Disease relevance of Gclm

• We conclude that the Gclm(-/-) mouse represents a model of chronic GSH depletion that will be very useful in evaluating the role of the GCLM subunit and GSH in numerous pathophysiological conditions as well as in environmental toxicity associated with oxidant insult [1].
• Using lung epithelial cells, the progenitor cells of lung cancers, we report that crocidolite asbestos initially depletes intracellular glutathione followed by up-regulation of both catalytic and modifier subunits of gamma-glutamylcysteine synthetase [2].
• We have studied the effect of buthionine sulfoximine (BSO; a gamma-glutamylcysteine synthetase inhibitor) administration, either alone or combined with misonidazole (MISO), on five human tumor xenografts (three melanomas: Bell, Mall, and Nall; and two rectocolic adenocarcinomas: HT29 and HRT18) transplanted into mice [3].

Psychiatry related information on Gclm

• This study investigated the role of cellular antioxidant defense mechanisms in modulating the neurotoxicity of domoic acid (DomA), by using cerebellar granule neurons (CGNs) from mice lacking the modifier subunit of glutamate-cysteine ligase (Gclm) [4].

High impact information on Gclm

• Skeletal muscle degeneration associated with mitochondrial damage was found after marked depletion of glutathione produced by administration to mice of buthionine sulfoximine, an irreversible inhibitor of gamma-glutamylcysteine synthetase [5].
• Depletion of glutathione by inhibition of its synthesis by buthionine sulfoximine, an irreversible inhibitor of gamma-glutamylcysteine synthetase, leads to increased sensitivity to (i) irradiation and (ii) oxidative stress [6].
• The function of the gamma-glutamyl cycle was explored in in vivo studies in which amino acids and specific inhibitors of cycle enzymes (gamma-glutamyl transpeptidase, gamma-glutamyl cyclotransferase, gamma-glutamylcysteine synthetase, and 5-oxoprolinase) were administered to mice [7].
• The better tolerance of the Vanin-1(-/-) mice is associated with an enhanced gamma-glutamylcysteine synthetase activity in liver, probably due to the absence of cysteamine and leading to elevated stores of glutathione (GSH), the most potent cellular antioxidant [8].
• A novel missense mutation in the gamma-glutamylcysteine synthetase catalytic subunit gene causes both decreased enzymatic activity and glutathione production [9].

Chemical compound and disease context of Gclm

• To further characterize the role of glutathione and oxidative stress in the toxicity of arsenic, we have used fetal fibroblasts from Gclm(-/-) mice, which lack the modifier subunit of glutamate-cysteine ligase, the rate-limiting enzyme in glutathione biosynthesis [10].
• We Studied the effect of GSH depletion by buthionine sulfoximine (BSO), a potent inhibitor of gamma-glutamylcysteine synthetase, on doxorubicin (DOX) toxicity in mice [11].

Biological context of Gclm

• Gclm(-/-) mice are viable and fertile and have no overt phenotype [1].
• The nonhomologous Gclc and Gclm genes are located on mouse chromosomes 9 and 3, respectively [12].
• Glutamate-cysteine ligase modifier subunit: mouse Gclm gene structure and regulation by agents that cause oxidative stress [13].
• Transient and stable transfection studies, using luciferase reporter constructs containing incremental Gclm 5'-flanking deletions (4.7-0.5 kb), showed high basal activity but only modest ( approximately 2-fold) inducibility by tBHQ [13].
• The Gclm 5'-flanking region is GC-rich and lacks a canonical TATA box [13].

Anatomical context of Gclm

• The major decrease in GSH, combined with diminished GCL activity, rendered Gclm(-/-) fetal fibroblasts strikingly more sensitive to chemical oxidants such as H(2)O(2) [1].
• In liver, lung, pancreas, erythrocytes, and plasma, however, GSH levels in Gclm(-/-) mice were 9-16% of that in Gclm(+/+) littermates [1].
• Treatment of RAW 264.7 mouse macrophages and mouse peritoneal macrophages with oxLDL (30 microg/mL) induces increased expression of both Gclc and Gclm in vitro [14].
• No treatment-related changes in Glclr protein in either gd 12 or gd 16 yolk sacs or fetuses were found [15].
• To elucidate the pathological metabolism of glutathione synthesis in diabetic endothelial cells, we studied the expression of gamma-glutamylcysteine synthetase (gamma-GCS) using a mouse vascular endothelial cell line [16].

Associations of Gclm with chemical compounds

• Cysteine levels in Gclm(-/-) mice were 9, 35, and 40% of that in Gclm(+/+) mice in kidney, pancreas, and plasma, respectively, but remained unchanged in the liver and erythrocytes [1].
• Gclm(-/-) mouse embryo fibroblasts (MEFs) are eight times more sensitive to arsenite-induced apoptotic death [10].
• Long exposure to high glucose concentration impairs the responsive expression of gamma-glutamylcysteine synthetase by interleukin-1beta and tumor necrosis factor-alpha in mouse endothelial cells [16].
• Here, we show that adducts of N(epsilon)-(carboxymethyl)lysine (CML), a major AGE, and bovine serum albumin (CML-BSA) stimulated gamma-glutamylcysteine synthetase (gamma-GCS), which is a key enzyme of glutathione (GSH) synthesis, in RAW264.7 mouse macrophage-like cells [17].
• Induction of glutamate-cysteine ligase (gamma-glutamylcysteine synthetase) in the brains of adult female mice subchronically exposed to methylmercury [18].

Regulatory relationships of Gclm

• The gamma-glutamylcysteine synthetase and glutathione regulate asbestos-induced expression of activator protein-1 family members and activity [2].

Other interactions of Gclm

• Site-directed mutagenesis of the AREs within the Gclc and Gclm promoters resulted in a decrease of oxLDL-induced luciferase activity [14].
• The findings strongly indicate that methionine sulfoximine-induced convulsions are closely associated with inhibition of glutamine synthetase rather than with inhibition of gamma-glutamylcysteine synthetase [19].
• A spectrophotometric assay of gamma-glutamylcysteine synthetase and glutathione synthetase in crude extracts from tissues and cultured mammalian cells [20].

Analytical, diagnostic and therapeutic context of Gclm

• Western and Northern blots for Glcl-catalytic (Glclc) and Glcl-regulatory (Glclr) subunits were performed on gd 12 and gd 16 fetuses [15].
• Reverse transcription-polymerase chain reaction (RT-PCR) was used to amplify and clone the regulatory subunit of mouse glutamate-cysteine ligase (Glclr) using primers adapted from the published rat Glclr cDNA sequence, and from mouse genomic DNA [21].
• Molecular cloning and sequencing of the cDNA encoding mouse glutamate-cysteine ligase regulatory subunit [21].
• A 2-kb fragment of the proximal promoter region of the gene was cloned and sequenced, and sequence analysis reveals a high degree of homology when compared to the human glutamate-cysteine ligase regulatory subunit gene promoter [22].
• D-54 MG, a human glioma-derived continuous cell line growing as subcutaneous or intracranial xenografts in athymic mice, was found to be sensitive to the effects of D,L-buthionine-(SR)-sulfoximine, a selective inhibitor of gamma-glutamylcysteine synthetase [23].

References