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PubMed1977

The secretion of glucose into the egg of Gallus domesticus and observations on the uterine secretion of cations.

1. The concentrations of glucose, K+, Na+ and Ca2+ were measured in the uterine fluid and albumen of eggs removed from the shell gland at intervals of from 6 to 20 h after the previous oviposition. 2. A steady increase in the concentrations of glucose and K+ occurred in the uterine fluid during the initial 13 h of the egg's sojourn in the gland, resulting in their diffusion into the albumen. Meanwhile Na+ concentrations of the fluid and albumen decreased. 3. After 14 h in the gland and until oviposition there was little change in the concentrations. 4. Uterine fluid drained artificially from the gland using a Perspex egg had lower glucose and K+, but higher Na+ concentrations than the normal fluid. 5. The rates of secretion of glucose and K+ measured with the artificial egg resembled their entry rates into the normal egg, but there was an apparent deficit in Ca2+ secretion.

Animals↗

PubMed1995

Maintained PC1 and PC2 expression in the AtT-20 variant cell line 6T3 lacking regulated secretion and POMC: restored POMC expression and regulated secretion after cAMP treatment.

Two variant cell lines were recently established from parent AtT-20 cells. Whereas HYA.15.10.T.2 have a reduced level of secretory granules, HYA.15.6.T.3 are completely devoid of both the regulated pathway of secretion and of dense-core secretory granules. AtT-20 cells normally express the processing enzymes PC1, PC2, furin, carboxypeptidase E, and peptidylglycine alpha-amidating monooxygenase, as well as proopiomelanocortin, chromogranin B, and 7B2. We measured the expression of these mRNAs in both variant cell lines. Although some differences in mRNA level were noted, HYA.15.10.T.2 and HYA.15.6.T.3 cell lines maintained their expression of the processing enzymes and of 7B2. Furthermore, PC1 and PC2 were shown to be functionally active in the HYA.15.6.T.3 cells. In contrast, proopiomelanocortin and chromogranin B mRNA levels were no longer detectable in HYA.15.6.T.3 cells. Interestingly, stimulation of the HYA.15.6.T.3 cells with cAMP restored proopiomelanocortin mRNA, beta-endorphin immunoreactivity, and dense-core granules. Furthermore, at the ultrastructural level, beta-lipotropin immunoreactivity was detected in granules of cAMP-induced HYA.15.6.T.3 cells. Finally, depolarization of cAMP-induced HYA.15.6.T.3 cells with 56 mM potassium chloride resulted in a marked increase in the release of beta-endorphin immunoreactivity. These observations demonstrate that cAMP restores the regulated pathway of secretion in HYA.15.6.T.3 cells, which under untreated conditions do not demonstrate regulated release. These variant cell lines are unique models to understand better the relationship of the regulated pathway and the expression of the processing enzymes.

Animals↗

PubMed1987

A new round in the discussion on the action of secretin on pancreatic protein secretion: a further study on the effect of secretin on pancreatic secretion in dogs.

Whether or not secretin stimulates pancreatic protein secretion is a controversial question. In this investigation, dose-response studies with different secretin preparations were performed in dogs with two different types of pancreatic fistulae. Pure natural secretin (Karolinska Institute, Stockholm), synthetic secretin (Hoechst, Frankfurt), synthetic secretin (Hoechst, Frankfurt), synthetic D-Ala17-secretin (Roche, Basel), and natural secretin (Kabi, Munich) were tested in dogs equipped with a Thomas cannula for collection of pure pancreatic juice. The synthetic secretin was also tested in dogs with a modified Herrera fistula. Potency of the pure natural and the unmodified synthetic secretins was similar. Whereas protein output was significantly stimulated by these secretin preparations, protein concentrations fell to approximately 10 mg ml-1 with incremental doses of infused secretin. The high protein concentrations of 60 up to 120 mg ml-1 found in pure basal pancreatic secretion, suggest that pancreatic protein output may have been a "washout" phenomenon, and that the increasing protein output values were due to rising volume flow of pancreatic juice which is not completely protein-free. Impure secretin preparations and indirect collection techniques also lead to an elevation of pancreatic protein output.

