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Abstract
The definition of mitogenic activity of insulin is controversial. Under physiological conditions, mitogenic refers to cell proliferation and tissue repair. In pathological conditions, it may refer to stimulation of tumour cells in pre-existing (undiagnosed) tumours. The in vitro investigations using benign and malignant cell lines compare proliferative activity of insulin molecules (animal, human and analogues). In these studies, inclusion of [B10-Asp] insulin would be a valuable link to the existing evidence on proliferation of mammary tissue in rodents. Animal and human insulin have growth promoting activity on spontaneously arising tumours (e.g. mammary tumours in rodents). They have no carcinogenic activity (cell transformation), and moreover insulin is not a co-carcinogen when evaluated in special toxicology. Mitogenicity (growth promoting activity) of insulin may be a problem in people with undiagnosed tumours, and may require definition of patient groups who would benefit from targeted monitoring.
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Affiliation(s)
- Juergen Sandow
- Centre of Pharmacology, Johann-Wolfgang-Goethe University, Frankfurt-Main, Germany.
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2
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Villevalois-Cam L, Tahiri K, Chauvet G, Desbuquois B. Insulin-induced redistribution of the insulin-like growth factor II/mannose 6-phosphate receptor in intact rat liver. J Cell Biochem 2000; 77:310-22. [PMID: 10723096 DOI: 10.1002/(sici)1097-4644(20000501)77:2<310::aid-jcb13>3.0.co;2-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The ability of acute insulin treatment to elicit a redistribution of the liver insulin-like growth factor-II/ mannose 6-phosphate (IGF-II/M6P) receptor has been studied in rats, using cell fractionation. Injection of insulin (0.4-50 microg) led to a time- and dose-dependent decrease in IGF-II binding activity in Golgi-endosomal (GE) fractions, along with an increase in activity in the plasma membrane (PM) fraction; only receptor number was affected. Quantitative subfractionation of the microsomal fraction on sucrose density gradients showed that IGF-II binding activity distributed similarly to galactosyltransferase (a Golgi marker), at slightly higher densities than in vivo internalized (125)I-insulin, and at lower densities than 5' nucleotidase and alkaline phosphodiesterase (two plasma membrane markers). Insulin treatment led to a slight time-dependent and reversible shift of IGF-II binding activity toward higher densities. Subfractionation of the GE fraction on Percoll gradients showed that IGF-II binding activity was broadly distributed, with about 60% at low densities coinciding with galactosyltransferase and early internalized (125)I-insulin and with 40% at high densities in the region of late internalized (125)I-insulin. Insulin treatment caused a time-dependent and reversible shift of the distribution of IGF-II binding activity toward low densities. On SDS-PAGE, the size of the affinity-labeled IGF-II/M6P receptor was comparable in GE and PM fractions (about 255 kDa), but on Western blots receptor size was slightly lower in the latter (245 kDa) than in the former (255 kDa). Insulin treatment did not affect the size, but modified the abundance of the IGF-II/M6P receptor in a manner similar to that of IGF-II binding. In vivo chloroquine treatment fully suppressed the changes in IGF-II binding activity in liver GE and PM fractions observed in insulin-treated rats. We conclude that insulin elicits a time-dependent and reversible redistribution of liver IGF-II receptors from Golgi elements and endosomes to the plasma membrane, presumably via early endosomes.
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Affiliation(s)
- L Villevalois-Cam
- Unité 30 INSERM, Hôpital Necker Enfants-Malades, 75015 Paris, France
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3
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Costello M, Baxter RC, Scott CD. Regulation of soluble insulin-like growth factor II/mannose 6-phosphate receptor in human serum: measurement by enzyme-linked immunosorbent assay. J Clin Endocrinol Metab 1999; 84:611-7. [PMID: 10022425 DOI: 10.1210/jcem.84.2.5488] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The soluble form of the insulin-like growth factor II/mannose 6-phosphate (IGF-II/M6-P) receptor has been detected in serum from a variety of mammalian species. We report the development of a highly sensitive quantitative human IGF-II/M6-P receptor immunoassay. Antibodies raised to receptor purified from a human hepatoma cell line by phosphomannan affinity chromatography were used to develop a specific enzyme-linked immunosorbent assay. In this assay, the serum level of soluble receptor for healthy adult subjects was 0.70 +/- 0.23 mg/L. We have shown that soluble receptor is developmentally regulated, with levels in infant (1.12 +/- 0.28 mg/L) and prepubertal (1.18 +/- 0.6 mg/L) subjects dropping by 40% during adolescence (0.73 +/- 0.61 mg/L) and remaining constant throughout adulthood. Further, the receptor is gestationally regulated, with a highly significant association between gestational age and maternal serum receptor levels (r = 0.947; P < 0.0001). Noninsulin-dependent diabetes mellitus (0.98 +/- 0.25 mg/L) and insulin-dependent diabetes mellitus (0.98 +/- 0.25 mg/L) mildly elevated soluble receptor levels, whereas end-stage renal failure (0.75 +/- 0.23 mg/L) and acromegaly (0.79 +/- 0.25 mg/L) did not affect receptor levels. Additionally, we have shown that soluble receptor is present in amniotic fluid, but at a 100-fold lower concentration than serum levels. The ability to quantitate soluble IGF-II/M6-P receptor levels in serum and other fluids provides a valuable tool that will help to further elucidate the role of the receptor in human physiology and disease states.
