HIF1α-dependent induction of the T-Type calcium channel CaV3.2 mediates hypoxia-induced neuronal hyperexcitability

Abstract

Post-stroke epilepsy (PSE) is a leading cause of acquired epilepsy in adults, yet the molecular mechanisms linking post-ischemic hypoxia to neuronal hyperexcitability remain poorly understood. The transcription factor hypoxia-inducible factor 1 (HIF1) is a central mediator of the cellular response to hypoxia and may contribute to epileptogenesis by regulating ion channel expression. Here, we identify the T-type calcium channel CaV3.2 (encoded by Cacna1h) as a direct transcriptional target of HIF1 and demonstrate its role in hypoxia-induced network hyperexcitability. Oxygen-glucose deprivation followed by reoxygenation (OGD/R) induced a persistent increase in neuronal firing rate. In murine and human organotypic brain slices, hypoxia led to a marked increase in HIF1 and Cacna1h expression at both transcript and protein levels. Using neuronal cell lines and primary cortical neurons we show that HIF1 activation through HIF1 overexpression, consistently increases Cacna1h expression. In NS20Y cells, overexpression of a normoxia-stable HIF1 variant increased Cacna1h promoter activity in both fluorescent and dual-luciferase reporter assays. The same effect was observed in primary cortical neurons, where HIF1 overexpression also elevated network activity measured by multielectrode array recordings, replicating the effect of the OGD/R model. Together, these results establish HIF1 as a key transcriptional regulator of CaV3.2 in neurons and reveal a conserved hypoxia-HIF1-CaV3.2 pathway that enhances neuronal excitability. This mechanism may underlie hypoxia-induced network hyperactivity and contribute to the pathogenesis of post-ischemic epileptogenesis, offering a potential molecular target for intervention.