Animals↗

PubMed2002

Amylase secretion from dispersed human pancreatic acini: neither cholecystokinin a nor cholecystokinin B receptors mediate amylase secretion in vitro.

INTRODUCTION: In humans, cholecystokinin (CCK) stimulates pancreatic secretion, and CCK-A receptor antagonists prevent it in vivo. However, the human pancreas has been reported to express mainly CCK-B receptors. AIM: To elucidate this discrepancy. METHODOLOGY: We prepared dispersed acini from human pancreas and examined whether various doses of CCK stimulated the release of amylase, in comparison with the effects of neuromedin C, carbamylcholine, and secretin. RESULTS: Human pancreatic acini did not respond to any dose of CCK or secretin. Amylase release was stimulated by carbamylcholine and neuromedin C dose-dependently and was inhibited by respective antagonists. The localizations of CCK receptors in the human duodenum were determined. High concentrations of CCK-A receptors were detected in the mucosa as well as in smooth muscle of the duodenum by microautoradiography. CONCLUSION: In conclusion, human pancreatic acinar cells are responsible for carbamylcholine and neuromedin C but not for secretin. Neither CCK-A nor CCK-B receptor mediates amylase release from human pancreatic acini in vitro. Pancreatic secretion in humans in vivo may be regulated indirectly by CCK (via CCK-A receptors).

Amylases↗

PubMed2006

Expression of and secretion through the Aeromonas salmonicida type III secretion system.

Aeromonas salmonicida subsp. salmonicida is the aetiological agent of furunculosis, a disease of farmed and wild salmonids. The type III secretion system (TTSS) is one of the primary virulence factors in A. salmonicida. Using a combination of differential proteomic analysis and reverse transcriptase (RT)-PCR, it is shown that A. salmonicida A449 induces the expression of TTSS proteins at 28 degrees C, but not at its more natural growth temperature of 17 degrees C. More modest increases in expression occur at 24 degrees C. This temperature-induced up-regulation of the TTSS in A. salmonicida A449 occurs within 30 min of a growth temperature increase from 16 to 28 degrees C. Growth conditions such as low-iron, low pH, low calcium, growth within the peritoneal cavity of salmon and growth to high cell densities do not induce the expression of the TTSS in A. salmonicida A449. The only other known growth condition that induces expression of the TTSS is growth of the bacterium at 16 degrees C in salt concentrations ranging from 0.19 to 0.38 M NaCl. It is also shown that growth at 28 degrees C followed by exposure to low calcium results in the secretion of one of the TTSS effector proteins. This study presents a simple in vitro model for the expression of TTSS proteins in A. salmonicida.

Aeromonas salmonicida↗

PubMed1970

Synthesis and Secretion of Hypoxyproline-containing Macromolecules in Carrots: III. Metabolic Requirements for Secretion.

Using pulse-chase experiments with radioactive proline, it is possible to study the rapid transfer from the cytoplasm to the cell wall of the hydroxyproline-rich protein found in the cell walls of higher plants. The secretion of this protein is not obligatorily coupled to protein synthesis. Secretion is completely inhibited by uncouplers of oxidative phosphorylation and strongly inhibited by the inhibitors of electron transport, cyanide and azide. It is concluded that the transfer of proteins from the cytoplasm to the cell wall is an energy-requiring step.

Journal Article↗

PubMed1975

Studies on the secretion of maize root cap slime: I. Some properties of the secreted polymer.

The secreted slime from root cap cells of corn (Zea mays, cv. SX-17) was studied. Production of slime by excised root tips is stimulated by the addition of 40 mM sucrose or fucose and half-strength Hoagland's solution to the incubation medium. Secreted slime was recovered from aqueous solution by precipitation with ethanol. The polymer has a molecular weight greater than 2 x 10(-6) daltons and a density of 1.63 g cm(-3). Protein is not present in material purified by density gradient centrifugation with cesium chloride. Fucose (39%) and galactose (30%) are the principle neutral sugars found in the purified polymer. Galacturonic and glucuronic acids, arabinose, xylose, mannose, and glucose are also present.

