Search

Ethnopharmacological relevance We isolated a single compound, 1-methoxyoctadecan-1-ol (MOD), from dried hooks and stems of Uncaria sinensis, which is used in traditional Korean medicine to provide relief from various nervous related symptoms. Materials and methods Neuroprotective effects of MOD against glutamate-induced oxidative stress in HT22 cells were investigated by analyzing cell viability, lactate dehydrogenase, flow cytometry, reactive oxygen species (ROS) and Western blot assays. Results Exposure to glutamate alone resulted in remarkable hippocampal neuronal cell death; however, pretreatment with MOD resulted in suppression of neuronal death and ROS accumulation in connection with cellular Ca2+ level after exposure to glutamate. Stimulation by glutamate also caused significant protein level of phosphorylated p38 mitogen-activated protein kinases (MAPK), and dephosphorylated phosphatidylinositol-3 kinase (PI3K), however, pretreatment with MOD resulted in inhibition of these changes in protein level. Treatment with glutamate alone led to suppressed protein level of mature brain-derived neurotrophic factor (BDNF) and phosphorylated cAMP response element binding protein (CREB); however, pretreatment with MOD resulted in significant enhancement of this level of protein. Anti-oxidant N-acetyl-L-cysteine and both Ca2+ inhibitors, BAPTA and EGTA, showed effects similar to those of MOD in all proteins examined, except mature BDNF. Conclusions Our results suggest that MOD mainly exerted neuroprotective effects in suppression of ROS accumulation and up-regulation of mature BDNF in association with p38 MAPK and PI3K signaling in hippocampal neuronal cells. [ABSTRACT FROM AUTHOR]

Excessive receptor activator of NF-KB ligand (RANKL) signaling causes enhanced osteoclast formation and bone resorption. Thus, down-regulation of RANKL expression or its downstream signals may be a therapeutic approach to the treatment of pathological bone loss. In this study, we investigated the effects of Trolox, a water-soluble vitamin E analogue, on osteoclastogenesis and RANKL signaling. Trolox potently inhibited interleukin-i-induced osteoclast formation in bone marrow cell-osteoblast coculture by abrogating RANKL induction in osteoblasts. This RANKL reduction was attributed to the reduced production of prostaglandin E2 via a down-regulation of cyclooxygen- ase-2 activity. We also found that Trolox inhibited osteoclast formation from bone marrow macrophages induced by macrophage colony-stimulating factor plus RANKL in a reversible manner. Trolox was effective only when present during the early stage of culture, which implies that it targets early osteoclast precursors. Pretreatment with Trolox did not affect RANKL- induced early signaling pathways, including MAPKs, NF-KB, and Akt. We found that Trolox down-regulated the induction by RANKL of c-Fos protein by suppressing its translation. Ectopic overexpression of c-Fos rescued the inhibition of osteoclasto-genesis by Trolox in bone marrow macrophages. Trolox also suppressed interleukin- 1-induced osteoclast formation and bone loss in mouse calvarial bone. Taken together, our findings indicate that Trolox prevents osteoclast formation and bone loss by inhibiting both RANKL induction in osteoblasts and c-Fos expression in osteoclast precursors. [ABSTRACT FROM AUTHOR]

Osteoclasts are multinucleated cells with the unique ability to resorb bone. Elevated activity of these cells under pathologic conditions leads to the progression of bone erosion that occurs in osteoporosis, periodontal disease, and rheumatoid arthritis. Thus, the regulation of osteoclast apoptosis is important for bone homeostasis. In this study, we examined the effects of the Janus tyrosine kinase 2 specific inhibitor AG490 on osteoclast apoptosis. We found that AG490 greatly inhibited osteoclast apoptosis. AG490 stimulated the phosphorylation of Akt and ERK. Adenovirus-mediated expression of dominant negative (DN)-Akt and DN-Ras in osteoclasts inhibited the survival of osteoclasts despite the presence of AG490. Cytochrome Å release during osteoclast apoptosis was inhibited by AG490 treatment, but this effect was inhibited in the presence of LY294002 or U0126. AG490 suppressed the proapoptotic proteins Bad and Bim, which was inhibited in osteoclasts infected with DN-Akt and DN-Ras adenovirus. In addition, constitutively active MEK and myristoylated- Akt adenovirus suppressed the cleavage of pro-caspase-9 and -3 and inhibited osteoclast apoptosis induced by etoposide. Taken together, our results suggest that AG490 inhibited cytochrome Å release into the cytosol at least partly by inhibiting the pro-apoptotic proteins Bad and Bim, which in turn suppressed caspase-9 and -3 activation, thereby inhibiting osteoclast apoptosis. [ABSTRACT FROM AUTHOR]

