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)

The time courses of gene expression, and the nutritional regulation of gene expression of lipogenic enzymes (acetyl-CoA carboxylase, fatty acid synthase, ATP citrate-lyase, malic enzyme, and glucose-6-phosphate dehydrogenase) in epididymal adipose tissue after refeeding food-deprived rats have been investigated and compared with those in liver (previously reported). The mRNA concentrations of lipogenic enzymes reached maximum levels at 24 h after the refeeding in adipose tissue and at 8-16 h in liver, while the enzyme induction reached maximum at 48-72 h in both tissues. Moreover, the mRNAs were more strongly induced in adipose tissue than in liver, whereas the enzyme induction (except malic enzyme) was lower. In adipose tissue of rats fed a carbohydrate diet without protein, the mRNA concentrations of acetyl-CoA carboxylase, ATP-citrate lyase, malic enzyme, and fatty acid synthase reached comparable levels to those of the carbohydrate/protein diet group. The protein feeding increased the enzyme induction in adipose tissue. As regards reduction of gene expression, lipogenic enzyme mRNA concentrations were not so markedly reduced by starvation or polyunsaturated fatty acids in adipose tissue as in liver. The differences in regulation of lipogenic enzyme gene expression and induction between adipose tissue and liver can be ascribed to tissue specificity.
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PMID:Nutritional regulation of lipogenic enzyme gene expression in rat epididymal adipose tissue. 888 6

Herein we report on the kinetic and protein expression of glucose-6-phosphate dehydrogenase (G6PDH), 6-phosphogluconate dehydrogenase, and malic enzyme (ME) in the liver of the trout (Oncorhynchus mykiss) during a long-term starvation-refeeding cycle. Starvation significantly depressed the activity of these enzymes by almost 60%, without changing the Michaelis constant. The time response to this nutritional stimulus increased with fish weight. The sharp decline in G6PDH and ME activities was due to a specific protein-repression phenomenon, as demonstrated by molecular and immunohistochemical analyses. Also, the dimeric banding pattern of liver G6PDH shifted from the fully reduced and partially oxidized forms, predominant in control, to a fully oxidized form, more sensitive to proteolytic inactivation. Refeeding caused opposite effects in both protein concentration and enzyme activities of about twice the control values in the first stages, later reaching the normal enzyme activity levels. Additionally, the partially oxidized form of G6PDH increased. The kinetics of these enzymes were examined in relation to the various metabolic roles of NADPH. These results clearly indicate that trout liver undergoes protein repression-induction processes under these two contrasting nutritional conditions.
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PMID:Impact of starvation-refeeding on kinetics and protein expression of trout liver NADPH-production systems. 960 11

Expression of glucose-6-phosphate dehydrogenase (G6PD) gene during starvation and refeeding is regulated by a posttranscriptional mechanism occurring in the nucleus. The amount of G6PD mRNA at different stages of processing was measured in RNA isolated from the nuclear matrix fraction of mouse liver. This nuclear fraction contains nascent transcripts and RNA undergoing processing. Using a ribonuclease protection assay with probes that cross an exon-intron boundary in the G6PD transcript, the abundance of mRNAs that contain the intron (unspliced) and without the intron (spliced) was measured. Refeeding resulted in 6- and 8-fold increases in abundance of G6PD unspliced and spliced RNA, respectively, in the nuclear matrix fraction. However, the amount of G6PD unspliced RNA was at most 15% of the amount of spliced RNA. During refeeding, G6PD spliced RNA accumulated at a rate significantly greater than unspliced RNA. Further, the amount of partially spliced RNA exceeded the amount of unspliced RNA indicating that the enhanced accumulation occurs early in processing. Starvation and refeeding did not regulate either the rate of polyadenylation or the length of the poly(A) tail. Thus, the G6PD gene is regulated during refeeding by enhanced efficiency of splicing of its RNA, and this processing protects the mRNA from decay, a novel mechanism for nutritional regulation of gene expression.
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PMID:Regulation of the processing of glucose-6-phosphate dehydrogenase mRNA by nutritional status. 1112 67

