Probing for the cellular identity of Bronchioalveolar Stem Cells (BASCs) derived from variant club cells post antibody-mediated Notch inhibition.

Abstract

Cell fate in adult tissues is tightly regulated by signaling mechanisms that maintain homeostasis and facilitate repair. In the lung, club cells act as facultative progenitors, self-renewing and giving rise to multiciliated cells. Under specific injury conditions, they can also contribute to alveolar regeneration. While Notch signaling maintains club cell identity, its inhibition typically drives transdifferentiation into ciliated cells. However, a recent study from our lab identified a subset of variant Club cells that evade this fate switch and instead enter a dual-identity state, co-expressing the Club cell marker CC10/Scgb1a1 and the alveolar type 2 (AT2) marker SPC/Sftpc, resembling bronchioalveolar stem cells (BASCs). These cells are enriched at neuroepithelial bodies (NEBs) and bronchioalveolar duct junctions (BADJs), niches known for regenerative potential. To characterize these BASCs derived from club cells derived from variant club cells, we took two approaches. First, the immunohistochemistry approach is to see if they express any other gene at the protein level of the club or alveolar type 2 cell. Second, I contributed to isolating these cells with my lab members, on which single-cell RNA sequencing analysis was done. Our findings show that while these cells express markers of both club and AT2 cells, they lack other definitive markers, suggesting their lineage-ambiguous nature. This intermediate state allows them to either revert to Club cells or transition into other epithelial lineages, highlighting their potential role in lung repair and regeneration and providing new insights into airway epithelial plasticity.