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Boutchueng-Djidjou M, Faure RL. Network medicine-travelling with the insulin receptor: Encounter of the second type. EClinicalMedicine 2019; 13:14-20. [PMID: 31517259 PMCID: PMC6734015 DOI: 10.1016/j.eclinm.2019.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 05/08/2019] [Accepted: 07/18/2019] [Indexed: 01/21/2023] Open
Abstract
Important progress has been made in understanding many aspects of insulin action in the last 10 years. Attention will be focused here on the physical protein interaction network of the internalized insulin receptor (IR) and its relationships with the genetic architecture of type 2 diabetes mellitus (T2D). The IR recognizes signals from the outside (circulating insulin) and engages the insulin signaling response. Within seconds, the IR is also involved in insulin internalization and its subsequent degradation in endosomes (physiological clearance of insulin). A T2D disease module sharing functional similarities with insulin secretion in pancreatic islets was recently identified in the close neighborhood of the internalized IR in liver. This module brought a new light on the apparent functional heterogeneity of numerous genes at risk to T2D by linking them to a few noncanonical layers of signaling feedback loops. These findings should be translated into a better understanding of the primary mechanisms of the disease and consequently a more precise sub-classification of T2D, ultimately leading to precision medicine and the development of new therapeutical drugs.
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Affiliation(s)
- Martial Boutchueng-Djidjou
- Départment of Pediatrics, Faculty of Medicine, Laval University, CHU de Québec Research Center, Québec City G1V4G2, Canada
| | - Robert L. Faure
- Centre de Recherche du CHU de Québec, Laboratoire de Biologie Cellulaire, local T3-55 2705, Boulevard Laurier Québec, QC, G1V4G2
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2
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Antonescu CN, McGraw TE, Klip A. Reciprocal regulation of endocytosis and metabolism. Cold Spring Harb Perspect Biol 2014; 6:a016964. [PMID: 24984778 DOI: 10.1101/cshperspect.a016964] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The cellular uptake of many nutrients and micronutrients governs both their cellular availability and their systemic homeostasis. The cellular rate of nutrient or ion uptake (e.g., glucose, Fe(3+), K(+)) or efflux (e.g., Na(+)) is governed by a complement of membrane transporters and receptors that show dynamic localization at both the plasma membrane and defined intracellular membrane compartments. Regulation of the rate and mechanism of endocytosis controls the amounts of these proteins on the cell surface, which in many cases determines nutrient uptake or secretion. Moreover, the metabolic action of diverse hormones is initiated upon binding to surface receptors that then undergo regulated endocytosis and show distinct signaling patterns once internalized. Here, we examine how the endocytosis of nutrient transporters and carriers as well as signaling receptors governs cellular metabolism and thereby systemic (whole-body) metabolite homeostasis.
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Affiliation(s)
- Costin N Antonescu
- Department of Chemistry and Biology, Ryerson University, Toronto, Ontario M5B 2K3, Canada
| | - Timothy E McGraw
- Department of Biochemistry, Weill Medical College of Cornell University, New York, New York 10065
| | - Amira Klip
- Program in Cell Biology, The Hospital for Sick Children, Toronto, Ontario M5G 1X8, Canada
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Jensen M, De Meyts P. Molecular mechanisms of differential intracellular signaling from the insulin receptor. VITAMINS AND HORMONES 2009; 80:51-75. [PMID: 19251034 DOI: 10.1016/s0083-6729(08)00603-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Binding of insulin to the insulin receptor (IR) leads to a cascade of intracellular signaling events, which regulate multiple biological processes such as glucose and lipid metabolism, gene expression, protein synthesis, and cell growth, division, and survival. However, the exact mechanism of how the insulin-IR interaction produces its own specific pattern of regulated cellular functions is not yet fully understood. Insulin analogs, anti-IR antibodies as well as synthetic insulin mimetic peptides that target the two insulin-binding regions of the IR, have been used to study the relationship between different aspects of receptor binding and function as well as providing new insights into the structure and function of the IR. This review focuses on the current knowledge of activation of the IR and how activation of the IR by different ligands initiates different cellular responses. Investigation of differential activation of the IR may provide clues to the molecular mechanisms of how the insulin-receptor interaction controls the specificity of the downstream signaling response. Differences in the kinetics of ligand-interaction with the IR, the magnitude of the signal as well as its subcelllar location all play important roles in determining/eliciting the different biological responses. Additional studies are nevertheless required to dissect the precise molecular mechanisms leading to the differential signaling from the IR.
