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)

1. The specific activity of UDPglucose 4-epimerase (EC 5.1.3.2) increases by about 50% during the first 24 h of starvation-induced differentiation (spherulation) of Physarum polycephalum. 2. At all stages during differentiation, the enzyme activity is very sensitive to actinomycin-C and cycloheximide, inhibitors of transcription and translation, with a half life against cycloheximide of about 20 min (if added 12 h after the induction of differentiation). 3. The isoenzyme pattern, as revealed by isoelectric focusing in sucrose gradients, does not change during spherulation. One main band with a pI of 6.7, with a shoulder (pI 7.6) and a minor band (pI 6.0) was observed in extracts both from growing and differentiating cultures. 4. Density labelling experiments using deuterated amino acids with subsequent analysis by equilibrium density gradient sedimentation in 15-35% (w/w) metrizamide gradients revealed a rather slow rate of enzyme synthesis, which is in contrast to the observed high sensitivity against actinomycin-C and cycloheximide.
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PMID:Activity, isoenzyme pattern, and synthesis of UDPglucose 4-epimerase during differtiation of Physarium polycephalum. 4 62

Glycogen synthase I (UDP glucose: glycogen alpha-4-glycosyltransferase, EC2.4.1.11) of the tapeworm Hymenolepis diminuta is the form of the enzyme which is active in vivo, while the D-form represents an inactive "storage form." Utilizing the differential effect of inorganic phosphate (Pi) on the I and D-forms, the ratio of the 2 forms in vivo has been determined under conditions of starvation of the host and refeeding of the parasite with glucose. This procedure reveals that conversion of the inactive D-form to the active I-form takes place when glycogen-depleted worms are incubated in glucose. The activity of glycogen synthase I also is affected by the molecular weight of the primer glycogen. With certain molecular weight fractions, enzymatic activity is higher than with others. This specificity of the glycogen primer could explain the relatively low concentrations of those molecular weight fractions which confer the highest synthase activity.
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PMID:Glycogen synthase of Hymenolepis diminuta. II. Nutritional state, interconversion of forms, and primer glycogen molecular weight as control factors. 10 7

When deprived of glucose, the cultured HT 29 adenocarcinoma cells are able to mobilize their glycogen within 4 hours. Glycogen phosphorylase is strongly activated during the first hour of glucose starvation. Then, while the a/a + b ratio for phosphorylase is declining, glycogen synthase is partially converted into the a form; this conversion does occur although glycogen phosphorylase is far from being totally inactivated. After 4 hours, activity of both a and total forms of glycogen synthase decrease. Cell UDP-glucose and glucose-6-P levels are declining during the 24 hours period of glucose starvation. Cell ATP content decreases by only 50 percent over the same period of time.
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PMID:Activity of glycogen metabolizing enzymes in glucose deprived HT 29 adenocarcinoma cell-line. 640 56

Although the glycogen content of mouse tail skin was decreased during starvation and was restored on re feeding, the proportion of glycogen synthase in the I form remained constant throughout at about 10% of the total. During the phase of net glycogen synthesis 1.5h after access to food was restored, the concentration of UDP glucose was markedly increased and the proportion of phosphorylase in the a form was significantly decreased.
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PMID:The effects of starvation and re-feeding on glycogen metabolism in mouse tail skin. 641 Oct 70

The glycogen content of muscle was correlated with the activity of glycogen synthase and glycogen phosphorylase from the parasitic roundworm Ascaris suum maintained in vitro. Adult female worms were maintained in the laboratory in a perfusion system during periods of starvation and feeding. During starvation, the levels of glucogen decreased at a rate of 0.1 to 0.2 mumoles/min/g wet weight of muscle-cuticle. During this time, 95% of the glycogen synthase (E.C. 2.4.1.11) was in the active D-form, and 48% of the phosphorylase (E.C. 2.4.1.1) was in the active a-form. Upon feeding, the rate of incorporation of glycosyl residues into glycogen proceeded at a rate of 0.75 to 1.0 mumoles/min/g muscle-cuticle. Glycogen synthase was 22% in the active I-form and phosphorylase a-levels remained virtually unchanged at 41% as compared with the starved worm. Total levels of both enzymes remained constant over the starvation-feeding period with 3.9 units/g phosphorylase and 0.4 units/g glycogen synthase. The apparent Km value for the substrate UDPG for glycogen synthase was 0.22 +/- 0.02 mM. For glycogen phosphorylase the Km value for G-1-P was 1.76 +/- 0.38 mM.
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PMID:Glycogen metabolizing enzymes during starvation and feeding of Ascaris suum maintained in a perfusion chamber. 679 Jun 95

