the prism at opposite corners. These images, together with the data from the recently determined 3D structure of the first three domains of the insulin-like growth factor type I receptor, suggest that the IR dimer is organized into two layers with the L1/cys-rich/L2 domains occupying the upper (membrane distal) region of the U-shaped prism and the fibronectin type III domains and the insert domains located predominantly in the membrane-proximal region.
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Affiliation(s)
- P A Tulloch
- Biomolecular Research Institute, 343 Royal Parade, Parkville, Victoria, 3052, Australia
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26
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Pardridge WM, Kang YS, Buciak JL, Yang J. Human insulin receptor monoclonal antibody undergoes high affinity binding to human brain capillaries in vitro and rapid transcytosis through the blood-brain barrier in vivo in the primate. Pharm Res 1995; 12:807-16. [PMID: 7667183 DOI: 10.1023/a:1016244500596] [Citation(s) in RCA: 225] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
PURPOSE The ability of monoclonal antibodies against the human insulin receptor to undergo transcytosis through the blood-brain barrier (BBB) was examined in the present studies. METHODS Two murine monoclonal antibodies (MAb83-7 and MAb83-14) which bind different epitopes within the alpha-subunit of the human insulin receptor were examined using isolated human brain capillaries, frozen sections of primate brain, and in vivo pharmacokinetic studies in anesthetized Rhesus monkeys. RESULTS Both antibodies strongly illuminated capillary endothelium in immunocytochemical analysis of frozen sections of brain from Rhesus monkey but not squirrel monkey. Both monoclonal antibodies, in the iodinated forms, bound to human brain microvessels, although the binding and endocytosis of MAb83-14 was approximately 10-fold greater than MAb83-7. The active binding of MAb83-14 to the human insulin receptor was paralleled by a very high rate of transport of this antibody through the BBB in vivo in two anesthetized Rhesus monkeys. The BBB permeability-surface area (PS) product in neocortical gray matter was 5.4 +/- 0.6 microL/min/g, which is severalfold greater than previous estimates of the PS product for receptor-specific monoclonal antibody transport through the BBB. The brain delivery of MAb83-14 to the Rhesus monkey brain was high and 3.8 +/- 0.4% of the injected dose was delivered to 100 g of brain at 3 hours after a single intravenous injection. In contrast, there was no brain uptake of the mouse IgG2a isotype control antibody. CONCLUSIONS These studies demonstrate an unexpected high degree of transcytosis of a monoclonal antibody through the primate BBB in vivo.
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Affiliation(s)
- W M Pardridge
- Department of Medicine and Brain Research Institute, UCLA School of Medicine 90024, USA
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27
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Chang PY, Goodyear LJ, Benecke H, Markuns JS, Moller DE. Impaired insulin signaling in skeletal muscles from transgenic mice expressing kinase-deficient insulin receptors. J Biol Chem 1995; 270:12593-600. [PMID: 7759507 DOI: 10.1074/jbc.270.21.12593] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Transgenic mice which overexpress kinase-deficient human insulin receptors in muscle were used to study the relationship between insulin receptor tyrosine kinase and the in vivo activation of several downstream signaling pathways. Intravenous insulin stimulated insulin receptor tyrosine kinase activity by 7-fold in control muscle versus < or = 1.5-fold in muscle from transgenic mice. Similarly, insulin failed to stimulate tyrosyl phosphorylation of receptor beta-subunits or insulin receptor substrate 1 (IRS-1) in transgenic muscle. Insulin substantially stimulated IRS-1-associated phosphatidylinositol (PI) 3-kinase in control versus absent stimulation in transgenic muscles. In contrast, insulin-like growth factor 1 modestly stimulated PI 3-kinase in both control and transgenic muscle. The effects of insulin to stimulate p42 mitogen-activated protein kinase and c-fos mRNA expression were also markedly impaired in transgenic muscle. Specific immunoprecipitation of human receptors followed by measurement of residual insulin receptors suggested the presence of hybrid mouse-human heterodimers. In contrast, negligible hybrid formation involving insulin-like growth factor 1 receptors was evident. We conclude that (i) transgenic expression of kinase-defective insulin receptors exerts dominant-negative effects at the level of receptor auto-phosphorylation and kinase activation; (ii) insulin receptor tyrosine kinase activity is required for in vivo insulin-stimulated IRS-1 phosphorylation, IRS-1-associated PI 3-kinase activation, phosphorylation of mitogen-activated protein kinase, and c-fos gene induction in skeletal muscle; (iii) hybrid receptor formation is likely to contribute to the in vivo dominant-negative effects of kinase-defective receptor expression.
