Disease relevance of Gclm

• Possibly significant similarity of sequence of amino acids was found between the light subunit and E. coli gamma-glutamylcysteine synthetase, which is a single polypeptide [1].
• The concentration of GSH and activity of the rate-limiting GSH-synthesizing enzyme, gamma-glutamylcysteine synthetase (gamma-GCS), significantly decreased in embryos exposed to hyperglycemia compared with controls (7.9 +/- 0.6 vs. 12.5 +/- 0.9 nmol/mg protein, P < 0.01 and 13.3 +/- 1.9 vs. 22.6 +/- 1.1 microU/mg protein, P < 0.01, respectively) [2].
• Incubation of rat-cultured astrocytes and C6 glioma cells with the specific gamma-glutamylcysteine synthetase inhibitor L-buthionine-(S:,R:)-sulfoximine (L-BSO; 0.1-1 mM) decreased the total specific content of glutathione in a dose- and time-dependent fashion [3].
• Inhibition of nitric oxide synthesis led to malignant hypertension and to a marked decrease in glutathione synthesis through down-regulation of the rate-limiting enzyme gamma-glutamylcysteine synthetase (GCS) [4].
• Nerve growth factor reduces injury owing to oxidative stress in rat pheochromocytoma (PC12) cells by increasing intracellular glutathione, in part owing to its stimulation of the activity of gamma-glutamylcysteine synthetase, which is the rate-limiting enzyme in the synthesis of glutathione [5].

High impact information on Gclm

• Thus, two classes of hormones acting through distinct signal transduction pathways may down-regulate hepatic GSH synthesis by phosphorylation of gamma-glutamylcysteine synthetase [6].
• The rate of resynthesis in depleted ethanol-fed cells in the presence of methionine and serine was similar to control cells and gamma-glutamylcysteine synthetase remained unaffected by chronic ethanol [7].
• CONCLUSIONS: Extracellular GSH protects cultured gastric cells from H2O2 damage by accelerating intracellular GSH synthesis; this is mediated by membrane-bound gamma-glutamyl transpeptidase acting on extracellular GSH (which supplies these cells with cysteine) and then by intracellular gamma-glutamylcysteine synthetase [8].
• Protection by pretreatment with GSH was prevented by buthionine sulfoximine (an inhibitor of gamma-glutamylcysteine synthetase) [8].
• Glutathione deficiency induced in newborn rats by giving buthionine sulfoximine, a selective inhibitor of gamma-glutamylcysteine synthetase, led to markedly decreased cerebral cortex glutathione levels and striking enlargement and degeneration of the mitochondria [9].

Chemical compound and disease context of Gclm

• Depletion of brain GSH with buthionine sulfoximine, a selective inhibitor for gamma-glutamylcysteine synthetase, exacerbated cortical infarction and edema after ischemia [10].

Biological context of Gclm

• Ovarian GSH concentrations and Gclc and Gclm mRNA levels, but not GCL subunit protein levels, varied significantly with estrous cycle stage [11].
• These results suggest that follicular apoptosis may be associated with down-regulation of Gclm and Gclc transcription in granulosa cells and oocytes [12].
• On the active site thiol of gamma-glutamylcysteine synthetase: relationships to catalysis, inhibition, and regulation [13].
• Amino acid sequence and function of the light subunit of rat kidney gamma-glutamylcysteine synthetase [1].
• Differential regulation of gamma-glutamylcysteine synthetase heavy and light subunit gene expression [14].

Anatomical context of Gclm

• Gclm was highly expressed in the granulosa cells and oocytes of healthy, growing follicles, not in atretic follicles [12].
• TUNEL staining was found to be significantly associated with absence of Gclm hybridization in granulosa cells and oocytes and with lack of strong Gclc hybridization in granulosa cells [12].
• Gclc was also highly expressed in follicles; however, unlike Gclm, Gclc was also expressed in corpora lutea and interstitial cells [12].
• Gamma-glutamylcysteine synthetase from erythrocytes [15].
• We previously reported that the activity of gamma-glutamylcysteine synthetase (GCS), the rate-limiting enzyme in GSH synthesis, is under both hormonal and cell density regulation in cultured rat hepatocytes [16].

Associations of Gclm with chemical compounds

• In situ hybridization with (35)S-labeled riboprobes was used to localize ovarian mRNA expression of the catalytic and modulatory subunits of glutamate cysteine ligase (Gclc and Gclm), the rate-limiting enzyme in GSH synthesis, during each stage of the rat estrous cycle [12].
• The heavy subunit (M(r), 72,614) of rat kidney gamma-glutamylcysteine synthetase, the enzyme that catalyzes the first step of glutathione (GSH) synthesis, mediates the catalytic activity of this enzyme and its feedback inhibition by GSH [1].
• gamma-Glutamylcysteine synthetase has a thiol group in the vicinity of its glutamate-binding site [17].
• gamma-Glutamylcysteine synthetase, previously known to be potently inhibited by cystamine, has been found to bind covalently to cystamine-Sepharose [18].
• Glutathione deficiency in newborn rats, produced by administration of L-buthionine-(S,R)-sulfoximine, a transition-state inactivator of gamma-glutamylcysteine synthetase, decreases ascorbate levels of kidney, liver, brain, and lung [19].

Other interactions of Gclm

• In both experiments the ovaries were harvested for [1] total GSH assay, [2] Western analysis for GCL catalytic (GCLc) and regulatory (GCLm) subunit protein levels, or [3] Northern analysis for Gclc and Gclm mRNA levels [11].
• Western-blot analysis demonstrated that gamma-glutamylcysteine synthetase catalytic subunit (gamma-GCSC) and cyclin D1 showed a similar pattern to that found in the RT-PCR analysis [20].
• In examining possible mechanisms for increased liver GSH, both cysteine level and gamma-glutamylcysteine synthetase (GCS) activity were significantly higher than controls, while the activity of GSH synthetase was unchanged [21].
• 3. L-alpha Aminoadipate was a competitive inhibitor of both glutamine synthetase, and gamma-glutamylcysteine synthetase, with Ki values of 209 microM and 7 mM respectively [22].
• The effect of 4-coumaric acid (50 mg/kg) on the expression of some glutathione-related enzymes (glutathione-S-transferase (GST)-P, GST-M2, GST-M1, gamma-glutamylcysteine synthetase, glutathione peroxidase (GSPX)1 and GSPX4) was also investigated at the level of the colonic mucosa [23].

Analytical, diagnostic and therapeutic context of Gclm

• Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) was used to detect apoptotic cells in the ovaries, and in situ hybridization for Gclm and Gclc was performed in adjacent sections of the same ovaries [12].
• Intracellular glutathione was depleted by exposing cell cultures to buthionine sulfoximine (BSO), a specific inhibitor of gamma-glutamylcysteine synthetase; this caused an increase in lipofuscin-specific autofluorescence, reflecting lipofuscin accumulation [24].
• Twenty-four hours after treatment, BSO + trans-platinum caused inhibition of gamma-glutamylcysteine synthetase activity, whereas this activity in animals treated with BSO alone had returned to control values [25].
• Determination of glutamate-cysteine ligase (gamma-glutamylcysteine synthetase) activity by high-performance liquid chromatography and electrochemical detection [26].
• Perfusion with buthionine sulfoximine, a specific inhibitor of gamma-glutamylcysteine synthetase, resulted in a dose-dependent reduction in GSH released, indicating inhibition of de novo synthesis during perfusion [27].

References