Fig. 3.

RANKL-induced ST3Gal1 transcription by activating the binding of FOS to its promoter. a Immunostaining of α2,3 and α2,6 sialic acids (SAs) in WT BMMs treated as indicated. Quantification of the fluorescence intensity. b Hierarchical clustering heatmap showing the expression of SA transferase family members in BMMs, pOCs and mOCs detected and analyzed by RNA-seq. c Immunostaining of α2,3 SA with TLR2 or Siglec15 in Siglec15^fl/fl (WT) and Siglec15^ΔLysM BMMs. d Colocalization of α2,3 SA with TLR2 or Siglec15. e FOS and CREB1 binding sites in the St3gal1 promoter core enhancer. f ChIP assay validation of FOS and CREB binding activities. g Site-directed mutagenesis of the FOS binding sites in the St3gal1 core enhancer. Quantification of the normalized luciferase activity of a luciferase gene reporter assay performed with BMMs transfected with a c-Fos expression vector, n = 5. Data represent the mean ± SD, and statistically significant differences are indicated as **P < 0.01