Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: UNIPROT:P61278 (somatostatin)
22,083 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The morphological and functional characteristics of the endocrine cells of the oxyntic (acid-secreting) mucosa of the human stomach, a target of the trophic effect of gastrin, are reviewed. In healthy subjects these cells account for 0.90 +/- 0.35% of the volume of the entire mucosa and for 1.21 +/- 0.44% of the volume of the epithelial mucosal component alone. The cells show no extension to the glandular lumen and show an intimate anatomic relationship with contiguous non-endocrine epithelial cells. This configuration indicates undefined local functions of the paracrine type not influenced by the gastric lumen content. Seven cell types were identified ultrastructurally, three of which (enterochromaffin-like (ECL), P and D) cumulatively account for more than 75% of the total endocrine cell mass. The secretory product(s) of the endocrine cells has not been demonstrated definitively with the exception of minor cell populations producing glucagon (only in the fetal life), somatostatin and 5-HT. Recently, production of histamine and glycoprotein hormone alpha-subunit by oxyntic endocrine cells of man have been reported. However, histamine seems to occur in these cells normally, whereas the production of glycoprotein hormone alpha-subunit appears to be virtually restricted to cells of patients with hypergastrinaemic conditions.
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PMID:Structure and function of endocrine cells in the oxyntic (acid-secreting) mucosa of human stomach. 269 Mar 28

Pancreatic tissue of the channel catfish (Ictalurus punctatus) contains two somatostatins. The amino acid sequence of a 14-residue containing peptide (SS-14) is identical in sequence and has the same mass ion by fast atom bombardment mass spectrometry as mammalian SS-14. A 22-residue somatostatin (SS-22) has also been isolated and its amino acid sequence determined. The amino acid sequence differs from that reported by Oyama et al. (J Biol Chem 255:2251, 1980) in two of the 22-residues (positions 5 and 19). Somatostatin-22 is a glycoprotein, with carbohydrate attached at Thr-5. Several 22-residue peptides have been purified and all of them have identical amino acid compositions and different carbohydrate structure and/or composition. SS-22 has 7 amino acid residues which are identical to those observed in SS-14. The nucleotide sequence of the two cDNAs coding for SS-14 and SS-22 have been determined. The mRNAs encode precursors to SS-14 and SS-22 of 114 and 105 residues, respectively. The two precursors also have different amino acid sequence at the site of prohormone proteolytic processing. Analysis of genomic DNA reveals that SS-14 and SS-22 sequences are present on different restriction fragments and thus are encoded by separate genes.
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PMID:Somatostatins of the channel catfish. 286 31

The receptor for somatostatin present in rat pancreatic plasma membranes was characterized by affinity labeling with [125I-Tyr11]somatostatin utilizing three different heterobifunctional cross-linking agents: N-5-azido-2-nitrobenzoyloxy-succinimide, N-succinimidyl 6-(4-azido 2'-nitrophenylamine)hexanoate, and N-hydroxysuccinimidyl 4-azido-benzoate. Analysis by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography revealed a broad band of Mr = 92,000 when any of the three cross-linkers was used; N-succinimidyl 6-(4-azido 2'-nitrophenylamine), however, was most efficient. Labeling of the Mr = 92,000 protein band was not affected by reducing agents but was sensitive to somatostatin and guanine nucleotides, particularly GTP gamma S, at concentrations which reduced binding to the receptor. The affinity-labeled protein could be solubilized completely with Zwittergent 3-12, partially with Triton X-100 and 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid, and poorly with Zwittergent 3-08 and digitonin. When exposed to agarose-coupled lectins, the detergent solubilized, labeled Mr = 92,000 protein was completely adsorbed to wheat germ agglutinin, partially to ricin communis II, and not at all to concanavalin A or lotus or lentil lectin. The Mr = 92,000 protein bound to wheat germ agglutinin-agarose was not eluted by N-acetylglucosamine but was by triacetylchitotriose, providing a considerable purification of the somatostatin receptor. These data allow us to conclude that the somatostatin receptor is a monomeric glycoprotein with an Mr = 90,000 binding subunit which probably contains a polymeric arrangement of N-acetylglucosamine residues.
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PMID:Characterization of covalently cross-linked pancreatic somatostatin receptors. 287 90

