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)

Transcripts of the somatostatin receptor subtypes sst3 and sst2 are expressed in meninges from rat brain as well as in immunocytochemical pure rat meningeal cells and rat fibroblasts in culture. mRNA of three other subtypes tested are absent or detected in trace amounts by reverse transcription-polymerase chain reaction. Presence of active receptors on the surface of meningeal cells and fibroblasts could be verified by direct visualisation of binding sites by affinity labelling with a somatostatin gold conjugate. The metabolically stable somatostatin agonist SMS 201-995 (octreotide) had a time-dependent effect on the [3H]thymidine incorporation by meningeal cells: after 2-5 h, the agonist inhibited cell proliferation to about 80% of controls, after 24 h proliferation was stimulated to about 150% of controls. Apart from being targets for somatostatin, meningeal cells had a high capacity to inactivate the peptide by proteolytic degradation. By analysis of cleavage sites and use of specific inhibitors, endopeptidase-24.11 ('enkephalinase', neutral endopeptidase, neprilysin, EC 3.4.24.11) was identified to be responsible for the initial catabolism of the peptide whereas aminopeptidase(s) truncated the fragments. Thus, meningeal cells express transcripts of multiple somatostatin receptor subtypes and produce peptidases that inactivate the neuropeptide somatostatin.
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PMID:Meningeal cells are targets and inactivation sites for the neuropeptide somatostatin. 907 71

We investigated whether yeast signals could regulate hormone processing in mammalian cells. Chmeric genes coding for the prepro region of yeast alpha-factor and the functional hormone region of anglerfish somatostatin was expressed in rat pituitary GH(3) cells. The nascent prepro-alpha-factor-somatostatin peptides disappeared from cells with a half-life of 30 min, and about 20% of unprocessed precursors remained intracellular after a 2 h chase period. Disappearance of propeptide was insensitive to lysosomotropic agents, but was inhibited at 15 degrees C or 20 degrees C, suggesting that the hybrid propeptides were not degraded in the secretory pathway to the trans Golgi network or in lysosomes. It appeared that while most unprocessed precursors were constitutively secreted into the medium, a small portion were processed at their paired dibasic sites by prohormone-processing enzymes located in trans Golgi network/secretory vesicles, resulting in the production of mature somatostatin peptides. To test this hypothesis, we investigated the processing pattern of two different hybrid precursors: the 52-1 hybrid precursor, which has a Glu-Ala spacer between the prepro region of alpha-factor and somatostatin, and the 58-1 hybrid precursor, which lacks the Glu-Ala spacer. Processing of metabolically labeled hybrid propeptides to smaller somatostatin peptides was assessed by HPLC. When pulse-labeled cells were chased for up to 2 h, 68% of the initially synthesized propeptides were secreted constitutively. About 22% of somatostatin-related products were proteolytically processed to mature somatostatin, of which 38.7% were detected intracellularly after 2 h. From N-terminal peptide sequence determination of somatostatin-related products in GH(3)-52 and GH(3)-58 cells, we found that both hybrid precursors were accurately cleaved at their dibasic amino acid sites. Notably, we also observed that the Glu-Ala spacer sequence was removed from 52-1 hybrid precursors. The latter result strongly suggests that a novel dipeptidyl aminopeptidase activity - a yeast STE13-like enzyme - is present in the post-trans Golgi network compartment of GH(3) cells. The data from these studies indicate that mechanisms which control protein secretion are conserved between yeast and mammalian cells.
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PMID:Evidence of a novel dipeptidyl aminopeptidase in mammalian GH(3) cells: new insights into the processing of peptide hormone precursors. 1220 45

Biometric parameters, glycemia and activity levels of plasma neutral aminopeptidase (APN) and dipeptidyl peptidase IV (DPPIV) were measured in monosodium glutamate obese and food-deprived rats (MSG-FD), to analyze the involvement of these enzymes in such situations. Plasma APN was distinguished as sensitive (PSA) (K(m) = 7.8 x 10(-5) mol/l) and predominantly insensitive (APM) (K(m) = 21.6 x 10(-5) mol/l) to puromycin, whereas DPPIV was sensitive (DPPIV-DS) (K(m) = 0.24 x 10(-5) mol/l) and predominantly insensitive (DPPIV-DI) (K(m) = 7.04 x 10(-5) mol/l) to diprotin A. Although unchanged in the MSG and food-deprived animals, APM activity levels were closely correlated with body mass, Lee index, and mass of retroperitoneal fat pad in the food deprived, but not in the MSG animals. DPPIV-DI activity levels decreased by 33% and were correlated with body mass, Lee index, and mass of periepididymal fat pad in the food-deprived MSG rats. These data suggest that APM and DPPIV-DI are respectively related to the downregulation of somatostatin in food-deprived rats, and to the recovery of energy balance in MSG obese rats during food deprivation.
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PMID:Neutral aminopeptidase and dipeptidyl peptidase IV activities in plasma of monosodium glutamate obese and food-deprived rats. 1987 9

To investigate dietary protein level effects on digestive mechanisms, weaned piglets were fed for 45 d with diets containing 20%, 17%, or 14% crude protein (CP) supplemented to meet requirements for essential amino acids. This article describes the influence of dietary protein on gastrointestinal hormones and expression of an array of digestive enzymes in the gastrointestinal tract and pancreas. Results indicated that there were no significant differences in expression of enzymes involved in carbohydrate digestion, except for maltase in the duodenum. In the jejunum, amylase expression in pigs fed 20% CP was much higher than that in pigs fed other diets (P<0.05) and maltase expression in those fed 17% CP was higher than that in other treatments (P<0.05). Although there were no remarkable differences in expression of aminopeptidase in the small intestine or carboxypeptidase in the pancreas (P>0.05), there was a trend towards higher expression of various proteases in pigs fed 17% CP. The duodenal expression of enteropeptidase in diets with 14% and 17% CP was significantly higher than that with 20% CP (P<0.05), but treatment differences did not existed in jejunum (P>0.05). The expression of GPR93 as a nutrient-responsive G protein-coupled receptor in 14% and 17% CP diets was significantly higher than that in 20% CP diet in the small intestine (P<0.05). The expressions of genes for pancreatic enzymes, lipase and elastase, were significantly higher in pigs fed diets with low CP, while similar trends occurred for carboxypeptidase, chymotrypsin and amylase. Conversely, the gastric expressions of pepsinogen A and progastricsin were lower with the 17% CP diet. Differences between treatments were found in the gastric antral contents of cholecystokinin and somatostatin: both increased in pigs fed 17% CP, accompanied by decreased content of motilin, which was also seen in plasma concentrations. These patterns were not reflected in duodenal contents. In general, 17% dietary CP was beneficial to the digestion of nutrient substance in the gastrointestinal tract.
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PMID:Influence of low protein diets on gene expression of digestive enzymes and hormone secretion in the gastrointestinal tract of young weaned piglets. 2770 44


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