Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: 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)

Although fatty liver (FL) is considered an innocuous condition, the frequent incidence of graft failure when FL are transplanted has renewed interest in the intracellular disorders causative of or consequent to fatty degeneration. Oxidative stress and nutritional status modulate the tolerance to reperfusion injury in control livers (CL), but very little is known in the case of FL. This study was designed to compare the oxidative balance in CL and FL from fed and food-deprived rats. Serum and liver samples were collected from fed and starved (18 h) rats with CL or FL induced by a choline-deficient diet. Hepatic injury was assessed by transaminase activities and histology. The hepatic concentrations of glutathione (GSH), vitamin C, alpha-tocopherol, thiobarbituric acid-reactive substances (TBARS) and protein carbonyls (PC) were measured. Fed rats with FL had significantly greater TBARS and lower alpha-tocopherol and vitamin C levels than those with CL, whereas GSH and PC concentrations were not affected. Starvation impaired the oxidative balance in both groups. However, compared with the other groups, FL from food-deprived rats generally had the lowest hepatic concentrations of alpha-tocopherol, vitamin C and GSH. Unlike in CL, protein oxidation occurred in FL. These data indicate that fatty liver induced by consumption of a choline-deficient diet is associated with a lower level of antioxidants, which results in lipid peroxidation. Starvation further affects these alterations and extends the damage to proteins. In conclusion, steatosis and starvation may act synergistically on the depletion of antioxidants, predisposing fatty livers to a reduced tolerance to oxidative injury.
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PMID:Starvation impairs antioxidant defense in fatty livers of rats fed a choline-deficient diet. 1095 3

In the yeast Saccharomyces cerevisiae, the enzyme gamma-glutamyl transpeptidase (gamma-GT; EC 2.3.2.2) is a glycoprotein that is bound to the vacuolar membrane. The kinetic parameters of GSH transport into isolated vacuoles were measured using intact vacuoles isolated from the wild-type yeast strain Sigma 1278b, under conditions of gamma-GT synthesis (nitrogen starvation) and repression (growth in the presence of ammonium ions). Vacuoles devoid of gamma-GT displayed a K(m) (app) of 18+/-2 mM and a V(max) (app) of 48.5+/-5 nmol of GSH/min per mg of protein. Vacuoles containing gamma-GT displayed practically the same K(m), but a higher V(max) (app) (150+/-12 nmol of GSH/min per mg of protein). Vacuoles prepared from a disruptant lacking gamma-GT showed no increase in V(max) (app) with nitrogen starvation. From a comparison of the transport data obtained for vacuoles isolated from various reference and mutant strains, it appears that the yeast cadmium factor 1 (YCF1) transport system accounts for approx. 70% of the GSH transport capacity of the vacuoles, the remaining 30% being due to a vacuolar (H(+)) ATPase-coupled system. The V(max) (app)-increasing effect of gamma-GT concerns only the YCF1 system. gamma-GT in the vacuolar membrane activates the Ycf1p transporter, either directly or indirectly. Moreover, GSH accumulating in the vacuolar space may exert a feedback effect on its own entry. Excretion of glutamate from radiolabelled GSH in isolated vacuoles containing gamma-GT was also measured. It is proposed that gamma-GT and a L-Cys-Gly dipeptidase catalyse the complete hydrolysis of GSH stored in the central vacuole of the yeast cell, prior to release of its constitutive amino acids L-glutamate, L-cysteine and glycine into the cytoplasm. Yeast appears to be a useful model for studying gamma-GT physiology and GSH metabolism.
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PMID:gamma-Glutamyl transpeptidase in the yeast Saccharomyces cerevisiae and its role in the vacuolar transport and metabolism of glutathione. 1167 38

