Pluto Bioinformatics

GSE145569: Smooth muscle cell-derived vascular progenitor cells promote arterial remodeling and fibrosis through loss of Klf4 activity and spontaneous differentiation into myofibroblasts

Bulk RNA sequencing

Resident vascular adventitial progenitor cells express the stem cell marker, Sca1 (AdvSca1 cells). Using smooth muscle cell (SMC) lineage tracing models, we identified a subpopulation of AdvSca1 cells (AdvSca1-SM) that originate from mature SMCs that undergo reprogramming in situ and exhibit a multipotent phenotype. The adventitial microenvironment and induction of the transcription factor, Klf4 is critical to reprogramming; however, the mechanism of Klf4 induction is unknown. We aimed to define the signaling pathways involved in SMC reprogramming and the fate of AdvSca1-SM cells in response to vascular injury. Flow sorting was used to isolate YFP+Sca1- SMCs, YFP+Sca1+ AdvSca1-SM cells, and YFP-Sca1+ non-SMC-derived AdvSca1 cells from aortae (AO) and carotid arteries (CA) of SMC YFP reporter mice. RNA-seq analysis and unbiased hierarchical clustering revealed that genes related to hedgehog/Wnt/-catenin signaling are significantly enriched in AdvSca1-SM cells, emphasizing the importance of this signaling axis in SMC reprogramming. CA injury was induced by ligating the left common CA of SMC YFP reporter mice. In response to injury, AdvSca1-SM cells downregulate genes in the hedgehog/Wnt/beta-catenin signaling pathway, as well as stemness-related genes, and adopt a myofibroblast-like phenotype. To selectively fate-map AdvSca1-SM cells, we took advantage of the selective expression of Gli1 by AdvSca1-SM cells and generated Gli1-CreERT2-Rosa26-YFP reporter mice. Immunofluorescent (IF) staining show that YFP was expressed exclusively in a subpopulation of adventitial Sca1-positive cells. RNA-seq confirmed YFP+Sca1+ cell population in SMC and Gli1 lineage tracing models exhibit a highly similar gene expression profile, supporting this model to faithfully track AdvSca1-SM cells. CA injury induced proliferation and differentiation of AdvSca1-SM cells to myofibroblasts rather than macrophages, as indicated by IF stainings and flow cytometry. Surprisingly, AdvSca1-SM cells selectively contributed to adventitial remodeling and fibrosis, but little neointima formation. AdvSca1-SM cell specific genetic knockout of Klf4 induced spontaneous differentiation and expansion of AdvSca1-SM cells and increased perivascular fibrosis. SOURCE: Mary,C.M.,Weiser-Evans (Mary.weiser@ucdenver.edu) - Dr. Mary C.M. Weiser-Evans University of Colorado Anschutz Medical Campus