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Affiliation(s)
- Maja Jensen
- Hagedorn Research Institute, 2820 Gentofte, Denmark
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Affiliation(s)
- J L Carpentier
- Department of Morphology, University of Geneva Medical School, Switzerland
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Carpentier JL. Insulin receptor internalization: molecular mechanisms and physiopathological implications. Diabetologia 1994; 37 Suppl 2:S117-24. [PMID: 7821727 DOI: 10.1007/bf00400835] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
The initial interaction between insulin and its receptor on target cell surface is followed by a series of surface and intracellular steps which participate in the control of insulin action. Abnormalities of any of these steps could result in mishandling of the receptor leading to defective modulation of receptor number on the cell surface and to inappropriate cell sensitivity to the hormone. Thus, the identification of each of these steps as well as understanding the mechanisms governing them is obligatory to unravel some aspects of the pathogenesis of insulin resistance states. This was the goal of the studies we have carried out during recent years using combined molecular and cellular biology as well as biochemical techniques. These studies allowed us to propose the following ordered sequence of events: 1) insulin binds to receptors preferentially associated with microvilli on the cell surface; 2) insulin triggers receptor kinase activation and autophosphorylation which not only results in initiation of the various biological signals leading to insulin action but also in redistribution of the hormone-receptor complex in the plane of the membrane; 3) on the non-villous domain of the cell surface, insulin receptors anchor to clathrin-coated pits through specific "internalization sequences" present in their cytoplasmic juxtamembrane domain; 4) insulin-receptor complexes are internalized together with other receptors present in the same clathrin-coated pits through the formation of clathrin-coated vesicles; 5) the complexes are delivered to endosomes, the acidic pH of which induces the dissociation of insulin molecules from insulin receptors and their sorting in different directions; 6) insulin molecules are targetted to late endosomes and lysosomes where they are degraded; 7) receptors are recycled back to the cell surface in order to be reused.
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Affiliation(s)
- J L Carpentier
- Department of Morphology, University of Geneva, Switzerland
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6
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Carpentier JL. Robert Feulgen Prize Lecture 1993. The journey of the insulin receptor into the cell: from cellular biology to pathophysiology. HISTOCHEMISTRY 1993; 100:169-84. [PMID: 8244769 DOI: 10.1007/bf00269090] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The data that we have reviewed indicate that insulin binds to a specific cell-surface receptor. The complex then becomes involved in a series of steps which lead the insulin-receptor complex to be internalized and rapidly delivered to endosomes. From this sorting station, the hormone is targeted to lysosomes to be degraded while the receptor is recycled back to the cell surface. This sequence of events presents two degrees of ligand specificity: (a) The first step is ligand-dependent and requires insulin-induced receptor phosphorylation of specific tyrosine residues. It consists in the surface redistribution of the receptor from microvilli where it preferentially localizes in its unoccupied form. (b) The second step is more general and consists in the association with clathrin-coated pits which represents the internalization gate common to many receptors. This sequence of events participates in the regulation of the biological action of the hormone and can thus be implicated in the pathophysiology of diabetes mellitus and various extreme insulin resistance syndromes, including type A extreme insulin resistance, leprechaunism, and Rabson-Mendehall syndrome. Alterations of the internalization process can result either from intrinsic abnormalities of the receptor or from more general alteration of the plasma membrane or of the cell metabolism. Type I diabetes is an example of the latter possibility, since general impairment of endocytosis could contribute to extracellular matrix accumulation and to an increase in blood cholesterol. Thus, better characterization of the molecular and cellular biology of the insulin receptor and of its journey inside the cell definitely leads to better understanding of disease states, including diabetes.