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Affiliation(s)
- M Costello
- Kolling Institute of Medical Research, University of Sydney, Royal North Shore Hospital, St. Leonards, New South Wales, Australia
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4
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Ishibe M, Nojima T, Ishibashi T, Koda T, Rosier RN, Puzas JE, Kaneda K. Comparison of the type-2 insulin-like growth factor receptor in normal osteoblasts and osteosarcoma-derived osteoblast-like cells. J Orthop Res 1995; 13:643-8. [PMID: 7472741 DOI: 10.1002/jor.1100130502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Insulin-like growth factor-II is known to stimulate the proliferation and differentiation of osteoblasts in part through activation of the type-2 insulin-like growth factor receptor. The present study examined the type-2 insulin-like growth factor receptors of three normal osteoblast-like cells and three osteosarcoma-derived osteoblast-like cells (OGA, SU, and IMAI) from humans. [125I]insulin-like growth factor-II was used for the binding studies. All of the cell types had high affinity binding sites for insulin-like growth factor-II (dissociation constants [Kd] < or = 1 nM). The concentration of these sites was 10 to 24-fold higher in normal osteoblasts than in the osteosarcoma cells studied. Unlabeled insulin-like growth factor-II inhibited the binding of [125I]insulin-like growth factor-II to the cells in a dose-dependent manner; however, unlabeled insulin-like growth factor-I and insulin were less effective. Covalent crosslinking of insulin-like growth factor-II binding sites gave molecular mass estimates of M(r) 250,000 in human osteoblast cells, 250,000 and 130,000 in OGA cells, 240,000 in SU cells, and 250,000 and 130,000 in IMAI cells. Unlabeled insulin-like growth factor-II inhibited all affinity labeling. In Northern blot analysis, the type-2 insulin-like growth factor receptor mRNA of normal osteoblasts was seen in greater abundance than it was in osteosarcoma cells. These results indicate that the numbers of type-2 insulin-like growth factor receptors differ between normal and transformed osteoblasts and that the differential expression of the receptor may be due to the differentiation of osteoblasts.
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Affiliation(s)
- M Ishibe
- Department of Orthopaedic Surgery, NTT (Nippon Telegraph and Telephone Corporation) Sapporo Hospital, Japan
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5
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Kiess W, Terry C, Burgess WH, Linder B, Lopaczynski W, Nissley P. Insulin-like growth factor-II is a substrate for dipeptidylpeptidase I (cathepsin C). Biological properties of the product. EUROPEAN JOURNAL OF BIOCHEMISTRY 1994; 226:179-84. [PMID: 7957246 DOI: 10.1111/j.1432-1033.1994.tb20039.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
We observed that the lysosomal enzyme, dipeptidylaminopeptidase I (DAP-I) caused the release of trichloroacetic-acid-soluble radioactivity from rat 125I-insulin-like growth factor-II (IGF-II). This activity could be blocked by dipeptide inhibitors of DAP-I, and was enhanced by chloride. Treatment of unlabeled rat IGF-II with DAP-I converted approximately 50% of the IGF-II to a species with a slightly shorter elution time on reverse-phase HPLC, whereas treatment of human IGF-II caused complete conversion to the species with the shorter elution time. Rat IGF-II purified from the rat BRL 3A cell line is a mixture of two molecules beginning with Ala-Tyr-Arg-Pro-Ser- and Tyr-Arg-Pro-Ser- [Marquardt, H., Todaro, G. J., Henderson, L. E. & Oroszlan, S. (1981) J. Biol. Chem. 256, 6859-6865] while human IGF-II begins with Ala-Tyr-Arg-Pro-Ser-. Determination of the N-terminal amino acid sequence of human IGF-II before and after digestion with DAP-I showed that DAP-I cleaved Ala-Tyr, terminating at Arg-Pro-; the rat IGF-II species beginning with Tyr-Arg-Pro-Ser- was resistant to digestion. In order to compare DAP-I-treated IGF-II with native IGF-II for binding to IGF receptors and IGF-binding proteins and in a bioassay, rat and human IGF-II were treated with DAP-I and the digested and undigested species were isolated by reverse-phase HPLC. The IGF-II/mannose 6-phosphate receptor was purified from rat placental membranes, the IGF-I receptor was solubilized from human placental membranes and IGF-binding proteins were partially purified from adult and three-day-old rat sera by sequential gel filtration on Sephadex G-200 (pH 8.0) and Sephadex G-50 (acid pH). The dose/response curves of the two IGF-II species were indistinguishable in radioreceptor assays utilizing the IGF-II/mannose 6-phosphate receptor and the IGF-I receptor and in IGF competitive binding assays utilizing partially purified IGF-binding proteins. The DAP-I-digested and native IGF-II species were also equipotent in stimulating [3H]thymidine incorporation into DNA in the human osteosarcoma cell line, MG-63. We conclude that DAP-I cleaves an N-terminal dipeptide from IGF-II and that this does not result in a change in the biological activity of the molecule.
