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)

A new strain, named WRT cells, has been generated from primary cultures of rat thyroids. The primary culture was grown in Coon's modified Ham's F12 medium with 5% calf serum, insulin, hydrocortisone, transferrin, somatostatin, glycyl-L-histidyl-L-lysine and thyrotropin (TSH). On the basis of the following facts, the WRT cell strain, cloned from the primary culture, was considered 'normal': the cells are euploid, not carcinogenic, not able to grow in soft agar, and show contact inhibition. Their differentiated functions consist of the ability to synthesize thyroglobulin and to take up iodide, and they have a TSH-dependent adenylate cyclase system. TSH increases cellular adenosine 3',5'-cyclic monophosphate (cAMP) levels and [3H]thymidine incorporation in WRT cells from a concentration similar to that active on another clonal rat cell line (FRTL-5), even though the cell replication appears to be differently regulated in the two cell strains. In fact, the WRT cell doubling time is 42 h and they are also able to grow in the absence of TSH, though more slowly. In the same conditions, FRTL-5 cells have a population doubling time of 38 h, but they are not able to grow in the absence of TSH. When the effect of the other growth factors of the medium was studied, insulin appears to be a growth stimulus by itself, while it is only a facilitative step for TSH action in FRTL-5 cells. WRT cells, unlike FRTL-5 cells, can grow with a population doubling time of 80 h, when cultured for prolonged periods in a medium with a low serum concentration (0.5%), but containing insulin plus TSH. In conclusion, the WRT cell strain is a new and interesting experimental model for studying growth factors at the level of the thyroid, especially for their mechanism of action on the TSH receptor.
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PMID:Insulin stimulates cell growth of a new strain of differentiated rat thyroid cells. 282 50

A novel 28-residue somatostatin (SS) has been isolated from anglerfish pancreatic islets and characterized by complete Edman degradation, peptide mapping, and amino acid analysis. The primary structure of this anglerfish SS-28 (aSS-28) containing hydroxylysine (Hyl) was established to be H-Ser-Val-Asp-Ser-Thr-Asn-Asn-Leu-Pro-Pro-Arg-Glu-Arg-Lys-Ala-Gly-Cys- Lys-Asn-Phe-Tyr-Trp-Hyl-Gly-Phe-Thr-Ser-Cys-OH. This sequence (with the exception of hydroxylysine-23, which is replaced by lysine) is identical to the sequence of the COOH-terminal 28 residues of prepro-SS II predicted on the basis of cDNA analysis [Hobart, P., Crawford, R., Shen, L., Pictet, R. & Rutter, W. J. (1980) Nature (London) 288, 137-141]. This is the first instance in which hydroxylysine (to date characteristically observed in collagen or collagen-like structures) has been found in a potential regulatory peptide. Chromatographic characterization of peptides, radiolabeled in islet culture, revealed that aSS-28 contained 10-12% of the radioactivity incorporated into the 8000- to 1000-dalton SS-like polypeptides, whereas 88-90% of this radioactivity was detected in anglerfish SS-14. It appears probable that aSS-28 represents the predominant primary cleavage product derived from prepro-SS II by cleavage at the COOH-terminal side of a single arginine. Based on knowledge of the collagen biosynthesis, it is speculated that hydroxylation may take place as an early post-translational event.
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PMID:Processing of an anglerfish somatostatin precursor to a hydroxylysine-containing somatostatin 28. 285 89

To characterize the functional aspect of prolactin (Prl) cells coexisting with corticotroph adenomas, pituitary adenoma cells obtained from a patient with Cushing's disease and a patient with Nelson's syndrome, who were associated with hyperprolactinaemia, were cultured in monolayer and their Prl responses to various secretagogues were compared with those of prolactinoma cells in culture. Immunohistochemistry performed in one of these two adenomas demonstrated the presence of Prl-containing cells in addition to ACTH cells. When ACTH-Prl adenoma cells were exposed to ovine corticotrophin-releasing factor (CRF), a dose-dependent increase in both ACTH and Prl secretion was observed, which was blocked by coincubation with hydrocortisone. In contrast, no stimulatory effect of CRF on Prl release was observed in all of the experiments using prolactinoma cells. Thyrotrophin-releasing hormone, which consistently stimulated Prl secretion in ACTH-Prl adenomas, was effective in triggering Prl release in only 25% of the prolactinomas. Exposure of the cultured cells to lysine vasopressin, growth hormone-releasing factor and vasoactive intestinal peptide resulted in an increase in ACTH and Prl secretion in one ACTH-Prl adenoma, however, none of the prolactinomas responded to these stimuli to secrete Prl. Dopamine and somatostatin, on the other hand, uniformly suppressed Prl secretion from ACTH-Prl adenomas as well as from prolactinoma cells. These results suggest that the mode of Prl secretion by mixed ACTH-Prl pituitary adenomas is not identical to that by pure prolactinomas and is, at least in part, common to that of ACTh secretion.
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PMID:Prolactin secretion by mixed ACTH-prolactin pituitary adenoma cells in culture. 285 25

