Functional expression of the rat pancreatic islet glucose-dependent insulinotropic polypeptide receptor: ligand binding and intracellular signaling properties. 1995

M B Wheeler, and R W Gelling, and C H McIntosh, and J Georgiou, and J C Brown, and R A Pederson
Department of Medicine, University of Toronto, Ontario, Canada.

Incretins are endogenous peptides released from the gastrointestinal tract into the circulation during a meal that potentiate glucose-stimulated insulin secretion. At present, there are two established incretins: glucose-dependent insulinotropic polypeptide (GIP) and the truncated glucagon-like peptides (tGLPs), which are now being investigated for use in the treatment of diabetes mellitus. In the present study we cloned a rat islet GIP receptor complementary DNA (GIP-R1) to answer several important questions regarding the ligand-binding and intracellular signaling properties of the GP receptor. GIP-R1, when expressed transiently in monkey kidney (COS-7) or stably in Chinese hamster ovary (CHO-K1) cells, demonstrated comparable high affinity binding for either synthetic porcine (sp) GIP or synthetic human (sh) GIP. The IC50 values for displacement of [125I]spGIP in CHO-K1 cells were 2.6 +/- 0.8 and 3.1 +/- 0.9 nM for two different preparations of shGIP, and 3.7 +/- 1.5 and 3.6 +/- 0.4 nM for two preparations of spGIP. Saturation isotherms obtained with both intact cells and membranes gave monophasic binding curves with apparent Kd values of 204 +/- 17 and 334 +/- 94 pM, respectively. Cells expressed 12-15 x 10(3) receptors/cell. In COS-7 cells, spGIP and shGIP also exhibited similar IC50 values (7.6 +/- 1.2 and 8.9 +/- 1.8 nM, respectively). The receptor in CHO-K1 cells bound GIP-(1-30) with lower affinity (IC50 = 39 +/- 17 nM), whereas the fragments GIP-(19-30), GIP-(18-28), and GIP-(21-26) showed no apparent binding. The specificity of the receptor was further examined using several structurally related peptides. Surprisingly, exendin-(9-39) [Ex-(9-39)], a GLP-1 receptor antagonist, and Ex-4-(1-39), a GLP-1 receptor agonist, demonstrated some affinity for the GIP receptor, with 39% and 21% displacement of [125I]spGIP, respectively, at 1 microM. Other members of the secretin/vasoactive intestinal peptide family of peptides tested showed no interaction. GIP-R1 receptor binding correlated with activation of the adenylyl cyclase system, whereby spGIP and shGIP evoked concentration-dependent increases in cAMP accumulation with EC50 values of 8.7 +/- 1.5 x 10(-10)M and 8.1 +/- 1.6 x 10(-10)M for spGIP and shGIP, respectively. Increases in cAMP in the presence of 10 nM spGIP were not dependent on the ambient glucose concentration, with 22- and 18-fold increases in cAMP accumulation at 0.1 and 5.5 mM glucose, respectively.(ABSTRACT TRUNCATED AT 400 WORDS)