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Affiliation(s)
- W Kiess
- Metabolism Branch, National Cancer Institute, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda
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6
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Gelato MC, Rutherford C, San-Roman G, Shmoys S, Monheit A. The serum insulin-like growth factor-II/mannose-6-phosphate receptor in normal and diabetic pregnancy. Metabolism 1993; 42:1031-8. [PMID: 8345808 DOI: 10.1016/0026-0495(93)90019-k] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The extracellular domain of the insulin-like growth factor-II/mannose-6-phosphate (IGF-II/Man-6-P) receptor is present in the circulation of several species including man. The purpose of the present study was to establish whether this truncated receptor is present in higher concentrations in fetal sera compared with adult sera and whether the metabolic status of the individual alters serum concentrations of this protein. Nondiabetic and diabetic pregnant women were studied throughout gestation, and at term fetal cord sera were obtained. Levels of IGF-I increased throughout pregnancy in normal and diabetic women. IGF-II levels significantly increased during the third trimester in both groups and levels of IGF-I and IGF-II were significantly elevated in fetal cord samples from diabetic women only. Serum samples were gel-filtered on Sephadex G-200, and column fractions were assayed for binding of radiolabeled IGF-II and IGF-I. There was specific binding (SB) of IGF-II in the void volume fractions in all samples examined. Normal women had 3% +/- 0.5% SB, whereas in cord sera SB was 5% +/- 0.7% and in pregnant sera 10% +/- 2%. There was no difference in SB in fetal cord or pregnant samples from normal and diabetic women. In addition, there was a peak of binding activity of both IGF-I and -II in gamma-globulin and postalbumin fractions of the columns in pregnant and nonpregnant women, but only in postalbumin fractions in fetal cord samples.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M C Gelato
- Department of Medicine, State University of New York, Stony Brook 11794
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7
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Göke R, Oltmer B, Sheikh SP, Göke B. Solubilization of active GLP-1 (7-36)amide receptors from RINm5F plasma membranes. FEBS Lett 1992; 300:232-6. [PMID: 1313374 DOI: 10.1016/0014-5793(92)80852-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Glucagon-like peptide-1 (7-36)amide (GLP-1 (7-36)amide) represents a physiologically important incretin in mammals including man. Receptors for GLP-1 (7-36)amide have been described in RINm5F cells. We have solubilized active GLP-1(7-36)amide receptors from RINm5F cell membranes utilizing the detergents octyl-beta-glucoside and CHAPS; Triton X-100 and Lubrol PX were ineffective. Binding of radiolabeled GLP-1(7-36)amide to the solubilized receptor was inhibited concentration-dependently by addition of unlabeled peptide. Scatchard analysis of binding data revealed a single class of binding sites with Kd = 0.26 +/- 0.03 nM and Bmax = 65.4 +/- 21.24 fmol/mg of protein for the membrane-bound receptor and Kd = 22.54 +/- 4.42 microM and Bmax = 3.9 +/- 0.79 pmol/mg of protein for the solubilized receptor. The binding of the radiolabel to the solubilized receptor was dependent both on the concentrations of mono- and divalent cations and the protein/detergent ratio in the incubation buffer. The membrane bound receptor is sensitive to guanine-nucleotides, however neither GTP-gamma-S nor GDP-beta-S affected binding of labeled peptide to solubilized receptor. These data indicate that the solubilized receptor may have lost association with its G-protein. In conclusion, the here presented protocol allows solubilization of the GLP-1(7-36)amide receptor in a functional state, and opens up the possibility for further molecular characterization of the receptor protein.
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Affiliation(s)
- R Göke
- Department of Internal Medicine, Phillipps-University of Marburg, Germany
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8
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Vignon F, Rochefort H. Interactions of pro-cathepsin D and IGF-II on the mannose-6-phosphate/IGF-II receptor. Breast Cancer Res Treat 1992; 22:47-57. [PMID: 1421424 DOI: 10.1007/bf01833333] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The mannose-6-phosphate (Man-6P)/IGF-II receptor is a multifunctional receptor which binds with a high affinity on distinct sites two strikingly different classes of ligands: IGF-II, and Man-6P bearing molecules such as lysosomal enzymes or other biologically relevant ligands (TGF beta precursor, EGF receptor, proliferin...). Binding of each ligand on its cognate site is severely decreased in the presence of the other type of ligand, thus revealing that the two distinct sites are strongly interacting (steric hindrance, conformational change). Any imbalance in ligands and receptor concentration in various pathological situations (transformation, tumor, altered hormonal levels...) is thus likely to perturb their associated biological functions in the targeting and routing of lysosomal enzymes or Man-6P ligands or in the autocrine/paracrine IGF-II--induced cellular responses.
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Affiliation(s)
- F Vignon
- INSERM Unit 148 on "Hormones and Cancer", Montpellier, France
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9
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Janicot M, Flores-Riveros J, Lane M. The insulin-like growth factor 1 (IGF-1) receptor is responsible for mediating the effects of insulin, IGF-1, and IGF-2 in Xenopus laevis oocytes. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(18)92830-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
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10
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Affiliation(s)
- P Nissley
- Endocrinology Section, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892
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11
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Kiess W, Thomas CL, Sklar MM, Nissley SP. Beta-galactosidase decreases the binding affinity of the insulin-like-growth-factor-II/mannose-6-phosphate receptor for insulin-like-growth-factor II. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 190:71-7. [PMID: 2163834 DOI: 10.1111/j.1432-1033.1990.tb15547.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The insulin-like growth-factor-II/mannose-6-phosphate (IGF-II/Man6P) receptor binds two classes of ligands, insulin-like growth factors and lysosomal enzymes. We have examined the ability of the lysosomal enzyme, beta-galactosidase, to modulate the binding of 125I-IGF-II to the receptor. beta-Galactosidase purified from bovine testis was fractionated on a DEAF-Sephacel ion-exchange column. Column fractions were assayed for enzymatic activity and for ability to inhibit the binding of 125I-IGF-II to the IGF-II/Man6P receptor. Enzyme fractions eluting at higher NaCl concentrations which had previously been shown to exhibit greater uptake by cells in culture, exhibited greater potency in inhibiting the binding of 125I-IGF-II to the receptor. A pool of these fractions from the DEAE-Sephacel column inhibited 125I-IGF-II binding to pure receptor by 80% with the concentration required for half-maximal inhibition being 25 nM. The inhibition of binding by beta-galactosidase was completely blocked by simultaneous incubation with Man6P. Inhibition of the enzymatic activity of beta-galactosidase with D-galactonic acid gamma-lactone did not affect the ability of beta-galactosidase to inhibit the binding of 125I-IGF-II to the receptor. Scatchard analysis of IGF-II binding to pure receptor in the presence and absence of beta-galactosidase showed that beta-galactosidase decreased the binding affinity for IGF-II (Kd 0.26 nM versus 1.0 nM in the presence of 57 nM beta-galactosidase). We confirmed the observations of others that Man6P alone actually increases the binding of 125I-IGF-II to the IGF-II/Man6P receptor, but we found that this phenomenon was dependent upon the method of preparation of the IGF-II/Man6P receptor. Microsomal membrane preparations, solubilized membranes, and receptors purified on an IGF-II-Sepharose column all exhibited stimulation of 125I-IGF-II binding by Man6P, whereas receptors purified on lysosomal enzyme affinity columns showed little or no stimulation of 125I-IGF-II binding by Man6P. We conclude that beta-galactosidase decreases the binding affinity of the IGF-II/Man-6-P receptor for IGF-II by binding with high affinity to the Man6P-recognition site.
