PDGF-C is a new protease-activated ligand for the PDGF alpha-receptor

Platelet-derived growth factors (PDGFs) are important in many types of mese nchymal cell. Here we identify a new PDGF, PDGF-C, which binds to and activ ates the PDGF alpha-receptor. PDGF-C is activated by proteolysis and induce s proliferation of fibroblasts when overexpressed in transgenic mice. In si tu hybridization analysis In the murine embryonic kidney shows preferential expression of PDGF-C messenger RNA in the metanephric mesenchyme during ep ithelial conversion. Analysis of kidneys lacking the PDGF alpha-receptor sh ows selective loss of mesenchymal cells adjacent to sites of expression of PDGF-C mRNA; this is not found in kidneys from animals lacking PDGF-A or bo th PDGF-A and PDGF-B, indicating that PDGF-C may have a unique function.