Decreased EAAT2 protein expression in the essential tremor cerebellar cortex

Michelle Lee, Melody M. Cheng, Chi Ying Lin, Elan D. Louis, Phyllis L. Faust, Sheng Han Kuo

Research output: Contribution to journalReview article

19 Scopus citations

Abstract

Genetic polymorphisms in Solute carrier family 1 (glial high affinity glutamate transporter), member 2 (SLC1A2) have been linked with essential tremor. SLC1A2 encodes excitatory amino acid transporter type 2 (EAAT2), which clears glutamate from the synaptic cleft. One postulated mechanism for essential tremor is the over-excitation of glutamatergic olivo-cerebellar climbing fibers, leading to excitotoxic death of Purkinje cells. Other glutamatergic excitatory signals are transmitted to Purkinje cells via parallel fibers of cerebellar granule neurons. Therefore, the expression level of glutamate transporters could be important in essential tremor pathogenesis. Using Western blotting, we compared the expression levels of the two main glutamate transporters in the cerebellar cortex, EAAT1 and EAAT2, in postmortem tissue from 16 essential tremor cases and 13 age-matched controls. We also studied the localization of EAAT1 and EAAT2 using immunohistochemistry in 10 essential tremor cases and 12 controls. EAAT1 protein levels were similar in cases and controls (1.12 ± 0.83 vs. 1.01 ± 0.69, p =0.71) whereas EAAT2 protein levels in essential tremor cases were only 1/3 of that in controls (0.35 ± 0.23 vs. 1.00 ± 0.62, p < 0.01). Interestingly, EAAT2, but not EAAT1, was expressed in astrocytic processes surrounding the Purkinje cell axon initial segment, a region of previously observed pathological changes in essential tremor. Our main finding, a significant reduction in cerebellar cortical EAAT2 protein levels in essential tremor, suggests that Purkinje cells in essential tremor might be more vulnerable to excitotoxic damage than those of controls.

Original languageEnglish (US)
Article number157
JournalActa Neuropathologica Communications
Volume2
Issue number1
DOIs
StatePublished - Jan 27 2014
Externally publishedYes

Keywords

  • EAAT1
  • EAAT2
  • Essential tremor
  • Excitotoxicitiy
  • Neurodegenerative
  • Purkinje cell

ASJC Scopus subject areas

  • Pathology and Forensic Medicine
  • Clinical Neurology
  • Cellular and Molecular Neuroscience

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