No abstract

No abstract

Stem cells are used for the investigation of developmental processes at both cellular and organism levels and offer tremendous potentials for clinical applications as an unlimited source for transplantation. Gangliosides, sialic acid-conjugated glycosphingolipids, play important regulatory roles in cell proliferation and differentiation. However, their expression patterns in stem cells and during neuronal differentiation are not known. Here, we investigated expression of gangliosides during the growth of mouse embryonic stem cells (mESCs), mesenchymal stem cells (MSCs) and differentiated neuronal cells by using high-performance thin-layer chromatography (HPTLC). Monosialoganglioside 1 (GM1) was expressed in mESCs and MSCs, while GM3 and GD3 were expressed in embryonic bodies. In the 9-day old differentiated neuronal cells from mESCs cells and MSCs, GM1 and GT1b were expressed. Results from immunostaining were consistent with those observed by HPTLC assay. These suggest that gangliosides are specifically expressed according to differentiation of mESCs and MSCs into neuronal cells and expressional difference of gangliosides may be a useful marker to identify differentiation of mESCs and MSCs into neuronal cells.

TGF-β/BMPs have widely recognized roles in mammalian development, including in bone and tooth formation. To define the functional relevance of the autonomous requirement for TGF-β signaling in mouse tooth development, we analyzed osteocalcin-Cre mediated Tgfbr2 (OCCreTgfbr2fl/fl) conditional knockout mice, which lacks functional TGF-β receptor II (TβRII) in differentiating cementoblasts and cementocytes. Strikingly, OCCreTgfbr2fl/fl mutant mice exhibited a sharp reduction in cellular cementum mass with reduced matrix secretion and mineral apposition rates. To explore the molecular mechanisms underlying the roles of TGF-β signaling through TβRII in cementogenesis, we established a mouse cementoblast model with decreased TβRII expression using OCCM-30 cells. Interestingly, the expression of osterix (Osx), one of the major regulators of cellular cementum formation, was largely decreased in OCCM-30 cells lacking TβRII. Consequently, in those cells, functional ALP activity and the expression of genes associated with cementogenesis were reduced and the cells were partially rescued by Osx transduction. We also found that TGF-β signaling directly regulates Osx expression through a Smad-dependent pathway. These findings strongly suggest that TGF-β signaling plays a major role as one of the upstream regulators of Osx in cementoblast differentiation and cementum formation.

Due to their capability of modifying chromatin structure and thereby regulating gene transcription, histone deacetylases (HDACs) have been reported to play important roles in osteogenesis and considered a promising potential therapeutic target for bone diseases, including osteoporosis. We showed that the novel marine-derived HDAC inhibitor largazole exhibits in vitro and in vivo osteogenic activity. Largazole significantly induced the expression of ALP and OPN. The osteogenic activity of largazole was mediated through the increased expression of Runx2 and BMPs. Importantly, largazole showed in vivo bone-forming efficacy in the mouse calvarial bone formation assay and the rabbit calvarial bone fracture healing model. The dual action of largazole to stimulate bone formation and inhibit bone resorption would be a useful feature in drug development for bone-related disorders.

PurposeTo investigate the healing pattern of the mucous membrane after tooth extraction necessitated by periodontal disease in the maxillary sinus.MethodsOne hundred and three patients with 119 maxillary sinuses were investigated. Before implant placement, cone-beam computed tomography (CT) scanning was performed. The causes of extraction, the time elapsed since extraction, smoking, periodontal disease in adjacent teeth, and gender were recorded. In addition, the thickness of the mucous membrane of the maxillary sinus and the height of residual alveolar bone at the extracted area were calculated from CT images.ResultsThe thickness of the mucous membrane in the periodontal disease group (3.05±2.71 mm) was greater than that of the pulp disease group (1.92±1.78 mm) and the tooth fracture group (1.35±0.55 mm; P<0.05). The causes of extraction, the time elapsed since extraction, and gender had relationships with a thickening of the mucous membrane of the maxillary sinus (P<0.05). In contrast, the height of the residual alveolar bone at the extracted area, periodontal disease in adjacent teeth, and smoking did not show any relation to the thickening of the mucous membrane of the maxillary sinus.ConclusionsThe present study revealed distinct differences in healing patterns according to the causes of extraction in the maxillary sinus, especially periodontal disease, which resulted in more severe thickening of the mucous membrane.

Binding of N-formyl-methionyl-leucyl-phenylalanine (fMLP) to its specific cell surface receptor, N-formyl peptide receptor (FPR), triggers different cascades of biochemical events, eventually leading to cellular activation. However, the physiological role of fMLP and FPR during differentiation of mesenchymal stem cells is unknown. In this study, we attempted to determine whether fMLP regulates differentiation of mesenchymal stem cells derived from bone marrow. Analysis by quantitative-PCR and flow cytometry showed significantly increased expression of FPR1, but not FPR2 and FPR3, during osteoblastic differentiation. fMLP, a specific ligand of FPR1, promotes osteoblastic commitment and suppresses adipogenic commitment under differentiation conditions. Remarkably, fMLP-stimulated osteogenesis is associated with increased expression of osteogenic markers and mineralization, which were blocked by cyclosporine H, a selective FPR1 antagonist. In addition, fMLP inhibited expression of peroxisome proliferator-activated receptor-␥1, a major regulator of adipocytic differentiation. fMLP-stimulated osteogenic differentiation was mediated via FPR1-phospholipase C/phospholipase D-Ca 2؉ -calmodulin-dependent kinase II-ERK-CREB signaling pathways. Finally, fMLP promoted bone formation in zebrafish and rabbits, suggesting its physiological relevance in vivo. Collectively, our findings provide novel insight into the functional role of fMLP in bone biology, with important implications for its potential use as a therapeutic agent for treatment of bone-related disorders.

No abstract