Impaired AMPK Control of Alveolar Epithelial Cell Metabolism Promotes Pulmonary Fibrosis
Alveolar epithelial type II (AT2) cell dysfunction is implicated in the pathogenesis of familial and sporadic idiopathic pulmonary fibrosis (IPF). We previously demonstrated that expression of an AT2 cell exclusive disease-associated protein isoform (SP-CI73T) in murine and patient-specific induced pluripotent stem cell (iPSC)-derived AT2 cells leads to a block in late macroautophagy and promotes time-dependent mitochondrial impairments; however, how a metabolically dysfunctional AT2 cell results in fibrosis remains elusive. Here, using murine and human iPSC-derived AT2 cell models expressing SP-CI73T, we characterize the molecular mechanisms governing alterations in AT2 cell metabolism that lead to increased glycolysis, decreased mitochondrial biogenesis, disrupted fatty acid oxidation, accumulation of impaired mitochondria, and diminished AT2 cell progenitor capacity manifesting as reduced AT2 self-renewal and accumulation of transitional epithelial cells. We identify deficient AMP-kinase signaling as a key upstream driver of AT2 cell dysfunction and demonstrate that targeting this druggable signaling hub can rescue the aberrant AT2 cell metabolic phenotype and mitigate lung fibrosis in vivo. Overall design: This data set is composed of samples from four different experiments.  The scRNA samples are derived from SftpcI73T mice 28 days post tamoxifen induction and dosed via intraperitoneal injections with either Metformin or vehicle beginning at day 12 post tamoxifen induction.  Single cell suspension from whole lungs were CD45 and CD31 depeleted prior to library generation.  There is also an RNA-seq data set derived from murine AT2 cells isolated at 3 and 14 days post tamoxifen from SftpcI73T mice using a CD45 depeletion and adhereance binding protocol that enriches for 95% AT2 cells (libraries names AT2-#).  Additionally we have a third data set derived from flow sorted murine AT2 cells isolated at 14 days post tamoxifen from SftpcI73T mice using MHCII and CD51 to enrich for transitional AT2 cells.  Finally we have included an RNA-seq data set from Human iPSC derived cells differentiated into iAT2s and challenged for 24 hours with AICAR.