Glucagon-like peptide-1 (GLP-1) releases thyrotropin (TSH): characterization of binding sites for GLP-1 on alpha-TSH cells
Autor: | S.R. Bloom, David M. Smith, J D Hurley, S. A. Beak, Caroline J. Small, I Ilovaiskaia, M. A. Ghatei |
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Rok vydání: | 1996 |
Předmět: |
Male
endocrine system medicine.medical_specialty Thyrotropin Peptide Polymerase Chain Reaction Cell Line Cell membrane Endocrinology Pituitary Gland Anterior Internal medicine medicine Cyclic AMP Animals Binding site Rats Wistar Receptor Caenorhabditis elegans Proteins chemistry.chemical_classification Messenger RNA Binding Sites Membrane Glycoproteins Receptors Notch digestive oral and skin physiology Rats Dissociation constant Blotting Southern medicine.anatomical_structure Membrane Cross-Linking Reagents Biochemistry chemistry hormones hormone substitutes and hormone antagonists Intracellular |
Zdroj: | Endocrinology. 137(10) |
ISSN: | 0013-7227 |
Popis: | We have demonstrated specific binding sites for [125I]glucagon-like peptide 1 (GLP-1) on membranes from the rodent thyrotrope cell line, alpha-TSH. Specific [125I]GLP-1 binding was saturable and time dependent. Equilibrium saturation binding analysis was consistent with the presence of a single class of binding site (binding capacity, 85 +/- 7 fmol/mg protein) with a dissociation constant (Kd) of 28 +/- 13 pM. The specific GLP-1 receptor agonists, exendin-4 and exendin-3, and the antagonist, exendin-(9-39), bound to the receptor sites with high affinity (Ki = 190 +/- 70 pM; 130 +/- 50 and 1200 +/- 470 pM, respectively). Chemical cross-linking of [125I]GLP-1-receptor complexes revealed a single band of 64,300 +/- 100 Mr in alpha-TSH membranes. In addition, specific PCR studies demonstrated the presence of GLP-1 receptor messenger RNA. Binding of the peptide to alpha-TSH cell membranes resulted in increased intracellular cAMP concentrations (10 nM GLP-1, 1010 +/- 83 pmol/10(6) cells.h; control, 175 +/- 60 pmol/10(6) cells.h; P0.002), indicating that the receptor is linked to stimulation of adenylyl cyclase. GLP-1-mediated increases in cAMP were inhibited by exendin-(9-39) in a dose-dependent manner. Furthermore, GLP-1 stimulates basal TSH release from dispersed anterior pituitary cells in a concentration-dependent manner (100 nM GLP-1, 63 +/- 3 fmol/10(6) cells.h; control, 35 +/- 1 fmol/10(6) cells.h; P0.0005), but had no effect on basal PRL, GH, or LH release. |
Databáze: | OpenAIRE |
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