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Affiliation(s)
- P Y Chang
- Charles A. Dana Research Institute, Boston, Massachusetts, USA
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28
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Tranum-Jensen J, Christiansen K, Carlsen J, Brenzel G, Vinten J. Membrane topology of insulin receptors reconstituted into lipid vesicles. J Membr Biol 1994; 140:215-23. [PMID: 7932656 DOI: 10.1007/bf00233710] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Insulin receptors were incorporated into liposomes by two different procedures, one using dialysis and one using detergent removal by Bio-Beads. Receptor incorporation was analyzed by gradient centrifugation and electron microscopy. Reconstituted receptors projected up to 12 nm above the membrane and exhibited a T-shaped structure compatible with that previously described for the solubilized receptor. Insulin binding and autophosphorylation experiments indicated that approx. 50% of the receptors were incorporated right-side out. Such random orientation was confirmed by immunogold labeling of the alpha- and the beta-subunit of the receptor. Immunogold labeling of the C-terminus of the beta-subunit indicates that it resides about 6 nm off the membrane, while two alpha-subunit epitopes were labeled at about twice this distance, confirming that the alpha-subunit is harbored in the cross-bar of the T-structure.
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Affiliation(s)
- J Tranum-Jensen
- Department of Medical Anatomy, Panum Institute, University of Copenhagen, Denmark
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29
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Clary DO, Weskamp G, Austin LR, Reichardt LF. TrkA cross-linking mimics neuronal responses to nerve growth factor. Mol Biol Cell 1994; 5:549-63. [PMID: 7919537 PMCID: PMC301067 DOI: 10.1091/mbc.5.5.549] [Citation(s) in RCA: 194] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
TrkA, a tyrosine kinase receptor, is an essential component of the nerve growth factor (NGF) response pathway. The binding of NGF to the receptor induces receptor autophosphorylation and activation of intracellular signaling pathways, resulting in diverse biological effects. We prepared polyclonal antibodies against the entire extracellular domain of rat trkA produced using a baculovirus expression system. These antibodies specifically recognize rat trkA on antigen blots and in immunoprecipitations. Both IgG and Fab fragments block binding of NGF to trkA expressed by the PC12 cell line. In NGF binding studies using anti-trkA and anti-low-affinity NGF receptor (LNGFR) immunoglobulin (Ig) G, essentially all binding of NGF can be inhibited. The results imply that > or = 97% of the NGF binding sites on PC12 cells are accounted for by trkA and the LNGFR. The binding data also argue that all low-affinity NGF binding sites on PC12 cells reflect interactions with the LNGFR, while all high-affinity sites are trkA dependent. A fraction of the high-affinity (or slow) binding sites seem to require both trkA and the LNGFR. Although the monovalent anti-trkA Fab fragments inhibited the biological effects of NGF, such as induction of tyrosine phosphorylation, and survival and neurite outgrowth of sympathetic neurons, the IgG preparation was not effective as an inhibitor. Instead, the IgG fraction by itself was almost as effective as NGF at stimulating receptor activation, cell survival, and neurite outgrowth. Thus, it appears oligomerization of trkA by antibody-induced cross-linking is sufficient to produce the known cellular effects of NGF.