To structurally characterize the somatostatin receptor in the anterior pituitary, the chemical cross-linking reagent N-5-azido-nitrobenzoyloxysuccinimide was used to attach covalently [125I-Tyr11]somatostatin-14 to its receptor in pituitary membranes. Rat anterior pituitary membranes were incubated with [125I-Tyr11]somatostatin-14, washed, and then treated with 100 microM cross-linker, which was activated by exposure to UV light. Gel electrophoresis followed by autoradiography revealed a broad band centered at 88,000 mol wt. The appearance of this band was unaffected by dithiothreitol. Competitive inhibition of binding by unlabeled somatostatin resulted in a parallel inhibition of labeling of the 88,000 mol wt protein. The addition of guanine nucleotides in concentrations that inhibit binding similarly inhibited cross-linking. The cross-linked membranes were solubilized in Zwittergent 3-12, a nondenaturing detergent, and the glycosylation pattern of the labeled protein was investigated by incubation with various lectins coupled to agarose. The cross-linked protein was selectively adsorbed by wheat germ agglutinin, and this interaction was blocked by the addition of N,N',N"-triacetylchitotriose, indicating that the rat anterior pituitary somatostatin receptor is a glycoprotein containing polymeric beta-1-4 linked N-acetylglucosamine groups. The results of this study show that the rat anterior pituitary somatostatin receptor is a glycoprotein of 88,000 mol wt containing no disulfide-linked subunits.
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PMID:Structural characterization of the somatostatin receptor in rat anterior pituitary membranes. 288 81

Somatostatin binding and cross-linking to its receptors on rat cerebrocortical membranes were characterized with [125I-Tyr1]somatostatin-14 and [125I-Leu8, D-Trp22, Tyr25]somatostatin-28. When [125I-Tyr1]somatostatin-14 was cross-linked to its receptors with the photoreactive cross-linker, N-(5-azido-2-nitrobenzoyloxy)succinimide, the hormone was specifically associated with a Mr = 72,000 protein band in the presence or absence of reducing agents. Affinity labeling of the Mr = 72,000 protein band was decreased with increasing concentrations of unlabeled somatostatin-14 and nonhydrolyzable guanine nucleotide analog, guanyl-5'-yl imidodiphosphate (Gpp(NH)p). Pretreatment of cerebrocortical membranes with islet-activating protein resulted in a decrease in subsequent labeled somatostatin-14 binding and affinity-labeling of the protein and abolished an inhibitory effect of somatostatin-14 on vasoactive intestinal peptide-stimulated increase in adenylate cyclase activity. When the affinity-labeled protein was solubilized with Zwittergent 3-12 and adsorbed to wheat germ agglutinin-agarose, it was eluted by N-acetylglucosamine. [125I-Leu8, D-Trp22, Tyr25]somatostatin-28 cross-linking to cerebrocortical and pancreatic membranes with the same photoreactive agent revealed specifically labeled protein bands of a Mr = 74,000 in cerebrocortical membranes and a Mr = 94,000 in pancreatic membranes, respectively. These results suggest that: 1) somatostatin receptor on cerebrocortical membranes is a monomeric glycoprotein with a Mr = 70,000 binding subunit, coupled to guanine nucleotide regulatory protein, and 2) the Mr = 70,000 protein may be a common receptor for somatostatin-28 and somatostatin-14 and is distinct from a common pancreatic type receptor.
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PMID:Somatostatin receptors on rat cerebrocortical membranes. Structural characterization of somatostatin-14 and somatostatin-28 receptors and comparison with pancreatic type receptors. 290 82

