Fig. 4.

Downregulation of Dkk1 and Sost in Bmpr1a cKO rib bones. (A) qRT-PCR analysis for Wnt target genes Axin2, Ctgf, and Lef1 using P₂₁ rib bones. Expression levels of Axin2, Ctgf, and Lef1 were increased significantly in cKO rib bones. Values in cKO bones (striped bar) are expressed relative to controls (open bar). (B) qRT-PCR analysis for Dkk1, Lrp5, and Sost using P₂₁ rib bones. Expression levels of Wnt inhibitors (Dkk1 and Sost) were reduced significantly in cKO rib bones (striped bar), whereas expression of coreceptor Lrp5 was unchanged. (C) qRT-PCR analysis for Dkk1, Sost, and Bmpr1a using primary osteoblasts from P₁₀ Bmpr1a cKO and control calvariae. Expression levels of Dkk1, Sost, and Bmpr1a were reduced significantly in cKO osteoblasts (striped bar) compared with control osteoblasts (open bar). (D) Suppressed expression of Dkk1 and Sost by Noggin treatment ex vivo, as assessed by qRT-PCR. Newborn calvariae from wild-type mice were treated with Noggin (100 ng/mL) for 5 days. The asterisk indicates a statistically significant difference between Noggin treatment (Noggin⁺) and nontreatment (Noggin^–) from three independent experiments. (A–D) Mean ± SD; t test; *p < .05; **p < .02; ***p < .01.