In nuclear transplantation, serum starvation is a general method to synchronize donor cells at the quiescent stage (G(0)) of the cell cycle. However, serum starvation during culture of mammalian cells may induce cell death, especially through apoptosis, thus contributing to the low efficiency of nuclear transplantation. This study was performed to characterize apoptosis during serum starvation and to determine the effects of apoptosis inhibitors such as a protease inhibitor [alpha(2)-macroglobulin (MAC)] and antioxidants [N-acetylcysteine (NAC), glutathione (GSH)] on serum starved porcine embryonic fibroblasts (PEF). PEF, collected from day 25-30 porcine fetuses, were cultured for 5 days in media containing 0.5% FBS to induce quiescence. Serum starved PEF showed typical morphology of apoptotic cells and stained for DNA fragmentation by TUNEL assay (26.7%). All apoptosis inhibitors tested in this study significantly (P < 0.05) reduced apoptosis of serum starved PEF, with antioxidants having better results (MAC: 7.4% vs. NAC: 1.0%, and GSH: 0.8%). Equally and importantly, the treatment with apoptosis inhibitors did not change the proportion of G(0)/G(1) stage cells. Therefore, the addition of MAC and antioxidants during serum starvation of PEF reduces apoptosis of quiescent fibroblasts and may contribute to increasing the efficiency of nuclear transplantation by improving the quality of donor nuclei.
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PMID:Inhibition of apoptosis in serum starved porcine embryonic fibroblasts. 1193 67

Obesity is commonly associated with a high incidence and prevalence of dyslipidaemia, cardiovascular disease and Type II diabetes. Interestingly, studies have also reported decreased antioxidant levels in obese subjects. This may constitute an independent risk factor in the pathogenesis of coronary artery disease as obese subjects would have a decreased capacity to prevent the oxidative modification of low-density lipoproteins, which is a mechanism suggested as central to the development of atherogenesis. As part of a study to investigate responses to weight loss, we have assessed the effects on GSH status of a decrease in body mass of 5%, either after 6 days of complete starvation or 11 days of a very low calorie diet (2.55 MJ/day). There were significant differences between the two groups in the synthesis rate of erythrocyte GSH in response to weight loss. Both the fractional and the erythrocyte synthesis rate of GSH decreased significantly (P<0.01) in the starvation group by 22% and 16% respectively. In contrast, no change in synthesis rates was observed in the very low calorie diet group (P>0.05). Total erythrocyte concentration of GSH was unaffected by the weight loss within both groups. These results suggest that erythrocyte GSH synthesis is depressed in response to a very rapid weight loss induced by fasting. An acute reduction in GSH synthesis in response to a rapid weight loss may constitute a risk factor during periods of increased GSH demands.
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PMID:The effect of rate of weight loss on erythrocyte glutathione concentration and synthesis in healthy obese men. 1198 May 77

The dual role of glutathione as a transducer of S status (A.G. Lappartient and B. Touraine [1996] Plant Physiol 111: 147-157) and as an antioxidant was examined by comparing the effects of S deprivation, glutathione feeding, and H2O2 (oxidative stress) on SO42- uptake and ATP sulfurylase activity in roots of intact canola (Brassica napus L.). ATP sulfurylase activity increased and SO42- uptake rate severely decreased in roots exposed to 10 mM H2O2, whereas both increased in S-starved plants. In split-root experiments, an oxidative stress response was induced in roots remote from H2O2 exposure, as revealed by changes in the reduced glutathione (GSH) level and the GSH/oxidized glutathione (GSSG) ratio, but there was only a small decrease in SO42- uptake rate and no effect on ATP sulfurylase activity. Feeding plants with GSH increased GSH, but did not affect the GSH/GSSG ratio, and both ATP sulfurylase activity and SO42- uptake were inhibited. The responses of the H2O2-scavenging enzymes ascorbate peroxidase and glutathione reductase to S starvation, GSH treatment, and H2O2 treatment were not to glutathione-mediated S demand regulatory process. We conclude that the regulation of ATP sulfurylase activity and SO42- uptake by S demand is related to GSH rather than to the GSH/GSSG ratio, and is distinct from the oxidative stress response.
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PMID:Glutathione-Mediated Regulation of ATP Sulfurylase Activity, SO42- Uptake, and Oxidative Stress Response in Intact Canola Roots. 1222 97

