[Characterization of type II insulin-like growth factor binding on rat hepatocytes of primary monolayer culture: regulation of the binding by IGF-I and related peptides]. 1988

M Yamasaki, and N Watanabe, and T Inoue, and S Saito
First Department of Internal Medicine, School of Medicine, University of Tokushima, Japan.

Nature of insulin-like growth factor (IGF) binding on rat hepatocytes of primary monolayer culture and its regulation by IGF-related peptides were studied. The specific binding of 125I-IGF-I to the rat hepatocytes was saturable and dependent on incubation time and temperature. The optimal pH of incubation medium was 7.8-8.2. The steady-state binding was attained at 20 degrees C for 6 h, and averaged 12% per 4 X 10(5) cells. Fifty percent displacement of the 125I-IGF-I binding was observed at concentrations of 10 ng/ml of IGF-I and 5 ng/ml of IGF-II, but insulin (10 ng/ml-10 micrograms/ml) did not inhibit the binding. IGF-II inhibited the binding of 125I-IGF-II to the hepatocytes half maximally at concentrations of 2 ng/ml. A Scatchard plot of the data of binding was linear, and indicated association constant of 1.0 X 10(9)M-1 and a binding site of 44,000 per cell. Preincubation of the hepatocytes with either IGFs or insulin at 37 degrees C for 24 h resulted in the reduction of 125I-IGF-I binding to the hepatocytes in a dose-related manner, being dependent on incubation time and insulin concentrations. The binding was reduced to 20% of the control value in the presence of 10(-7)M IGF-I, and to 85% of the control in the presence of 5 X 10(-8)M IGF-II. Although insulin showed no affinity to the type II IGF receptors, 125I-IGF-I binding to the hepatocytes was decreased to 60% of the control after preincubation with 10(-10)M insulin. These results indicate that 1) the hepatocytes of primary monolayer cultures have only type II IGF binding, 2) preincubation of the cells with IGF-I, IGF-II or insulin induces the reduction of 125I-IGF-I binding to the cells, indicating down-regulation of the binding, and 3) this binding site of rat hepatocytes is regulated by not only IGF-I and IGF-II but also insulin of physiological concentrations.

UI MeSH Term Description Entries
D007328 Insulin A 51-amino acid pancreatic hormone that plays a major role in the regulation of glucose metabolism, directly by suppressing endogenous glucose production (GLYCOGENOLYSIS; GLUCONEOGENESIS) and indirectly by suppressing GLUCAGON secretion and LIPOLYSIS. Native insulin is a globular protein comprised of a zinc-coordinated hexamer. Each insulin monomer containing two chains, A (21 residues) and B (30 residues), linked by two disulfide bonds. Insulin is used as a drug to control insulin-dependent diabetes mellitus (DIABETES MELLITUS, TYPE 1). Iletin,Insulin A Chain,Insulin B Chain,Insulin, Regular,Novolin,Sodium Insulin,Soluble Insulin,Chain, Insulin B,Insulin, Sodium,Insulin, Soluble,Regular Insulin
D007334 Insulin-Like Growth Factor I A well-characterized basic peptide believed to be secreted by the liver and to circulate in the blood. It has growth-regulating, insulin-like, and mitogenic activities. This growth factor has a major, but not absolute, dependence on GROWTH HORMONE. It is believed to be mainly active in adults in contrast to INSULIN-LIKE GROWTH FACTOR II, which is a major fetal growth factor. IGF-I,Somatomedin C,IGF-1,IGF-I-SmC,Insulin Like Growth Factor I,Insulin-Like Somatomedin Peptide I,Insulin Like Somatomedin Peptide I
D007335 Insulin-Like Growth Factor II A well-characterized neutral peptide believed to be secreted by the LIVER and to circulate in the BLOOD. It has growth-regulating, insulin-like and mitogenic activities. The growth factor has a major, but not absolute, dependence on SOMATOTROPIN. It is believed to be a major fetal growth factor in contrast to INSULIN-LIKE GROWTH FACTOR I, which is a major growth factor in adults. IGF-II,Multiplication-Stimulating Activity,Somatomedin MSA,IGF-2,Insulin Like Growth Factor II,Insulin-Like Somatomedin Peptide II,Multiplication-Stimulating Factor,Somatomedin A,Factor, Multiplication-Stimulating,Insulin Like Somatomedin Peptide II,Multiplication Stimulating Activity,Multiplication Stimulating Factor
D008099 Liver A large lobed glandular organ in the abdomen of vertebrates that is responsible for detoxification, metabolism, synthesis and storage of various substances. Livers
D011919 Rats, Inbred Strains Genetically identical individuals developed from brother and sister matings which have been carried out for twenty or more generations or by parent x offspring matings carried out with certain restrictions. This also includes animals with a long history of closed colony breeding. August Rats,Inbred Rat Strains,Inbred Strain of Rat,Inbred Strain of Rats,Inbred Strains of Rats,Rat, Inbred Strain,August Rat,Inbred Rat Strain,Inbred Strain Rat,Inbred Strain Rats,Inbred Strains Rat,Inbred Strains Rats,Rat Inbred Strain,Rat Inbred Strains,Rat Strain, Inbred,Rat Strains, Inbred,Rat, August,Rat, Inbred Strains,Rats Inbred Strain,Rats Inbred Strains,Rats, August,Rats, Inbred Strain,Strain Rat, Inbred,Strain Rats, Inbred,Strain, Inbred Rat,Strains, Inbred Rat
D011956 Receptors, Cell Surface Cell surface proteins that bind signalling molecules external to the cell with high affinity and convert this extracellular event into one or more intracellular signals that alter the behavior of the target cell (From Alberts, Molecular Biology of the Cell, 2nd ed, pp693-5). Cell surface receptors, unlike enzymes, do not chemically alter their ligands. Cell Surface Receptor,Cell Surface Receptors,Hormone Receptors, Cell Surface,Receptors, Endogenous Substances,Cell Surface Hormone Receptors,Endogenous Substances Receptors,Receptor, Cell Surface,Surface Receptor, Cell
D002478 Cells, Cultured Cells propagated in vitro in special media conducive to their growth. Cultured cells are used to study developmental, morphologic, metabolic, physiologic, and genetic processes, among others. Cultured Cells,Cell, Cultured,Cultured Cell
D006863 Hydrogen-Ion Concentration The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH pH,Concentration, Hydrogen-Ion,Concentrations, Hydrogen-Ion,Hydrogen Ion Concentration,Hydrogen-Ion Concentrations
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D013002 Somatomedins Insulin-like polypeptides made by the liver and some fibroblasts and released into the blood when stimulated by SOMATOTROPIN. They cause sulfate incorporation into collagen, RNA, and DNA synthesis, which are prerequisites to cell division and growth of the organism. Sulfation Factor,Somatomedin,Factor, Sulfation

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