Journal Article↗

PubMed1990

Purification and characterization of abundant secreted protein in suspension-cultured pumpkin cells : abundant secreted protein may be a chitinase.

The abundant secreted protein with molecular weight of 32,000 was purified from the culture medium of suspension-cultured pumpkin (Cucurbita sp.) cells. Two steps, ammonium sulfate fractionation and Sepharose 6B column chromatography, were sufficient for purification to homogeneity. Antibodies against the pure protein were used to show that a protein of the same size is made by callus cells. There is considerable homology between the amino-terminal amino acid sequence of this secreted protein and chitinase isolated from tobacco (Nicotiana tabacum L.) or bean (Phaseolus vulgaris L.).

Journal Article↗

PubMed1995

Characterization of the gene encoding the MPB51, one of the major secreted protein antigens of Mycobacterium bovis BCG, and identification of the secreted protein closely related to the fibronectin binding 85 complex.

The secreted protein MPB51 is one of the major proteins in the culture filtrate of Mycobacterium bovis BCG (BCG) and is a protein immunologically cross-reacting with the fibronectin binding 85 complex secreted by this bacterium. The gene encoding MPB51 (mpb51) was cloned, sequenced, and expressed in Escherichia coli. The mpb51 gene was mapped downstream of the gene for 85A component with 179 bp spaces. The mpb51 gene encoded 299 amino acids, including 33 amino acids for the signal peptide, followed by 266 amino acids for the mature protein with a molecular mass of 27807.37 Da. This is the first complete sequence of MPB51. MPB51 showed 37-43% homology to the components of 85 complex. Two-dimensional electrophoresis of culture fluids of BCG and Western blotting indicated the existence of the other novel protein(s) which strongly cross-reacted with the alpha antigen (85B) and MPB51.

Amino Acid Sequence↗

PubMedDate not supplied

Comparative study of plasma dopamine-beta-hydroxylase activities in noradrenaline-secreting and adrenaline-secreting phaeochromocytomae.

1. Circulating dopamine-beta-hydroxylase activities were measured in two hypertensive patients, with a phaeochromocytoma tumour. Tumours were found to differ by their secretory properties, one secreting noradrenaline, the other adrenaline. After removal of the tumour, the plasma dopamine-beta-hydroxylase activities in both patients gradually decreased to reach a stable value in correlation with urinary, excreted catecholamine levels. The only difference was the rate of the plasma enzyme activity decrease. 2. Thus, it appeared that some phaeochromocytomae are able to secrete dopamine-beta-hydroxylase in addition to catecholamines. Therefore, dopamine-beta-hydroxylase activity measurements may be of interest: (1) in determining secretory properties of phaeochromocytoma tumours, and (2) in following the evolution during the postoperative period.

Adrenal Gland Neoplasms↗

PubMed2006

Local balance of transforming growth factor-beta1 secreted from cholangiocarcinoma cells and stromal-derived factor-1 secreted from stromal fibroblasts is a factor involved in invasion of cholangiocarcinoma.

Tumor-stromal interactions are important for the progression of malignant tumors. The purpose of the present study was to examine interactions of cholangiocarcinoma (CC) cells and stromal fibroblasts with respect to stromal-derived factor-1 (SDF-1) and transforming growth factor (TGF)-beta1. Two cell lines of CC (HuCCT-1 and CCKS-1) and WI-38 fibroblast cell line were used for cell culture, and 12 CC tissue specimens for immunohistochemical studies. Invasion of CC cells was increased significantly by the supernatant from fibroblast cultures, but not by the supernatant from fibroblasts cocultured with CC cells. Expression of SDF-1 in cultured fibroblasts was downregulated by TGF-beta1 treatment, and coculture with CC cells and anti-TGF-beta1 neutralizing antibody restored the decreased SDF-1 expression, suggesting that TGF-beta1 secreted from CC cells might have reduced the expression of SDF-1 by fibroblasts and might have reduced the increased invasion of CC cells induced by the supernatant from fibroblasts. Immunohistochemical expression of TGF-beta1 in CC cells was focal or negative and that of SDF-1 was evident in stromal fibroblasts at the invasive front of CC. In conclusion, local mutual influence of TGF-beta1 secreted from carcinoma cells and SDF-1 expressed by stromal fibroblasts may be involved in invasion of CC cells.