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Affiliation(s)
- D O Clary
- Department of Physiology, University of California, San Francisco 94143
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30
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Lee J, Pilch PF. The insulin receptor: structure, function, and signaling. THE AMERICAN JOURNAL OF PHYSIOLOGY 1994; 266:C319-34. [PMID: 8141246 DOI: 10.1152/ajpcell.1994.266.2.c319] [Citation(s) in RCA: 264] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
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).
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Affiliation(s)
- J Lee
- Department of Biochemistry, Boston University, School of Medicine, Massachusetts 02118
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31
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Taub R, Greene MI. Functional validation of ligand mimicry by anti-receptor antibodies: structural and therapeutic implications. Biochemistry 1992; 31:7431-5. [PMID: 1324714 DOI: 10.1021/bi00148a001] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- R Taub
- Department of Genetics, University of Pennsylvania School of Medicine, Philadelphia 19104
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32
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Wilden P, Siddle K, Haring E, Backer J, White M, Kahn C. The role of insulin receptor kinase domain autophosphorylation in receptor-mediated activities. Analysis with insulin and anti-receptor antibodies. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42273-9] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
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33
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Xiong L, Kasuya J, Li SL, Kato J, Fujita-Yamaguchi Y. Growth-stimulatory monoclonal antibodies against human insulin-like growth factor I receptor. Proc Natl Acad Sci U S A 1992; 89:5356-60. [PMID: 1319060 PMCID: PMC49290 DOI: 10.1073/pnas.89.12.5356] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Monoclonal antibodies (mAbs) against purified human placental insulin-like growth factor I (IGF-I) receptors were prepared and characterized. Three IgG mAbs were specific for the human IGF-I receptor and displayed negligible crossreactivity with the human insulin receptor. They stimulated 125I-labeled IGF-I (125I-IGF-I) or 125I-IGF-II binding to purified human placental IGF-I receptors and to IGF-I receptors expressed in NIH 3T3 cells in contrast to the well-studied mAb alpha IR-3, which inhibits 125I-IGF-I or 125I-IGF-II binding to both forms of IGF-I receptors. The mAbs introduced in this study stimulated DNA synthesis in NIH 3T3 cells expressing human IGF-I receptors approximately 1.5-fold above the basal level and the IGF-I- or IGF-II-stimulated level. In contrast, alpha IR-3 inhibited both basal and IGF-I or IGF-II-stimulated DNA synthesis by approximately 30%. Inhibition of IGF-II-stimulated DNA synthesis by alpha IR-3 was as potent as its inhibition of IGF-I-stimulated DNA synthesis, although IGF-II binding to the IGF-I receptors was not inhibited by IGF-II as potently as was IGF-I. With the purified IGF-I receptors, both inhibitory and stimulatory mAbs were shown to activate autophosphorylation of the IGF-I receptor beta subunit and to induce microaggregation of the receptors. These results suggest that conformational changes resulting from receptor dimerization in the presence of either type of mAb may affect the signal-transducing function of the IGF-I receptor differently. These additional mAbs and alpha IR-3 immunoprecipitated nearly 90% of IGF-I binding activity from Triton X-100-solubilized human placental membranes, indicating that IGF-I receptor reactive with these mAbs is the major form of the IGF-I receptor in human placenta.
