Ocstamp, short for osteoclast stimulatory transmembrane protein, is crucial for osteoclast multinucleation, a key process in osteoclast maturation. It is considered one of the "master fusogens" and is involved in the unique cell-cell fusion process that enables bone resorption. This process is essential for bone remodeling and homeostasis [1,3].

In a study on silicosis, overexpression of Ocstamp in MLE-12 cells promoted epithelial-mesenchymal transition (EMT), endoplasmic reticulum (ER) stress, and cellular senescence. Knockdown of Ocstamp inhibited cellular senescence in these cells transfected with pcmv6-Ocstamp, indicating that Ocstamp plays a role in promoting cellular senescence in alveolar epithelial cell type II in silicosis [2]. In another study, treatment with Ocstamp siRNA alleviated the progression of silicosis in mice, suggesting its potential as a diagnostic and therapeutic target for silicosis. In vivo, Ocstamp accelerates the fibrotic process of silicosis, potentially by triggering ferroptosis of alveolar type II epithelial cells and promoting EMT [5]. Also, in the context of secondary osteoporosis associated with doxorubicin chemotherapy, resveratrol inhibited doxorubicin-induced osteoclast differentiation and reduced the expression of Oc-stamp, indicating its role in osteoclast fusion and activation [4].

In conclusion, Ocstamp is vital for osteoclast multinucleation and thus for normal bone remodeling. Its role in promoting cellular senescence in silicosis and its potential as a therapeutic target for this disease, as well as its involvement in osteoclast-related processes in secondary osteoporosis, highlight its significance in understanding and treating bone-related and silicosis-related pathologies. Studies using loss-of-function models like knockdown of Ocstamp have been instrumental in revealing these functions [2,4,5].

References:

1. Kodama, Joe, Kaito, Takashi. 2020. Osteoclast Multinucleation: Review of Current Literature. In International journal of molecular sciences, 21, . doi:10.3390/ijms21165685. https://pubmed.ncbi.nlm.nih.gov/32784443/

2. Li, Tian, Yang, Xin-Yu, Xu, Ding-Jie, Yang, Fang, Xu, Hong. 2021. OC-STAMP Overexpression Drives Lung Alveolar Epithelial Cell Type II Senescence in Silicosis. In Oxidative medicine and cellular longevity, 2021, 4158495. doi:10.1155/2021/4158495. https://pubmed.ncbi.nlm.nih.gov/34426759/

3. Miyamoto, Takeshi. 2013. STATs and macrophage fusion. In JAK-STAT, 2, e24777. doi:10.4161/jkst.24777. https://pubmed.ncbi.nlm.nih.gov/24069561/

4. Poudel, Sunil, Martins, Gil, Cancela, M Leonor, Gavaia, Paulo J. 2022. Resveratrol-Mediated Reversal of Doxorubicin-Induced Osteoclast Differentiation. In International journal of molecular sciences, 23, . doi:10.3390/ijms232315160. https://pubmed.ncbi.nlm.nih.gov/36499492/

5. Wu, Jing, Zhang, Bingyu, Du, Wei, Ke, Yanyan, Yi, Xue. 2025. OC-STAMP is a potential biomarker and therapeutic target for Silicosis: an exploratory investigation. In Journal of translational medicine, 23, 214. doi:10.1186/s12967-024-05981-3. https://pubmed.ncbi.nlm.nih.gov/39985047/