Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During the first few hours of starvation, Dictyostelium discoideum amoebae excrete a macromolecule, probably a glycoprotein, which stimulates cell differentiation to aggregation competence. 3':5'-Cyclic AMP pulses, which mimic the chemotactic signal, and this factor (differentiation stimulating factor) are shown to exert a cooperative effect in inducing cell differentiation. Data suggest that the appearance of the factor determines the moment amoebae become responsive to cyclic AMP pulses.
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PMID:A differentiation stimulating factor induces cell sensitivity to 3':5'-cyclic AMP pulses in dictyostelium discoideum. 17 82

A temperature-sensitive mutant of Chinese hamster cells is described which has two interesting properties: (1) it is a cell cycle mutant and (2) glycoprotein synthesis appears to be affected at the at the non-permissive temerature (40degreesC). Synchronized cells shifed to 40degreesC in the beginning of their G1 phase do not incorporate [3H]-thymidine into DNA during the expected S-phase, but once DNA synthesis has been initiated ( approximately 10 hours after termination of serum starvation) a shift to 40 degrees C no longer leads to an arrest of DNA synthesis. Flow microfluorimetric analysis of DNA content/cell supports this conclusion and indicates that a majority of cells become arrested in the G1 phase of the cell cycle when a non-synchronized population of cells is transferred to 40degreesC. Apparently at all times in the cell cycle there is a drastic reduction if incorporation of labeled sugars (particularly fucose) into glycoproteins. The uptake of fucose and its conversion to GDP-fucose appears to be normal at 40degreesC. Chromatographic analysis indicates that all classes of glycoproteins are affected, and we do not find any evidence for partially completed oligosaccharides at 40 degrees C. Overall protein synthesis is not reduced at he nonpermissive temperature during the time interval under consideration and the number of polysomes attached to membranes (RER) is also normal at 40degreesC. This suggests that the defect is at an early step in the synthesis or regulation of synthesis of glycoproteins. The mutation is a recessive mutation in hybrid cells and mutagen induced revertants can be obtained which grow normally at 40degreesC and in which glycoprotein synthesis at 40 degrees C is restored to normal, wild type levels.
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PMID:Glycoprotein synthesis in a temperature-sensitive Chinese hamster cell cycle mutant. 55 44

To investigate the role of cilia in mating interactions of Tetrahymena thermophila, ciliary membrane-rich fractions were isolated from two wild-type strains, a non-discharge mucocyst mutant which possesses mating behavior similar to wild-type, and a mating mutant which is able to costimulate cells of complementary mating type but cannot enter into pair formation. In each case, proteins from the ciliary membrane-rich fractions of starved, mating-competent ("initiated") cells were compared with those from non-starved, mating-incompetent ("non-initiated") cells, by gel electrophoresis and lectin blotting. In stained gels, a 43 kDa polypeptide was reduced or absent in initiated cells but present in non-initiated cells, in all strains. In silver-stained gels, a 25 kDa polypeptide was present in all strains, both initiated and non-initiated. In blots probed with Con A-peroxidase, a 25 kDa glycoprotein was present in ciliary membrane fractions from non-initiated cells and absent in membranes of initiated cells of the two wild-type strains and the mucocyst mutant, but is present in initiated and non-initiated cells of the mating mutant (several hypotheses are presented to explain these findings). In addition, ciliary proteins of the mating mutant included at least two unique Con A-binding polypeptides. Our results support the idea that development of mating competence during starvation involves an extensive remodeling of ciliary membranes, and identify a 25 kDa glycoconjugate as having a potential role in control of pair formation during mating.
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PMID:Ciliary polypeptides and glycoconjugates of wild-type and mutant Tetrahymena thermophila: starved versus nonstarved. 139 38

