The transcription factor bmi1 increases hypoxic signaling in oral cavity epithelia

Biochim Biophys Acta Mol Basis Dis. 2024 Apr 8:167161. doi: 10.1016/j.bbadis.2024.167161. Online ahead of print.ABSTRACTThe tongue epithelium is maintained by a proliferative basal layer. This layer contains long-lived stem cells (SCs), which produce progeny cells that move up to the surface as they differentiate. B-lymphoma Mo-MLV insertion region 1 (Bmi1), a protein in mammalian Polycomb Repressive Complex 1 (PRC1) and a biomarker of oral squamous cell carcinoma, is expressed in almost all basal epithelial SCs of the tongue, and single, Bmi1-labelled SCs give rise to cells in all epithelial layers. We previously developed a transgenic mouse model (KrTB) containing a doxycycline- (dox) controlled, Tet-responsive element system to selectively overexpress Bmi1 in the tongue basal epithelial SCs. Here, we used this model to assess Bmi1 actions in tongue epithelia. Genome-wide transcriptomics revealed increased levels of transcripts involved in the cellular response to hypoxia in Bmi1-overexpressing (KrTB + DOX) oral epithelia even though these mice were not subjected to hypoxia conditions. Ectopic Bmi1 expression in tongue epithelia increased the levels of hypoxia inducible factor-1 alpha (HIF1α) and HIF1α targets linked to metabolic reprogramming during hypoxia. We used chromatin immunoprecipitation (ChIP) to demonstrate that Bmi1 associates with the promoters of HIF1A and HIF1A-activator RELA (p65) in tongue epithelia. We also detected increased SC proliferation and oxidati...
Source: Molecular Medicine - Category: Molecular Biology Authors: Source Type: research