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Affiliation(s)
- W Kiess
- Endocrinology Section, National Cancer Institute, National Institutes of Health, Bethesda
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12
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Sinha MK, Buchanan C, Raineri-Maldonado C, Khazanie P, Atkinson S, DiMarchi R, Caro JF. IGF-II receptors and IGF-II-stimulated glucose transport in human fat cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1990; 258:E534-42. [PMID: 2156441 DOI: 10.1152/ajpendo.1990.258.3.e534] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Insulin-like growth factor II (IGF-II) receptors have been described in rat but not in human adipocytes. In both species, IGF-II has been reported to stimulate glucose transport by interacting with the insulin receptor. In this study, we have unequivocally demonstrated the presence of IGF-II receptors in human adipocytes. 125I-labeled IGF-II specifically binds to intact adipocytes, membranes, and lectin-purified detergent solubilized extracts. Through the use of 0.5 mM disuccinimidyl suberate, 125I-IGF-II is cross-linked to a 260-kDa protein that is identified as the IGF-II receptor by displacement experiments with unlabeled IGF-II, IGF-I, and insulin and either by immunoprecipitation or by Western blot analysis with mannose 6-phosphate receptor antibodies. The concentrations of IGF-II required for half-maximal and maximal stimulation of glucose transport in human adipocytes are 35 and 100 times more than that of insulin. The possibility of IGF-II stimulating glucose transport by interacting predominantly with the insulin receptor is suggested by the following: 1) the concentration of IGF-II that inhibits half of insulin binding is only 20 times more than that of insulin; 2) the lack of an additive effect of IGF-II and insulin for maximal stimulation of glucose transport; 3) the ability of monoclonal insulin receptor antibodies to decrease glucose transport stimulated by submaximal concentrations of both IGF-II and insulin; and 4) the ability of IGF-II to stimulate insulin receptor autophosphorylation albeit at a reduced potency when compared with insulin.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- M K Sinha
- Department of Medicine, East Carolina University School of Medicine, Greenville, North Carolina 27858-4354
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13
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The insulin-like growth factor II/mannose-6-phosphate receptor : IGF-II/Man-6-P receptor. Cytotechnology 1989; 2:287-305. [PMID: 22358870 DOI: 10.1007/bf00364994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
Recent evidence from molecular cloning, biochemical and immunological experiments has established that the cation-independent mannose-6-phosphate (Man-6-P) receptor and insulin-like growth factor-II (IGF-II) receptor are the same protein. Although the role of the IGF-II/Man-6-P receptor as a transporter of hydrolytic enzymes in the biogenesis of lysosomes is certain, elucidation of the receptor's structure has not yet provided major insights into the function of IGF-II binding. Mutually exclusive binding of IGF-II and naturally occurring phosphomannosyl ligands to distinct but proximal sites on the receptor suggests that the IGF-II/Man-6-P receptor cannot simultaneously fulfill the functional requirements of both IGF-II and lysosomal enzymes. Does the receptor transduce on intracellular signal in order to mediate the biological effects of IGF-II? If so, then the receptor must interact with an effector molecule, perhaps a G protein, in the mechanism of IGF-II action. Further information from ligand binding and especially mutagenesis experiments will be needed to elucidate the potentially multiple functions of the IGF-II/Man-6-P receptor.
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14
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Sklar MM, Kiess W, Thomas CL, Nissley SP. Developmental Expression of the Tissue Insulin-like Growth Factor II/Mannose 6-Phosphate Receptor in the Rat. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(19)84766-x] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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15
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Barreca A, Minuto F. Somatomedins: chemical and functional characteristics of the different molecular forms. J Endocrinol Invest 1989; 12:279-93. [PMID: 2545770 DOI: 10.1007/bf03349988] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Affiliation(s)
- A Barreca
- Cattedre di Endocrinologia, ISMI, University of Genova, Italy
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16
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Kiess W, Thomas CL, Greenstein LA, Lee L, Sklar MM, Rechler MM, Sahagian GG, Nissley SP. Insulin-like growth factor-II (IGF-II) inhibits both the cellular uptake of β-galactosidase and the binding of β-galactosidase to purified IGF-II/mannose 6-phosphate receptor. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)83801-7] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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17
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Serum Form of the Rat Insulin-like Growth Factor II/Mannose 6-Phosphate Receptor Is Truncated in the Carboxyl-terminal Domain. J Biol Chem 1989. [DOI: 10.1016/s0021-9258(18)94060-3] [Citation(s) in RCA: 74] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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18
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Scott CD, Baxter RC. Purification and characterization of insulin-like growth factor-II receptors. Methods Enzymol 1989; 168:309-24. [PMID: 2542727 DOI: 10.1016/0076-6879(89)68022-6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
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19
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Biochemical evidence that the type II insulin-like growth factor receptor is identical to the cation-independent mannose 6-phosphate receptor. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(19)76546-6] [Citation(s) in RCA: 131] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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20
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Abstract
This review focusses on the roles that membrane receptors and their transducers play in the physiology and pathology of the gastrointestinal tract. The multifactorial regulation of [correction] mucosal growth and function is discussed in relation to the heterogeneity of exocrine and endocrine populations that originate from progenitor cells in stomach and intestine.
