Hypercapnia has deleterious effects on cell function, including inhibition of alveolar epithelial cells (AEC) and fibroblast proliferation without causing cell death. Classical studies and lineage-trace models demonstrated that surfactant-producing AT2 cells can serve as stem cells for the structurally and functionally distinct alveolar type 1 cells (AT1) This AT2 reprogramming depends on Wnt/βcat signaling, a pathway that plays critical roles in tissue development and homeostasis throughout the organism lifespan. We found that high CO2 inhibits AT2 cell proliferation and self renewal, and promote their differentiation to ATEC and AT1 cells Overall design: Transcriptomic profiles of flow sorted alveolar type 2 cells from C57Bl/6 mice exposed to 10% CO2 undernormoxic conditions for 0, 7 and 21 days were generated by standard illumina RNA-Seq protocols.