<i>Lrig1</i>-expressing quiescent stem cells maintain vocal fold mucosal homeostasis via <i>Notch</i> signaling.

Abstract

Identifying progenitor cells in laryngeal and vocal fold (VF) mucosa is essential for advancing stem cell-based therapies for VF diseases. In this study, we used <i>Lrig1</i> (leucine-rich repeats and immunoglobulin-like domains 1) gene to label tissue-resident stem cells within laryngeal and VF mucosa, aiming to investigate cellular networks underlying VF homeostasis and regeneration. <i>Lrig1</i>⁺ cells exhibited hallmark features of quiescent stem cells-including slow cycling, long-term persistence, and differentiation potential-and contributed to sustained VF regeneration and repair after naphthalene injury. By one week post injury <i>Lrig1</i>⁺ progeny restored the damaged VF epithelium. Transcriptionally, these cells suppressed cell type specific genes and proliferation while activating programs related to RNA metabolism, epigenetic regulation, and protein ubiquitination, consistent with quiescence and readiness for activation. <i>Lrig1</i>⁺ cells were enriched in basal, parabasal, and immature secretory populations within surface epithelium and submucosal glands, residing in niches characterized by transcriptional flexibility and spatial shielding from direct stress-features that likely prevent premature or chronic mobilization. Notably, analogous LRIG1 expressing cells were identified in human laryngeal and VF tissues, highlighting the translational relevance of our findings. To explore regulation of <i>Lrig1</i>⁺ cell quiescence, we conditionally deleted <i>Notch1,</i> which led to epithelial hyperplasia, expansion of secretory populations, and mucus hyperproduction. In summary, <i>Lrig1</i> marks a conserved, quiescent stem cell population in the larynx and VFs that supports long-term tissue homeostasis and repair, with quiescence maintained via <i>Notch1</i> signaling.