Fig. 7
Suppression of sclerostin expression by parathyroid hormone (PTH) depends in part on TG-interacting factor 1 (Tgif1). a Relative expression of Dkk1 mRNA and of b Sost mRNA in tibiae of Tgif1+/+ and Tgif1−/− mice 4 h after injection of PTH or vehicle (Veh) (Tgif1+/++Veh: N = 18, Tgif1+/++PTH: N = 14, Tgif1−/−+Veh: N = 12, Tgif1−/−+PTH: N = 13). c Immunohistochemical staining of sclerostin expression in tibiae of Tgif1+/+ and Tgif1−/− mice after treatment with PTH or Veh. Scale bars indicate 50 μm (lower magnification, upper panel) and 10 μm (higher magnification, lower panel). d Relative expression of Mef2c mRNA in UMR-106 cells. Cells were transfected with scrambled (scr) control GapmeR or GapmeR targeting Tgif1. After 48 h, cells were stimulated with PTH or Veh for 8 h (N = 3). e Immunoblot demonstrating the protein abundance of Mef2c in UMR-106 cells. Cells were transfected with scr siRNA or siRNA targeting Tgif1 (siTgif1). After 48 h, cells were stimulated with PTH or Veh for 8 h. Immunoblot for Actin was used as a loading control. Normalized fold expression and molecular weight in kilo Dalton (kDa) are indicated (representative image of 3 experiments). f UMR-106 cells were transfected with scr GapmeR or GapmeR targeting Tgif1 and 24 h later with a hSOST-ECR5 reporter construct. After 8 h, cells were stimulated with PTH or Veh for 16 h. Shown is the relative luciferase activity (GapmeR scr+Veh: N = 3, GapmeR scr+PTH: N = 3, GapmeR Tgif1+Veh: N = 3, GapmeR Tgif1+PTH: N = 3). a, b *p<0.05, **p<0.01 vs. Veh of the same genotype. d, f ***p<0.001 vs. the respective GapmeR+Veh, ##p<0.005 vs. GapmeR scr+PTH. Error bars represent the s.e.m. Statistical analysis was performed using analysis of variance (ANOVA) followed by Newman–Keuls post-hoc test. g Schematic drawing of the function of Tgif1 in osteoblasts, osteocytes and in response to the activation of the canonical Wnt and PTH bone anabolic pathways
