SRP190125 PRJNA530392 GSE129177 DNMT1 is required for proximal-distal patterning of the lung endoderm and restraining alveolar type 2 cell fate Lung endoderm development occurs through a series of finely coordinated transcriptional processes that are regulated by epigenetic mechanisms. However, the role of DNA methylation in regulating lung endoderm development remains poorly understood. We demonstrate that DNA methyltransferase 1 (Dnmt1) is required for early branching morphogenesis of the lungs and for restraining epithelial fate specification. Loss of Dnmt1 leads to an early branching defect, a loss of proximal endodermal cell differentiation, and an expansion of the distal endoderm compartment. Dnmt1 deficiency also leads to precocious distal endodermal cell differentiation with premature expression of alveolar type 2 cell restricted genes. These data reveal an important requirement for Dnmt1 mediated DNA methylation in early lung development to promote proper branching morphogenesis, maintain proximal endodermal cell fate, and suppress premature activation of the distal epithelial fate. Overall design: Lung were harvested from E12.5 wild-type littermate and ShhCre-Dnmt1KO mice. GSE129177 pubmed 31242446