Fig. 4.

1,25(OH)₂D₃ induces VHL transcripts to regulate HIF-1α levels. a and b Western blot analyses (a) of HOKs challenged with LPS or saline following 1,25(OH)₂D₃ treatments, and densitometric analysis (b). c and d western blot analyses of scramble-siRNA- (c) or hHIF-1α-siRNA-transfected (d) HOKs followed by various stimulations as indicated. e Two putative VDR binding sites (red) in human VHL gene promoter. The initiation codon was labeled in bold font. f Promoter of VHL gene harboring 2 VDR binding sites. VDRE1 was located between − 505 and − 512, and VDRE2 was located between − 849 and − 857. g Western blot analyses of HOKs transfected with various concentrations of VDR plasmid followed by LPS or saline challenge as indicated. *P < 0.05, **P < 0.01 vs. corresponding controls; Ctrl, control; 1,25VD, 1,25(OH)2D3. All assays were conducted for three times, n = 3