The activity of ATP sulfurylase extracted from roots of intact canola (Brassica napus L. cv Drakkar) increased after withdrawal of the S source from the nutrient solution and declined after refeeding SO42- to S-starved plants. The rate of SO42- uptake by the roots was similarly influenced. Identical responses were obtained in SO42- -fed roots when one-half of the root system was starved for S. The internal levels of SO42- and glutathione (GSH) declined after S starvation of the whole root system, but only GSH concentration declined in +S roots of plants from split root experiments. The concentration of GSH in phloem exudates decreased upon transfer of plants to S-free solution. Supplying GSH or cysteine to roots, either exogenously or internally via phloem sap, inhibited both ATP sulfurylase activity and SO42- uptake. Buthionine sulfoximine, an inhibitor of GSH synthesis, reversed the inhibitory effect of cysteine on ATP sulfurylase. It is hypothesized that GSH is responsible for mediating the responses to S availability. ATP sulfurylase activity and the SO42- uptake rate are regulated by similar demand-driven processes that involve the translocation of a phloem-transported message (possibly GSH) to the roots that provides information concerning the nutritional status of the leaves.
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PMID:Demand-Driven Control of Root ATP Sulfurylase Activity and SO42- Uptake in Intact Canola (The Role of Phloem-Translocated Glutathione). 1222 81

In Saccharomyces cerevisiae, the CIS2 gene encodes gamma-glutamyl transpeptidase (gamma-GT; EC 2.3.2.2), the main GSH-degrading enzyme. The promoter region of CIS2 contains one stress-response element (CCCCT) and eight GAT(T/A)A core sequences, probably involved in nitrogen-regulated transcription. We show in the present study that expression of CIS2 is indeed regulated according to the nature of the nitrogen source. Expression is highest in cells growing on a poor nitrogen source such as urea. Under these conditions, the GATA zinc-finger transcription factors Nil1 and Gln3 are both required for CIS2 expression, Nil1 appearing as the more important factor. We further show that Gzf3, another GATA zinc-finger protein, acts as a negative regulator in nitrogen-source control of CIS2 expression. During growth on a preferred nitrogen source like NH(4)(+), CIS2 expression is repressed through a mechanism involving (at least) the Gln3-binding protein Ure2/GdhCR. Induction of CIS2 expression during nitrogen starvation is dependent on Gln3 and Nil1. Furthermore, rapamycin causes similar CIS2 activation, indicating that the target of rapamycin signalling pathway controls CIS2 expression via Gln3 and Nil1 in nitrogen-starved cells. Finally, our results show that CIS2 expression is induced mainly by nitrogen starvation but apparently not by other types of stress.
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PMID:Nitrogen-source regulation of yeast gamma-glutamyl transpeptidase synthesis involves the regulatory network including the GATA zinc-finger factors Gln3, Nil1/Gat1 and Gzf3. 1252 69

Glutathione (GSH: L-gamma-glutamyl-L-cysteinylglycine) is present in high concentrations up to 10 mM in yeast cells. Its very low redox potential (E'(o)=-240 mV for thiol disulfide exchange) gives this tripeptide the properties of a cellular redox buffer. In Saccharomyces cerevisiae and non-conventional yeasts (NCY), GSH may be involved in basic cellular functions such as the maintenance of mitochondrial and membrane integrity. GSH also assumes pivotal roles in (i) response to sulfur and nitrogen starvation; (ii) detoxification of endogenous toxic metabolites, such as excess formaldehyde produced during the growth of the methylotrophic yeasts Hansenula polymorpha, Candida boidinii and Kloeckera sp.; (iii) protection against oxidative stress provoked by exposure of the cells to reactive oxygen species including peroxides and hydroperoxides; (iv) detoxification of xenobiotics such as halogenated aromatics, alkylating agents and arsenite; (v) resistance to heavy-metal stress exemplified by the responses of S. cerevisiae and Schizosaccharomyces pombe to cadmium salts; (vi) yeast<-->mycelium transition in Candida and Aureobasidium sp.
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PMID:An overview on glutathione in Saccharomyces versus non-conventional yeasts. 1270 79

