DMP1-Mediated FAK Activation Contributes to P Utilization of Broiler Osteoblasts by Suppressing FGF23 Expression

Improving phosphorus (P) utilization in broilers is crucial for reducing feed costs and environmental pollution. Bone mineralization trait is strongly associated with P utilization in poultry and is thus often used as an alternative trait for evaluating P utilization. Dentin matrix protein 1 (DMP1), an essential matrix protein for bone mineralization and P deposition, has been shown to be actively involved in P utilization in broilers, but the underlying mechanisms remain unclear. The current study aimed to investigate the possible mechanisms whereby DMP1 regulates P utilization of poultry by using gene silencing and overexpression technologies, combined with an in vitro model of primary broiler osteoblasts. The results showed that DMP1 overexpression augmented the P utilization of broiler osteoblasts, characterized by significant increases (p < 0.001) in P utilization rate, mineralization formation, alkaline phosphatase activity, and bone gla protein content. Meanwhile, DMP1 overexpression effectively (p < 0.05) activated the focal adhesion kinase (FAK) signaling, along with obvious (p < 0.01) decreases in fibroblast growth factor 23 (FGF23) expression and production. In contrast, DMP1 silencing reversed (p < 0.05) the above effects. Consistently, FAK activation promoted (p < 0.05) P utilization accompanied by remarkable (p < 0.05) decreases in FGF23 expression and production. Furthermore, gain- and loss-of-function assays demonstrated that a high level of FGF23 contributed to impaired P utilization, while a low level was beneficial. Interestingly, blocking FAK signaling not only recovered (p < 0.05) the FGF23 expression and production in DMP1 overexpressed cells but also obviously (p < 0.05) weakened their P utilization. These findings indicate that DMP1 inhibits FGF23 expression by activating FAK, thereby contributing to P utilization in broiler osteoblasts. They reveal a novel DMP1-FAK-FGF23 regulatory axis in broiler osteoblasts and provide a potential target for improving P efficiency in poultry.