Changes in glutathione homeostasis during liver regeneration in the rat

Huang, Zong–Zhi; Li, Hongyan; Cai, Jiaxin; Kuhlenkamp, John; Kaplowitz, Neil; Lu, Shelly C.

doi:10.1002/hep.510270123

Cited by 85 publications

(94 citation statements)

References 42 publications

(80 reference statements)

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“…This finding may indicate that the abundant evidence of CYP3A4 homo-and heterotropic cooperativity represent a manifestation of an allosteric mechanism designed to be triggered by physiological effectors, such as GSH, the concentration of which in tissues is consistent with this role. For instance, the average concentration of GSH in rat liver was shown to be in the range of 4 -8 mM [73]. Moreover, the GSH level in primary cultures of rat hepatocytes is reported to be 40 -60 nmol/10 6 cells [74,75], which is equivalent to a concentration of 8 -12 mM (calculated assuming the volume of a single hepatocyte cell equal to 4940 µm 3 [76]).…”

Section: Discussionmentioning

confidence: 99%

“…Moreover, the GSH level in primary cultures of rat hepatocytes is reported to be 40 -60 nmol/10 6 cells [74,75], which is equivalent to a concentration of 8 -12 mM (calculated assuming the volume of a single hepatocyte cell equal to 4940 µm 3 [76]). This concentration is subject to substantial changes in response to various stimuli [41,48,73,77,78]. In particular, exposure of human hepatocarcinoma Hep2 cells to organochlorine insecticides, such as DDT, decreases the GSH concentration from 4 -5 down to 1.2 -1.5 mM (calculated from [48] assuming the protein content in hepatocytes to be of 220 mg/g [79]).…”

Section: Discussionmentioning

confidence: 99%

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Effect of glutathione on homo- and heterotropic cooperativity in cytochrome P450 3A4

Davydov

Davydova

Tsalkova

et al. 2008

Archives of Biochemistry and Biophysics

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Glutathione (GSH) exerted a profound effect on the oxidation of 7-benzyloxy-4-(trifluoromethyl) coumarin (BFC) and 7-benzyloxyquinoline (BQ) by human liver microsomes as well as by CYP3A4-containing insect cell microsomes (Baculosomes). The cooperativity in O-debenzylation of both substrates is eliminated in the presence of 1-4 mM GSH. Addition of GSH also increased the amplitude of the 1-PB induced spin shift with purified CYP3A4 and abolished the cooperativity of 1-PB or BFC binding. Changes in fluorescence of 6-bromoacetyl-2-dimethylaminonaphthalene attached to the cysteine-depleted mutant CYP3A4(C58,C64) suggest a GSH-induced conformational changes in proximity of α-helix A. Importantly, the K S value for formation of the GSH complex and the concentrations in which GSH decreases CYP3A4 cooperativity are consistent with the physiological concentrations of GSH in hepatocytes. Therefore, the allosteric effect of GSH on CYP3A4 may play an important role in regulation of microsomal monooxygenase activity in vivo.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Effect of glutathione on homo- and heterotropic cooperativity in cytochrome P450 3A4

Davydov

Davydova

Tsalkova

et al. 2008

Archives of Biochemistry and Biophysics

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“…31 GCS activity (in nanomoles of GSH synthesized per minute per milligram of protein) was determined using monochlorobimane as previously described. 32 Nucleic Acids Extraction. RNA was isolated from frozen liver specimens according to the method of Chomczynski and Sacchi.…”

Section: Methodsmentioning

confidence: 99%

“…Northern hybridization analysis was performed on total RNA using standard procedures as described using specific GCS-HS and GCS-LS cDNA probes. 10,32 Both probes were labeled with [ 32 P]dCTP using a random-primer kit (Primer-It II Kit, Stratagene, La Jolla, CA). To ensure equal loading of RNA samples and transfer in each of the lanes, before hybridization, membranes were rinsed with ethidium bromide and photographed, and the same membranes were also rehybridized with a 32 P-labeled 18S cDNA probe comprised of a 303-base pair fragment corresponding to nucleotides 1003 to 1305 of the rat 18S sequence.…”

Section: Methodsmentioning

confidence: 99%

“…In the liver, GCS-HS gene expression is induced under oxidative stress 1,[8][9][10][11][12] and under periods of rapid liver growth. 32 Chronic ethanol administration to micropigs increases both apoptosis and regenerative proliferation. 40 To see if there is increased regenerative proliferation in our model, the steady-state protein level of PCNA was measured.…”

Section: Effects Of Chronic Ethanol Andmentioning

confidence: 99%

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Effect of ethanol and high-fat feeding on hepatic γ-glutamylcysteine synthetase subunit expression in the rat