UI MeSH Term Description Entries
D007515 Islets of Langerhans Irregular microscopic structures consisting of cords of endocrine cells that are scattered throughout the PANCREAS among the exocrine acini. Each islet is surrounded by connective tissue fibers and penetrated by a network of capillaries. There are four major cell types. The most abundant beta cells (50-80%) secrete INSULIN. Alpha cells (5-20%) secrete GLUCAGON. PP cells (10-35%) secrete PANCREATIC POLYPEPTIDE. Delta cells (~5%) secrete SOMATOSTATIN. Islands of Langerhans,Islet Cells,Nesidioblasts,Pancreas, Endocrine,Pancreatic Islets,Cell, Islet,Cells, Islet,Endocrine Pancreas,Islet Cell,Islet, Pancreatic,Islets, Pancreatic,Langerhans Islands,Langerhans Islets,Nesidioblast,Pancreatic Islet
D008969 Molecular Sequence Data Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories. Sequence Data, Molecular,Molecular Sequencing Data,Data, Molecular Sequence,Data, Molecular Sequencing,Sequencing Data, Molecular
D011964 Receptors, Gastrointestinal Hormone Cell surface proteins that bind gastrointestinal hormones with high affinity and trigger intracellular changes influencing the behavior of cells. Most gastrointestinal hormones also act as neurotransmitters so these receptors are also present in the central and peripheral nervous systems. Gastrointestinal Hormone Receptors,Intestinal Hormone Receptors,Receptors, Gastrointestinal Peptides,Gastrointestinal Hormone Receptor,Intestinal Hormone Receptor,Receptors, Gastrointestinal Hormones,Receptors, Intestinal Hormone,Gastrointestinal Hormones Receptors,Gastrointestinal Peptides Receptors,Hormone Receptor, Gastrointestinal,Hormone Receptor, Intestinal,Hormone Receptors, Gastrointestinal,Hormone Receptors, Intestinal,Hormones Receptors, Gastrointestinal,Peptides Receptors, Gastrointestinal,Receptor, Gastrointestinal Hormone,Receptor, Intestinal Hormone
D002118 Calcium A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes. Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D002460 Cell Line Established cell cultures that have the potential to propagate indefinitely. Cell Lines,Line, Cell,Lines, Cell
D003924 Diabetes Mellitus, Type 2 A subclass of DIABETES MELLITUS that is not INSULIN-responsive or dependent (NIDDM). It is characterized initially by INSULIN RESISTANCE and HYPERINSULINEMIA; and eventually by GLUCOSE INTOLERANCE; HYPERGLYCEMIA; and overt diabetes. Type II diabetes mellitus is no longer considered a disease exclusively found in adults. Patients seldom develop KETOSIS but often exhibit OBESITY. Diabetes Mellitus, Adult-Onset,Diabetes Mellitus, Ketosis-Resistant,Diabetes Mellitus, Maturity-Onset,Diabetes Mellitus, Non-Insulin-Dependent,Diabetes Mellitus, Slow-Onset,Diabetes Mellitus, Stable,MODY,Maturity-Onset Diabetes Mellitus,NIDDM,Diabetes Mellitus, Non Insulin Dependent,Diabetes Mellitus, Noninsulin Dependent,Diabetes Mellitus, Noninsulin-Dependent,Diabetes Mellitus, Type II,Maturity-Onset Diabetes,Noninsulin-Dependent Diabetes Mellitus,Type 2 Diabetes,Type 2 Diabetes Mellitus,Adult-Onset Diabetes Mellitus,Diabetes Mellitus, Adult Onset,Diabetes Mellitus, Ketosis Resistant,Diabetes Mellitus, Maturity Onset,Diabetes Mellitus, Slow Onset,Diabetes, Maturity-Onset,Diabetes, Type 2,Ketosis-Resistant Diabetes Mellitus,Maturity Onset Diabetes,Maturity Onset Diabetes Mellitus,Non-Insulin-Dependent Diabetes Mellitus,Noninsulin Dependent Diabetes Mellitus,Slow-Onset Diabetes Mellitus,Stable Diabetes Mellitus
D005749 Gastric Inhibitory Polypeptide A gastrointestinal peptide hormone of about 43-amino acids. It is found to be a potent stimulator of INSULIN secretion and a relatively poor inhibitor of GASTRIC ACID secretion. Glucose-Dependent Insulinotropic Peptide,Gastric-Inhibitory Polypeptide,Glucose Dependent Insulinotropic Peptide,Glucose-Dependent Insulin-Releasing Peptide,Glucose Dependent Insulin Releasing Peptide,Inhibitory Polypeptide, Gastric,Insulin-Releasing Peptide, Glucose-Dependent,Insulinotropic Peptide, Glucose-Dependent,Peptide, Glucose-Dependent Insulin-Releasing,Peptide, Glucose-Dependent Insulinotropic,Polypeptide, Gastric Inhibitory,Polypeptide, Gastric-Inhibitory
D000242 Cyclic AMP An adenine nucleotide containing one phosphate group which is esterified to both the 3'- and 5'-positions of the sugar moiety. It is a second messenger and a key intracellular regulator, functioning as a mediator of activity for a number of hormones, including epinephrine, glucagon, and ACTH. Adenosine Cyclic 3',5'-Monophosphate,Adenosine Cyclic 3,5 Monophosphate,Adenosine Cyclic Monophosphate,Adenosine Cyclic-3',5'-Monophosphate,Cyclic AMP, (R)-Isomer,Cyclic AMP, Disodium Salt,Cyclic AMP, Monoammonium Salt,Cyclic AMP, Monopotassium Salt,Cyclic AMP, Monosodium Salt,Cyclic AMP, Sodium Salt,3',5'-Monophosphate, Adenosine Cyclic,AMP, Cyclic,Adenosine Cyclic 3',5' Monophosphate,Cyclic 3',5'-Monophosphate, Adenosine,Cyclic Monophosphate, Adenosine,Cyclic-3',5'-Monophosphate, Adenosine,Monophosphate, Adenosine Cyclic
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
D001483 Base Sequence The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence. DNA Sequence,Nucleotide Sequence,RNA Sequence,DNA Sequences,Base Sequences,Nucleotide Sequences,RNA Sequences,Sequence, Base,Sequence, DNA,Sequence, Nucleotide,Sequence, RNA,Sequences, Base,Sequences, DNA,Sequences, Nucleotide,Sequences, RNA

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