In early starvation tissue protein degradation increases, however in later starvation proteolysis declines so as to pace gradual atrophy during synthetic failure. Secondary decline of proteolytic pathways under progressive nutritional desperation is unexplained. After several days of starvation tissue GSH is partly depleted and GSSG/GSH is increased, followed by onset of ketonemia from fat breakdown. Ketone bodies inexplicably delay net muscle protein loss. Recent studies identify a proteome subset of more than 200 proteins with reactive sulfhydryl sites as candidates for coordinate redox control of diverse cell functions. Ketones cause protein sulfhydryl oxidation and protein S-glutathionylation. Here, redox-responsive proteolytic pathways were bio-assayed by release of [3H]leucine from rat myocardium under non-recirculating perfusion. More than 75% of myocardial protein degradation was inhibited and defined by infusion of diamide (100 microM) under constant physiologic concentrations of complete amino acids. Diamide-inhibitable proteolysis includes all lysosomal and some extra-lysosomal proteolysis. Following diamide washout, the reversal of proteolytic inhibitory action was greatly enhanced by artificial repletion of GSH by supra-physiologic extra-cellular GSH (1mM) exposure. Therefore, GSH maintains much of constitutive protein degradation in a primary tissue bioassay. Physiologic acetoacetate infusion (5mM) inhibited redox-responsive protein degradation. Uniformly [3H]leucine labeled 3T3 cells exhibited similar redox-dependent and redox-independent subcomponents of protein degradation. Independent of ketones, steady state cathepsin B reaction rate ex vivo was graded in proportion to the GSH concentration without GSSG, and inversely proportional to the GSSG/GSH redox ratio with inhibitory threshold at 0.5% oxidized. Linkage of some cysteine protease reaction rates to the interplay between GSH-GSSG/GSH status and ketonemia is suggested among transcendent mechanisms coordinating and pacing proteome turnover under prolonged starvation. The possibility of pre-emptive, redox coordination of distinct proteolytic pathways is speculatively discussed.
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PMID:Redox pacing of proteome turnover: influences of glutathione and ketonemia. 1294

C11-BODIPY(581/591) is a fluorescent lipid peroxidation reporter molecule that shifts its fluorescence from red to green when challenged with oxidizing agents, i.e., reactive oxygen species (ROS) or reactive nitrogen species (RNS). To understand the molecular mechanism responsible for this shift, we studied the molecular rearrangements leading to the shift in fluorescence in C11-BODIPY(581/591). Furthermore, we aimed to determine if these rearrangements were dependent on the nature of the applied ROS, in homogenous solution, bilayer vesicles, and living cells. C11-BODIPY(581/591) was challenged with various ROS- or RNS-generating systems, including peroxynitrite, NO(2)(?), peroxides, and hydroxyl, alkoxyl, tyrosyl, and peroxyl radicals. The reaction products were subsequently analyzed by means of mass spectrometry. Our results show that the initial target for free radical-mediated oxidation is the conjugated diene interconnection between the BODIPY core and the terminal phenyl moiety, which already explains the shift in fluorescence properties of the probe. After oxidative challenge, three different stable products were identified, one of which was specific for oxidation by peroxynitrite. The two other stable end products had lost the entire phenyl moiety, irrespective of the type of radical generating system used. These products were also recovered from Rat-1 fibroblasts stressed either by GSH depletion/serum starvation or by exposure to peroxynitrite, and were the only C11-BODIPY(581/591) oxidation products detectable in these cells.
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PMID:Mass spectrometric characterization of the oxidation of the fluorescent lipid peroxidation reporter molecule C11-BODIPY(581/591). 1518 63


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