Small molecule glutaminase inhibitors block glutamate release from stimulated microglia

Ajit G. Thomas, Cliona M. O'Driscoll, Joseph Bressler, Walter Kaufmann, Camilo J. Rojas, Barbara S. Slusher

Research output: Contribution to journalArticlepeer-review

Abstract

Glutaminase plays a critical role in the generation of glutamate, a key excitatory neurotransmitter in the CNS. Excess glutamate release from activated macrophages and microglia correlates with upregulated glutaminase suggesting a pathogenic role for glutaminase. Both glutaminase siRNA and small molecule inhibitors have been shown to decrease excess glutamate and provide neuroprotection in multiple models of disease, including HIV-associated dementia (HAD), multiple sclerosis and ischemia. Consequently, inhibition of glutaminase could be of interest for treatment of these diseases. Bis-2-(5-phenylacetimido-1,2,4-thiadiazol-2-yl)ethyl sulfide (BPTES) and 6-diazo-5-oxo- l-norleucine (DON), two most commonly used glutaminase inhibitors, are either poorly soluble or non-specific. Recently, several new BPTES analogs with improved physicochemical properties were reported. To evaluate these new inhibitors, we established a cell-based microglial activation assay measuring glutamate release. Microglia-mediated glutamate levels were significantly augmented by tumor necrosis factor (TNF)-α, phorbol 12-myristate 13-acetate (PMA) and Toll-like receptor (TLR) ligands coincident with increased glutaminase activity. While several potent glutaminase inhibitors abrogated the increase in glutamate, a structurally related analog devoid of glutaminase activity was unable to block the increase. In the absence of glutamine, glutamate levels were significantly attenuated. These data suggest that the in vitro microglia assay may be a useful tool in developing glutaminase inhibitors of therapeutic interest.

Original languageEnglish (US)
Pages (from-to)32-36
Number of pages5
JournalBiochemical and Biophysical Research Communications
Volume443
Issue number1
DOIs
StatePublished - Jan 3 2014

Keywords

  • Glutamate
  • Glutaminase
  • Glutamine
  • HIV-associated dementia (HAD)
  • Inflammation
  • Microglia

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology

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