Osteoclasts are bone-resorbing multinucleated giant cells formed by the fusion of monocyte/macrophage lineages. Various small GTPases are involved in the multinucleation and differentiation of osteoclasts. However, the roles of small GTPases regulatory molecules in osteoclast differentiation remain unclear. In the present study, we examined the role of Dennd2c, a putative guanine nucleotide exchange factor for Rab GTPases, in osteoclast differentiation. Knockdown of promoted osteoclast differentiation, resorption, and expression of osteoclast markers. Morphologically, knockdown induced the formation of larger osteoclasts with several protrusions. In contrast, overexpression of inhibited the multinucleation and differentiation of osteoclasts, bone resorption, and the expression of osteoclast markers. -overexpressing macrophages exhibited spindle-shaped mononuclear cells and long thin protrusions. Treatment of -overexpressing cells with the Cdc42 inhibitor ML-141 or the Rac1 inhibitor 6-thio-GTP prevented protrusion formation. Moreover, treatment of -overexpressing cells with the actin polymerization inhibitor latrunculin B restored multinucleated and TRAP-positive osteoclast formation. These results indicate that Dennd2c negatively regulates osteoclast differentiation and multinucleation by modulating protrusion formation in macrophages.
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http://dx.doi.org/10.3390/ijms252111479 | DOI Listing |
Calcif Tissue Int
January 2025
Jerry L. Pettis Memorial VA Medical Center, VA Loma Linda Healthcare System, Loma Linda, CA, USA.
This study assessed the feasibility of miR17 ~ 92-based antiresorptive strategy by determining the effects of conditional transgenic (cTG) overexpression of miR17 ~ 92 in myeloid cells on bone and osteoclasts. Osteoclasts of male and female cTG mutant mice each showed 3- to fivefold overexpression of miR17 ~ 92 cluster genes compared to those of age- and sex-matched wildtype (WT) littermates. Male but not female cTG mutant mice had more trabecular and cortical bones as well as lower bone resorption reflected by reduction in osteoclast number and resorbing surface.
View Article and Find Full Text PDFBackground: Yes-associated protein (YAP) is a crucial mechanosensor involved in mechanotransduction, but its role in regulating mechanical force-induced bone remodeling during orthodontic tooth movement (OTM) is unclear. This study aims to elucidate the relationship between mechanotransduction and mechanical force-induced alveolar bone remodeling during OTM.
Results: Our study confirms an asynchronous (temporal and spatial sequence) remodeling pattern of the alveolar bone under mechanical force during OTM.
Nat Commun
January 2025
Faculty of Dentistry, Institute of Science Tokyo, Tokyo, Japan.
Bone remodeling maintains the robustness of the bone tissue by balancing bone resorption by osteoclasts and bone formation by osteoblasts. Although these cells together play a crucial role in bone remodeling, only a few reports are available on the common factors involved in the differentiation of the two types of cells. Here, we show family with sequence similarity 102 member A (Fam102a) as a bone-remodeling factor that positively regulates both osteoclast and osteoblast differentiation.
View Article and Find Full Text PDFJ Clin Invest
January 2025
Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.
ATP-dependent chromatin remodeling protein ATRX is an essential regulator involved in maintenance of DNA structure and chromatin state and regulation of gene expression during development. ATRX was originally identified as the monogenic cause of X-linked α-thalassemia mental retardation (ATR-X) syndrome. Affected individuals display a variety of developmental abnormalities and skeletal deformities.
View Article and Find Full Text PDFFront Immunol
January 2025
Department of Pharmacy, College of Pharmacy, Pusan National University, Busan, Republic of Korea.
Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by joint swelling, pain, and bone remodeling. We previously reported that autotaxin (ATX) deficiency disrupts lipid rafts in macrophages. Lipid raft disruption results in the dysregulation of RANK signaling, which is crucial for osteoclastogenesis and the pathogenesis of RA.
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