Photoswitchable Inhibitor of a Glutamate Transporter

• Published in: ACS chemical neuroscience 2017-08, Vol.8 (8), p.1668-1672
• Main Authors: Cheng, Bichu, Shchepakin, Denis, Kavanaugh, Michael P, Trauner, Dirk
• Format: Article
• Language: English
• Subjects: Animals; Aspartic Acid - analogs & derivatives; Aspartic Acid - chemical synthesis; Aspartic Acid - chemistry; Aspartic Acid - pharmacology; Dose-Response Relationship, Drug; Excitatory Amino Acid Transporter 1 - antagonists & inhibitors; Excitatory Amino Acid Transporter 1 - metabolism; Excitatory Amino Acid Transporter 3 - antagonists & inhibitors; Excitatory Amino Acid Transporter 3 - metabolism; Glutamate Plasma Membrane Transport Proteins - antagonists & inhibitors; Glutamate Plasma Membrane Transport Proteins - metabolism; Humans; Isomerism; Light; Membrane Potentials - drug effects; Membrane Transport Modulators - chemical synthesis; Membrane Transport Modulators - chemistry; Membrane Transport Modulators - pharmacology; Molecular Structure; Oocytes; Patch-Clamp Techniques; Photochemical Processes; Xenopus laevis
• ISSN: 1948-7193; 1948-7193
• DOI: 10.1021/acschemneuro.7b00072

Excitatory amino acid transporters clear glutamate from the synaptic cleft and play a critical role in glutamatergic neurotransmission. Their differential roles in astrocytes, microglia, and neurons are poorly understood due in part to a lack of pharmacological tools that can be targeted to specific cells and tissues. We now describe a photoswitchable inhibitor, termed ATT, that interacts with the major mammalian forebrain transporters EAAT1–3 in a manner that can be reversibly switched between trans (high-affinity) and cis (low-affinity) configurations using light of different colors. In the dark, ATT competitively inhibited the predominant glial transporter EAAT2 with ∼200-fold selectivity over the neuronal transporter EAAT3. Brief exposure to 350 nm light reduced the steady-state blocker affinity by more than an order of magnitude. Illumination of EAAT2 complexed with ATT induced a corresponding increase in the blocker off-rate monitored in the presence of glutamate. ATT can be used to reversibly manipulate glutamate transporter activity with light and may be useful to gain insights into the dynamic physiological roles of glutamate transporters in the brain, as well as to study the molecular interactions of transporters with ligands.