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Affiliation(s)
- C Gespach
- INSERM U.55, Hôpital Saint-Antoine, Paris, France
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21
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Smith M, Clemens J, Kerchner GA, Mendelsohn LG. The insulin-like growth factor-II (IGF-II) receptor of rat brain: regional distribution visualized by autoradiography. Brain Res 1988; 445:241-6. [PMID: 2967099 DOI: 10.1016/0006-8993(88)91185-7] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The presence of insulin-like growth factor-II (IGF-II) in brain and cerebral spinal fluid prompted us to investigate the distribution of receptors for this peptide in rat brain slices. Human 125I-IGF-II (10 pM) was incubated for 16 h at 4 degrees C with thaw-mounted slices of rat brain from 11 different brain regions. Incubations in the absence or presence of excess unlabeled human IGF-II or insulin were performed and the labeled tissues were exposed to X-ray film for 4-7 days. Autoradiographs showed dense labeling in the granule layers of the olfactory bulbs, deep layers of the cerebral cortex, pineal gland, anterior pituitary, hippocampus (CA1-CA4, and dentate gyrus), and the granule cell layers of the cerebellum. Unlabeled IGF-II eliminated most of the binding in these brain regions while insulin produced only a minimal reduction in the amount of 125I-IGF-II bound. These results indicate that a neural receptor for IGF-II is uniquely distributed in rat brain tissue supporting the notion that this peptide might play an important role in neuronal functioning.
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Affiliation(s)
- M Smith
- Department of Biochemistry, Lilly Research Laboratories, Eli Lilly and Co., Indianapolis, IN 46285
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22
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Tong PY, Tollefsen SE, Kornfeld S. The cation-independent mannose 6-phosphate receptor binds insulin-like growth factor II. J Biol Chem 1988. [DOI: 10.1016/s0021-9258(18)69105-7] [Citation(s) in RCA: 89] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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23
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Hill JM, Lesniak MA, Kiess W, Nissley SP. Radioimmunohistochemical localization of type II IGF receptors in rat brain. Peptides 1988; 9 Suppl 1:181-7. [PMID: 2856642 DOI: 10.1016/0196-9781(88)90242-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In competition studies 125I-IGF-II binding in brain has different characteristics than binding in other tissues. We show here that an antibody to the type II IGF receptor binds to a approximately 245 kDa protein in rat brain membranes. This antibody was used in a novel radioimmunohistochemical technique to determine the distribution of type II IGF receptors in rat brain. The results of this method are found to be indistinguishable from the distribution pattern achieved with 125I-IGF-II autoradiography, thus verifying that, in brain, 125I-IGF-II binds to the type II IGF receptor. Type II IGF receptors are found to be most abundant in brain regions composed of tight clusters of neuronal perikarya (e.g., the pyramidal cell layer of the hippocampus, and the granule cell layers of the dentate gyrus and cerebellar cortex) which suggests that type II IGF receptors are present on neuron cell bodies. A neuronal localization of both IGF-II and the type II IGF receptor suggests that, in addition to growth-promoting effects, IGF-II in brain may have neurotransmitter/neuromodulatory functions since IGF-II could act as a neuron-to-neuron message.
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Affiliation(s)
- J M Hill
- Section on Brain Biochemistry, National Institute of Mental Health, NIH, Bethesda, MD 20892
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Balasubramanian AS. Phosphomannose binding proteins: the phosphomannosyl receptor and insulin like growth factor II receptor. Life Sci 1988; 43:1953-9. [PMID: 2850416 DOI: 10.1016/0024-3205(88)90568-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Proteins that bind phosphomannose residues in glycoproteins exhibit widely different functions. They are found as receptors of lysosomal enzymes, as ligatin that binds peripheral glycoproteins and as a lectin in parasites. The identity of the phosphomannosyl receptor for lysosomal enzymes and the insulin like growth factor II receptor raises interesting questions regarding their function.
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Affiliation(s)
- A S Balasubramanian
- Department of Neurological Sciences, Christian Medical College Hospital, Vellore, India
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Scott CD, Baxter RC. Insulin-like growth factor-II receptors in cultured rat hepatocytes: regulation by cell density. J Cell Physiol 1987; 133:532-8. [PMID: 2961772 DOI: 10.1002/jcp.1041330314] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Insulin-like growth factor-II (IGF-II) receptors in primary cultures of adult rat hepatocytes were characterized and their regulation by cell density examined. In hepatocytes cultured at 5 X 10(5) cells per 3.8 cm2 plate [125I]IGF-II bound to specific, high affinity receptors (Ka = 4.4 +/- 0.5 X 10(9) l/mol). Less than 1% cross-reactivity by IGF-I and no cross-reactivity by insulin were observed. IGF-II binding increased when cells were permeabilized with 0.01% digitonin, suggesting the presence of an intracellular receptor pool. Determined by Scatchard analysis and by polyacrylamide gel electrophoresis after affinity labeling, the higher binding was due solely to an increase in binding sites present on 220 kDa type II IGF receptors. In hepatocytes cultured at low densities, the number of cell surface receptors increased markedly, from 10-20,000 receptors per cell at a culture density of 6 X 10(5) cells/well to 70-80,000 receptors per cell at 0.38 X 10(5) cells/well. The increase was not due simply to the exposure of receptors from the intracellular pool, as a density-related increase in receptors was also seen in cells permeabilized with digitonin. There was no evidence that IGF binding proteins, either secreted by hepatocytes or present in fetal calf serum, had any effect on the measurement of receptor concentration or affinity. We conclude that rat hepatocytes in primary culture contain specific IGF-II receptors and that both cell surface and intracellular receptors are regulated by cell density.