Pregnant dogs were starved for 72 hr before a term delivery. Maternal (1.68 +/- 0.39 versus 0.74 +/- 0.20 mM) and fetal (0.39 +/- 0.03 versus 0.22 +/- 0.07) circulating free fatty acids and maternal (2.99 +/- 0.79 versus 1.04 +/- 0.84) and fetal (2.53 +/- 0.35 versus 1.01 +/- 0.32) ketones were elevated whereas blood glucose values remained unchanged at the time of delivery. After birth, pups born to starved mothers had significantly lower blood glucose values during 3, 6, 9, and 24 hours of neonatal fasting. Intracerebral glucose concentrations paralleled those in the blood as they were depressed at 3, 6, and 9 hours of age. Cerebral glycogen content was lower in pups born to starved mothers at 6 (2.72 +/- 0.43 versus 4.32 +/- 0.56 mumoles/g) and 24 (2.31 +/- 0.17 versus 3.48 +/- 0.39 mumoles/g) hr, whereas UDP-glucose concentrations were significantly elevated in these pups during fetal, 3, 9, and 24 hr of age. Phosphoenolpyruvate was higher after maternal starvation in the fetus and at 6 and 9 hr, whereas cerebral pyruvate concentrations were elevated at 3, 6, and 9 hr of age. The elevation of pyruvate with no alteration of lactate concentration resulted in an elevated cytoplasmic NAD/NADH ratio at 3 hr of age (1381 +/- 194 versus 792 +/- 198). Cerebral alpha-ketoglutarate and calculated oxaloacetate concentrations were elevated throughout the day after maternal starvation whereas malate concentrations were depressed at 3 and 9 hr of age. Cerebral energy charge was unaffected, whereas the calculated energy reserve was lower at 3, 6, and 24 hours. Cerebral amino acids demonstrated elevated aspartate concentrations at 3 and 6 hr. Cerebral glutamine concentrations were lower during fetal stage (7.86 +/- 0.52 versus 10.01 +/- 0.41 mumoles/g) and 3, 6, and 9 hr of life.
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PMID:Fetal and neonatal cerebral metabolism following maternal canine starvation. 724 89

1,3-beta-D-Glucan is a major structural polymer of yeast and fungal cell walls and is synthesized from UDP-glucose by the multisubunit enzyme 1,3-beta-D-glucan synthase. Previous work has shown that the FKS1 gene encodes a 215-kDa integral membrane protein (Fks1p) which mediates sensitivity to the echinocandin class of antifungal glucan synthase inhibitors and is a subunit of this enzyme. We have cloned and sequenced FKS2, a homolog of FKS1 encoding a 217-kDa integral membrane protein (Fks2p) which is 88% identical to Fks1p. The residual glucan synthase activity present in strains with deletions of fks1 is (i) immunodepleted by antibodies prepared against FKS2 peptides, demonstrating that Fks2p is also a component of the enzyme, and (ii) more sensitive to the echinocandin L-733,560, explaining the increased sensitivity of fks1 null mutants to this drug. Simultaneous disruption of FKS1 and FKS2 is lethal, suggesting that Fks1p and Fks2p are alternative subunits with essential overlapping function. Analysis of FKS1 and FKS2 expression reveals that transcription of FKS1 is regulated in the cell cycle and predominates during growth on glucose, while FKS2 is expressed in the absence of glucose. FKS2 is essential for sporulation, a process which occurs during nutritional starvation. FKS2 is induced by the addition of Ca2+ to the growth medium, and this induction is completely dependent on the Ca2+/calmodulin-dependent phosphoprotein phosphatase calcineurin. We have previously shown that growth of fks1 null mutants is highly sensitive to the calcineurin inhibitors FK506 and cyclosporin A. Expression of FKS2 from the heterologous ADH1 promoter results in FK506-resistant growth. Thus, the sensitivity of fks1 mutants to these drugs can be explained by the calcineurin-dependent transcription of FKS2. Moreover, FKS2 is also highly induced in response to pheromone in a calcineurin-dependent manner, suggesting that FKS2 may also play a role in the remodeling of the cell wall during the mating process.
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PMID:Differential expression and function of two homologous subunits of yeast 1,3-beta-D-glucan synthase. 756 18

