Oxidative Stress Underlies the Ischemia/Reperfusion-Induced Internalization and Degradation of AMPA Receptors

• Published in: International journal of molecular sciences 2021-01, Vol.22 (2), p.717
• Main Authors: Achzet, Lindsay M, Davison, Clara J, Shea, Moira, Sturgeon, Isabella, Jackson, Darrell A
• Format: Article
• Language: English
• Subjects: AMPA receptor; Apoptosis; Calcium ions; Calcium permeability; Cell death; Cell Survival; Cells, Cultured; Degradation; Deprivation; Endosomes; Excitotoxicity; Fluorescent Antibody Technique; GluA1; GluA2; Hypoxia; Internalization; Ischemia; Ischemia - etiology; Ischemia - metabolism; ischemic/reperfusion injury; Markers; Metalloporphyrins - pharmacology; Neurons - metabolism; Oxidative Stress; oxygen glucose-deprivation/reperfusion (OGD/R); Physiology; Porphyrins; Post-transcription; Pretreatment; Protein Subunits; Protein Transport; Protein turnover; Proteins; Proteolysis; reactive oxygen species; Receptors, AMPA - chemistry; Receptors, AMPA - metabolism; Reperfusion; Reperfusion Injury - etiology; Reperfusion Injury - metabolism; Stroke; Superoxide dismutase; α-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid; α-Amino-3-hydroxy-5-methyl-4-isoxazole propionic acid receptors
• ISSN: 1422-0067; 1661-6596; 1422-0067
• DOI: 10.3390/ijms22020717

Stroke is the fifth leading cause of death annually in the United States. Ischemic stroke occurs when a blood vessel supplying the brain is occluded. The hippocampus is particularly susceptible to AMPA receptor-mediated delayed neuronal death as a result of ischemic/reperfusion injury. AMPA receptors composed of a GluA2 subunit are impermeable to calcium due to a post-transcriptional modification in the channel pore of the GluA2 subunit. GluA2 undergoes internalization and is subsequently degraded following ischemia/reperfusion. The subsequent increase in the expression of GluA2-lacking, Ca -permeable AMPARs results in excitotoxicity and eventually delayed neuronal death. Following ischemia/reperfusion, there is increased production of superoxide radicals. This study describes how the internalization and degradation of GluA1 and GluA2 AMPAR subunits following ischemia/reperfusion is mediated through an oxidative stress signaling cascade. U251-MG cells were transiently transfected with fluorescently tagged GluA1 and GluA2, and different Rab proteins to observe AMPAR endocytic trafficking following oxygen glucose-deprivation/reperfusion (OGD/R), an in vitro model for ischemia/reperfusion. Pretreatment with Mn(III)tetrakis(1-methyl-4-pyridyl)porphyrin (MnTMPyP), a superoxide dismutase mimetic, ameliorated the OGD/R-induced, but not agonist-induced, internalization and degradation of GluA1 and GluA2 AMPAR subunits. Specifically, MnTMPyP prevented the increased colocalization of GluA1 and GluA2 with Rab5, an early endosomal marker, and with Rab7, a late endosomal marker, but did not affect the colocalization of GluA1 with Rab11, a marker for recycling endosomes. These data indicate that oxidative stress may play a vital role in AMPAR-mediated cell death following ischemic/reperfusion injury.