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Affiliation(s)
- J L Carpentier
- Department of Morphology, University of Geneva, Switzerland
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7
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Drejer K. The bioactivity of insulin analogues from in vitro receptor binding to in vivo glucose uptake. DIABETES/METABOLISM REVIEWS 1992; 8:259-85. [PMID: 1338040 DOI: 10.1002/dmr.5610080305] [Citation(s) in RCA: 120] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- K Drejer
- Diabetes Research, Novo Nordisk A/S, Bagsvaerd, Denmark
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8
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Backer JM, Shoelson SE, Weiss MA, Hua QX, Cheatham RB, Haring E, Cahill DC, White MF. The insulin receptor juxtamembrane region contains two independent tyrosine/beta-turn internalization signals. J Cell Biol 1992; 118:831-9. [PMID: 1500426 PMCID: PMC2289561 DOI: 10.1083/jcb.118.4.831] [Citation(s) in RCA: 86] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
We have investigated the role of tyrosine residues in the insulin receptor cytoplasmic juxtamembrane region (Tyr953 and Tyr960) during endocytosis. Analysis of the secondary structure of the juxtamembrane region by the Chou-Fasman algorithms predicts that both the sequences GPLY953 and NPEY960 form tyrosine-containing beta-turns. Similarly, analysis of model peptides by 1-D and 2-D NMR show that these sequences form beta-turns in solution, whereas replacement of the tyrosine residues with alanine destabilizes the beta-turn. CHO cell lines were prepared expressing mutant receptors in which each tyrosine was mutated to phenylalanine or alanine, and an additional mutant contained alanine at both positions. These mutations had no effect on insulin binding or receptor autophosphorylation. Replacements with phenylalanine had no effect on the rate of [125I]insulin endocytosis, whereas single substitutions with alanine reduced [125I]insulin endocytosis by 40-50%. Replacement of both tyrosines with alanine reduced internalization by 70%. These data suggest that the insulin receptor contains two tyrosine/beta-turns which contribute independently and additively to insulin-stimulated endocytosis.
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Affiliation(s)
- J M Backer
- Joslin Diabetes Center, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts
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9
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Briner VA, Williams B, Tsai P, Schrier RW. Demonstration of processing and recycling of biologically active V1 vasopressin receptors in vascular smooth muscle. Proc Natl Acad Sci U S A 1992; 89:2854-8. [PMID: 1348360 PMCID: PMC48761 DOI: 10.1073/pnas.89.7.2854] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The present study examines the binding and postbinding cellular processing and recycling of the V1 arginine vasopressin (AVP) receptor in cultured vascular smooth muscle cells (VSMCs). The surface binding of AVP to VSMCs was temperature dependent and reached equilibrium within 60 min at 4 degrees C. Displacement studies with unlabeled AVP or a specific V1 AVP antagonist revealed a single class of V1 receptors (Bmax, 1.99 pmol [corrected] per mg of protein; Kd, 2.15 nM). Incubation of VSMCs with unlabeled 10 nM AVP to promote receptor internalization resulted in a time- and temperature-dependent loss of AVP surface binding. At 37 degrees C, maximum loss of binding sites (65%) occurred within 20 min. Recovery of AVP binding occurred rapidly (t1/2, 15-20 min at room temperature) and was uninfluenced by inhibiting protein synthesis with cycloheximide. Pretreating VSMCs with chloroquine prevented AVP receptor recycling, indicating that the AVP-receptor complex requires endosomal processing. The biological competence of the recycled AVP receptor was shown by AVP-induced Ca2+ uptake. The results of these studies therefore indicate that, after surface binding, the AVP-receptor complex internalizes and dissociates in an endosomal compartment. It is demonstrated that in VSMCs biologically active V1 AVP receptors recycle back to the cell surface, thus attenuating the loss of AVP surface binding sites.
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Affiliation(s)
- V A Briner
- Department of Medicine, University of Colorado School of Medicine, Denver 80262
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10
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Knutson VP. Ligand-independent internalization and recycling of the insulin receptor. Effects of chronic treatment of 3T3-C2 fibroblasts with insulin and dexamethasone. J Biol Chem 1992. [DOI: 10.1016/s0021-9258(18)48374-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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11
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Carpentier JL, Gorden P, Lew DP. Calcium ions are required for the intracellular routing of insulin and its receptor. Exp Cell Res 1992; 198:144-9. [PMID: 1727048 DOI: 10.1016/0014-4827(92)90160-a] [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: 12/28/2022]
Abstract
We have studied the role of the cytosolic-free calcium concentration ([Ca2+]i) on the early and later internalization steps of insulin and its receptor. As before, we find that the rate of 125I-insulin internalization in HL60 cells remains normal when [Ca2+]i is lowered 10 times below normal resting level by the use of an intracellular Ca2+ chelator. By contrast, the subsequent intracellular steps, i.e. insulin receptor recycling and insulin degradation, are inhibited in calcium-depleted cells. Under low [Ca2+]i conditions, the association of 125I-insulin with late endosomes and lysosomes is also reduced. This suggests that calcium ions are required for fusion processes occurring at the endosomal or postendosomal stage of internalization. Thus, by regulating insulin receptor recycling and by controlling insulin degradation, Ca2+ ions play a key role in the regulation of insulin action.
