Osteoactivin inhibition of osteoclastogenesis is mediated through CD44-ERK signaling

Abstract

Osteoactivin is a heavily glycosylated protein shown to have a role in bone remodeling. Previous studies from our lab have shown that mutation in Osteoactivin enhances osteoclast differentiation but inhibits their function. To date, a classical receptor and a signaling pathway for Osteoactivin-mediated osteoclast inhibition has not yet been characterized. In this study, we examined the role of Osteoactivin treatment on osteoclastogenesis using bone marrow-derived osteoclast progenitor cells and identify a signaling pathway relating to Osteoactivin function. We reveal that recombinant Osteoactivin treatment inhibited osteoclast differentiation in a dose-dependent manner shown by qPCR, TRAP staining, activity and count. Using several approaches, we show that Osteoactivin binds CD44 in osteoclasts. Furthermore, recombinant Osteoactivin treatment inhibited ERK phosphorylation in a CD44-dependent manner. Finally, we examined the role of Osteoactivin on receptor activator of nuclear factor-κ B ligand (RANKL)-induced osteolysis in vivo. Our data indicate that recombinant Osteoactivin inhibits RANKL-induced osteolysis in vivo and this effect is CD44-dependent. Overall, our data indicate that Osteoactivin is a negative regulator of osteoclastogenesis in vitro and in vivo and that this process is regulated through CD44 and ERK activation.

Developing a periodontal disease antibody array for the prediction of severe periodontal disease using machine learning classifiers

“…Finally, IL‐1β upregulates IL‐8 and OPG in both primary human gingival fibroblasts and periodontal ligament fibroblasts . Osteoactivin, the fifth protein that was differentially expressed between SP patients and NOR, plays a key role in osteoclast differentiation and activity, with OPN levels in GCF increasing with the progression of periodontal disease . ‒ It is also associated with the bacterial composition in GCF from periodontitis patients…”

“…42 Osteoactivin, the fifth protein that was differentially expressed between SP patients and NOR, plays a key role in osteoclast differentiation and activity, with OPN levels in GCF increasing with the progression of periodontal disease. [43][44][45] It is also associated with the bacterial composition in GCF from periodontitis patients. 46 Finally, we compared the diagnostic performance of five machine learning methods (SVM, RF, kNN, LDA, CART) in identifying SP patients.…”

A novel regulatory role of TRAPPC9 in L‐plastin‐mediated osteoclast actin ring formation

“…28 In brief, the cells were fixed in 10% formalin for 20 minutes at room temperature. OCs were differentiated as described above.…”

“…Then, differentiated and fixed OCs were stained for TRAP as previously described. 28 In brief, the cells were fixed in 10% formalin for 20 minutes at room temperature. For staining, OCs were washed with Diwater then incubated with 100 μL TRAP staining solution (0.5 mg/mL Fast Red Violet Dye, 0.1 mg/mL of Naphthol, 15 μL/mL N,N-Dimethyl Form amide in TRAP buffer) at 37°C for 30 minutes.…”

Microglia express GPNMB in the brains of Alzheimer's disease and Nasu-Hakola disease

“…DBA/2J mice that have a GPNMB mutation resulting in a truncated nonfunctional protein show less bone formation (12). On the other hand, GPNMB acts as a negative regulator of osteoclastogenesis (13). GPNMB is shown to inhibit osteoclast differentiation through binding to CD44 and inhibiting ERK activation.…”