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Affiliation(s)
- L Xiong
- Department of Molecular Genetics, Beckman Research Institute of the City of Hope, Duarte, CA 91010
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34
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Soos M, Field C, Lammers R, Ullrich A, Zhang B, Roth R, Andersen A, Kjeldsen T, Siddle K. A panel of monoclonal antibodies for the type I insulin-like growth factor receptor. Epitope mapping, effects on ligand binding, and biological activity. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42367-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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35
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Paccaud J, Siddle K, Carpentier J. Internalization of the human insulin receptor. The insulin-independent pathway. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)42386-1] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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36
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Sung CK. Monoclonal antibody to the human insulin receptor, but not insulin, stimulates S6 kinase via human insulin receptors mutated at three major tyrosine autophosphorylation sites. J Cell Biochem 1992; 48:324-35. [PMID: 1328257 DOI: 10.1002/jcb.240480313] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Studies were carried out to examine the role of the major insulin receptor tyrosine autophosphorylation sites in stimulation of S6 kinase activity. For these studies, we employed HTC rat hepatoma cells transfected with and expressing human insulin receptors. In cells transfected with and expressing a large number of normal human insulin receptors (HTC-IR cells), the sensitivity of cells to insulin to stimulate S6 kinase was increased tenfold when compared to untransfected wild type HTC cells (HTC-WT cells). However, in cells transfected with and expressing a large number of mutated human insulin receptors where the tyrosines at three major autophosphorylation sites (1158, 1162, and 1163) were mutated to phenylalanines (HTC-F3 cells), there was no change in insulin sensitivity when compared to HTC-WT cells. We next studied the effect of a human-specific monoclonal antibody to the human insulin receptor, MA-5, on S6 kinase activation. In HTC-WT cells, MA-5 did not interact with endogenous rat insulin receptors and thus did not stimulate S6 kinase. In HTC-IR cells expressing normal human insulin receptors, MA-5 stimulated S6 kinase. Interestingly, MA-5, unlike insulin, was also able to stimulate S6 kinase in HTC-F3 cells expressing mutated receptors. In order to further understand the signaling mechanisms by MA-5 and insulin, two potential intermediate protein kinases were investigated. Neither insulin nor MA-5 appears to activate either microtubule-associated protein 2 (MAP-2) kinase or protein kinase C in these cells. These studies suggest therefore that: 1) insulin and MA-5 may signal S6 kinase activation by independent mechanisms that do not employ either MAP-2 kinase or protein kinase C; and 2) under certain circumstances, S6 kinase appears to be activated by mechanisms that are independent of insulin receptor tyrosine autophosphorylation.
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Affiliation(s)
- C K Sung
- Department of Medicine, Mount Zion Medical Center of the University of California, San Francisco 94120
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37
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Sung CK, Han XL, Brunetti A, Maddux B, Yamamoto-Honda R, Goldfine ID. Regulation of biological functions by an insulin receptor monoclonal antibody in insulin receptor beta-subunit mutants. Biochemistry 1992; 31:168-74. [PMID: 1731870 DOI: 10.1021/bi00116a025] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
We investigated the effects of MA-5, a human-specific monoclonal antibody to the insulin receptor alpha-subunit, on transmembrane signaling in cell lines transfected with and expressing both normal human insulin receptors and receptors mutated in their beta-subunit tyrosine kinase domains. In cell lines expressing normal human insulin receptors, MA-5 stimulated three biological functions: aminoisobutyric acid (AIB) uptake, thymidine incorporation, and S6 kinase activation. Under conditions where these biological functions were stimulated, there was no detectable stimulation of receptor tyrosine kinase. We then combined the use of this monoclonal antibody with cells expressing insulin receptors with mutations in the beta-subunit tyrosine kinase domain; two of ATP binding site mutants V1008 (Gly----Val) and M1030 (Lys----Met) and one triple-tyrosine autophosphorylation site mutant F3 (Tyr----Phe at 1158, 1162, and 1163). In cells expressing V1008 receptors, none of the three biological functions of insulin was stimulated. In cells expressing M1030 receptors, AIB uptake was stimulated to a small, but significant, extent whereas the other two functions were not. In cells expressing F3 receptors, AIB uptake and S6 kinase activation, but not thymidine incorporation, were fully stimulated. The data suggest, therefore, that (1) activation of insulin receptor tyrosine kinase may not be a prerequisite for signaling of all the actions of insulin and (2) there may be multiple signal transduction pathways to account for the biological actions of insulin.
