Project description:Purpose: The goal of this study is to investigate mesenchymal cell-type specific role of KLF4 in the context of lung fibrosis. Methods: Adult Pdgfrb-CreERT2, ROSA26R(Zs/+) mice were induced with tamoxifen (1mg/day for 5 days), rested for 5 days. The lungs were harvested and prepared to obtain single cell suspension. Live Zs+ cells were isolated by FACS, cultured, and subjected to Klf4 siRNA or Scr RNA treatment. Total RNA was purified after 72 hrs. and subjected to bulk RNA-seq. using Illumina HiSeq 2000. Similarly, wild type mice airway smooth muscle cells (cell biologics) were treated with Klf4 siRNA or Scr RNA. Total RNA was purified after 72 hrs. and subjected to bulk RNA-seq. Results: Expression profile of the transcriptome are compared between cell-types; PDGFR-β+ cells and airway smooth muscle cells. Conclusions: Significant difference in the expression of genes involved in pathogenesis of fibrosis was observed
Project description:During lung fibrosis, the epithelium induces signaling to underlying mesenchyme to generate excess myofibroblasts and extracellular matrix; herein, we focus on signaling in the mesenchyme. Our studies indicate that platelet-derived growth factor receptor (PDGFR)-β+ cells are the predominant source of myofibroblasts and Kruppel-like factor (KLF) 4 is upregulated in PDGFR-β+ cells, inducing TGFβ pathway signaling and fibrosis. In fibrotic lung patches, KLF4 is down-regulated, suggesting KLF4 levels decrease as PDGFR-β+ cells transition into myofibroblasts. In contrast to PDGFR-β+ cells, KLF4 reduction in α-smooth muscle actin (SMA)+ cells non-cell autonomously exacerbates lung fibrosis by inducing macrophage accumulation and pro-fibrotic effects of PDGFR-β+ cells via a Forkhead box M1 to C-C chemokine ligand 2-receptor 2 pathway. Taken together, in the context of lung fibrosis, our results indicate that KLF4 plays opposing roles in PDGFR-β+ cells and SMA+ cells and highlight the importance of further studies of interactions between distinct mesenchymal cell types.