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Affiliation(s)
- C D Scott
- Department of Endocrinology, Royal Prince Alfred Hospital, Camperdown, Australia
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Abstract
The specificity of the type 2 insulinlike growth factor (IGF) receptor is evaluated in human placenta membranes and the human cell line K562. K562 cells have type 2 but not type 1 IGF receptors. Native IGF-2 isolated from human plasma and synthetic IGF-2 were equipotent in competing with labeled IGF-2 in both systems. Pure IGF-1 isolated from plasma, synthetic IGF-1 and recombinant IGF-1 could not crossreact with the type 2 IGF receptor in concentrations up to 1 microgram/ml in both systems. Studies on placenta membrane were done in the presence of 300 ug/ml insulin to block the type 1 IGF receptors. It is concluded that IGF-1, as well as insulin, cannot crossreact with the human type 2 IGF receptor.
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Affiliation(s)
- M Tally
- Department of Endocrinology, Karolinska Institutet, Stockholm, Sweden
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Morgan DO, Edman JC, Standring DN, Fried VA, Smith MC, Roth RA, Rutter WJ. Insulin-like growth factor II receptor as a multifunctional binding protein. Nature 1987; 329:301-7. [PMID: 2957598 DOI: 10.1038/329301a0] [Citation(s) in RCA: 700] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The primary structure of human insulin-like growth factor II receptor, predicted from the complementary DNA sequence, reveals a transmembrane receptor molecule with a large extracellular domain made up of fifteen repeat sequences and a small region homologous to the collagen-binding domain of fibronectin. The structural and biochemical features of the IGF-II receptor appear identical to those of the cation-independent mannose-6-phosphate receptor.
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28
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An antibody that blocks insulin-like growth factor (IGF) binding to the type II IGF receptor is neither an agonist nor an inhibitor of IGF-stimulated biologic responses in L6 myoblasts. J Biol Chem 1987. [DOI: 10.1016/s0021-9258(18)45269-6] [Citation(s) in RCA: 157] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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Mason RM, Bansal MK. Different growth rates of swarm chondrosarcoma in Lewis and Wistar rats correlate with different thyroid hormone levels. Connect Tissue Res 1987; 16:177-85. [PMID: 2952454 DOI: 10.3109/03008208709002005] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The transplantable Swarm rat chondrosarcoma grew to twice the weight in 5 weeks in Lewis strain rats (approximately 80 g) as it did in Wistar strain rats (approximately 40 g). Wistar tumor passaged into Lewis rats adopted the accelerated growth rate of the Lewis tumor on the second passage. Conversely Lewis tumor passaged into Wistar rats grew like Wistar lineage chondrosarcoma after two passages. Lewis and Wistar tumors had a similar histological appearance. The extracellular matrix composition of the two tumors was very similar. Tumor explant cultures synthesized about the same amount of 35S-proteoglycans and the same proportion of 3H-hyaluronate: 3H-chondroitin sulfate. Serum levels of growth hormone and insulin were the same in the two strains but T3 and T4 levels were 50% higher in Lewis rats compared to Wistar rats. It is likely that accelerated tumor growth in Lewis strain rats is related to the higher thyroid hormone levels.
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Maly P, Lüthi C. Characterization of affinity-purified type I insulin-like growth factor receptor from human placenta. Biochem Biophys Res Commun 1986; 138:1257-62. [PMID: 3019338 DOI: 10.1016/s0006-291x(86)80418-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The binding affinities of type I IGF receptor, purified to near homogeneity from human placental membranes, were characterized. For this receptor preparation, free of type II IGF receptor and essentially free of insulin receptor, dissociation constants of Kd = 0.05 nM for IGF I and of Kd = 0.2 nM for IGF II (linear Scatchard plots) were determined. Competitive binding studies indicated a cross-reactivity of approximately 40% for IGF II to the type I IGF receptor.
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Rosenfeld RG, Hodges D, Pham H, Lee PD, Powell DR. Purification of the insulin-like growth factor II (IGF-II) receptor from an IGF-II-producing cell line, and generation of an antibody which both immunoprecipitates and blocks the type 2 IGF receptor. Biochem Biophys Res Commun 1986; 138:304-11. [PMID: 3017320 DOI: 10.1016/0006-291x(86)90280-9] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
18,54-SF cells, which secrete rat insulin-like growth factor II (rIGF-II), have abundant type 2 IGF receptors. We have purified the type 2 receptor from these cells by solubilization of crude membranes in Triton X-100, followed by chromatography on agarose-immobilized rIGF-II. A partially purified receptor preparation, obtained by chromatography of solubilized membranes over wheat germ agglutinin, was used to immunize a rabbit. The antibody generated both immunoprecipitates the type 2 receptor, and specifically inhibits IGF-II binding to a variety of rat tissues, including 18,54-SF cells, BRL-3A cells and placenta. The presence of abundant type 2 receptors on an rIGF-II-secreting cell line is consistent with an autocrine role for IGF-II in select cells.
