Project description:The platelet-derived growth factor receptor alpha (PDGFRα) exhibits divergent effects in skeletal muscle. At physiological levels, signaling through this receptor promotes muscle development in growing embryos and proper angiogenesis in regenerating adult muscle. However, either increased PDGF ligands or enhanced PDGFRα pathway activity causes pathological fibrosis. This excessive collagen deposition, which is seen in aged and diseased muscle, interferes with proper muscle function and limits the effectiveness of gene- and cell-based therapies for muscle disorders. Although compelling evidence exists for the role of PDGFRα in fibrosis, little is known about the cells through which this pathway acts. Here we show that PDGFRα signaling regulates a population of muscle-resident fibro/adipogenic progenitors (FAPs) that play a supportive role in muscle regeneration but may also cause fibrosis when aberrantly regulated. We found that FAPs produce multiple transcriptional variants of PDGFRα with different polyadenylation sites, including an intronic variant that codes for a protein isoform containing a truncated kinase domain. This variant, upregulated during regeneration, acts as a decoy to inhibit PDGF signaling and to prevent FAP over-activation. Moreover, increasing expression of this isoform limits fibrosis in vivo, suggesting both biological relevance and therapeutic potential of modulating polyadenylation patterns in stem cell populations. We used microarrays to explore the biological effects of altering intronic polyadenylation of PDGFRα in FAPs in vivo.
Project description:The platelet-derived growth factor receptor alpha (PDGFRα) exhibits divergent effects in skeletal muscle. At physiological levels, signaling through this receptor promotes muscle development in growing embryos and proper angiogenesis in regenerating adult muscle. However, either increased PDGF ligands or enhanced PDGFRα pathway activity causes pathological fibrosis. This excessive collagen deposition, which is seen in aged and diseased muscle, interferes with proper muscle function and limits the effectiveness of gene- and cell-based therapies for muscle disorders. Although compelling evidence exists for the role of PDGFRα in fibrosis, little is known about the cells through which this pathway acts. Here we show that PDGFRα signaling regulates a population of muscle-resident fibro/adipogenic progenitors (FAPs) that play a supportive role in muscle regeneration but may also cause fibrosis when aberrantly regulated. We found that FAPs produce multiple transcriptional variants of PDGFRα with different polyadenylation sites, including an intronic variant that codes for a protein isoform containing a truncated kinase domain. This variant, upregulated during regeneration, acts as a decoy to inhibit PDGF signaling and to prevent FAP over-activation. Moreover, increasing expression of this isoform limits fibrosis in vivo, suggesting both biological relevance and therapeutic potential of modulating polyadenylation patterns in stem cell populations. We used microarrays to explore the biological effects of altering intronic polyadenylation of PDGFRα in FAPs.
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from Mus musculus tissues (Heart, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:SILAC based protein correlation profiling using size exclusion of protein complexes derived from seven Mus musculus tissues (Heart, Brain, Liver, Lung, Kidney, Skeletal Muscle, Thymus)
Project description:PDGFRα+ cells are interstitial/perivascular mesenchymal progenitor cells that have been associated with fibro-adipogenic processes. However, their function during tissue homeostasis or in response to revascularization and regeneration stimuli remains to be fully defined. Here, by high-throughput transcriptomic analysis, adoptive transfer and multicolor lineage tracking we showed that PDGFRα+ cells from skeletal muscle cluster as a population that is transcriptionally distinct from other mesenchymal stromal cells and with an essential role in tissue revascularization and restructuring of ischemic areas. We further showed that tissue regeneration involves the removal of differentiated PDGFRα+-derived cells, while pathological healing occurred if PDGFRα+-derived cells persisted as terminally differentiated mesenchymal cells (e.g. myofibroblasts). From the perspective of tissue regeneration, these studies support a context-dependent 'yin-yang' biology of PDGFRα+ cells, that possess an innate ability to stabilize newly formed blood vessels and concurrently limit injury expansion after ischemia, while also being capable of promoting fibrosis in an unfavorable environment.