Figure 9. FGF23 targets osteoprogenitors via FGFR/ERK/PI3K signaling.

Single-cell RNA-sequencing analysis was performed on bone marrow stromal cells isolated from 12-week-old WT (n = 3), Fgf23^Dmp1-cKO (n = 3), Dmp1^KO (n = 3), and Dmp1^KO Fgf23^Dmp1-cKO (n = 3) mice and cultured for 21 days in osteoblast differentiation medium containing 10 mM of beta-glycerophosphate. (A) Venn diagram identifies genes showing altered expression in Dmp1^KO but not in Dmp1^KO Fgf23^cKO osteoblasts (colored area) in each cluster of differentiation. (B) Heatmaps represent the expression of genes identified in A in the osteoprogenitor cluster (green dot) and used in Ingenuity Pathway Analysis (IPA) to define the most represented canonical pathways regulated by FGF23. (C–J) Violin plots representing the expression of most regulated target genes in Dmp1^KO and corrected in Dmp1^KO Fgf23^cKO osteoprogenitors. (K) IPA gene network analysis showing most connected gene targets in the osteoprogenitor cluster and identifying FGF receptor 1 (FGFR1), ERK1/2, and PI3K/AKT as common regulators of these targets. Statistical tests were Mann-Whitney’s U test and corrected by the false discovery rate (P < 0.1).