The solubilization of somatostatin receptors from guinea-pig pancreas by different non-denaturing detergents was investigated after stabilization of the receptors by prior binding of 125I-[Tyr11]somatostatin or its analogue 125I-[Leu8,DTrp22,Tyr25]somatostatin 28, to pancreatic plasma membranes. The somatostatin-receptor complexes were solubilized in a high yield by Zwittergent 3-14 (3-[tetradecyldimethylammonio]-1-propanesulfonate), a zwitterionic detergent. Other detergents, digitonin, Triton X-100, Chaps (3-[cholamidopropyldimethylammonio]-1-propanesulfonate) and octyl beta-D-glycopyranoside, achieved only partial solubilization. The recovery of receptor complexes was increased by glycerol. In order to characterize solubilized somatostatin-receptor complexes, membranes receptors were covalently labelled using N-5-azido-2-nitrobenzoyloxysuccinimide as cross-linking reagent before solubilization. Gel filtration chromatography analysis resulted in the identification of a major protein component of apparent Mr = 93,000 which interacted with the two radioligands. In addition, a similar component of Mr = 88,000 was characterized after analysis by SDS-PAGE of membrane receptors covalently cross-linked with 125I-[Leu8,DTrp22,Tyr25]somatostatin 28 by different heterobifunctional reagents: N-5-azido-2-nitrobenzoyloxysuccinimide, N-hydroxysuccinimidyl 4-azidobenzoate, N-succinimidyl 6-(4'-azido-2'-nitrophenylamino)hexanoate. Optimal cross-linking results were obtained with N-5-azido-2-nitrobenzoyloxysuccinimide. The solubilized somatostatin-receptor complex was adsorbed to wheat-germ agglutinin-agarose column and eluted by specific sugars. We concluded that the guinea-pig pancreatic somatostatin receptor in the membrane and in the non-denaturing detergent solution behaves as a protein monomer of apparent Mr approximately 85,000-90,000. The somatostatin receptor is a glycoprotein which contains complex-type carbohydrate chains.
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PMID:Solubilization and characterization of guinea-pig pancreatic somatostatin receptors. 303 26

Continuous cell lines have been established from a variety of biopsy and postmortem species of tumor from patients with small-cell carcinoma of the lung (SCCL) and have been maintained over several years. The medium from the cultures has been assayed for peptide, glycoprotein, and steroid hormones. Significant amounts of 14 hormones including calcitonin, adrenocorticotropin (ACTH), parathormone, luteinizing hormone, chorionic gonadotropin, glucagon, growth hormone, somatostatin, prolactin, beta-endorpin, lipotropin, oxytocin-neurophysin, vasopressin-neurophysin, and estradiol have been demonstrated. Up to ten different hormones have been produced by a single cell line. Most produce ACTH and all evaluated so far produce estradiol. These studies indicate that cells from SCCL have a potential for producing a wide variety of hormones and that this characteristic can be maintained for prolonged periods of culture in vitro.
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PMID:Hormone production by cultures of small-cell carcinoma of the lung. 626 22

Goblet-cell carcinoids are particular mucus-producing tumors combining features of typical carcinoids and adenocarcinomas. The immunoreactivity of five goblet-cell carcinoids of the appendix and one tumor of the ileum for 5-hydroxytryptamine (5-HT, serotonin), glucagon, somatostatin, substance P (SP), neuron-specific enolase (NSE), lysozyme, secretory component (SC) and carcino-embryonic antigen (CEA) was compared with that of the mucosa of the appendix (n = 24) and ileum (n = 12), and of typical carcinoids (appendix: n = 10; ileum: n = 3). The goblet-cell carcinoids were consistently lysozyme-, SC- and CEA-reactive and contained weakly NSE reactive endocrine cells, while typical carcinoids were lysozyme-, SC- and CEA-negative, but strongly NSE- reactive. Two goblet-cell carcinoids were glucagon-reactive, one displayed SP-reactivity, one malignant tumor was reactive to the alpha-chain of glycoprotein hormones; six of ten typical appendix carcinoids were SP reactive, as were the three typical ileum carcinoids. Using the immunogold technique combined with the alcian-blue reaction, the presence of 5-hydroxytryptamine (5-HT) and mucus was demonstrated within the same cell. These findings suggest histogenetic differences between goblet-cell carcinoids and typical carcinoids; the former are possibly derived from undifferentiated stem cells, whereas the latter probably arise from endocrine cells in the mucosal stroma.
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PMID:Combined production of mucus, amines and peptides by goblet-cell carcinoids of the appendix and ileum. 648 83

