Fig. 8: DCSTAMP antagonist hinders the interaction between DCSTAMP and RAP1B, thereby impeding cytoskeletal remodeling and osteoclastogenesis.

a The proteins engaged in the interaction with the DCSTAMP protein in WT and Dcstamp-tail^−/− lysates were discerned through mass spectrometry subsequent to RNA pulldown in mBMMs. b The presence of the RAP1B protein was ascertained via mass spectrometry analysis. c The Co-IP was conducted using an anti-DCSTAMP antibody with WT, Dcstamp-tail^−/− and WT + E8431 lysates. d The Co-IP was performed using an anti-RAP1A antibody with WT, Dcstamp-tail^−/− and WT + E8431 lysates. e The Co-IP was carried out utilizing an anti-RAP1B antibody with WT, Dcstamp-tail^−/− and WT + E8431 lysates. f The levels of RAP1-GTP and RAP1 within the proteins obtained via Co-IP in WT, Dcstamp-tail^−/− and WT + E8431 lysates were evaluated. g Molecular docking simulations unveiled the interaction between RAP1B and murine DCSTAMP. h The molecular docking simulations demonstrated the impact of E8431 on the binding between RAP1B and murine DCSTAMP. i A schematic illustration depicting E8431’s molecular mechanisms in regulating DCSTAMP functionality and skeletal homeostasis. E8431 orchestrates the potent inhibition of osteoclastogenesis through the disruption of DCSTAMP–RAP1B molecular complexes, consequently attenuating RAP1–RAC1-dependent cytoskeletal remodeling essential for osteoclast maturation and cellular fusion. Moreover, E8431 intervention markedly ameliorates OVX-induced skeletal deterioration via the preservation of preosteoclast populations, culminating in suppressed bone resorption along with enhanced osteogenesis and neovascularization. The data are presented as mean ± s.d. with individual data points depicted as dots. Statistical significance levels are denoted as follows: *P < 0.05, **P < 0.01, ***P < 0.001; ns, not significant.