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Affiliation(s)
- C K Sung
- Department of Medicine, Mount Zion Medical Center, University of California, San Francisco 94120
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38
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Lee AW. Signal transduction by the colony-stimulating factor-1 receptor; comparison to other receptor tyrosine kinases. CURRENT TOPICS IN CELLULAR REGULATION 1992; 32:73-181. [PMID: 1318184 DOI: 10.1016/b978-0-12-152832-4.50005-7] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- A W Lee
- Clinical Hematology Branch, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, Maryland 20892
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39
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Carpentier JL, Paccaud JP, Gorden P, Rutter WJ, Orci L. Insulin-induced surface redistribution regulates internalization of the insulin receptor and requires its autophosphorylation. Proc Natl Acad Sci U S A 1992; 89:162-6. [PMID: 1729685 PMCID: PMC48196 DOI: 10.1073/pnas.89.1.162] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
The role of insulin-induced receptor autophosphorylation in its internalization was analyzed by comparing 125I-labeled insulin (125I-insulin) internalization in Chinese hamster ovary (CHO) cell lines transfected with normal (CHO.T) or mutated insulin receptors. In four cell lines with a defect of insulin-induced autophosphorylation, 125I-insulin internalization was impaired. By contrast, in CHO.T cells and in two other CHO cell lines with amino acid deletions or insertions that do not perturb autophosphorylation, 125I-insulin internalization was not affected. A morphological analysis showed that the inhibition is linked to the ligand-specific surface redistribution in which the insulin-receptor complexes leave microvilli and concentrate on nonvillous segments of the membrane where endocytosis occurs.
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Affiliation(s)
- J L Carpentier
- Department of Morphology, University of Geneva Medical Center, Switzerland
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40
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Sung CK. Insulin receptor signaling through non-tyrosine kinase pathways: evidence from anti-receptor antibodies and insulin receptor mutants. J Cell Biochem 1992; 48:26-32. [PMID: 1316358 DOI: 10.1002/jcb.240480106] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Although there is general agreement that insulin receptor tyrosine kinase activity mediates many of the actions of insulin, two types of studies suggest that non-tyrosine kinase dependent pathways may also exist. First, both monoclonal and polyclonal antibodies to the receptor have been shown to mediate many of insulin's actions with little or no stimulation of receptor kinase. Second, insulin receptor mutants, with reduced or no tyrosine kinase activity, have been shown to mediate several actions of insulin. Non-tyrosine kinase pathways that could signal insulin effects through the insulin receptor include non-covalent activation of G proteins, phospholipase Cs, or docking proteins such as IRS-1. Further studies on the chemical structures of phospholipids and their hydrolysis products involved in insulin action will be required to sort out the underlying mechanisms of insulin action via non-tyrosine kinase dependent pathways.
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Affiliation(s)
- C K Sung
- Division of Diabetes and Endocrine Research, Mount Zion Medical Center, University of California, San Francisco 94120
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41
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Pillay TS, Whittaker J, Lammers R, Ullrich A, Siddle K. Multisite serine phosphorylation of the insulin and IGF-I receptors in transfected cells. FEBS Lett 1991; 288:206-11. [PMID: 1652474 DOI: 10.1016/0014-5793(91)81035-7] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Serine phosphorylation of insulin/IGF-I receptors in transfected fibroblasts was analysed by peptide mapping. PMA stimulated the phosphorylation of 5 distinct insulin receptor phosphopeptides: a single major phosphothreonine peptide containing Thr-1348, one major and 3 minor phosphoserine peptides. The major insulin-stimulated phosphoserine peptides were the same as those after PMA, with the exception of 2 minor phosphoserine peptides. PMA stimulated phosphorylation of a single major IGF-I receptor phosphoserine peptide which was phosphorylated to a lesser extent after IGF-I. We conclude that insulin/IGF-I and PMA stimulate phosphorylation of the same sites, but differ in the extents of phosphorylation.
