Involvement of ampa receptor and its flip and flop isoforms in retinal ganglion cell death following oxygen/glucose deprivation

Yong H. Park, Heather V. Broyles, Shaoqing He, Nolan R. McGrady, Linya Li, Thomas Yorio

Research output: Contribution to journalArticle

5 Scopus citations

Abstract

PURPOSE. The a-amino-3-hydroxy-5-methyl-4-isoxazoleproprionic acid (AMPA) receptors (AMPAR) subunits can be posttranscriptionally modified by alternative splicing forming flip and flop isoforms. We determined if an ischemia-like insult to retinal ganglion cells (RGCs) increases AMPAR susceptibility to s-AMPA–mediated excitotoxicity through changes in posttranscriptional modified isoforms. METHODS. Purified neonatal rat RGCs were subjected to either glucose deprivation (GD) or oxygen/glucose deprivation (OGD) conditions followed by treatment with either 100 lM s- AMPA or Kainic acid. A live–dead assay and caspase 3 assay was used to assess cell viability and apoptotic changes, respectively. We used JC-1 dye and dihydroethidium to measure mitochondria depolarization and reactive oxygen species (ROS), respectively. Calcium imaging with fura-2AM was used to determine intracellular calcium, while the fluorescentlylabeled probe, Nanoprobe1, was used to detect calcium-permeable AMPARs. Quantitative PCR (qPCR) analysis was done to determine RNA editing sites AMPAR isoforms. RESULTS. Glucose deprivation, as well as an OGD insult followed by AMPAR stimulation, produced a significant increase in RGC death. Retinal ganglion cell death was independent of caspase 3/7 activity, but was accompanied by increased mitochondrial depolarization and increased ROS production. This was associated with an elevated intracellular Ca2+ and calcium permeable-AMPARs. The mRNA expression of GLUA2 and GLUA3 flop isoform decreased significantly, while no appreciable changes were found in the corresponding flip isoforms. There were no changes in the Q/R editing of GLUA2, while R/G editing of GLUA2 flop declined under these conditions. CONCLUSIONS. Following oxidative injury, RGCs become more susceptible to AMPAR-mediated excitotoxicity. RNA editing and changes in alternative spliced flip and flop isoforms of AMPAR subunits may contribute to increased RGC death.

Original languageEnglish
Pages (from-to)508-526
Number of pages19
JournalInvestigative Ophthalmology and Visual Science
Volume57
Issue number2
DOIs
StatePublished - Feb 2016

Keywords

  • ADAR proteins
  • AMPA
  • Cell death
  • Flip/flop isoforms
  • RGCs

Fingerprint Dive into the research topics of 'Involvement of ampa receptor and its flip and flop isoforms in retinal ganglion cell death following oxygen/glucose deprivation'. Together they form a unique fingerprint.

  • Cite this