David B. Frank

promote enhanced AT2 cell growth during generation of the alveolus. Activating Wnt signaling results in the expansion of AT2s, whereas inhibition of Wnt signaling inhibits AT2 cell development and shunts alveolar epithelial development toward the alveolar type 1 cell lineage. These findings reveal a wave of Wnt-dependent AT2 expansion required for lung alveologenesis and maturation.

The lung alveolus is the functional unit of the respiratory system required for gas exchange. During the transition to air breathing at birth, biophysical forces are thought to shape the emerging tissue niche. However, the intercellular signaling that drives these processes remains poorly understood. Applying a multimodal approach, we identified alveolar type 1 (AT1) epithelial cells as a distinct signaling hub. Lineage tracing demonstrates that AT1 progenitors align with receptive, force-exerting myofibroblasts in a spatial and temporal manner. Through single-cell chromatin accessibility and pathway expression (SCAPE) analysis, we demonstrate that AT1-restricted ligands are required for myofibroblasts and alveolar formation. These studies show that the alignment of cell fates, mediated by biophysical and AT1-derived paracrine signals, drives the extensive tissue remodeling required for postnatal respiration.