DEVELOPING CHIMERIC GLUTAMATE-GATED POTASSIUM CHANNELS (GKV) AS NOVEL TOOLS FOR NEURAL CIRCUIT MANIPULATION

Mammalian ionotropic glutamate receptors are cation channels that mediate excitatory signalling, and their dysregulation is associated with neurological disorders such as epilepsy and autism. Previously, a C. elegans-derived glutamate-gated chloride channel was developed to successfully attenuate seizures. Thus, glutamate-gated inhibitory channels represent a promising strategy for activity-dependent neural circuit manipulation. Here, we developed chimeric glutamate-gated potassium channels (GKv) by combining the ligand-binding domain of human GluA1 with a viral potassium channel pore. AlphaFold prediction suggests that GKv assembles into a stable tetrameric structure. We demonstrate that GKv is activated in a glutamate-dependent manner and exhibits high potassium selectivity in Neuro2a cells. In cultured neurons, GKv expression prolongs action potential firing latency and increases the firing threshold, consistent with an inhibitory effect. However, multielectrode array (MEA) recordings reveal that GKv prolongs burst duration and increases spike numbers under in vivo acute pentylenetetrazol (PTZ)-induced conditions. Consistently, GKv shows a similar pro-excitatory phenotype in an acute PTZ-induced convulsion model. These findings suggest that GKv acts as a glutamate-gated potassium channel but may evoke homeostatic compensatory responses that counteract its intended inhibitory function. Nevertheless, our study establishes a feasible strategy for engineering glutamate-gated potassium chimeras and provides a pipeline for developing new tools for neural circuit manipulation.