Figure 3: SOX7 transcription factor mediates the PDGF-BB-PDGFRβ-induced IL-33 expression.

(a) Western immunoblotting analysis of phosphorylation of PDGFRβ of vehicle-, PDGF-BB- and IL-33-treated lung pericytes cultured in vitro. Beta-actin indicates loading levels. (b) Western immunoblotting analysis of Erk phosphorylation, Akt phosphorylation of vehicle-, PDGF-BB- and IL-33-treated pericytes. Beta-actin indicates loading levels. (c) qPCR analysis of Il33 mRNA of vehicle-, U0126- or Akti-1/2-treated PDGF-BB-stimulated or non-stimulated lung pericytes cultured in vitro. (PC; n=6 samples per group). NS, not significant. (d) Heatmap profiling of transcription factor gene expression of vehicle- and PDGF-BB-stimulated lung pericytes cultured in vitro. (e) qPCR analysis of Sox7 mRNA expression levels of anti-PDGFRα- or anti-PDGFRβ-treated lung pericytes that received PDGF-BB-stimulation (n=6 samples per group). Vehicle-treated pericytes served as controls (n=6 samples per group). NS, not significant; PC, pericyte. (f) qPCR analysis of Il33 mRNA expression levels of vehicle- or PDGF-BB-stimulated lung pericytes that were transfected with scrambled or Sox7 siRNA (n=6 samples per group). PC, pericyte. (g) Schematic diagram of IL-33 expression in pericytes regulated by the PDGF-BB-PDGFRβ signalling through SOX7 transcriptional regulation. PDGF-BB-activated PDGFRβ induces SOX7 that targets the SRY boxes located in the Il33 promoter. (h) ChIP assay of SOX7 binding to the Il33 gene promoter. Non-immune IgG and Il33 coding region served as controls (n=6 samples per group) (mean±s.e.m., NS, not significant, Student’s t-test). Full-gel images for a,b are shown in Supplementary Fig. 9.