Single-cell RNA-seq has led to novel designations for mesenchymal cells associated with bone as well as multiple designations for what appear to be the same cell type. The main goals of this study were to increase the amount of single-cell RNA sequence data for osteoblasts and osteocytes, to compare cells from the periosteum to those inside bone, and to clarify the major categories of cell types associated with murine bone. We created an atlas of murine bone--associated cells by harmonizing published datasets with in-house data from cells targeted by Osx1-Cre and Dmp1-Cre driver strains. Cells from periosteal bone were analyzed separately from those isolated from the endosteum and trabecular bone. Over 100,000 mesenchymal cells were mapped to reveal 11 major clusters designated fibro-1, fibro-2, chondrocytes, articular chondrocytes, tenocytes, adipo-Cxcl12 abundant reticular (CAR), osteo-CAR, preosteoblasts, osteoblasts, osteocytes, and osteo-X, the latter defined in part by periostin expression. Osteo-X, osteo-CAR, and preosteoblasts were closely associated with osteoblasts at the trabecular bone surface. Wnt16 was expressed in multiple cell types from the periosteum but not in cells from endocortical or cancellous bone. Fibro-2 cells, which express markers of stem cells, localized to the periosteum but not trabecular bone in adult mice. Suppressing bone remodeling eliminated osteoblasts and altered gene expression in preosteoblasts but did not change the abundance or location of osteo-X or osteo-CAR cells. These results provide a framework for identifying bone cell types in murine single-cell RNA-seq datasets and suggest that osteoblast progenitors reside near the surface of remodeling bone. [ABSTRACT FROM AUTHOR]

Hem1 (hematopoietic protein 1), a hematopoietic cell-specific member of the Hem family of cytoplasmic adaptor proteins, is essential for lymphopoiesis and innate immunity as well as for the transition of hematopoiesis from the fetal liver to the bone marrow. However, the role of Hem1 in bone cell differentiation and bone remodeling is unknown. Here, we show that deletion of Hem1 resulted in a markedly increase in bone mass because of defective bone resorption in mice of both sexes. Hem1-deficient osteoclast progenitors were able to differentiate into osteoclasts, but the osteoclasts exhibited impaired osteoclast fusion and decreased bone-resorption activity, potentially because of decreased mitogen-activated protein kinase and tyrosine kinase c-Abl activity. Transplantation of bone marrow hematopoietic stem and progenitor cells from wildtype into Hem1 knockout mice increased bone resorption and normalized bone mass. These findings indicate thatHem1plays a pivotal role in the maintenance of normal bone mass. [ABSTRACT FROM AUTHOR]

A decline of the levels and activity of Sirtuin1 (Sirt1), a NAD+ class III histone deacetylase, with age contributes to the development of several diseases including type 2 diabetes, neurodegeneration, inflammation, and cancer. The anti-aging effects of Sirt1 evidently result from the deacetylation of many transcription factors and co-factors including members of the Forkhead boxO(FoxO) family andβ-catenin. Wnt/β-catenin is indispensable for osteoblast generation. FoxOs, on the other hand, sequester β-catenin and inhibit osteoprogenitor proliferation. Here, we have deleted Sirt1 in osteoprogenitors expressing Osterix1 (Osx1)-Cre and their descendants. Sirt1ΔOsx1 mice had lower cortical thickness in femora and vertebrae because of reduced bone formation at the endocortical surface. In line with this, osteoprogenitor cell cultures from the Sirt1ΔOsx1 mice exhibited lower alkaline phosphatase activity and mineralization, as well as decreased proliferation and increased apoptosis. These changes were associated with decreased Wnt/β-catenin signaling and expression of cyclin D1 and resulted from increased binding of FoxOs to β-catenin. These findings demonstrate that Sirt1-induced deacetylation of FoxOs unleashes Wnt signaling. A decline in Sirt1 activity in osteoblast progenitors with aging may, therefore, contribute to the age-related loss of bone mass. Together with evidence that Sirt1 activators increase bone mass in aged mice, our results also suggest that Sirt1 could be a therapeutic target for osteoporosis. [ABSTRACT FROM AUTHOR]