The glycoprotein gp115 (Mr = 115,000, pI 4.8-5) is localized in the plasma membrane of Saccharomyces cerevisiae cells and maximally expressed during G1 phase. To gain insight on the mechanism regulating its synthesis, we have examined various conditions of cell proliferation arrest. We used pulse-labeling experiments with [35S]methionine and two-dimensional gel electrophoresis analysis, which allow the detection of the well characterized 100-kDa precursor of gp115 (p100). In the cAMP-requiring mutant cyr1, p100 synthesis is active during exponential growth, shut off by cAMP removal, and induced when growth is restored by cAMP readdition. The inhibition of p100 synthesis also occurs in TS1 mutant cells (ras1ras2-ts1) shifted from 24 to 37 degrees C. During nitrogen starvation of rca1 cells, a mutant permeable to cAMP, p100 synthesis is also inhibited. cAMP complements the effect of ammonium deprivation, promoting p100 synthesis, even when added to cells which have already entered G0. Experiments with the bcy1 and cyr1bcy1 mutants have indicated the involvement of the cAMP-dependent protein kinases in the control of p100 synthesis. Moreover, the synthesis of p100 was unaffected in A364A cells, terminally arrested at START B by alpha-factor. These results indicate that the switch operating on p100 synthesis is localized in early G1 (START A) and is one of the multiple events controlled by the cAMP pathway.
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PMID:cAMP promotes the synthesis in early G1 of gp115, a yeast glycoprotein containing glycosyl-phosphatidylinositol. 216 14

The fate of the yolk platelets and their constituent yolk glycoproteins was studied in Strongylocentrotus purpuratus eggs and embryos cultured through the larval stage. Previous studies have shown that the yolk glycoproteins undergo limited proteolysis during early embryonic development. We present evidence that the yolk glycoproteins stored in the yolk platelets exist as large, disulfide-linked complexes that are maintained even after limited proteolysis have occurred. We provide additional evidence that acidification of the yolk platelet may activate a latent thiol protease in the yolk platelet that is capable of correctly processing the major yolk glycoprotein into the smaller yolk glycoproteins. Because we previously showed that these yolk glycoproteins are not catabolized during early embryonic development, it was of interest to study their fate during larval development. Using a specific polyclonal antibody to a yolk glycoprotein, we found that both yolk glycoproteins and the yolk platelets disappeared in feeding, Day 7, larval stage embryos, but that starvation did not significantly affect the levels of the yolk glycoproteins. We also found that the yolk glycoproteins reappeared in 30-day-old premetamorphosis larvae.
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PMID:Loss of yolk platelets and yolk glycoproteins during larval development of the sea urchin embryo. 230 67

Upon starvation the cellular slime mold, Dictyostelium purpureum, develops a form of cell-cell adhesion aiding in the formation of large multicellular aggregates, which are capable of further differentiation. The molecule that mediates this adhesion is a glycoprotein of Mr approximately 40,000. The protein shares a common carbohydrate epitope with another well-characterized cell adhesion molecule from Dictyostelium discoideum, contact sites A, but the polypeptides to which it is attached differ for each species. Although mediating a developmental form of adhesiveness, the protein is synthesized in vegetative cells at a time when they do not adhere. Most of the vegetative protein is associated with cell membranes and appears to be on the surface of these cells. The protein is compared to other cell adhesion molecules from other species of cellular slime molds, and possible explanations for its inability to function in vegetative cells are discussed.
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PMID:Developmentally regulated cell-cell adhesion in Dictyostelium purpureum is mediated by a glycoprotein synthesized in nonadhesive cells. 249 94

During early starvation-induced development, amoebae of Dictyostelium discoideum have been previously shown to increase sulfation and fucosylation of glycoprotein-linked oligosaccharides to levels above those observed in axenically growing cells. We report here that the axenic broth culture itself induces generation of high levels of fucosylated glycoprotein-linked oligosaccharides at all stages in the growth curve. However, when grown on bacteria, amoebae of both the axenic strain and the wild type show dramatic depression in fucose incorporation during early exponential growth. In mid- and late-exponential stages of growth, fucosylation rises to the levels found at all stages of axenic culture. Sulfation also increases during early development, but, in contrast to fucosylation, oligosaccharide sulfation is not altered by growth in axenic medium and does not increase during growth on bacteria. Starvation of bacterially grown cells results in increased sulfation and a further rise in fucosylation, as is also characteristic of broth-grown cells. The ability of axenic culture to uncouple control of these two classes of glycan-modification steps suggests that the synchronous increases during early development actually reflect responses to different regulatory signals, even though they participate in the same metabolic process. The increase in in vivo fucosyltransferase activity, which can act on many substrate glycoproteins, may alter many characteristics of the cells.
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PMID:Differential regulation of glycoprotein sulfation and fucosylation during growth of Dictyostelium discoideum. 274 70