Aged↗

PubMed1999

Acid-evoked quantal catecholamine secretion from rat phaeochromocytoma cells and its interaction with hypoxia-evoked secretion.

1. Amperometric recordings using polarized carbon fibre microelectrodes were used to detect exocytosis of catecholamines from rat phaeochromocytoma (PC12) cells in response to a reduction in pHo. 2. Exocytosis was detected at pHo levels of between 7.2 and 6.8. This was probably due to intracellular acidification, since acid-evoked secretion was enhanced by the Na+-H+ exchange blocker ethylisopropylamiloride (30 microM), and was mimicked by sodium propionate (10 mM), which causes selective intracellular acidosis. 3. Acid-evoked exocytosis was abolished by removal of Ca2+o or application of 200 microM Cd2+. It was unaffected by nifedipine, but significantly reduced by either omega-conotoxin GVIA (1 microM) or omega-agatoxin GIVA (200 nM). The two toxins applied together almost completely abolished (> 97 %) acid-evoked secretion. 4. Hypoxia-evoked catecholamine release was potentiated under acidic conditions and suppressed under alkaline conditions in a manner which indicated a greater than additive interaction of these two stimuli. 5. Our results indicate that, like carotid body arterial chemoreceptors, PC12 cells represent model chemoreceptor cells for both hypoxia and acidity and that the release of catecholamines in response to these physiological stimuli is dependent on Ca2+ influx through voltage-gated N- and P/Q-type Ca2+ channels.

Animals↗

PubMed1993

Secretion of the Hormoconis resinae glucoamylase P enzyme from Trichoderma reesei directed by the natural and the cbh1 gene secretion signal.

Secretion of the Hormoconis resinae glucoamylase P (GAMP) enzyme from Trichoderma reesei using either the natural N-terminal extension of the premature glucoamylase P or the cellobiohydrolase I (CBHI) signal peptide was examined. The expression conditions for the heterologous glucoamylase P (gamP) gene in T. reesei were standardized by targeting one copy of a plasmid fragment, containing the gamP gene, to the cbh1 locus of the host. The results showed that the transient N-terminal extension of the premature GAMP acts as an efficient secretion signal in T. reesei and leads to a higher yield of extracellular glucoamylase activity than does the signal peptide of CBHI.

Amino Acid Sequence↗

PubMed1997

Paternal leukocytes selectively increase secretion of IL-4 in peripheral blood during normal pregnancies: demonstrated by a novel one-way MLC measuring cytokine secretion.

PROBLEM: It has been proposed that immune responses in normal pregnancy are Th2-like, thereby protecting the fetus and placenta from being rejected. Some studies have shown Th2-deviated systemic responses to different antigens and mitogens. The aim of this study was to demonstrate the specific T cell cytokine responses directed toward paternal histocompatibility leukocyte antigen (HLA), because this is the most prominent target for rejection of the feto-placental unit. METHOD OF STUDY: A novel one-way mixed leukocyte culture (MLC) combined with the detection of cytokine secretion with a sensitive ELISPOT assay was developed. Peripheral blood from 11 pregnant women was investigated with respect to allo-reactivity toward paternal leukocytes and pooled leukocytes from unrelated blood donors. This was done at three different occasions during pregnancy and 8 weeks after delivery. Nine age-matched non-pregnant women served as controls. RESULTS: In the second and third trimesters of pregnancy significantly larger numbers of IL-4-secreting cells (Th2) were induced by paternal leukocytes as compared to unrelated leukocytes. CONCLUSIONS: The findings indicate a selective immune deviation toward Th2, which may protect the fetus from rejection and thus may be an important homeostatic mechanism in normal pregnancies.

