FIGURE 4.

TGF-β1 promotes PIEZO1 expression through C/EBPβ. (A) TGF-β1 dose-dependently induces PIEZO1 mRNA and protein expression. (B) PIEZO1, HIF-1α and TGF-β1 protein expression were futher enhanced by addition of TGF-β1 to cells subjectd to irradiation (IR). (C) Intracellular Ca²⁺ concentration was increased after TGF-β1 co-culture. (D) TGF-β1 inhibits C/EBPβ protein expression. (E) C/EBPβ protein expression was decreased after IR. (F) C/EBPβ mRNA and protein expression were successful inhibited by specific siRNA to C/EBPβ. (G) Compared to TGF-β1 co-culture alone, PIEZO1 protein was further increased when C/EBPβ expression was inhibited by siRNA targeting C/EBPβ (si-C/EBPβ). (H) The PROMO (prediction of transcription factor binding sites) database indicates a potential binding site of C/EBPβ in the PEIZO1 promoter locus. (I) Dual-luciferase reporter assay suggests that C/EBPβ binds to PIEZO1 gene promoter. (J) Chromatin immunoprecipitation (ChIP) reporter gene analyses found two binding sites of C/EBPβ in the upstream region of the PIEZO1 promoter. Data are presented with the means ± SEMs (n = 3). *, p < 0.05; and **, p < 0.01.