Somatotroph adenomas of the pituitary secrete growth hormone in excess and are associated with acromegaly. Morphologically, they can be separated into two entities, densely and sparsely granulated variants. It has been shown that a number of somatotroph adenomas produce alpha-subunit of glycoprotein hormones; however, it is not clear whether alpha-subunit production correlates with tumor cell morphology. We studied 32 surgically removed pituitary somatotroph adenomas in tissue culture to determine structure-function correlations of growth hormone and alpha-subunit production. All tumors were classified on the basis of detailed histological, immunocytochemical and electron-microscopic studies. Fifteen tumors were densely granulated and 17 were sparsely granulated. In addition to growth hormone, all 15 densely granulated tumors released alpha-subunit in vitro, whereas of the 17 sparsely granulated tumors only 4 released alpha-subunit; moreover, the mean baseline levels of alpha-subunit were significantly higher in densely granulated adenomas than in sparsely granulated adenomas. Parallel response of release of both hormones was found during stimulation with growth hormone-releasing hormone or thyrotropin-releasing hormone and during suppression with somatostatin or bromocriptine in densely granulated tumors. alpha-subunit response to stimulation or suppression could not be determined with significance in sparsely granulated tumors because of low basal levels. The results indicate that alpha-subunit production and release is characteristic of densely granulated somatotroph adenomas and that alpha-subunit is coregulated with growth hormone by adenohypophysiotropic substances; in contrast, alpha-subunit production, by sparsely granulated somatotroph adenomas is rare and, when present, much lower in quantity.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Production of alpha-subunit of glycoprotein hormones by pituitary somatotroph adenomas in vitro. 810 89

The enterochromaffin-like (ECL) cell of the oxyntic, acid-secreting mucosa is at present the most extensively studied endocrine cell type in the gastrointestinal tract. It is functionally related to acid secretion through paracrine release of histamine. Its ability to undergo proliferation in response to the trophic stimulus of hypergastrinemia has important implications in pathology, being involved in the development of ECL-cell carcinoid tumors of rodents treated with powerful inhibitors of acid secretion as well as in that of most human gastric carcinoids which, with rare exceptions, are composed of ECL cells. The various aspects of the ECL-cell response to hypergastrinemia in humans are discussed in this review. The trophic effect of gastrin is specific for ECL cells and its sensitivity is enhanced by the female sex and by the genetic background of the multiple endocrine neoplasia type 1 (MEN-1) syndrome. Exposure of ECL cells to hypergastrinemia induces peculiar changes in the structure of cytoplasmic granules and triggers the phenotypic expression of a novel protein, the alpha subunit of glycoprotein hormones, absent in normal cells. The ECL-cell hyperplasia driven by hypergastrinemia may influence the hypersecretory gastric state of patients with Zollinger-Ellison syndrome (ZES) by inappropriate intramucosal secretion of histamine and may contribute to the high circulating levels of basic fibroblast growth factor (bFGF), an ECL-cell product responsible for parathyroid mitogenic effects in MEN-1 patients. However, hypergastrinemia per se cannot promote evolution of hyperplasia into carcinoid tumors, for which additional unknown factors, particularly associated with atrophic gastritis or MEN-1 syndrome, are required. ECL-cell carcinoids developing within these backgrounds have a strikingly more favorable course than their gastrin-independent counterpart. Suppression of hypergastrinemia, either by antrectomy or treatment with somatostatin analogues, may induce regression of both ECL-cell hyperplasia and gastrin-sensitive ECL-cell carcinoids.
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PMID:Hypergastrinemia and gastric enterochromaffin-like cells. 776 39


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