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Affiliation(s)
- T S Pillay
- Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, UK
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42
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Myers M, Backer J, Siddle K, White M. The insulin receptor functions normally in Chinese hamster ovary cells after truncation of the C terminus. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)99268-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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43
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Kohanski RA, Schenker E. Control of insulin receptor autophosphorylation by polypeptide substrates: inhibition and stimulation by interaction with the catalytic subunit. Biochemistry 1991; 30:2406-14. [PMID: 1848096 DOI: 10.1021/bi00223a016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Autophosphorylation of purified insulin receptor, in the absence of insulin, was stimulated by selected polypeptide substrates. In the presence of 1 microM insulin these peptides inhibited autophosphorylation. Stimulation was observed with reduced [S-(carboxamidomethyl)cysteinyl]lysozyme (RCAM-lysozyme) and three peptides generated by CNBr cleavage, V8 proteinase digestion and/or chemical modification. We also generated two peptide substrates from RCAM-lysozyme which did not stimulate receptor autophosphorylation and were very weak inhibitors. As a control peptide, the simple substrate angiotensin inhibited receptor autophosphorylation in the absence or presence of insulin. However, stimulatory peptide, but not insulin, significantly shifted the concentration dependence for inhibition by angiotensin. The stimulatory peptides also increased autophosphorylation of the cloned cytoplasmic domain of the kinase [R-BIRK; Villalba, M., Wente, S. R., Russell, D. S., Ahn, J., Reichelderfer, C. F., & Rosen, O. M. (1989) Proc. Natl. Acad. Sci. U.S.A. 86, 7848]. Therefore, stimulation occurs by interaction with the cytoplasmic process of the beta-subunit and not through interaction with the insulin binding alpha-subunit of the native receptor. Autophosphorylation was analyzed by mapping 32P-labeled tryptic phosphopeptides from the beta-subunit and from R-BIRK. Nearly identical phosphopeptide maps were found, comparing first, basal R-BIRK and basal native receptor, second, peptide- and insulin-stimulated native receptor, and third, peptide-stimulated R-BIRK and insulin-stimulated native receptor. Therefore, R-BIRK functions as a basal-state enzyme and can be stimulated in an insulin-like manner. On the basis of these observations, stimulation by insulin and by peptides yields similar functional results, but by apparently different mechanisms.
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Affiliation(s)
- R A Kohanski
- Department of Biochemistry, Mount Sinai School of Medicine, New York, New York 10029
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44
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Affiliation(s)
- R Taylor
- Human Metabolism Research Centre, Department of Medicine, Medical School, Newcastle upon Tyne, UK
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45
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Treadway JL, Morrison BD, Soos MA, Siddle K, Olefsky J, Ullrich A, McClain DA, Pessin JE. Transdominant inhibition of tyrosine kinase activity in mutant insulin/insulin-like growth factor I hybrid receptors. Proc Natl Acad Sci U S A 1991; 88:214-8. [PMID: 1846039 PMCID: PMC50780 DOI: 10.1073/pnas.88.1.214] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Classical insulin and insulin-like growth factor I (IGF-I) receptors exist as well defined alpha 2 beta 2 heterotetrameric complexes that are assembled from two identical alpha beta heterodimeric half-receptor precursors. Recent evidence suggests that insulin and IGF-I half-receptors can heterologously assemble to form alpha 2 beta 2 insulin/IGF-I hybrid receptor complexes in vivo and in vitro. We have utilized hybrid receptor complexes to examine ligand-stimulated transmembrane signaling of wild-type insulin (alpha beta INS.WT) or IGF-I (alpha beta IGF.WT) half-receptors assembled with a kinase-defective insulin half-receptor mutant (alpha beta INS.A/K). In vitro assembly of either (alpha beta)IGF.WT/(alpha beta)INS.A/K or (alpha beta)INS.WT/(alpha beta)INS.A/K hybrid receptors resulted in decreased substrate protein kinase activity. The degree of protein kinase inactivation directly correlated with the amount of immunologically cross-reactive hybrid receptors formed. In contrast to substrate kinase activity, insulin-stimulated autophosphorylation of the (alpha beta)INS.WT/(alpha beta)INS.A/K hybrid receptor complex was completely unaffected in comparison to the wild-type (alpha beta)INS.WT/(alpha beta)INS.WT receptor. To assess a molecular basis for this difference, autophosphorylation of a hybrid receptor composed of a truncated beta-subunit insulin half-receptor with the kinase-defective half-receptor, (alpha beta)INS. delta CT/(alpha beta)INS.A/K, demonstrated the exclusive autophosphorylation of the (alpha beta)INS.A/K half-receptor beta subunit. These results demonstrate that ligand-dependent substrate phosphorylation by insulin and IGF-I holoreceptors requires interactions between two functional beta subunits within the alpha 2 beta 2 heterotetrameric complex and occurs through an intramolecular trans-phosphorylation reaction.
