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

Post-stroke epilepsy (PSE) is a major 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 1α (HIF1α) 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 HIF1α and demonstrate its role in hypoxia-induced network hyperexcitability. Using neuronal cell lines, primary cortical neurons, and organotypic brain slice cultures (OTCs) from mouse and human tissue, we show that HIF1α activation, either through hypoxia or HIF1α overexpression, consistently increases Cacna1h expression. In NS20Y cells, overexpression of a normoxia-stable HIF1α variant increased Cacna1h promoter activity in both fluorescent and dual-luciferase reporter assays. The same effect was observed in primary cortical neurons, where HIF1α overexpression also elevated network activity measured by multielectrode array recordings. In murine and human OTCs, hypoxia led to marked increase of HIF1α and Cacna1h expression at both transcript and protein levels. Furthermore, oxygen-glucose deprivation followed by reoxygenation (OGD/R) induced a persistent increase in neuronal firing rate, which was recapitulated by HIF1α overexpression alone. Together, these results establish HIF1α as a key transcriptional regulator of CaV3.2 in neurons and reveal a conserved hypoxia-HIF1α-CaV3.2 pathway that enhances neuronal excitability. This mechanism may underlie hypoxia-induced network hyperactivity and contribute to the pathogenesis of post-ischemic epileptogenesis.