EAAC1 Gene Deletion Alters Zinc Homeostasis and Exacerbates Neuronal Injury after Transient Cerebral Ischemia

Abstract

EAAC1 is a neuronal glutamate and cysteine transporter. EAAC1 uptake of cysteine provides substrate for neuronal glutathione synthesis, which plays a key role in both antioxidant defenses and intracellular zinc binding. Here we evaluated the role of EAAC1 in neuronal resistance to ischemia. EAAC1 Ϫ/Ϫ mice subjected to transient cerebral ischemia exhibited twice as much hippocampal neuronal death as wild-type mice and a corresponding increase in microglial activation. EAAC1 Ϫ/Ϫ mice also had elevated vesicular and cytosolic zinc concentrations in hippocampal CA1 neurons and an increased zinc translocation to postsynaptic neurons after ischemia. Treatment of the EAAC1 Ϫ/Ϫ mice with N-acetyl cysteine restored neuronal glutathione concentrations and normalized basal zinc levels in the EAAC1 Ϫ/Ϫ mice. Treatment of the EAAC1 Ϫ/Ϫ mice with either N-acetyl cysteine or with zinc chelators reduced ischemia-induced zinc translocation, superoxide production, and neuron death. These findings suggest that cysteine uptake by EAAC1 is important for zinc homeostasis and neuronal antioxidant function under ischemic conditions.

Nuclear Factor Erythroid 2-Related Factor 2 Facilitates Neuronal Glutathione Synthesis by Upregulating Neuronal Excitatory Amino Acid Transporter 3 Expression

“…After three rinses with PBS, they were incubated for 2h at room temperature with secondary antibodies coupled to Alexa Fluor (1:500, Invitrogen). To detect GSH in situ , we used two techniques: labeling with C5-maleimide (Aoyama et al, 2006; Won et al, 2010) and detection of GSH- N -ethylmaleimide (NEM) adducts (Miller et al, 2009). For C5-maleimide staining, the sections were incubated overnight at 4°C with 2.5 mM Alexa Fluor488 or Alexa Fluor 594 C5-maleimide (Invitrogen) in 0.1 M phosphate buffer containing 0.3% Triton X-100.…”

EAAT3 promotes amino acid transport and proliferation of porcine intestinal epithelial cells

“…[8] reported that EAAT3 expression in microglia cells increased after traumatic brain injury. Collectively, defective EAAT3 expression causes human dicarboxylic aminoaciduria [9] and exacerbates neuronal injury after transient cerebral ischemia [10, 11]. However, the mechanism of EAAT3 action in the intestine is still unclear.…”

Genetic deletion of the neuronal glutamate transporter, EAAC1, results in decreased neuronal death after pilocarpine-induced status epilepticus

“…One of the most striking examples of this is that EAAC1 −/− mice experience more cell death as a result of ischemia than do controls (Won et al, 2010). There are a few possible explanations for the opposite effect in a seizure model.…”

“…For example, aging mice deleted of EAAC1 display progressive neurodegeneration that is attenuated with N-acetylcysteine (Aoyama et al, 2006; Berman et al, 2011). EAAC1 −/− mice are also more sensitive to ischemia-induced cell death than wild-type mice (Won et al, 2010). EAAC1 null mice display increased cell death, and overexpression of EAAC1 decreases cell death, after axotomy (Kiryu-Seo et al, 2006).…”