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Affiliation(s)
- J L Carpentier
- Department of Morphology, CMU, University of Geneva, Switzerland
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12
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Wang JJ, Chang JP, Teng CS. Immunocytochemical demonstration of the binding and internalization of growth hormone in GERL of Chang hepatoma cells. Cell Tissue Res 1990; 262:273-81. [PMID: 2076535 DOI: 10.1007/bf00309882] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The binding and internalization of endogenous growth hormone in Chang hepatoma cells were localized on the cell surface and in the Golgi-endoplasmic reticulum-lysosome (GERL) area by various indirect immunocytochemical labeling techniques, namely, peroxidase or colloidal gold conjugated to secondary antibody, and avidin-biotin complex methods. Rabbit antiserum and monoclonal antibodies raised against HPLC-purified porcine growth hormone were used in this study. In fixed material, antigen-antibody complexes were found to be homogeneously distributed along the cell membrane. Control groups showed negative binding on the cell surface. Trypsin treatment before immunolabeling removed antibody binding completely, but hyaluronidase was ineffective. Pretreatment of lectins did not block the recognition of primary antibody to antigen molecules on cell surface. Internalization of the antigen-antibody peroxidase or gold complexes was demonstrated in the cells, which were immunolabeled at 4 degrees C, and then reincubated for 0-30 min at 37 degrees C before fixation. After reincubation, the internalized ligand complexes were found in vesicles near the cell surface or in the GERL area near the Golgi apparatus which, however, did not label for peroxidase. These findings suggest that the trypsin-sensitive growth hormone, specifically bound and internalized into Chang hepatoma cells, is localized in the GERL instead of the Golgi apparatus and might be involved in the mechanism of tumor cell growth.
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Affiliation(s)
- J J Wang
- Department of Biology and Anatomy, National Defense Medical Center, Taipei, Taiwan, Republic of China
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13
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Burwen SJ, Jones AL. Hepatocellular processing of endocytosed proteins. JOURNAL OF ELECTRON MICROSCOPY TECHNIQUE 1990; 14:140-51. [PMID: 2406388 DOI: 10.1002/jemt.1060140207] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
In conclusion, proteins of hepatobiliary transport utilize receptor-mediated endocytosis and intracellular vesicles and rely on functionally dynamic microtubules for their transport by hepatocytes. The many diverse transport pathways in hepatocytes reflect the many functions served by the uptake of various proteins from the blood. The mechanisms of sorting of ligands and their receptors in endosomes and the factors that regulate the intracellular transport pathways are not yet known. Future investigations in this area promise to yield many exciting discoveries about the hepatocellular processing of proteins.
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Affiliation(s)
- S J Burwen
- Cell Biology and Aging Section, Veterans Administration Medical Center, San Francisco, California 94121
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14
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Grenfell S, Smithers N, Miller K, Solari R. Receptor-mediated endocytosis and nuclear transport of human interleukin 1 alpha. Biochem J 1989; 264:813-22. [PMID: 2533500 PMCID: PMC1133658 DOI: 10.1042/bj2640813] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
In this study we demonstrate that 125I-labelled interleukin (IL) 1 alpha binds specifically to its receptor on the surface of EL4 6.1 cells and is subsequently endocytosed and translocated from the cell membrane to the nucleus, where it progressively accumulates. Two-dimensional polyacrylamide-gel electrophoresis revealed that the internalized 125I-IL1 alpha associated with the nucleus was intact, with negligible breakdown products present. Specific and saturable binding of 125I-IL1 alpha was demonstrated on purified nuclei isolated from these cells. Binding of the radiolabelled ligand showed similar kinetics to that of the plasma-membrane receptor, and was inhibited by both unlabelled IL1 alpha and IL1 beta. Equilibrium binding studies on isolated nuclei revealed a single high-affinity binding site, with a Kd of 17 +/- 2 pM, and 79 +/- 12 binding sites per nucleus. These studies demonstrate that receptor-mediated endocytosis of IL1 results in its accumulation in the nucleus, and this mechanism may play an important role in mediating some of the actions of IL1.