Adult↗

PubMed2006

Protease activity, secretion, cell entry, cytotoxicity, and cellular targets of secreted autotransporter toxin of uropathogenic Escherichia coli.

The secreted autotransporter toxin (Sat), found predominantly in uropathogenic Escherichia coli, is a member of the SPATE (serine protease autotransporters of Enterobacteriaceae) family and, as such, has serine protease activity and causes cytopathic effects on various cell types. To assess the contribution of the serine protease active site to the mechanism of action of Sat, mutations were made in the first (S256I), in the second (S258A), or in both (S256I/S258A) serine residues within the active site motif. Mutations in the first or both serines reduced protease activity to background levels (P<0.001); a single mutation in the second serine reduced activity by 60% compared to wild type (P<0.001). After reversion of the S256I mutation to wild type (I256S), we confirmed S256 as the catalytically active serine. None of these mutations affected secretion of the mature passenger domain or release into the supernatant. The S256I mutation, however, abrogated the cytotoxicity of Sat on human bladder (UM-UC-3) and kidney (HEK 293) epithelial cells, characterized by rounding and elongation, respectively, and a high level of cell detachment. Moreover, S256 is essential for Sat to mediate cytoskeletal contraction and actin loss in host cells as well as to degrade specific membrane/cytoskeletal (fodrin and leukocyte function-associated molecule 1) and nuclear [microtubule-associated proteins, LIM domain-only protein 7, Rap GTPase-activating protein, poly(ADP-ribose) polymerase] proteins in vitro. Lastly, Sat was internalized by host cells and localized to the cytoskeletal fraction where membrane/cytoskeletal target proteins reside.

Bacterial Toxins↗

PubMed2007

SiiE is secreted by the Salmonella enterica serovar Typhimurium pathogenicity island 4-encoded secretion system and contributes to intestinal colonization in cattle.

Here we report that Salmonella enterica serovar Typhimurium pathogenicity island 4 carries a type I secretion system (siiCDF) which secretes an approximately 600-kDa protein (encoded by siiE). SiiE is surface expressed, and its production is regulated by HilA. SiiE and SiiF influence colonization in cattle and the invasion of bovine enterocytes.

Animals↗

PubMed1992

MxiJ, a lipoprotein involved in secretion of Shigella Ipa invasins, is homologous to YscJ, a secretion factor of the Yersinia Yop proteins.

Shigella flexneri causes bacillary dysentery by invading epithelial cells of the colonic mucosa. The invasion process requires the synthesis and secretion of the virulence plasmid-encoded Ipa proteins. Using TnphoA mutagenesis, we have identified two virulence plasmid genes, mxiJ and mxiM, that encode proteins exported by the general export pathway. Analysis of the MxiJ and MxiM deduced amino acid sequences suggested that mxiJ and mxiM might encode lipoproteins, which was confirmed by [3H]palmitate labeling of MxiJ:PhoA and MxiM:PhoA fusion proteins. A mxiJ mutant was unable to invade HeLa cells, to induce the formation of plaques on confluent monolayers of HeLa cells, and to provoke keratoconjunctivitis in guinea pigs. In addition, secretion of seven polypeptides, including IpaA, IpaB, and IpaC, was abolished in the mxiJ mutant. Sequence comparisons indicated that MxiJ and MxiH, which is encoded by a gene located upstream from mxiJ, are homologous to the Yersinia enterocolitica YscJ and YscF proteins, respectively.

Adhesins, Bacterial↗

PubMed1996

The Pseudomonas syringae Hrp regulation and secretion system controls the production and secretion of multiple extracellular proteins.

Pseudomonas syringae pv. tomato DC3000 produces seven to eight major extracellular proteins (EXPs) in a minimal medium inducing hrp genes. Using a polyclonal antibody against DC3000 EXPs, we have determined that the production and secretion of five EXPs (EXP-60, EXP-45, EXP-43, EXP-22, and EXP-10) are under the control of the Hrp regulation and secretion system.

Amino Acid Sequence↗