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33
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Oka Y, Czech MP. The type II insulin-like growth factor receptor is internalized and recycles in the absence of ligand. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(18)67619-7] [Citation(s) in RCA: 68] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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34
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Corvera S, Whitehead RE, Mottola C, Czech MP. The insulin-like growth factor II receptor is phosphorylated by a tyrosine kinase in adipocyte plasma membranes. J Biol Chem 1986. [DOI: 10.1016/s0021-9258(19)57452-x] [Citation(s) in RCA: 46] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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35
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Bansal MK, Ward H, Mason RM. Proteoglycan synthesis in suspension cultures of Swarm rat chondrosarcoma chondrocytes and inhibition by exogenous hyaluronate. Arch Biochem Biophys 1986; 246:602-10. [PMID: 2423031 DOI: 10.1016/0003-9861(86)90315-2] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Conditions were established for short-term primary suspension culture of chondrocytes from the Swarm rat chondrosarcoma. Proteoglycan and hyaluronate synthesis on Day 0 to Day 2 in culture was investigated and compared with that for plated cultures. Incorporation of [35S]sulfate into proteoglycans was the same for both suspension and plated cultures. 35S-Proteoglycan synthesis decreased by about 80% between Days 0 and 1 irrespective of culture conditions. Suspension culture chondrocytes synthesized proteoglycans which were very similar to those made in plated cultures, with respect to hydrodynamic size, glycosaminoglycan, chain length, and composition. [3H]Hyaluronate synthesis accounted for 18 and 23% of the total 3H-glycosaminoglycans synthesized from [3H]glucosamine by suspension and plated cultures, respectively. Suspension culture chondrocytes responded to exogenous hyaluronate (1 mg/ml) by reducing their 35S-proteoglycan synthesis by about 50%. [3H]Hyaluronate synthesis was inhibited by 13% under these conditions. The inhibition was dependent on the concentration of exogenous hyaluronate and reached a plateau level within 2 h. Plated chondrocyte cultures showed little or no response to hyaluronate. Suspension cultures of chondrocytes were prelabeled with [3H]lysine and lysed, and a heavy membrane fraction (12,000g) was extracted with the detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate. A Sepharose-hyaluronate affinity gel was used to show that the extract contained hyaluronate binding 3H-labeled proteins and evidence was obtained suggesting that these came from the external face of the plasma membrane.
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36
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Lee PD, Hodges D, Hintz RL, Wyche JH, Rosenfeld RG. Identification of receptors for insulin-like growth factor II in two insulin-like growth factor II producing cell lines. Biochem Biophys Res Commun 1986; 134:595-600. [PMID: 3004456 DOI: 10.1016/s0006-291x(86)80461-2] [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: 01/03/2023]
Abstract
Specific high affinity membrane receptor(s) for insulin-like growth factor II have been characterized in two cell lines which produce this hormone and have the ability to proliferate in serum-free media. These receptor(s) have no affinity for either insulin or biosynthetic insulin-like growth factor I. Affinity cross-linking and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed an apparent Mr of 250K which does not change with disulfide bond reduction. Our findings are consistent with an autocrine function for insulin-like growth factor II and indicate that these continuous cell lines may provide unique systems for further investigations of this hormone and its receptor.
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38
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MacDonald RG, Czech MP. Biosynthesis and processing of the type II insulin-like growth factor receptor in H-35 hepatoma cells. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(17)39187-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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39
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Oka Y, Rozek LM, Czech MP. Direct demonstration of rapid insulin-like growth factor II Receptor internalization and recycling in rat adipocytes. Insulin stimulates 125I-insulin-like growth factor II degradation by modulating the IGF-II receptor recycling process. J Biol Chem 1985. [DOI: 10.1016/s0021-9258(17)39385-7] [Citation(s) in RCA: 148] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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40
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Evidence for the phosphorylation of the type II insulin-like growth factor receptor in cultured cells. Biochem Biophys Res Commun 1985; 130:793-9. [PMID: 2992487 DOI: 10.1016/0006-291x(85)90486-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The ATP pools of monolayer cultures of rat embryo fibroblasts and rat liver cells (BRL-3A2) were labeled with [32P]H3PO4. The type II insulin-like growth factor (IGF) receptor was purified by affinity chromatography on wheat germ lectin-Sepharose and IGF-II-Sepharose columns. A phosphorylated species having the expected size of the type II receptor (Mr = 220,000 without reduction, Mr = 260,000 with reduction) was identified by sodium dodecyl sulfate polyacrylamide gel electrophoresis and autoradiography. IGF-II stimulated phosphorylation of the type II receptor in BRL-3A2 rat liver cells. Lability of the receptor phosphate bonds to alkaline pH suggests that the bulk of phosphorylation was occurring on serine residues.
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Szecòwka J, Goldfine ID, Williams JA. Solubilization and characterization of CCK receptors from mouse pancreas. REGULATORY PEPTIDES 1985; 10:71-83. [PMID: 2986202 DOI: 10.1016/0167-0115(85)90001-1] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
To study the characteristics of the CCK receptor, plasma membranes were prepared from mouse pancreatic acini, and CCK receptors solubilized with 1% digitonin. To measure hormone binding, the solubilized receptors were incubated with 125I-CCK at 4 degrees C and the hormone-receptor complex was precipitated with 10% polyethylene glycol. Specific 125I-CCK binding by the solubilized CCK receptor was compared to that by the plasma membrane-bound CCK receptor. Both the solubilized and the membrane-bound receptor displayed optimal binding at an acidic pH (between 6.0 and 7.0) and showed a similar sensitivity to monovalent and divalent cations. The solubilized receptors preserved their relative specificity for CCK molecules: CCK-8 greater than CCK-33 greater than desulfated CCK-8 greater than CCK-4. However, the soluble CCK receptor had a lower binding affinity than plasma membrane-bound receptor. Solubilized receptors preserved their relative specificity for inhibitors of CCK binding and action: dibutyryl cyclic GMP greater than N-CBZ-tryptophan greater than proglumide. Solubilized receptors had affinities for these antagonists that were similar to receptors on intact plasma membranes. These data indicate, therefore, that the specific binding properties of the CCK receptor are inherent to the solubilized glycoprotein molecules.