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Affiliation(s)
- S Grenfell
- Department of Human Metabolism and Clinical Biochemistry, University of Sheffield Medical School, U.K
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15
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Jones AL, Burwen SJ. Pathways and Functions of Biliary Protein Secretion. Compr Physiol 1989. [DOI: 10.1002/cphy.cp060332] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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16
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Geiger D, Carpentier JL, Gorden P, Orci L. Down-regulation of insulin receptors is related to insulin internalization. Exp Cell Res 1989; 185:33-40. [PMID: 2680540 DOI: 10.1016/0014-4827(89)90034-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
In the present study, we have tested the influence of inhibition of endocytosis by hypertonic medium on the regulation of cell surface insulin receptors. We show that active internalization of 125I-insulin is markedly inhibited by hypertonic media and that, in parallel, cell surface invaginations are significantly diminished. These two events are accompanied by a marked inhibition of cell surface insulin receptor down-regulation. These data provide further strong evidence that receptor-mediated endocytosis is the major mechanism by which insulin receptors are regulated at the surface of target cells.
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Affiliation(s)
- D Geiger
- Institute of Histology and Embryology, University of Geneva Medical Center, Switzerland
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17
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Abstract
Following initial binding to specific cell surface receptors insulin is internalized in target cells. The fate of the internalized insulin-receptor complexes and how the processes involved are regulated is reviewed. The implications of these events in the effects of insulin on its target cells and in the physiopathology of diabetes and insulin resistance states are also considered.
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Affiliation(s)
- J L Carpentier
- Institute of Histology and Embryology, University of Geneva, Switzerland
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18
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Douen AG, Jones MN. Insulin processing and signal transduction in rat adipocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1989; 1010:363-8. [PMID: 2645939 DOI: 10.1016/0167-4889(89)90063-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A glycine-HCl buffer (glycine, 50 mM/NaCl, 0.15 M/HCl, pH 3.5) was used to strip insulin bound to adipocyte cell surfaces. Adipocytes retained their integrity in the glycine buffer and their binding capacity for [125I]iodoinsulin could be completely recovered on transfer of the cells to physiological media. At 37 degrees C, [125I]iodoinsulin binds rapidly to plasma membrane receptors; maximal binding occurs within 10 min. At this temperature, the initial binding is followed by rapid internalization, degradation of the hormone and subsequent loss of label. Insulin treatment, at 37 degrees C, induced internalization of 37% of the plasma membrane insulin receptors. Phenylarsine oxide (PAO), a confirmed inhibitor of protein internalization, allowed insulin binding but completely inhibited degradation of the hormone. Monensin, a carboxylic ionophore which impairs uncoupling hormone-receptor complexes, effectively restricted insulin degradation over short time periods (less than 30 min). Addition of monensin to insulin-stimulated cells did not impair D-glucose uptake. It has previously been reported that PAO inhibits hexose transport through the direct interaction with the glucose transporters and low concentrations of PAO (1 microM) transiently inhibit insulin-stimulated glucose uptake. This recovery phenomenon was again observed when PAO was added to insulin-stimulated, monensin-treated adipocytes. The data suggests that lysosomal degradation of insulin is not requisite for signal transduction.
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Affiliation(s)
- A G Douen
- Department of Biochemistry and Molecular Biology, School of Biological Sciences, University of Manchester, U.K
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19
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van Deurs B, Petersen OW, Olsnes S, Sandvig K. The ways of endocytosis. INTERNATIONAL REVIEW OF CYTOLOGY 1989; 117:131-77. [PMID: 2573583 DOI: 10.1016/s0074-7696(08)61336-4] [Citation(s) in RCA: 186] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- B van Deurs
- Department of Anatomy, Panum Institute, University of Copenhagen, Denmark
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20
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Thirion J, Wattiaux R. Effect of monensin on fluid phase and receptor mediated endocytosis by rat hepatocyte monolayers. Biochem Biophys Res Commun 1988; 152:1275-81. [PMID: 2454103 DOI: 10.1016/s0006-291x(88)80423-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
We have investigated the effect of monensin on the uptake of sucrose and sucrose-asialofetuin by rat hepatocyte monolayers and on the intracellular traffic of these molecules. Endocytosis of sucrose is not affected by monensin while that of sucrose-asialofetuin is markedly inhibited. Monensin causes a decrease of galactosyltransferase, a Golgi membrane enzyme without affecting dipeptidylpeptidase IV a plasma membrane enzyme and three lysosomal hydrolases. The inhibition of sucrose-asialofetuin uptake is proportional to the reduction of galactosyltransferase activity. Differential and isopycnic centrifugation results indicate that monensin at a concentration (10 mumol/l) that markedly decreases sucrose-asialofetuin uptake does not prevent the transfer of sucrose and sucrose-asialofetuin from endosomes to lysosomes.
