TAAR1-dependent astrocyte dysregulation during HAND and METH exposure

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2018-12

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Mythen, Shannon

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Abstract

Excitatory amino-acid transporter (EAAT)-2 is predominantly expressed in astrocytes and clears glutamate from tripartite synapses preventing excitotoxicity. EAAT- 2 dysregulation occurs during human immunodeficiency virus (HIV)-associated neuroinflammation and methamphetamine (METH) abuse, leading to neurotoxic outcomes. Trace amine associated receptor (TAAR) 1, a METH receptor in astrocytes, triggers EAAT-2 dysfunction. Protein kinase C (PKC) signaling promotes ubiquitination of EAAT-2 C-terminal lysine residues, resulting in EAAT-2 internalization. As a G protein coupled receptor, TAAR1's signaling is implicated in PKC activation. In this work, we investigated the role of TAAR1 in PKC-mediated EAAT-2 ubiquitination during HIV- associated neurocognitive disorders (HAND) and METH comorbidities. We evaluated a TAAR1 overexpression model in primary astrocytes to elucidate TAAR1-mediated functional changes. We found that TAAR1-selective inhibitor, EPPTB, reduced EAAT-2 ubiquitination, and a PKC activator decreased glutamate clearance in METH-pretreated human astrocytes. Therapies targeting astrocyte dysfunction may improve outcomes during HAND, METH abuse and other neuroinflammatory disorders.

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