SRP402673 PRJNA890628 GSE215797 An in vitro model of acute horizontal basal cell activation reveals dynamic gene regulatory networks underlying the acute activation phase Unlike most of the adult nervous system, the olfactory epithelium (OE) can regenerate neurons lost during normal homeostasis or after injury. This life-long regeneration is propagated by two populations of stem cells, the actively proliferating globose basal cells (GBCs) and the dormant horizontal basal cells (HBCs). HBCs only activate and contribute to epithelial regeneration in the context of severe injury, and this activation is mediated by the loss of the transcription factor Tp63. While the HBC differentiation trajectories that occur after activation have been described with lineage tracing and single-cell RNA seq experiments, the immediate consequences of injury on HBC gene expression and fate commitment have not been explored. We present an in vitro model of the acute activation process for HBCs in response to treatment with phorbol 12-myristate 13-acetate (PMA) to explore the molecular underpinnings of these early activation events. We find that treating HBCs with PMA induces the rapid degradation of TP63, and we find that this effect is partially reversed when cells are allowed to recover in maintenance media. Using bulk RNA sequencing we found that PMA-treated HBCs pass through various stages of acute activation identifiable by specific gene regulatory signatures. These transcriptomic phases are associated with varying degrees of plasticity with regards to activated HBCs ability to engraft in transplant models. Overall design: We performed gene expression profiling analysis using data obtained from RNA-seq of three HBC populations at three stages of activation (0H, 6H, and 12H). Cells were activated with 50nM phorbol 12-myristate 13-acetate (PMA). GSE215797 pubmed 39059377