title: Hijacking microglial glutathione by inorganic arsenic impels bystander death of immature neurons through extracellular cystine/glutamate imbalance.
abstract: Arsenic-induced altered microglial activity leads to neuronal death, but the causative mechanism remains unclear. The present study showed, arsenic-exposed (10 μM) microglial (N9) culture supernatant induced bystander death of neuro-2a (N2a), which was further validated with primary microglia and immature neuronal cultures. Results indicated that arsenic-induced GSH synthesis by N9 unfavorably modified the extracellular milieu for N2a by lowering cystine and increasing glutamate concentration. Similar result was observed in N9-N2a co-culture. Co-exposure of arsenic and 250 μM glutamate, less than the level (265 μM) detected in arsenic-exposed N9 culture supernatant, compromised N2a viability which was rescued by cystine supplementation. Therefore, microglia executes bystander N2a death by competitive inhibition of system Xc(-) (xCT) through extracellular cystine/glutamate imbalance. We confirmed the role of xCT in mediating bystander N2a death by siRNA inhibition studies. Ex-vivo primary microglia culture supernatant from gestationally exposed mice measured to contain lower cystine and higher glutamate compared to control and N-acetyl cysteine co-treated group. Immunofluorescence staining of brain cryosections from treated group showed more dead immature neurons with no such effect on microglia. Collectively, we showed, in presence of arsenic microglia alters cystine/glutamate balance through xCT in extracellular milieu leading to bystander death of immature neurons.
authors.affiliation: Immunotoxicology Laboratory, Food Drug and Chemical Toxicology Group and Nanotherapeutics &Nanomaterial Toxicology Group, CSIR-Indian Institute of Toxicology Research, Lucknow-226001, Uttar Pradesh, India.|Academy of Scientific and Innovative Research (AcSIR), CSIR-IITR Campus, Lucknow-226001, Uttar Pradesh, India.
authors.forename: Vikas
authors.initials: V
authors.lastname: Singh
authors.affiliation: Immunotoxicology Laboratory, Food Drug and Chemical Toxicology Group and Nanotherapeutics &Nanomaterial Toxicology Group, CSIR-Indian Institute of Toxicology Research, Lucknow-226001, Uttar Pradesh, India.|Academy of Scientific and Innovative Research (AcSIR), CSIR-IITR Campus, Lucknow-226001, Uttar Pradesh, India.
authors.forename: Ruchi
authors.initials: R
authors.lastname: Gera
authors.affiliation: Academy of Scientific and Innovative Research (AcSIR), CSIR-IITR Campus, Lucknow-226001, Uttar Pradesh, India.|System Toxicology Group, CSIR-Indian Institute of Toxicology Research, Lucknow-226001, Uttar Pradesh, India.
authors.forename: Rajesh
authors.initials: R
authors.lastname: Kushwaha
authors.affiliation: Immunotoxicology Laboratory, Food Drug and Chemical Toxicology Group and Nanotherapeutics &Nanomaterial Toxicology Group, CSIR-Indian Institute of Toxicology Research, Lucknow-226001, Uttar Pradesh, India.
authors.forename: Anuj Kumar
authors.initials: AK
authors.lastname: Sharma
authors.affiliation: Water Analysis Laboratory, Nanotherapeutics and Nanomaterial Toxicology Group, CSIR-Indian Institute of Toxicology Research, Lucknow-226001, Uttar Pradesh, India.
authors.forename: Satyakam
authors.initials: S
authors.lastname: Patnaik
authors.affiliation: Immunotoxicology Laboratory, Food Drug and Chemical Toxicology Group and Nanotherapeutics &Nanomaterial Toxicology Group, CSIR-Indian Institute of Toxicology Research, Lucknow-226001, Uttar Pradesh, India.
authors.forename: Debabrata
authors.initials: D
authors.lastname: Ghosh
mesh_terms: D027182:Amino Acid Transport System y+ / Q000378:metabolism; D000818:Animals; D001151:Arsenic / Q000009:adverse effects* / Q000494:pharmacology; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D003553:Cystine / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D018698:Glutamic Acid / Q000378:metabolism*; D005978:Glutathione / Q000378:metabolism*; D008297:Male; D051379:Mice; D017628:Microglia / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D009474:Neurons / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism
chemical_list: D027182:Amino Acid Transport System y+; D017382:Reactive Oxygen Species; C492255:Slc7a11 protein, mouse; D018698:Glutamic Acid; D003553:Cystine; D005978:Glutathione; D001151:Arsenic