Lu¹,

Huang²,

Yang³

et al. 1999

Hepatology

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Glutathione (GSH) is important in antioxidant defense. A major determinant of the rate of GSH synthesis is the activity of the rate-limiting enzyme, ␥-glutamylcysteine synthetase (GCS). A heavy (HS) and light subunit (LS) make up GCS; oxidative stress regulates both transcriptionally. Cis-acting elements important for the oxidative stressinduced transcriptional up-regulation of both subunits are antioxidant response element (ARE) and activator protein-1 (AP-1). Nuclear factor-B (NF-B) may also regulate the heavy subunit. Chronic ethanol ingestion causes oxidative stress, increases AP-1 expression, and depletes hepatic GSH. Data conflict regarding GSH synthesis and are lacking regarding GCS subunit gene expression. We examined the effect of chronic ethanol ingestion on ARE, AP-1, and NF-B activity and GCS subunit expression. Male Wistar rats were fed an ethanol and high-fat (28.7% cal) diet intragastrically for 9 weeks. Liver GSH level fell by 40%, although GCS activity doubled. GCS-HS mRNA level doubled, whereas GCS-LS mRNA level remained unchanged. Electrophoretic mobility shift assay (EMSA) showed that binding to ARE, AP-1, and NF-B probes all increased. In conclusion, chronic ethanol ingestion increased GCS-HS expression and GCS activity by activating cis-acting elements important for transcriptional up-regulation of GCS-HS. GCS-LS mRNA level remained unchanged despite activation of ARE and AP-1, suggesting that negative transcriptional factors may be involved or the mRNA may be unstable. Despite induction in GCS activity, GSH level fell because of alterations in the other factors important in determining the steady-state GSH level. (HEPATOLOGY 1999;30:209-214.) Glutathione (GSH) is a tripeptide, ␥-glutamylcysteinylglycine, which defends against toxins and free radicals. 1 The cellular GSH level is determined by a balance of the rate of its synthesis and the rates of its utilization (conjugation) and loss (export). 2 Synthesizing GSH from its constituent amino acids involves two adenosine triphosphate-requiring enzymatic steps: forming ␥-glutamylcysteine from glutamate and cysteine, and forming GSH from ␥-glutamylcysteine and glycine. The rate of GSH synthesis is determined by the availability of cysteine and the activity of the rate-limiting enzyme, ␥-glutamylcysteine synthetase (GCS), which is subject to feedback-competitive inhibition by GSH (K i ϭ 2.3 mmol/L). 1-3 The GCS enzyme is composed of a heavy (Mr ϳ 73,000) and a light (Mr ϳ 30,000) subunit that are encoded for by different genes and dissociate under reducing conditions. 4,5 The heavy subunit (HS) exhibits all of the catalytic activity of the isolated enzyme as well as the feedback inhibition by GSH. 6 The light subunit (LS) is enzymatically inactive but plays an important regulatory function by lowering the K m of GCS for glutamate and raising the K i for GSH. 5,7 Recent studies have shown that both GCS subunits are up-regulated transcriptionally by oxidative stress. 1,[8][9][10][11][12][13] The 5Ј-flanking region of both human GCS subunits ha...

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The effects of dietary flaxseed on the Fischer 344 rat. III. Protection against CCl4-induced liver injury

Hemmings¹,

Song²

2005

Cell Biochem. Funct.

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The hepatotoxic effect of carbon tetrachloride (CCl(4)) administered by gavage at 0.25 ml CCl(4) (1:1 in olive oil) per 100 g body weight was examined 24 h later in regular chow fed (RC) and 10% flax chow fed (FC) male and female Fischer 344 rats. CCl(4)-treated RC rats were subdued, lethargic and unkempt. CCl(4)-treated FC rats were much less affected. CCl(4) treatment resulted in loss of weight in RC and FC rats. In males, the weight loss was 6.7% body mass in RC rats compared to 5.6% body mass in FC rats. In females, the weight loss was 7.5% body mass in both RC and FC rats. While CCl(4) treatment increased the level of the liver injury marker plasma alanine aminotransferase (ALT) in RC rats, this CCl(4) effect was significantly attenuated in FC rats. In male rats, the ALT increase was 435-fold in RC rats and 119-fold in FC rats, over that of their respective controls. In female rats, the ALT increase was 454-fold in RC rats and 381-fold in FC rats, over that of their respective controls. These results provide evidence that flax consumption protects the liver against injury and that the extent of the protection is sex dependent. CCl(4) had no effect on the plasma level of gamma-glutamyltranspeptidase (gammaGT) in RC and FC rats supporting the contention that plasma gammaGT is not a useful marker for acute liver injury which is seen in this model. The activity of gammaGT was increased in the livers of FC rats compared to RC rats: 2.7-fold in males and 1.5-fold in females. In RC rats, the activity of liver gammaGT was decreased by CCl(4) treatment: 70% in the male and 25% in the female. However, this CCl(4) effect was reversed or abolished by flax consumption. Compared to RC rats: in male FC rats, CCl(4) actually increased the activity of liver gammaGT 1.28-fold; while in female FC rats, the depressing effect of CCl(4) treatment was abolished. The flax-induced preservation of gammaGT in the liver in response to injury may be involved in the observed hepatoprotection through generation of GSH. In RC male rats, CCl(4) treatment effected a 25% reduction in plasma glucose levels. There was no decrease in CCl(4)-treated FC male rats. In female rats, CCl(4) treatment effected a 21% decrease in plasma glucose levels in both RC and FC rats. In conclusion, multiple parameters for acute CCl(4)-induced injury were attenuated in the FC compared to the RC rat. That flaxseed consumption conferred greater protection against liver injury in the male than in the female suggests an involvement of the estrogenic lignan component of flaxseed. We discuss the possibility that this hepatoprotection is through a flax lignan-induced increase in reduced glutathione related to a flax effect on the activity of liver gammaGT in the resting state and the maintenance of its activity in response to injury.

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Changes in glutathione homeostasis during liver regeneration in the rat

Cited by 85 publications

References 42 publications

Effect of glutathione on homo- and heterotropic cooperativity in cytochrome P450 3A4

Effect of glutathione on homo- and heterotropic cooperativity in cytochrome P450 3A4

Effect of ethanol and high-fat feeding on hepatic γ-glutamylcysteine synthetase subunit expression in the rat

The effects of dietary flaxseed on the Fischer 344 rat. III. Protection against CCl4-induced liver injury

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