Masamichi Takami

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Osteoclast differentiation factor (ODF, also called RANKL/TRANCE/OPGL) stimulates the differentiation of osteoclast progenitors of the monocyte/macrophage lineage into osteoclasts in the presence of macrophage colony-stimulating factor (M-CSF, also called CSF-1). When mouse bone marrow cells were cultured with M-CSF, M-CSF-dependent bone marrow macrophages(More)
Osteoclasts (OCs) are multinucleated cells that resorb bone and are essential for bone homeostasis. They develop from hematopoietic cells of the myelomonocytic lineage. OC formation requires cell-to-cell interactions with osteoblasts and can be achieved by coculturing bone marrow precursor cells with osteoblasts/stromal cells. Two of the key factors(More)
Osteoclasts are derived from myeloid lineage cells, and their differentiation is supported by various osteotropic factors, including the tumor necrosis factor (TNF) family member TNF-related activation-induced cytokine (TRANCE). Genetic deletion of TRANCE or its receptor, receptor activator of nuclear factor kappaB (RANK), results in severely osteopetrotic(More)
Lipopolysaccharide (LPS), a cell component of Gram-negative bacteria, is a pathogen of inflammatory bone loss. To examine the effects of LPS on the survival and fusion of osteoclasts, mononuclear osteoclasts (preosteoclasts, pOCs) were collected from a mouse co-culture system and cultured in the presence or absence of LPS. Most pOCs died within 24 h in the(More)
LPS is a potent stimulator of bone resorption in inflammatory diseases. The mechanism by which LPS induces osteoclastogenesis was studied in cocultures of mouse osteoblasts and bone marrow cells. LPS stimulated osteoclast formation and PGE(2) production in cocultures of mouse osteoblasts and bone marrow cells, and the stimulation was completely inhibited by(More)
Interferon regulatory factor (IRF) 8 and IRF4 are structurally-related, hematopoietic cell-specific transcription factors that cooperatively regulate the differentiation of dendritic cells and B cells. Whilst in myeloid cells IRF8 is known to modulate growth and differentiation, the role of IRF4 is poorly understood. In this study, we show that IRF4 has(More)
We previously reported that p38 MAPK signaling is required for osteoclast differentiation but not osteoclast function. Here we further investigated the role of p38 MAPK in the function and differentiation of mouse bone marrow macrophages (BMM phi), common precursors of osteoclasts and dendritic cells. Lipopolysaccharide (LPS) activated the p38 MAPK(More)
The B-lymphoblastoid cell line JY undergoes homotypic aggregation in a lymphocyte function-associated antigen-1 (LFA-1)-mediated, intracellular adhesion molecule-1 (ICAM-1)-dependent manner when stimulated with phorbol 12-myristate 13-acetate or anti-LFA-1 antibodies. Under conditions that lead to cell aggregation, we observed rapid tyrosine phosphorylation(More)
Receptor activator of nuclear factor-kappaB ligand (RANKL) and osteoprotegerin (OPG) produced by osteoblasts/stromal cells are involved as positive and negative regulators in osteoclast formation. Three independent signals have been proposed to induce RANKL expression in osteoblasts/stromal cells: vitamin D receptor-, cAMP-, and gp130-mediated signals. We(More)
Osteoclasts, bone-resorptive multinucleated cells derived from hematopoietic stem cells, are associated with many bone-related diseases, such as osteoporosis. Osteoclast-targeting small-molecule inhibitors are valuable tools for studying osteoclast biology and for developing antiresorptive agents. Here, we have discovered that methyl-gerfelin (M-GFN), the(More)