Phosphorylation of phosvitin plays a crucial effects on the protein-induced differentiation and mineralization of osteoblastic MC3T3-E1 cells

This study investigated the effects of phosvitin (PV), one of the major proteins from egg yolk, with different degree of phosphorylation on the physiology of an osteoblast (MC3T3-E1) cell line. The proliferation and differentiation of MC3T3-E1 were analyzed using the CCK-8 and the alkaline phosphatase (ALP) assay, respectively. The effect of PV on the mineralization of MC3T3-E1 was monitored using the Alizarin-red staining. PV at 100 μg/mL increased the ALP activity by 145% of the control after 7 days of incubation. PV also stimulated the proliferation and differentiation of MC3T3-E1 in a phosphorylation level-dependent manner. The RT-PCR reactions indicated that PV stimulated the expression of BMP-2 and OPG mRNA in a phosphorylation-dependent manner, but inhibited RANKL mRNA expression in MC3T3-E1. This result suggested that the phosphate groups in PV not only stimulated the proliferation and differentiation of MC3T3-E1, but also controlled the mineralization by regulating the expression of BMP-2, RANKL and OPG mRNA in the osteoblast cell. •A protein from egg yolk was used to research its effect on the mineralization, considered its special role for the calcium absorption and the bone formation during hatch.•The effect of phosvitin with different degree of phosphorylation on an osteoblast cell was investigated for the first time.•The expressions of factors such as bone morphogenetic protein-2, RANKL and OPG mRNA, relating to signaling pathways in the process of osteogenesis, were analyzed to confirm the possible role of the OPG/RANKL system.