Interestingly, KCl-induced depolarization of cortical iPSC-derived neuronal cultures resulted in a transient down-regulation of NEAT1 (Fig. 2b), with temporal dynamics that closely mirrored the activity-dependent cytoplasmic increase in KCNAB2 protein (Fig. 1d). We verified that KCNAB2 localization was also altered in iPSC-derived neurons upon KCl-induced activation (Supplementary Fig. 6) as was observed in SH-SY5Y cells (Fig. 1e,f). To investigate the functional significance of activity-dependent NEAT1 down-regulation, we knocked down NEAT1 transcript using ASOs directed against NEAT1 (Fig. 2c) and measured the effect of this on neuronal excitability in iPSC-derived neurons through Fluorescent Imaging Plate Reader (FLIPR) intracellular calcium mobilization assays, as intracellular calcium changes are critical for synapse-induced neuronal responses22. Notably, ASO-mediated NEAT1-knockdown significantly increased depolarization-induced calcium influx (Fig. 2d), demonstrating that NEAT1 may modulate neuronal excitability.