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Affiliation(s)
- J Thirion
- Laboratoire de Chimie Physiologique, Facultés Universitaires Notre-Dame de la Paix, Namur, Belgium
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21
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Bergeron JJ, Lai WH, Kay DG, Doherty JJ, Khan MN, Posner BI. The endosomal apparatus and transmembrane signalling. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 1988; 234:213-24. [PMID: 3063087 DOI: 10.1007/978-1-4757-1980-2_14] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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23
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Carpentier JL, White MF, Orci L, Kahn RC. Direct visualization of the phosphorylated epidermal growth factor receptor during its internalization in A-431 cells. J Cell Biol 1987; 105:2751-62. [PMID: 2447100 PMCID: PMC2114686 DOI: 10.1083/jcb.105.6.2751] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Epidermal growth factor (EGF) rapidly stimulates receptor autophosphorylation in A-431 cells. After 1 min the phosphorylated receptor can be identified at the plasma membrane using an anti-phosphotyrosine antibody. With further incubation at 37 degrees C, approximately 50% of the phosphorylated EGF receptor was internalized (t1/2 = 5 min) and associated with the tubulovesicular system and later with multivesicular bodies, but not the nucleus. During this period, there was no change in the extent or sites of phosphorylation. At all times the phosphotyrosine remained on the cytoplasmic side of the membrane, opposite to the EGF ligand identified by anti-EGF antibody. These data indicate that (a) the tyrosine-phosphorylated EGF receptor is internalized in its activated form providing a mechanism for translocation of the receptor kinase to substrates in the cell interior; (b) the internalized receptor remains intact for at least 60 min, does not associate with the nucleus, and does not generate any tyrosine-phosphorylated fragments; and (c) tyrosine phosphorylation alone is not the signal for receptor internalization.
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Affiliation(s)
- J L Carpentier
- Institute of Histology and Embryology, University of Geneva Medical Center, Switzerland
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24
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Goldberg RI, Smith RM, Jarett L. Insulin and alpha 2-macroglobulin-methylamine undergo endocytosis by different mechanisms in rat adipocytes: II. Comparison of intracellular events. J Cell Physiol 1987; 133:213-8. [PMID: 3316258 DOI: 10.1002/jcp.1041330203] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
A previous ultrastructural study showed that gold-labeled insulin (Au-I) and the non-hormonal ligand gold-labeled alpha-2-macroglobulin-methylamine (Au-alpha 2MGMA) underwent endocytosis by dissimilar cell surface structures on rat adipocytes. The present ultrastructural study compared the intracellular routes taken by these two ligands in adipocytes. Intracellular Au-alpha 2MGMA was initially found within apparent coated vesicles but Au-I was not, consistent with the previous demonstration that Au-alpha 2MGMA underwent endocytosis by coated pits whereas Au-I was internalized by uncoated micropinocytotic invaginations. Early in the endocytic pathway, the two ligands were segregated within separate small vesicles and tubulovesicles. Au-alpha 2MGMA was concentrated in a small number of these structures whereas Au-I was sparsely distributed among a relatively large number. Subsequently, the two endocytic pathways converged as the ligands intermingled within pale multivesicular bodies and lysosome-like structures. Au-I was less efficiently transferred to lysosomes than Au-alpha 2MGMA since a greater proportion of intracellular Au-I remained associated with small vesicles and tubulovesicles. This study indicates that early intracellular events in the endocytic pathways of insulin and alpha 2MGMA are distinct. These findings are discussed in light of the fundamentally dissimilar biological roles of these two molecules and the possible involvement of the endocytic pathway in the insulin signaling mechanism.
