Small molecule glutaminase inhibitors block glutamate release from stimulated microglia

Area of Science:

• Neuroscience
• Biochemistry
• Pharmacology

Background:

• Glutaminase is crucial for glutamate synthesis, a key CNS neurotransmitter.
• Upregulated glutaminase in activated microglia contributes to excess glutamate release and neuroinflammation.
• Existing glutaminase inhibitors like BPTES and DON have limitations in solubility and specificity.

Purpose of the Study:

• To evaluate novel BPTES analogs as potential therapeutic agents for neurological disorders.
• To establish and validate a cell-based microglial activation assay for assessing glutaminase inhibitors.
• To investigate the role of glutaminase in microglia-mediated glutamate release.

Main Methods:

• Development of a cell-based assay to measure glutamate release from activated microglia.
• Treatment of activated microglia with TNF-α, PMA, and TLR ligands to induce glutamate release.
• Assessment of glutaminase activity and glutamate levels following treatment with various glutaminase inhibitors and analogs.
• Glutamine deprivation experiments to confirm glutaminase dependency.

Main Results:

• Microglial activation significantly increased glutamate levels and glutaminase activity.
• Potent glutaminase inhibitors effectively blocked the TNF-α, PMA, and TLR ligand-induced glutamate increase.
• A non-active glutaminase analog failed to inhibit glutamate release, confirming target specificity.
• Glutamate levels were significantly reduced in the absence of glutamine.

Conclusions:

• The developed in vitro microglial assay is a valuable tool for screening and developing effective glutaminase inhibitors.
• Inhibition of glutaminase demonstrates therapeutic potential for conditions involving neuroinflammation and excess glutamate.
• Novel BPTES analogs show promise as specific and effective glutaminase inhibitors.