It has been predicted on the basis of cDNA sequence analysis that anglerfish pancreatic islets contain at least two different preprosomatostatins (I and II). The C-terminal amino acid sequences of preprosomatostatin I and II were predicted to be identical to mammalian hypothalamic somatostatin-14 (SS-14) and its analog [Tyr7, Gly10]SS-14, respectively. That SS-14 is expressed in anglerfish pancreatic islets, has been shown earlier in pulse-chase experiments and by chemical characterization. However, it was observed that [Tyr7, Gly10]SS-14 was not expressed as such, but as part of larger polypeptides. Pulse-chase experiments combined with reverse-phase high pressure liquid chromatography, amino acid analysis with two different chromatographic systems, and complete Edman degradation indicated that preprosomatostatin II is processed in anglerfish islets to two different forms of somatostatin-28 (SS-28). The primary structure of the major form containing hydroxylysine (Hyl) was determined to be: H-Ser-Val-Asp-Ser-Thr-Asn-Asn-Leu-Pro-Pro-Arg- Glu-Arg-Lys-Ala-Gly-Cys-Lys-Asn-Phe-Tyr-Trp-Hyl-Gly-Phe-Thr-Ser-Cys-OH. The amino acid sequence of the minor form differs only at residue 23 by substitution of lysine for hydroxylysine. This is the first time that hydroxylysine, an amino acid which characteristically occurs in collagen or collagen-like structures has been identified in a potential regulatory peptide. It can be speculated that this amino acid is formed by post-translational hydroxylation of a lysine C-terminally linked to a glycine residue and thus modified at a site which has been recognized as hydroxylation site in collagen or collagen-like structures. The biological consequences of this unusual modification are being investigated.
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PMID:Anglerfish pancreatic islets produce two forms of somatostatin-28. 286 28

The effect of somatostatin (SRIH) on the release of growth hormone (GH) induced by lysine-vasopressin (LVP) was studied in six normal subjects. They were injected intravenously with 0.06 I. U./kg of LVP alone or in combination with SRIH (an intravenous bolus of 100 micrograms 10 minutes before LVP injection, followed by the constant infusion of 500 micrograms over 90 minutes). LVP strikingly increased serum concentrations of GH; this response was significantly reduced by the treatment with SRIH. This finding provides evidence that the effect of LVP on serum GH levels is sensitive to the inhibition by SRIH; it is proposed that the stimulating action of LVP on GH secretion might be mediated by the inhibition of endogenous SRIH.
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PMID:Inhibition by somatostatin of the release of growth hormone induced by lysine-vasopressin in normal subjects. 286 93

In previous work, radioimmunoassay was used to document the presence of somatostatin-like immunoreactive material in the rabbit retina. The present study was undertaken to determine the cellular localization of that material by light microscopic immunocytochemistry. Rabbit retinas were fixed by immersion in paraformaldehyde-lysine-periodate and reacted, either as whole retinas or as 50 microns Vibratome cross-sections, with an antiserum directed against somatostatin-14. Consistent staining of neuronal perikarya was seen only in the retinas of rabbits that had been pretreated with intravitreal injections of colchicine. Specifically stained cell bodies are present in the ganglion cell layer; the cells give rise to fibers in both the innermost and outermost sublaminas of the inner plexiform layer. In retinal whole mounts, the cells possess two or three primary dendrites with sparse branching. The dendritic fields are up to 1 mm in diameter, and adjacent dendritic fields overlap. Many cells have a thin varicose process arising from the soma or a proximal primary dendrite; these processes branch repeatedly within the retina and resemble intraretinal axons. The somatostatin-reactive cells may be associational ganglion cells or displaced amacrine cells; it is less likely that they are ganglion cells with axons projecting to the brain.
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PMID:Somatostatin immunocytochemistry in the rabbit retina. 286 4