A novel assay permitting the detection of UDPglucose 6-dehydrogenase activity in cell-free extracts obtained from phosphate-starved cultures of Bacillus subtilis is described. The critical step, the separation of phosphate-starvation-induced exo-enzymes, phosphatases and phosphodiesterases from the cytoplasmic fraction containing the UDPglucose dehydrogenase, was achieved by protoplasting and removal of the periplasmic fraction by protoplast washing. Using this method, the following were unambiguously demonstrated: (i) the presence in the cytoplasm of an enzymic activity oxidizing UDPglucose to UDPglucuronic acid, and (ii) that detection of the activity in whole-cell-free extracts is prevented by the presence of 'periplasmic' enzymes catalysing the degradation of the sugar nucleotides. With this method, several B. subtilis 168 mutants unable to synthesize teichuronic acid were examined. Strains inactivated in gene tuaD, whose product shares homology with UDPglucose 6-dehydrogenase and GDPmannose 6-dehydrogenase from other organisms, were shown to lack UDPglucose 6-dehydrogenase activity. Anion exchange chromatography revealed that mutants deficient in tuaD lacked a cytoplasmic UDPglucuronate pool.
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PMID:Assay for UDPglucose 6-dehydrogenase in phosphate-starved cells: gene tuaD of Bacillus subtilis 168 encodes the UDPglucose 6-dehydrogenase involved in teichuronic acid synthesis. 1037 20

Recent data suggest that superoxide dismutases are important in preventing lethal oxidative damage of proteins in Escherichia coli cells incubated under aerobic, carbon starvation conditions. Here, we show that the alkylhydroperoxide reductase AhpCF (AHP) is specifically required to protect cells incubated under aerobic, phosphate (Pi) starvation conditions. Additional loss of the HP-I (KatG) hydroperoxidase activity dramatically accelerated the death rate of AHP-deficient cells. Investigation of the composition of spent culture media indicates that DeltaahpCF katG cells leak nutrients, which suggests that membrane lipids are the principal target of peroxides produced in Pi-starved cells. In fact, the introduction of various mutations inactivating repair activities revealed no obvious role for protein or DNA lesions in the viability of ahp cells. Because the death of ahp cells was directly related to ongoing aerobic glucose metabolism, we wondered how glycolysis, which requires free Pi, could proceed. 31P nuclear magnetic resonance spectra showed that Pi-starved cells consumed Pi but were apparently able to liberate Pi from phosphorylated products, notably through the synthesis of UDP-glucose. Whereas expression of the ahpCF and katG genes is enhanced in an OxyR-dependent manner in response to H2O2 challenge, we found that the inactivation of oxyR and both oxyR and rpoS genes had little effect on the viability of Pi-starved cells. In stark contrast, the inactivation of both oxyR and rpoS genes dramatically decreased the viability of glucose-starved cells.
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PMID:Non-growing Escherichia coli cells starved for glucose or phosphate use different mechanisms to survive oxidative stress. 1125 23

A low level of UDP-Glc occurs in cells exposed to hypoxia or glucose starvation. This work reveals that a 65% reduction in the cellular UDP-Glc level causes up-regulation of the mitochondrial chaperone GRP75 and the endoplasmic reticulum (ER) resident chaperones GRP58, ERp72, GRP78, GRP94, GRP170, and calreticulin. Conditions that cause misfolding of proteins within the ER activate the transcription factors ATF6alpha/beta and induce translation of the transcription factors XBP-1/TREB5 and ATF4/CREB2. These transcription factors induce the overexpression of ER chaperones and CHOP/GADD153. However, the 65% decrease in the cellular UDP-Glc level does not cause activation of ATF6alpha, splicing of XBP-1/TREB5, induction of ATF4/CREB2, or expression of CHOP/GADD153. The activity of the promoters of the ER chaperones is increased in UDP-Glc-deficient cells, but the activity of the CHOP/GADD153 promoter is not affected, in comparison with their respective activities in cells having compensated for the UDP-Glc deficiency. The results demonstrate that the unfolded protein response remains functionally intact in cells with a 65% decrease in the cellular UDP-Glc level and provide evidence that this decrease is a stress signal in mammalian cells, which triggers the coordinate overexpression of mitochondrial and ER chaperones, independently of the ER stress elements.
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PMID:A cellular UDP-glucose deficiency causes overexpression of glucose/oxygen-regulated proteins independent of the endoplasmic reticulum stress elements. 1502 Jun 2


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