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Affiliation(s)
- J L Treadway
- Department of Physiology and Biophysics, University of Iowa, Iowa City 52242
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46
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47
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Hresko RC, Hoffman RD, Flores-Riveros JR, Lane MD. Insulin receptor tyrosine kinase-catalyzed phosphorylation of 422(aP2) protein. Substrate activation by long-chain fatty acid. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(17)45329-4] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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48
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Constitutive phosphorylation of the receptor for insulinlike growth factor I in cells transformed by the src oncogene. Mol Cell Biol 1990. [PMID: 2162477 DOI: 10.1128/mcb.10.7.3626] [Citation(s) in RCA: 30] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Many oncogene products have been shown to bear strong homology to or to interact with components of normal cellular signal transduction. We have previously shown that a glycoprotein band of 95 kilodaltons (kDa) becomes tyrosine phosphorylated in chick cells transformed by Rous sarcoma virus and that tyrosine phosphorylation of this protein band correlates tightly with phenotypic transformation in cells infected with a large and diverse panel of src mutants (L. M. Kozma, A. B. Reynolds, and M. J. Weber, Mol. Cell. Biol. 10:837-841, 1990). In this communication, we report that a component of the 95-kDa glycoprotein band is related or identical to the 95-kDa beta subunit of the receptor for insulinlike growth factor I (IGF-I). We found that the beta subunit of the IGF-I receptor comigrated on polyacrylamide gels with a component of the 95-kDa glycoprotein region from src-transformed cells under both reducing and nonreducing gel conditions and had a very similar partial phosphopeptide map. To further test the hypothesis that the beta subunit of the IGF-I receptor becomes tyrosine phosphorylated in cells transformed by pp60src, a human cell line that expressed the IGF-I receptor was transformed by src. Comparison of IGF-I receptors immunoprecipitated from normal and transformed cells revealed that the beta subunit of the IGF-I receptor became constitutively tyrosine phosphorylated in src-transformed cells. Moreover, IGF-I receptor phosphorylation induced by src was synergistic with that induced by the hormone: IGF-I-stimulated autophosphorylation of the receptor was much greater in src-transformed cells than in untransformed HOS cells even at maximal concentrations of IGF-I. This increased responsiveness to IGF-I was not due to increases in receptor number, time course of phosphorylation, or affinity for hormone. Finally, no IGF-I-like activity could be detected in culture supernatants collected from the src-transformed cells, suggesting that the increased receptor phosphorylation observed in the src-transformed cells may be mediated by an intracellular mechanism rather than an external autocrine stimulation. Our data demonstrate that the IGF-I receptor becomes constitutively tyrosine phosphorylated in src-transformed cells. This finding raises the possibility that pp60v-src alters growth regulation at least in part by phosphorylating and activating this growth factor receptor.