Pyridine nucleotide pools were measured in intact plastids from roots of barley (Hordeum vulgare L.) during the onset of NO2- assimilation and compared with the in vitro effect of the NADPH/NADP ratio on the activity of plastidic glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) from N-sufficient or N-starved roots. The NADPH/NADP ratio increased from 0.9 to 2.0 when 10 mM glucose-6-phosphate was supplied to intact plastids. The subsequent addition of 1 mM NaNO2 caused a rapid decline in this ratio to 1.5. In vitro, a ratio of 1.5 inactivated barley root plastid G6PDH by approximately 50%, suggesting that G6PDH could remain active during NO2- assimilation even at the high NADPH/NADP ratios that would favor a reduction of ferredoxin, the electron donor of NO2- reductase. Root plastid G6PDH was sensitive to reductive inhibition by dithiothreitol (DTT), but even at 50 mM DTT the enzyme remained more than 35% active. In root plastids from barley starved of N for 3 d, G6PDH had a substantially reduced specific activity, had a lower Km for NADP, and was less inhibited by DTT than the enzyme from N-sufficient root plastids, indicating that there was some effect of N starvation on the G6PDH activity in barley root plastids.
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PMID:In Vivo and in Vitro Studies of Glucose-6-Phosphate Dehydrogenase from Barley Root Plastids in Relation to Reductant Supply for NO2- Assimilation. 1222 80

The activities of key enzymes of pentose phosphate pathway, glucose-6-phosphate dehydrogenase (G-6 PD) and 6-phosphogluconate dehydrogenase (6-PGD), were studied in cytoplasmatic fractions of brain cortical (limbic, orbital, sensorimotor cortex) and subcortical (myelencefalon, mesencefalon, hypothalamus) structures of rats subjected to starvation for 1, 2, 3, 5 and 7 days. Short-term starvation (1-3 days) caused activation of 6-GPD and 6-PGD both in cortical and subcortical structures. Long-term starvation for 5-7 days caused a decrease of activities of the pentose phosphate pathway enzymes in all studied structures. It is suggested that enzymes of pentose phosphate pathway in nervous tissues are functionally and metabolically related to glutathione system and during starvation they indirectly participate in the regulation lipid peroxidation processes.
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PMID:[Intensity of pentose phosphate metabolism of carbohydrates in various brain areas in normal and starved animals]. 1249 92

Starvation induced changes in citrate synthase (CS), glucose-6-phosphate dehydrogenase (G6-PDH), lactate dehydrogenase (LDH), DNA, RNA, RNA/DNA ratio and protein were studied in the freshwater catfish Clarias batrachus. Starvation gradually decreased the activity of CS, G6-PDH and LDH in brain, liver and skeletal muscle of the freshwater catfish. The maximum reduction in these enzyme activities upto 35-45% was observed after 35 days of fasting. This shows substantial decline in aerobic and biosynthetic capacity during starvation period. DNA, RNA, RNA/DNA ratio and protein contents were also reduced from 40-67% which reflects reduction in an overall capacity of the protein synthesis. Starvation-induced macromolecular changes indicate impairment of metabolism in fish.
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PMID:Starvation-induced impairment of metabolism in a freshwater catfish. 1287 43

The aim of this work was to evaluate the effects of prolonged starvation and refeeding on antioxidant status and some metabolic-related parameters in common dentex (Dentex dentex) liver. Fish deprived of food for 5 weeks showed a significant increase in lipid peroxidation, measured as malondialdehyde (MDA) levels. The activity of the antioxidative enzymes superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPX) in starved fish significantly increased (by 42%, 22%, and 52%, respectively), whereas glutathione reductase (GR) activity was significantly depressed by 53% compared to controls. No qualitative changes in the SOD isoenzymatic pattern were detected by nondenaturing PAGE analysis, but the isoforms corresponding to CuZn-SOD I and II were enhanced in starved fish. The activity of the enzymes indicative of oxidative metabolism, beta-hydroxyacyl CoA dehydrogenase (HOAD) and citrate synthase (CS), significantly increased (by 123% and 28%, respectively), and that of glucose-6-phosphate dehydrogenase (G6PDH) was inhibited by 56%. Oxidative damage under these circumstances is reversible since all biomarkers assayed returned to control values after refeeding. Our results show that prolonged starvation leads to a pro-oxidant situation and oxidative stress despite activation of antioxidant defense mechanisms, and that inhibition of G6PDH activity might be responsible for this failure in cellular antioxidant defenses.
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PMID:Oxidative stress and antioxidant defenses after prolonged starvation in Dentex dentex liver. 1555 78

