Discoidin domain receptor 2 activation of p38 mitogen-activated protein kinase as an important pathway for osteonectin-regulating osteoblast mineralization

• Published in: Journal of orthopaedic surgery and research 2021-12, Vol.16 (1), p.711-711, Article 711
• Main Authors: Zhu, Yun-Sen, Zhang, Jiang-Nan, Mo, Ting-Ting, Jiang, Chang, Ma, Ru-Chao, Chen, Liang
• Format: Article
• Language: English
• Subjects: Analysis; Animals; Bone sialoprotein; Calcification, Physiologic; Cell Differentiation; Collagen; Collagen Type I; Discoidin Domain Receptor 2; Enzyme Activation; Experiments; Gene expression; Genes; Genetic research; Genetic transcription; Hydroxylapatite; Kinases; MAP kinase; Memory (Computers); Mineralization; Mitogens; Neonates; Orthopedics; Osteoblasts; Osteoblasts - metabolism; Osteocalcin; Osteonectin; Osteonectin - genetics; Osteopontin; p38 gene; p38 MAPK signaling pathway; p38 Mitogen-Activated Protein Kinases - metabolism; Phosphorylation; Polymerase chain reaction; Protein kinase; Protein kinases; Proteins; Rats; Rats, Sprague-Dawley; Reagents; Reverse transcription; RNA; RNA, Small Interfering - genetics; siRNA; Transmission electron microscopy
• ISSN: 1749-799X; 1749-799X
• DOI: 10.1186/s13018-021-02860-1

The present study aimed to determine the role of the discoidin domain receptor 2 (DDR2) in the osteonectin (ON) regulation of osteoblast mineralization through the activation of p38 mitogen-activated protein kinase (MAPK). Four groups were established: the ON group, the inhibitor group, the Ddr2-small interfering ribonucleic acid (siRNA) group, and the control group. Osteoblasts from the parietal bones of neonatal Sprague-Dawley rats were isolated and cultured. In the ON group, 1 µg/mL ON was added to the osteoblasts. The gene expressions of collagen 1 (Col 1) and Ddr2 were detected using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). In the inhibitor group, the osteoblasts were added to WRG-28 (a specific DDR2 inhibitor), and in the Ddr2-siRNA group, the osteoblasts were transfected with Ddr2-siRNA. The gene and protein expressions of DDR2, bone sialoprotein, osteocalcin, osteopontin, and p38 MAPK were determined using RT-qPCR and western blot analysis. Alizarin red staining and transmission electron microscopy were used to detect mineralization. The results showed that ON enhanced the osteoblast Col 1 and Ddr2 gene expressions, while the use of a Ddr2-siRNA/DDR2-blocker decreased the OPN, BSP, OCN, and P38 gene and protein expressions and reduced osteoblast cellular activity and mineralized nodules. The present study demonstrated that DDR2 activation of p38 MAPK is an important approach to ON-regulating osteoblast mineralization.