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Kozma LM, Weber MJ. Constitutive phosphorylation of the receptor for insulinlike growth factor I in cells transformed by the src oncogene. Mol Cell Biol 1990; 10:3626-34. [PMID: 2162477 PMCID: PMC360799 DOI: 10.1128/mcb.10.7.3626-3634.1990] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Many oncogene products have been shown to bear strong homology to or to interact with components of normal cellular signal transduction. We have previously shown that a glycoprotein band of 95 kilodaltons (kDa) becomes tyrosine phosphorylated in chick cells transformed by Rous sarcoma virus and that tyrosine phosphorylation of this protein band correlates tightly with phenotypic transformation in cells infected with a large and diverse panel of src mutants (L. M. Kozma, A. B. Reynolds, and M. J. Weber, Mol. Cell. Biol. 10:837-841, 1990). In this communication, we report that a component of the 95-kDa glycoprotein band is related or identical to the 95-kDa beta subunit of the receptor for insulinlike growth factor I (IGF-I). We found that the beta subunit of the IGF-I receptor comigrated on polyacrylamide gels with a component of the 95-kDa glycoprotein region from src-transformed cells under both reducing and nonreducing gel conditions and had a very similar partial phosphopeptide map. To further test the hypothesis that the beta subunit of the IGF-I receptor becomes tyrosine phosphorylated in cells transformed by pp60src, a human cell line that expressed the IGF-I receptor was transformed by src. Comparison of IGF-I receptors immunoprecipitated from normal and transformed cells revealed that the beta subunit of the IGF-I receptor became constitutively tyrosine phosphorylated in src-transformed cells. Moreover, IGF-I receptor phosphorylation induced by src was synergistic with that induced by the hormone: IGF-I-stimulated autophosphorylation of the receptor was much greater in src-transformed cells than in untransformed HOS cells even at maximal concentrations of IGF-I. This increased responsiveness to IGF-I was not due to increases in receptor number, time course of phosphorylation, or affinity for hormone. Finally, no IGF-I-like activity could be detected in culture supernatants collected from the src-transformed cells, suggesting that the increased receptor phosphorylation observed in the src-transformed cells may be mediated by an intracellular mechanism rather than an external autocrine stimulation. Our data demonstrate that the IGF-I receptor becomes constitutively tyrosine phosphorylated in src-transformed cells. This finding raises the possibility that pp60v-src alters growth regulation at least in part by phosphorylating and activating this growth factor receptor.
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Affiliation(s)
- L M Kozma
- Department of Microbiology, University of Virginia Health Sciences Center, Charlottesville 22908
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Brindle NP, Tavare JM, Dickens M, Whittaker J, Siddle K. Anti-(insulin receptor) monoclonal antibody-stimulated tyrosine phosphorylation in cells transfected with human insulin receptor cDNA. Biochem J 1990; 268:615-20. [PMID: 1694662 PMCID: PMC1131483 DOI: 10.1042/bj2680615] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The effects of insulin and anti-(insulin receptor) monoclonal antibodies on tyrosine phosphorylation were investigated in fibroblasts transfected with human insulin receptor cDNA (NIH 3T3HIR3.5 cells) using anti-phosphotyrosine immunoblotting. Insulin increased levels of tyrosine phosphorylation in two major proteins of molecular mass 97 kDa (pp97, assumed to be the insulin receptor beta-subunit) and 185 kDa (pp185). Insulin-mimetic anti-receptor antibodies also stimulated tyrosine phosphorylation of both pp97 and pp185. The observation of antibody-stimulated pp97 phosphorylation, as detected by immunoblotting, is in contrast with previous data which failed to show receptor autophosphorylation in NIH 3T3HIR3.5 cells labelled with [32P]P1. The effect of insulin on pp97 was maximal within 1 min, but the response to antibody was apparent only after a lag of 1-2 min and rose steadily over 20 min. The absolute level of antibody-stimulated phosphorylation of both pp97 and pp185 after 20 min was only about 20% of the maximum level induced by equivalent concentrations of insulin, even at concentrations of antibody sufficient for full occupancy of receptors. Another insulin-mimetic agent, wheat-germ agglutinin, stimulated receptor autophosphorylation with kinetics similar to those produced by the antibody. It is suggested that the relatively slow responses to both agents may be a function of the dependence on receptor cross-linking. These data are consistent with a role for the insulin receptor tyrosine kinase activity in the mechanism of action of insulin-mimetic anti-receptor antibodies.
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Affiliation(s)
- N P Brindle
- Department of Clinical Biochemistry, University of Cambridge, Addenbrooke's Hospital, U.K
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