Loss of ITGA6 Activates p38 MAPK Signaling to Drive Squamous Conversion of Human Airway Basal Cells

Human airway basal cells (BCs) rely on integrin–extracellular matrix (ECM) interactions to maintain epithelial integrity. In healthy airways, integrins α3β1 and α6β4 recognize laminins in the basement membrane, whereas injury-associated integrins (α2β1, α9β1, α5β1, and αv-containing complexes) engage ECM ligands that emerge during inflammation or tissue damage. Although α6 integrins are canonical laminin receptors and established BC markers, their expression and function are highly dependent on the surrounding ECM and are altered in chronic airway disease. Pathologic ECM stiffening and changes in laminin and collagen composition have been linked to disrupted epithelial architecture and abnormal BC phenotypes; however, how these matrix alterations influence α6 activation, mechanotransduction, and subsequent fate decisions remains unknown. We have observed similar ECM-dependent changes in BC behavior during ex vivo expansion. The role of α6 integrins in regulating human BC stemness therefore remains poorly defined, creating a critical barrier to understanding airway regeneration and developing targeted restorative therapies. We hypothesized that α6-integrin signaling networks control BC stemness, proliferation, and differentiation and are critical to maintaining long lived BC stemness in the airways. Using primary human bronchial basal cells (HBECs) from three independent donors, we combined CRISPR-based ITGA6 knockout with assessments of cellular behavior, including electrical cell impedance sensing, proliferation, and differentiation, to investigate mechanisms driving squamous-like conversion of airway BCs. Functional loss of ITGA6 markedly disrupted BC proliferation, tight junction formation, and adhesion/spreading dynamics. Knockout cells exhibited a significant upregulation of squamous-associated genes, including IVL and SPRR1B, and demonstrated a loss of functional differentiation at the air–liquid interface. Notably, ITGA6 knockout resulted in increased expression of other integrins (ITGA3, ITGB1, ITGA9) and was accompanied by enhanced p38 MAPK phosphorylation. Pharmacologic inhibition of p38 MAPK activity suppressed the induction of squamous cell-associated genes and significantly improved cell proliferation. In conclusion, these findings identify ITGA6 as a critical regulator of airway BC stemness, with its loss triggering p38 MAPK-dependent reprogramming toward a squamous, non-functional BC state. These results highlight ITGA6 loss changes BC adhesion dynamics associated with increased α3β1 and α9β1 expression which activate a stress-responsive p38 MAPK pathway. Chronic changes in integrin-ECM interactions in chronic lung disease highlight potential therapeutic targets for preserving or restoring BC function in regenerative and cell-based airway therapies. This research was funded by NSF-ENG-BIOTECH #15265800 awarded to ALR This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.