The aggregation program of Dictyostelium discoideum is extremely sensitive to the effects of tunicamycin when the drug is added to cells during the first few hours of starvation. Inhibition of development is observed with concentrations as low as 0.5 micrograms/ml, which cause only a 25%-30% inhibition of general N-linked glycosylation. However, 0.5 micrograms/ml tunicamycin can result in the total inhibition of N-linked glycosylation of specific, developmentally regulated, proteins, as exemplified by the glycoprotein 117 antigen. If added after the first hours of starvation, tunicamycin cannot inhibit aggregation even when present at 10 micrograms/ml, which maximally inhibits N-linked glycosylation. cAMP pulses can override the inhibitory effects of tunicamycin on cell aggregation. The data support the hypothesis that there is an early developmental pathway that is dependent on the N-linked glycosylation of one, or a small set of developmentally regulated proteins and that this pathway may involve the biogenesis of the chemotactic signalling system. In addition, the data raise questions as to the role of N-linked oligosaccharides in cell cohesion.
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PMID:Inhibition of N-linked glycosylation in Dictyostelium discoideum: effects of aggregate formation. 285 Feb 53

Fibronectin is a normal glycoprotein component of plasma, interstitial fluid, and extracellular matrix which has binding sites for collagen, gelatin, actin, glycosaminoglycans, fibrin, Staphylococcus aureus, and some cells. Since it is a dimer, it can crosslink these substances to each other or to extracellular components of basement membrane, thereby affecting many physiological processes. The level of circulating fibronectin is markedly reduced following even moderate blunt or operative trauma, thermal injury, starvation, advanced cancers, hemorrhage, etc. Replacement therapy has been tried with some success in patients who become septic following multiple injuries. The reduction in plasma fibronectin has been attributed to several causes including consumption by binding to cell debris at the site of injury, binding to circulating cell debris and its subsequent removal by elements of the phagocytic system, and degradation by proteolytic cleavage. However, the amount of fibronectin removed from circulation raises some question about this. In this paper, we used indomethacin, ibuprofen, imidazole, and essential fatty acid deprivation to inhibit the synthesis of prostaglandins in young adult rats. Thirty minutes after ip administration of one of the inhibitors, the rats were subjected to a midline laparotomy and mild intestinal manipulation. Blood samples were taken at intervals following closure of the incision and analyzed for fibronectin. In all cases, the normal decline in plasma fibronectin seen in untreated rats was abrogated by inhibiting prostaglandin synthesis. Since imidazole specifically inhibits thromboxane A synthesis, this strongly suggests that thromboxanes directly or indirectly control the trauma-induced reduction in circulating fibronectin. This was confirmed by ip injection of thromboxane into the rats which resulted in a decline in plasma fibronectin levels.
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PMID:Role of prostaglandins in controlling plasma fibronectin levels. 304 45

To study the properties of protein-bound oligosaccharides in neuronally differentiating cells, two model systems were used: murine N1E-115 and N-18 neuroblastoma cells inducible by serum starvation and rat PC12 pheochromocytoma cells inducible by nerve growth factor. Glycopeptides were prepared from cells metabolically labeled with [3H]glucosamine and analyzed by gel filtration. The properties of the high-molecular-weight glycopeptides were studied using enzymatic digestion with neuraminidase and endo-beta-galactosidase. In contrast to other cell lines analyzed, the neuroblastoma and pheochromocytoma lines contained predominantly glycopeptides completely cleavable with endo-beta-galactosidase, which indicated that they were linear-type poly-N-acetyllactosamine glycans. The proportion of these linear chains in the high-molecular-weight fraction increased during neuronal differentiation in both cell systems. The linear nature of the glycans was also correlated with positive anti-i and negative anti-I reactivity of the cells in immunofluorescence microscopy. Specific cell surface labeling for poly-N-acetyllactosamine glycans and sodium dodecyl sulfate-polyacrylamide gel electrophoresis revealed several glycoprotein components, some of which showed changes during neuronal differentiation. The high proportion of linear poly-N-acetyllactosamine chains in these neuronal cell lines and its increase during neuronal differentiation suggests that these glycans may be a characteristic feature of neuronal or neuronally differentiating cells.
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PMID:Poly-N-acetyllactosamine glycans of cellular glycoproteins: predominance of linear chains in mouse neuroblastoma and rat pheochromocytoma cell lines. 330 6


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