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Affiliation(s)
- R I Goldberg
- Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia 19104
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Soubigou P, Ali M, Plas C. Uncoupling between the insulin-receptor cycle and the cellular degradation of the hormone in cultured foetal hepatocytes. Effect of drugs and temperature that inhibit insulin degradation. Biochem J 1987; 246:567-73. [PMID: 3318811 PMCID: PMC1148318 DOI: 10.1042/bj2460567] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Sequential changes in the numbers of cell-surface receptors induced by a transitory exposure to insulin in cultured 18-day foetal-rat hepatocytes were investigated in the presence of drugs and at a temperature of 22 degrees C, which inhibit cellular insulin degradation. Chloroquine (70 microM) and monensin (3 microM) did not greatly change the initial rate of internalization of cell-surface receptor sites after exposure to 10 nM-insulin, but led to a steady state after 20 min, which represented 40% of the initial binding, compared with 5 min and 60% in the absence of the drug. Moreover, these drugs strongly decreased the proportion of receptor sites recovered at the cell surface after subsequent removal of the hormone. They were ineffective when insulin was not present. The removal of monensin together with the hormone allowed partial restoration of cell-surface receptor sites and degradation of cell-associated insulin to start again at the initial speed, indicating a reversible effect of the drug. During this phase, the drug concentration-dependence for the two effects showed that receptor recycling was restored with concentrations of monensin not as low as for insulin degradation. The effect of vinblastine (50-100 microM) was similar to that of chloroquine and monensin, whereas no modification in the internalization and recovery processes was observed in the presence of bacitracin concentrations (1-3 mM) that inhibit insulin degradation by 70%. A temperature of 22 degrees C did not prevent the receptor internalization, but had a slowing effect on the recycling process, which appeared to vary in experiments where insulin degradation remained inhibited. The present study shows that the process of insulin degradation mediated by receptor endocytosis is not a prerequisite for insulin-receptor recycling in cultured foetal hepatocytes.
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Affiliation(s)
- P Soubigou
- Laboratoire Interactions Cellulaires, U.E.R. Odontologie, Université Paris, France
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Podlecki D, Smith R, Kao M, Tsai P, Huecksteadt T, Brandenburg D, Lasher R, Jarett L, Olefsky J. Nuclear translocation of the insulin receptor. A possible mediator of insulin's long term effects. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)61511-x] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Smith RM, Jarett L. Ultrastructural evidence for the accumulation of insulin in nuclei of intact 3T3-L1 adipocytes by an insulin-receptor mediated process. Proc Natl Acad Sci U S A 1987; 84:459-63. [PMID: 3540967 PMCID: PMC304227 DOI: 10.1073/pnas.84.2.459] [Citation(s) in RCA: 62] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Monomeric ferritin-labeled insulin (Fm-Ins), a biologically active, electron-dense marker of occupied insulin receptors, was used to characterize the internalization of insulin in 3T3-L1 adipocytes. Fm-Ins bound specifically to insulin receptors and was internalized in a time- and temperature-dependent manner. Fm-Ins was found in cytoplasmic vesicles within 5-10 min at 37 degrees C and subsequently was observed in multivesicular bodies and lysosomes. In addition, small amounts of Fm-Ins were associated with nuclei after 30 min. The number of Fm-Ins particles observed in nuclei continued to increase in a time-dependent manner until at least 90 min. In the nucleus, several Fm-Ins particles usually were found in the same general location--near nuclear pores, associated with the periphery of the condensed chromatin. Addition of a 250-fold excess of unlabeled insulin or incubation at 15 degrees C reduced the number of Fm-Ins particles found in nuclei after 90 min by 99% or 92%, respectively. Nuclear accumulation of unlabeled ferritin was only 2% of that found with Fm-Ins after 90 min at 37 degrees C. Biochemical experiments utilizing 125I-labeled insulin and subcellular fractionation indicated that intact 3T3-L1 adipocytes internalized insulin rapidly and that approximately equal to 3% of the internalized ligand accumulated in nuclei after 1 hr. These data provide biochemical and high-resolution ultrastructural evidence that 3T3-L1 adipocytes accumulate potentially significant amounts of insulin in nuclei by an insulin receptor-mediated process. The transport of insulin or the insulin-receptor complex to nuclei in this cell or in others may be directly involved in the long-term biological effects of insulin--in particular, in the control of DNA and RNA synthesis.
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