Dorsomorphin attenuates Jagged1-induced mineralization in human dental pulp cells

To investigate whether TGF-β/BMP signalling participates in Jagged1-induced osteogenic differentiation in human dental pulp cells (hDPs).

Bioinformatic analysis of publicly available RNA sequencing data of Jagged1-treated hDPs was performed using NetworkAnalyst. The mRNA expression was validated using real-time polymerase chain reaction. hDPs were seeded on Jagged1 immobilized surfaces in the presence or absence of TGF-β or BMP inhibitor. Osteogenic differentiation was evaluated using alkaline phosphatase staining, osteogenic marker gene expression and mineralization assay. Statistical analyses were performed using a Kruskal-Wallis test, followed by a pairwise comparison for more than three group comparison. Mann-Whitney U-test was employed for two group comparison. The statistical significance was considered at p < .05.

Jagged1 treatment in growth medium significantly promoted TGFB1, TGFB2 and TGFB3 whilst significantly inhibited BMP2, BMP4 and BMP6 mRNA expression (p < .05). In osteogenic induction medium, Jagged1 significantly up-regulated TGFB1, TGFB2 and TGFB3 at days 1 and 3 (p < .05). Pre-treatment with TGF-β1, TGF-β2 or TGF-β3 prior to osteogenic induction resulted in the significant increase of osteogenic marker gene expression, collagen type 1 protein expression, alkaline phosphatase enzymatic activity and mineral deposition (p < .05). However, TGF-β signalling inhibition with SB431542 (4 μmol L^-1 ) or SB505124 (47 and 129 nmol L^-1 ) failed to attenuate the effect of Jagged1-induced osteogenic differentiation in hDPs. Dorsomorphin (4 and 8 μmol L^-1 ) treatment significantly abolished the effect of Jagged1 on mineralization by hDPs (p < .05).

Notch signalling activation by Jagged1 modulated TGF-β and BMP ligand expression. Dorsomorphin, but not TGF-β receptor inhibitor, attenuated Jagged1-induced osteogenic differentiation in hDPs.