AXON-TARGETED MAGNETOGENETICS INDUCE PRESYNAPTIC PLASTICITY IN CULTURED HIPPOCAMPAL NEURONS VIA MAGNETIC FIELD STIMULATION

Synaptic plasticity is a cellular mechanism that enables the nervous system to adapt in response to experiences or pathological conditions. Achieving external control over synaptic plasticity remains a major challenge, yet it holds promise for targeted modulation of neuronal circuits. Magnetogenetics comprises a set of approaches that rely on genetic modification to render cells responsive to magnetic stimulation. FeRIC (Ferritin Iron Redistribution to Ion Channels) is a magnetogenetic approach in which the TRPV4 channel is coupled to endogenous ferritin, allowing activation by radiofrequency (RF) magnetic fields. In this study, we aimed to selectively target FeRIC channels to axons and presynaptic terminals to enable remote magnetic modulation of neurotransmitter release. To achieve axonal localization, we fused the dipalmitoylation domain of growth-associated protein 43 (GAP43) to the N-terminus of TRPV4^FeRIC, generating an axon-targeted construct termed Axon-FeRIC. Cultured hippocampal neurons were transduced at 3 days in vitro and recorded between 10 and 14 days in vitro. RF stimulation of neurons expressing Axon-FeRIC induced an increase in axonal calcium levels, as measured by GCaMP6f fluorescence. Moreover, in whole-cell patch-clamp recordings, RF stimulation increased the frequency of spontaneous excitatory postsynaptic currents (sEPSCs), enhanced the amplitude of evoked EPSCs, and increased the paired-pulse ratio, consistent with an increased probability of neurotransmitter release. Our findings demonstrate that axon-targeted magnetogenetics enables compartment-specific control of presynaptic calcium dynamics and can induce presynaptic plasticity through remote magnetic stimulation.