Prkg2 regulates alveolar type 2-mediated re-alveolarization

Abstract

BackgroundThe cGMP-dependent type 2 protein kinase, encoded by the prkg2 gene, is highly expressed in alveolar type 2 epithelial (AT2) cells. It is unclear whether prkg2 regulates AT2 cell homeostasis and re-alveolarization of injured lungs. This study aimed to investigate the role of prkg2 in the regulation of the fate of AT2 in vitro.MethodsPrimary AT2 cells of wild-type (wt) and prkg2−/− mice were co-cultured with fibroblasts as three-dimensional organoids. The colony formation was analyzed between days 4 and 12 post-seeding. EdU assay was used to detect cells with active DNA synthesis. AT1 and AT2 cells in organoids were visualized with anti-podoplanin and anti-surfactant protein C antibodies, respectively.ResultsPrkg2−/− AT2 cells developed a greater number of organoids than wt controls. However, compared to wt organoids, a lower number of AT2 but a greater number of AT1 cells were visualized. In addition, a lower number of proliferated cells (EdU+) were observed in prkg2−/− organoids compared to wt controls. The numbers of organoids and EdU+ cells were significantly reduced in protein kinase A (PKA) inhibitor H89-treated wt and prkg2−/− cultures. Organoids and EdU+ cells were increased by lipopolysaccharides (LPS) in both wt and prkg2−/− groups. The increase in the proportion of AT1 and AT2 cells in organoids was only seen in wt controls.ConclusionsPrkg2 may regulate the lineage of AT2 cells, which is affected by endotoxins and the interactive PKA signaling pathway.