Notch signaling is a driver of glandular stem cell activity and regenerative migration after damage

Organoid models have significantly enhanced our understanding of adult stem cell function, however, uncovering regulatory mechanisms governing rare and often quiescent stem cells in glandular organs remains challenging. Here, we employ an integrative multi-omics approach, combining single-cell RNA sequencing, bulk ATAC and RNA sequencing, to profile the cellular populations and signaling pathways characterizing a mouse salivary gland organoid model across different temporal stages and after radiation-induced damage. Our findings identify Sox9- and Itgb1/Cd44-expressing cells as primitive adult stem/progenitor populations with a critical migratory role in tissue repair. Notch signaling is a key driver of self-renewal and migration in response to irradiation. Additionally, scRNA-seq analysis of irradiated salivary gland tissue confirms these findings in an in vivo setting. Extending these findings to murine and patient-derived salivary, mammary and thyroid gland organoids, we reveal the conserved role of Notch signaling in coordinating stem/progenitor cell-mediated regeneration across glandular tissues. These insights position Notch signaling as a central regulator of glandular stem cell-like populations and as a promising therapeutic target for enhancing glandular tissue regeneration following cancer therapies.