Nitrogen starvation requires cells to change their transcriptome in order to cope with this essential nutrient limitation. Here, using microarray analysis, we investigated changes in transcript profiles following nitrogen depletion in the unicellular cyanobacterium Synechocystis sp. PCC 6803. Results revealed that genes for sugar catabolic pathways including glycolysis, oxidative pentose phosphate (OPP) pathway, and glycogen catabolism were induced by nitrogen depletion, and activities of glucose-6-phosphate dehydrogenase (G6PD) and 6-phosphogluconate dehydrogenase (6PGD), two key enzymes of the OPP pathway, were demonstrated to increase under this condition. We recently showed that a group 2 sigma factor SigE, which is under the control of the global nitrogen regulator NtcA, positively regulated these sugar catabolic pathways. However, increases of transcript levels of these sugar catabolic genes under nitrogen starvation were still observed even in a sigE-deficient mutant, indicating the involvement of other regulatory element(s) in addition to SigE. Since these nitrogen activations were abolished in an ntcA mutant, and since these genes were not directly included in the NtcA regulon, we suggested that sugar catabolic genes were induced by nitrogen depletion under complex and redundant regulations including SigE and other unknown factor(s) under the control of NtcA.
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PMID:Nitrogen induction of sugar catabolic gene expression in Synechocystis sp. PCC 6803. 1704 57

The inhibitor of catalase 3-amino-1,2,4-triazole (AMT) was used to study the physiological role of catalase in the yeast Saccharomyces cerevisiae under starvation. It was shown that AMT at the concentration of 10 mM did not affect the growth of the yeast. In vivo and in vitro the degree of catalase inhibition by AMT was concentration- and time-dependent. Peroxisomal catalase in bakers' yeast was more sensitive to AMT than the cytosolic one. In vivo inhibition of catalase by AMT in S. cerevisiae caused a simultaneous decrease in glucose-6-phosphate dehydrogenase activity and an increase in glutathione reductase activity. At the same time, the level of protein carbonyls, a marker of oxidative modification, was not affected. Possible mechanisms compensating the negative effects caused by AMT inhibition of catalase are discussed.
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PMID:Inhibition of catalase by aminotriazole in vivo results in reduction of glucose-6-phosphate dehydrogenase activity in Saccharomyces cerevisiae cells. 1845 71

The activities of glucose-6-phosphate dehydrogenase (G6PDH, EC 1.1.1.49) and 6-phosphogluconate dehydrogenase (6PGDH, EC 1.1.1.44) were found to increase in suspension-cultured Arabidopsis thaliana cells after 10-day-old stationary phase cells were transferred to fresh Murashige-Skoog medium. The activities of these enzymes peaked early in the exponential growth stage of the culture (day 4) and then decreased gradually. The transcript levels of six isoform genes of G6PDH (AtG6PDI to AtG6PD6) and three of 6PGDH (At6PGD1 to At6PGD3) were monitored during the culture. Two distinct transcript accumulation patterns were observed. In type A, the level of transcripts increased rapidly one day after the cells were inoculated into the fresh medium, and then remained almost constant until the culture reached its stationary phase (day 7). In type B, the transcripts were accumulated transiently at the first day after cell inoculation, then promptly decreased. We also investigated the effect of phosphate (Pi)-starvation and recovery on the expression of these genes. For this, the early stationary phase cultures (day 7) were transferred to fresh Pi-free culture medium. During 7 days of phosphate starvation, no growth of cultures was observed, and the transcript levels of all G6PDH and 6PGDH isoform genes were reduced, apart from one G6PDH isoform gene, AtG6PD5, which was continuously expressed throughout Pi-starvation. Compared to the reduction of almost all isoform genes of G6PDH in Pi-starved cultures, the reduction of 6PGDH genes was less severe. We discuss the localization and possible role of individual isoform genes of G6PDH and 6PGDH in connection with published databases.
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PMID:Expression of glucose-6-phosphate dehydrogenase and 6-phosphogluconate dehydrogenase isoform genes in suspension-cultured Arabidopsis thaliana cells. 1904 Jan 12


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