Down regulation of glutathione and glutamate cysteine ligase in the inflammatory response of macrophages

Abstract

Glutathione (GSH) plays critical roles in the inflammatory response by acting as the master substrate for antioxidant enzymes and an important anti-inflammatory agent. In the early phase of the inflammatory response of macrophages, GSH content is decreased due to the down regulation of the catalytic subunit of glutamate cysteine ligase (GCLC). In the current study we investigated the underlying mechanism for this phenomenon. In human THP1-differentiated macrophages, GCLC mRNA had a half-life of 4 h under basal conditions, and it was significantly reduced to less than 2 h upon exposure to lipopolysaccharide (LPS), suggesting an increased decay of GCLC mRNA in the inflammatory response. The half-life of GCLC protein was >10 h under basal conditions, and upon LPS exposure the degradation rate of GCLC protein was significantly increased. The pan-caspase inhibitor Z-VAD-FMK but not the proteasome inhibitor MG132, prevented the down regulation of GCLC protein caused by LPS. Both caspase inhibitor Z-LEVD-FMK and siRNA of caspase-5 abrogated LPS-induced degradation of GCLC protein. In addition, supplement with γ-GC, the GCLC product, efficiently restored GSH content and suppressed the induction of NF-κB activity by LPS. In conclusion, these data suggest that GCLC down-regulation in the inflammatory response of macrophages is mediated through both increased mRNA decay and caspase-5-mediated GCLC protein degradation, and γ-GC is an efficient agent to restore GSH and regulate the inflammatory response.

Pharmacogenomics Guided Spaceflight: the intersection between space-flown drugs and space genes

“…46 We noted GCLC and GGT1 upregulation in the cardiomyocyte transcriptomic spaceflight profiles, important for glutathione production, suggesting an increased response to oxidative stress. 47,48 These results suggest convergence with current hypothesis regarding increased levels of oxidative stress within spaceflight environments. 49 We postpone our discussion of how physiological and gene expression changes alter elimination through hepatic metabolism and decreased urinary output to the Degradation and Excretion of Drug Products section.…”

“…46 We noted GCLC and GGT1 upregulation in the cardiomyocyte transcriptomic spaceflight profiles, important for glutathione production, suggesting an increased response to oxidative stress. 47,48 These results suggest convergence with current hypothesis regarding increased levels of oxidative stress within spaceflight environments. 49…”

The associations between metabolic profiles and sexual and physical abuse in depressed adolescent psychiatric outpatients: an exploratory pilot study

“…γ-Glutamyl cysteine formation may have been disrupted, for instance, due to reduced glutamate cysteine ligase (GCL) enzymatic activity or accumulated glutamate interrupting cysteine influx or synthesis under oxidative stress (Zhu et al, 2022 ). Downregulation of the catalytic part of GCL has been associated with reduced glutathione in inflammation (Zhang et al, 2020 ). In this respect, the negative γ-glutamyl cysteine trend with physical abuse might indicate disruptions in the pathways against cellular oxidative stress.…”

Ferroptosis in viral infection: the unexplored possibility

“…Cysteine depletion can also be attributed to the excessive and rapid incorporation of cysteine in the viral genome RNA proteins, which have several cysteine amino acids containing domains, which occurs mainly during viral replication and contributes to a decrease in GSH [ 136 , 137 ]. In response to the inflammation and depletion of cysteine, key enzymes in the synthesis of GSH are downregulated [ 138 – 140 ], which impairs the antioxidant function of GSH and its availability, leading to cellular loss of GPX4 function. As established earlier, GPX4 is identified as a key enzyme in response to lipid peroxidation and an inhibitor of ferroptosis.…”