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. Author manuscript; available in PMC: 2024 Feb 19.
Published in final edited form as: Annu Rev Pathol. 2022 Oct 21;18:337–359. doi: 10.1146/annurev-pathmechdis-031621-024344

Figure 2.

Figure 2

Alveolus intrinsic signals that promote proliferation and differentiation. AT2 cells serve as facultative progenitors for the alveolar epithelium. Recent work has uncovered subpopulations of AT2 cells that are preferentially endowed with proliferative capacity. AT2 cells are capable of regenerating both AT2 and AT1 lineages via proliferation and differentiation, respectively. Recent work has identified extracellular signals that promote (fibroblast growth factors, interleukin 1) or restrict (Tgf-β, interferons) AT2 cell proliferation. In contrast, Tgf-β promotes differentiation of AT2 cells into AT1 cells, while intracellular Yap/Taz signaling actively maintains AT1 identity by preventing differentiation back to the AT2 lineage. Abbreviations: AT1, alveolar type 1; AT2, alveolar type 2; Taz, transcriptional coactivator with PDZ-binding motif; Tgf-β, transforming growth factor beta; Yap, Yes-associated protein. Figure adapted from images created with BioRender.