Differentiation of the respiratory region of fetal mouse lungs was investigated in serum-free medium supplemented with growth factors and hormones. Terminal buds from the margins of a lobe were removed from 16-day fetuses and organ cultures prepared either in submersion culture or at the air-medium interface. It was found that glycyl-L-histidyl-L-lysine, transferrin, and somatostatin were sufficient to promote branching in the absence of serum. However, type II pneumocytes containing lamellar bodies formed only in the presence of thyroxine or dexamethasone. At concentrations of these hormones slightly above the physiological range most of the cells became cuboidal and contained lamellar bodies; at lower concentrations regions of flattened cells appeared. In submersion culture a large, central cavity surrounded by saccules was formed rather than a branched tree. Thus, the pattern of differentiation is significantly influenced by culture conditions.
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PMID:The effect of culture conditions on cytodifferentiation of fetal mouse lung respiratory passageways. 286 41

The effects of somatostatin on fasting and absorptive plasma ammonia and amino acids were studied in 12 cirrhotic patients. They received a 6 h intravenous infusion of somatostatin (500 micrograms/h) or saline, starting 90 min before protein feeding. During the fasting period somatostatin significantly reduced plasma ammonia (-18%) and total tryptophan (-39%), increased plasma leucine (+19%), isoleucine (+17%), glutamine (+22%), glycine (+13%), arginine (+14%) and lysine (+12%), and prevented the significant fall of phenylalanine (-8%), tyrosine (-6%), alanine (-8%) and threonine (-9%) seen with saline. The percent changes in ammonia and glutamine concentrations were inversely correlated (r = -80; p less than 0.001) After protein ingestion, somatostatin slowed the maximal plasma increase in ammonia and alpha-nitrogens by at least two hours, but their total 5 h plasma response was not reduced, and even, in some instances, significantly increased (valine, leucine, glutamine, alanine and serine) with respect to saline. The results suggest that in fasting cirrhotics somatostatin reduces plasma ammonia, probably through an impaired intestinal ammoniogenesis from circulating precursors, and inhibits the disposal of branched chain, aromatic (except tryptophan) and gluconeogenic amino acids. Furthermore, it delays, but does not reduce, the plasma increase in nitrogen after protein ingestion.
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PMID:Effects of somatostatin on plasma ammonia and amino acid profile during fasting and after protein feeding in cirrhotic patients. 287 93

Understanding of the biosynthesis of the somatostatin family of peptide hormones has greatly increased in recent years. Isolation and sequencing of the rat somatostatin gene indicates that it contains a single intron located between the codons for Gn(-57) and Glu(-56) of pre-prosomatostatin. The gene contains three repetitive sequences, one at the 5' end of the gene and two of them 3' to the coding portion. Two of the sequences consist of alternating purine-pyrimidine bases and have been shown to adopt Z-DNA structures in vitro. The cDNA for rat somatostatin codes for a 116-residue peptide structurally similar to the anglerfish and catfish precursors to the 14-residue somatostatin (SST-14). In addition to SST-14, the catfish and the anglerfish both contain an additional pancreatic somatostatin, each derived from a different gene. The catfish contains a 22-residue somatostatin, which is O-glycosylated at Thr-5. The second somatostatin gene from anglerfish encodes a prosomatostatin that is processed to a 28-residue peptide. The mature peptide contains a hydroxylated lysine at position 23.
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PMID:Biosynthesis and processing of the somatostatin family of peptide hormones. 287 3

The inhibitory effect of somatostatin (SRIF) on immunoreactive insulin release and on many other hormonal secretions has been widely studied in both animal and man. However, the mechanism by which SRIF acts on these functions remains poorly defined. Aim of this study is to determine the inhibitory effect of SRIF on insulin secretion induced by arginine after the administration of lysine acetylsalicylate (LAS) in a dose which inhibits the endogenous synthesis of prostaglandins. Ten healthy informed volunteer subjects were studied. Four studies were carried out in randomized order, each one separated by a three day interval. The first study was a test of arginine (25 g i.v. in 30 min). The second study was a test of arginine with SRIF infusion (150 micrograms bolus followed by 100 micrograms/h for 120 min). The third study was a test of arginine with an infusion of SRIF and LAS (66 mg/min for 120 min). The fourth study was a test of arginine with LAS infusion. Plasma insulin levels were determined by radioimmunoassay. After arginine administration the typical biphasic insulin response was observed with a precocious peak at 3 min and a late peak at 30 min. This response is not significantly modified under LAS infusion. With the infusion of SRIF at a dose of 100 micrograms/hr after arginine administration only a very modest insulin response was observed. The addition of LAS does not modify the inhibitory effect of SRIF on insulin secretion induced by arginine. This result demonstrates that the inhibitory action of SRIF on the secretion of insulin is not dependent upon the activation of the endocellular prostaglandin system.
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PMID:The effect of lysine acetylsalicylate on somatostatin inhibition of insulin secretion induced by arginine. 288 Jul 43


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