Ctdnep1 phosphatase is required for negative regulation of RANKL-induced osteoclast differentiation in RAW264.7 cells

• Published in: Biochemical and biophysical research communications 2024-07, Vol.719, p.150063, Article 150063
• Main Authors: Konno, Takuto, Murachi, Hitomi, Otsuka, Kanon, Kimura, Yuta, Sampei, Chisato, Arasaki, Yasuhiro, Kohara, Yukihiro, Hayata, Tadayoshi
• Format: Article
• Language: English
• Subjects: amino acid sequences; bone formation; bone resorption; Ctdnep1; cytoplasm; ligands; nuclear membrane; Osteoclast; osteoclasts; osteoporosis; phosphorylation; protein content; RANKL; RAW264.7; rheumatoid arthritis; skeletal development; superfamily; transcription factor NF-kappa B
• ISSN: 0006-291X; 1090-2104; 1090-2104
• DOI: 10.1016/j.bbrc.2024.150063

Osteoclasts are multinucleated cells with bone resorption activity. Excessive osteoclast activity has been implicated in osteoporosis, rheumatoid arthritis, and bone destruction due to bone metastases from cancer, making osteoclasts essential target cells in bone and joint diseases. C-terminal domain nuclear envelope phosphatase 1 (Ctdnep1, formerly Dullard) is a negative regulator of transforming growth factor (TGF)-β superfamily signaling and regulates endochondral ossification in mesenchymal cells during skeletal development. In this study, we investigated the role of Ctdnep1 in the Receptor activator of nuclear factor-kappa B ligand (RANKL)-induced RAW264.7 osteoclast differentiation. Expression of Ctdnep1 did not change during osteoclast differentiation; Ctdnep1 protein localized to the cytoplasm before and after osteoclast differentiation. Small interfering RNA-mediated knockdown of Ctdnep1 increased tartrate-resistant acid phosphatase-positive multinucleated osteoclasts and the expression of osteoclast marker genes, including Acp5, Ctsk, and Nfatc1. Interestingly, the knockdown of Ctdnep1 increased the protein level of Nfatc1 in cells unstimulated with RANKL. Knockdown of Ctdnep1 also enhanced calcium-resorbing activity. Mechanistically, the knockdown of Ctdnep1 increased the phosphorylation of RANKL signaling components. These results suggest that Ctdnep1 negatively regulates osteoclast differentiation by suppressing the RANKL signaling pathway. •Ctdnep1 knockdown results in a significant increase in osteoclast differentiation.•Ctdnep1 knockdown enhances the calcium-resorbing activity of osteoclasts.•Ctdnep1 knockdown increases Nfatc1protein levels.•Ctdnep1knockdown enhances the RANKL signaling pathway.