0000000000637530
AUTHOR
Pamela Maher
The plasma membrane channel ORAI1 mediates detrimental calcium influx caused by endogenous oxidative stress.
The mouse hippocampal cell line HT22 is an excellent model for studying the consequences of endogenous oxidative stress. Addition of extracellular glutamate depletes the cells of glutathione (GSH) by blocking the glutamate-cystine antiporter system x(c)(-). GSH is the main antioxidant in neurons and its depletion induces a well-defined program of cell death called oxytosis, which is probably synonymous with the iron-dependent form of non-apoptotic cell death termed ferroptosis. Oxytosis is characterized by an increase of reactive oxygen species and a strong calcium influx preceding cell death. We found a significant reduction in store-operated calcium entry (SOCE) in glutamate-resistant HT2…
Extracellular cyclic GMP and its derivatives GMP and guanosine protect from oxidative glutamate toxicity.
Cell death in response to oxidative stress plays a role in a variety of neurodegenerative diseases and can be studied in detail in the neuronal cell line HT22, where extracellular glutamate causes glutathione depletion by inhibition of the glutamate/cystine antiporter system xc(-), elevation of reactive oxygen species and eventually programmed cell death caused by cytotoxic calcium influx. Using this paradigm, we screened 54 putative extracellular peptide or small molecule ligands for effects on cell death and identified extracellular cyclic guanosine monophosphate (cGMP) as a protective substance. Extracellular cGMP was protective, whereas the cell-permeable cGMP analog 8-pCPT-cGMP or the …
The role of Ca(2+) in cell death caused by oxidative glutamate toxicity and ferroptosis
Ca(2+) ions play a fundamental role in cell death mediated by oxidative glutamate toxicity or oxytosis, a form of programmed cell death similar and possibly identical to other forms of cell death like ferroptosis. Ca(2+) influx from the extracellular space occurs late in a cascade characterized by depletion of the intracellular antioxidant glutathione, increases in cytosolic reactive oxygen species and mitochondrial dysfunction. Here, we aim to compare oxidative glutamate toxicity with ferroptosis, address the signaling pathways that culminate in Ca(2+) influx and cell death and discuss the proteins that mediate this. Recent evidence hints toward a role of the machinery responsible for stor…
Oxytosis/Ferroptosis—(Re-) Emerging Roles for Oxidative Stress-Dependent Non-apoptotic Cell Death in Diseases of the Central Nervous System
Although nerve cell death is the hallmark of many neurological diseases, the processes underlying this death are still poorly defined. However, there is a general consensus that neuronal cell death predominantly proceeds by regulated processes. Almost 30 years ago, a cell death pathway eventually named oxytosis was described in neuronal cells that involved glutathione depletion, reactive oxygen species production, lipoxygenase activation, and calcium influx. More recently, a cell death pathway that involved many of the same steps was described in tumor cells and termed ferroptosis due to a dependence on iron. Since then there has been a great deal of discussion in the literature about wheth…