Glutathione metabolism pathway (GSH metabolism)

The glutathione metabolism pathway is a complex biochemical network responsible for the de novo synthesis, utilization, and recycling of glutathione (GSH), the most abundant non-protein thiol and a master antioxidant in mammalian cells [1, 3]. Synthesis occurs via two ATP-dependent enzymatic steps: the formation of gamma-glutamylcysteine by glutamate-cysteine ligase (GCL)—the rate-limiting step—and the subsequent addition of glycine by glutathione synthetase (GSS) [1, 5]. This pathway is vital for maintaining cellular redox homeostasis, neutralizing reactive oxygen species (ROS), and detoxifying xenobiotics through conjugation reactions catalyzed by glutathione S-transferases (GSTs) [2, 4]. Turnover and recycling are facilitated by the gamma-glutamyl cycle and glutathione reductase (GR), which restores reduced GSH from its oxidized form (GSSG) [1, 3]. In oncology, cancer cells frequently upregulate this pathway to mitigate oxidative stress and develop resistance to chemotherapy and radiation, leading to the development of inhibitors like buthionine sulfoximine (BSO) [2]. Conversely, GSH depletion is a hallmark of neurodegenerative, cardiovascular, and inflammatory diseases, where therapeutic strategies focus on restoring GSH levels using precursors such as N-acetylcysteine (NAC) [4, 5]. Overall, the glutathione synthesis and turnover pathways represent a central hub for cellular defense and metabolic regulation [3, 5].

Other names

Gamma-glutamyl cycleGlutathione synthesis and turnoverGSH homeostasisGlutathione biosynthetic pathwayGlutathione redox cycle

Modulation of glutathione levels through inhibition of rate-limiting enzymes (e.g., GCL), inhibition of precursor transport (e.g., System Xc-), or supplementation of thiol-containing precursors (e.g., NAC) [1, 2, 5].