Glutaredoxin1 protects neuronal cells from copper-induced toxicity

Abstract

Glutaredoxin1 (GRX1) is a glutathione (GSH)-dependent thiol oxidoreductase. The GRX1/GSH system is important for the protection of proteins from oxidative damage and in the regulation of protein function. Previously we demonstrated that GRX1/GSH regulates the activity of the essential copper-transporting P1B-Type ATPases (ATP7A, ATP7B) in a copper-responsive manner. It has also been established that GRX1 binds copper with high affinity and regulates the redox chemistry of the metallochaperone ATOX1, which delivers copper to the copper-ATPases. In this study, to further define the role of GRX1 in copper homeostasis, we examined the effects of manipulating GRX1 expression on copper homeostasis and cell survival in mouse embryonic fibroblasts and in human neuroblastoma cells (SH-SY5Y). GRX1 knockout led to cellular copper retention (especially when cultured with elevated copper) and reduced copper tolerance, while in GRX1-overexpressing cells challenged with elevated copper, there was a reduction in both intracellular copper levels and copper-induced reactive oxygen species, coupled with enhanced cell proliferation. These effects are consistent with a role for GRX1 in regulating ATP7A-mediated copper export, and further support a new function for GRX1 in neuronal copper homeostasis and in protection from copper-mediated oxidative injury.

Thiol‐based copper handling by the copper chaperone Atox1

“…Such relatively low E 0 indicates a tendency to undergo oxidative thiol modification. Furthermore, the redox state of Atox1 is maintained by cytosolic glutathione with the assistance of Grx1 . In a previously proposed reaction scheme of the Atox1‐Grx1 reaction, oxidized Atox1 is reduced by transient glutathionylation and subsequent deglutathionylation, both of which are catalyzed by Grx1 .…”

PEP‑1‑glutaredoxin 1 protects against hippocampal neuronal cell damage from oxidative stress via regulation of MAPK and apoptotic signaling pathways

“…GLRX1 is distributed in various human tissues including the brain, which are involved in sulfhydryl homeostasis and exhibit roles in the regulation of redox signaling, and control a variety of cellular processes (9)(10)(11). A previous study demonstrated that GLRX1 has an important role as a ROS scavenger and protects against protein oxidation resulting from oxidative stress (12). However, the exact function of GLRX1 in ischemic injury remains to be fully elucidated.…”

Evidence for a role for the putative Drosophila hGRX1 orthologue in copper homeostasis

“…The thoracic cleft / reduced scutellum phenotypes are indicative of loss of underlying epithelial cells due to apoptosis, suggesting that CG6852 knockdown may be resulting in insufficient copper levels in a particular cellular compartment or pathway that is critical for cell survival. While caution must be taken in comparing between cell types and / or organisms, cultured MEFs from Grx1 knockout mice were found, in contrast, to have increased intracellular copper levels and a consequent sensitivity to copper supplementation (Cater, Materia et al 2014). One way to reconcile these apparently conflicting data would be to envisage a situation where reduction in Grx1 causes a redistribution of cellular copper; a localized deficiency would then trigger an increased uptake response in murine MEFs leading to higher copper levels and increased copper sensitivity.…”

“…Targeted knockdown of hGRX1 in HEK293T cells inhibited copper-stimulated translocation of ATP7A and ATP7B from the Golgi apparatus to the plasma membrane, resulting in increased accumulation of copper within the cytosol (Singleton, McInnes et al 2010) and indicating that glutathionylation is critical in regulating the copper efflux activity of these proteins. Furthermore, overexpression of hGRX1 has been found to provide cells with an increased tolerance to high copper levels, indicating that hGRX1 may be involved in binding intracellular copper (Cater, Materia et al 2014, De Benedetto, Capo et al 2014, for which it has a very high affinity (Hatori, Clasen et al 2012, Brose, La Fontaine et al 2014.…”