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[14] Affinity cross-linking of receptors for insulin and the insulin-like growth factors I and II. Methods Enzymol 1985. [DOI: 10.1016/0076-6879(85)09084-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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43
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Tally M, Tang XZ, Enberg G, Hall K. The binding of insulin-like growth factor II to the erythroleukemia cell line K562. Biosci Rep 1984; 4:1071-7. [PMID: 6099156 DOI: 10.1007/bf01116701] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
The erythroleukemia cell line K562 was previously shown to have specific binding sites for insulin but not for insulin-like growth factor I (IGF-I). In this study the presence of specific receptors for insulin-like growth factor II (IGF-II) is established. Scatchard analysis of the competition curve for IGF-II disclosed a non-cooperative binding kinetic with a calculated affinity constant 2.4 X 10(8) M-1 and a receptor number of 4.8 X 10(4) sites/cell. IGF-I displayed 10% crossreactivity over the IGF-II receptor but insulin did not crossreact at all. Instead insulin, present in high concentrations, enhanced the binding of IGF-II. The presence of IGF II but not IGF-I receptors makes the K562 cell line suitable for studying properties of the type-2 receptor.
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The type II insulin-like growth factor receptor does not mediate increased DNA synthesis in H-35 hepatoma cells. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(18)90803-3] [Citation(s) in RCA: 103] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
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45
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Gullick WJ, Downward DJ, Marsden JJ, Waterfield MD. A radioimmunoassay for human epidermal growth factor receptor. Anal Biochem 1984; 141:253-61. [PMID: 6093624 DOI: 10.1016/0003-2697(84)90454-8] [Citation(s) in RCA: 31] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The development of a radioimmunoassay (RIA) for the human epidermal growth factor receptor solubilized with nonionic detergents which employs iodinated epidermal growth factor (125I-EGF) as the specific ligand is described. A monoclonal antibody (R1) that binds specifically to human EGF receptors [Waterfield, M. D., et al. (1982) J. Cell Biochem. 20, 149-161] was used to separate solubilized receptors saturated with 125I-EGF from free ligand by absorption to protein A-Sepharose, and the bound radioactivity was determined. The RIA was linear when increasing amounts of solubilized membrane protein were added and, when compared to the standard polyethylene glycol assay, was more reproducible. In addition, the background nonspecific binding obtained in the presence of a hundred-fold excess of unlabeled EGF was less in the RIA. Substitution of normal mouse serum for the monoclonal antibody gave very low nonspecific background ligand binding and avoided the use of large amounts of unlabeled EGF in the assay. Two major classes of binding sites for EGF were observed in membrane preparations from the cervical carcinoma cell line A431 or from normal human placental tissue. These were present in approximately equal amounts, with apparent dissociation constants of 4 X 10(-10) and 4 X 10(-9) M. Upon solubilization with the nonionic detergent Triton X-100, only one class of EGF binding sites was detected in both cases, with a dissociation constant of 3 X 10(-8) M. The RIA can be used to monitor receptor purification and for quantitation of receptor number and affinity in various cell types.
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Insulin-like growth factor II receptors. Molecular radius and molecular weight determination using quantitative polyacrylamide gel electrophoresis. J Biol Chem 1984. [DOI: 10.1016/s0021-9258(17)43303-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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47
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Nissley SP, Rechler MM. Somatomedin/insulin-like growth factor tissue receptors. CLINICS IN ENDOCRINOLOGY AND METABOLISM 1984; 13:43-67. [PMID: 6202447 DOI: 10.1016/s0300-595x(84)80008-0] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
There are two types of Sm/IGF receptors based on results of competitive binding experiments and investigations of receptor structure. The type I receptor preferentially interacts with IGF I rather than IGF II and interacts weakly with insulin. This receptor has a binding subunit of Mr = 130 000 which is disulphide bonded to form larger structures of Mr greater than 300 000. The type II receptor prefers IGF II to IGF I and does not interact with insulin. Its binding subunit is not linked by disulphide bonds to other membrane components (Mr = 260 000 with reduction, 220 000 without reduction). Subunit organization of the type I receptor appears to be similar to that of the insulin receptor but it is unlikely that the insulin and Sm/IGF binding sites are on a common alpha subunit. The type I receptor is down-regulated by IGFs and insulin. A rapid increase in ligand binding to the type II receptor by insulin has been described in intact rat adipocytes. The original idea that an IGF receptor mediates the growth-promoting action of both IGFs and insulin while acute metabolic effects of insulin and IGFs are mediated by the insulin receptor is an oversimplification . There now are clear examples of insulin stimulating growth by acting through the insulin receptor and, conversely, instances of IGF stimulating glucose transport by acting through an IGF receptor. Radioreceptor assays which measure IGF I in preference to IGF II (human placental membrane) and which measure IGF II in preference to IGF I (rat liver and rat placental membranes) have been utilized for clinical measurements of Sm/IGF levels, but are less specific than the respective radioimmunoassays. With the demonstration of Sm/IGF receptors on circulating human mononuclear cells and human skin fibroblasts, it is expected that these systems will be useful for investigations of patients with possible end-organ resistance to Sm/IGF.
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