Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.1.3.16 (calcineurin)
17,112 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Systemic acidosis has detrimental effects on the skeleton, and local acidosis coincides with bone destruction in inflammatory and metastatic diseases. Acidification dramatically enhances osteoclastic resorption, although the underlying mechanism has remained elusive. We investigated the effect of acidosis on the osteoclastogenic transcription factor NFATc1, which upon dephosphorylation translocates from the cytoplasm to nuclei. Lowering extracellular pH dramatically increased accumulation of NFATc1 in nuclei of rat and rabbit osteoclasts to levels comparable with those induced by the proresorptive cytokine receptor activator of NF-kappaB ligand (RANKL). Activation of NFATc1 by RANKL was mediated by means of prolonged stimulation of the Ca2+/calmodulin-dependent protein phosphatase, calcineurin. In contrast, NFATc1 activation by acidosis involved stimulation of calcineurin and suppression of NFATc1 inactivation. Acidosis, like RANKL, induced transient elevation of cytosolic free Ca2+ concentration ([Ca2+]i), which persisted in Ca2+-free media and was abolished by inhibition of phospholipase C or depletion of intracellular Ca2+ stores. Real-time-PCR of osteoclast-like cells generated from RAW 264.7 cells revealed high levels of expression of ovarian cancer G protein-coupled receptor 1, which links extracellular acidification to elevation of [Ca2+]i. In addition, the calcineurin inhibitor cyclosporin A suppressed the stimulatory effect of acidification on resorption, implicating NFAT in mediating the actions of acidosis on osteoclast activity. In summary, acidification and RANKL induce signals in osteoclasts that converge on the Ca2+/calcineurin/NFAT pathway. Acidosis acts directly on osteoclasts to activate NFATc1 and stimulate resorption.
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PMID:Convergent signaling by acidosis and receptor activator of NF-kappaB ligand (RANKL) on the calcium/calcineurin/NFAT pathway in osteoclasts. 1569 91

In the present study, we aimed to determine whether tacrolimus (FK506) and cyclosporine A act directly on human osteoclast precursors obtained from patients with rheumatoid arthritis (RA) and influence monocyte-osteoclast differentiation induced by receptor activator of NF-kappaB ligand (RANKL) in vitro, the stage at which differentiation was affected and the manner in which tacrolimus or cyclosporine A affected the osteoclast signaling pathway. Peripheral blood mononuclear cells (PBMCs) were isolated from RA patients and cultured in the presence of RANKL and macrophage-colony stimulating factor (M-CSF). Tacrolimus or cyclosporine A was added to these cultures to determine the effect on the osteoclast differentiation. Osteoclast formation was determined by assessing the number of tartrate resistant acid phosphatase (TRAP) staining cells and measuring the extent of lacunar resorption. The expression of osteoclast transcription factors, such as TNF receptor-associated factor 6 (TRAF6), nuclear factor of activated T cells c1 (NFATc1), c-Fos, c-Jun, microphthalmia transcription factor (MITF) and PU.1 in mononuclear cells (MNCs) was assayed by quantitative reverse transcription-polymerase chain reaction. Addition of tacrolimus or cyclosporine A resulted in a decrease in the number of TRAP-positive multinucleated cells (TRAP+ MNCs) and a decrease in the extent of lacunar resorption pit formation as compared to the control cultures; thus, human monocyte-osteoclast differentiation was more effectively inhibited at the late stage and addition of tacrolimus or cyclosporine A resulted in a decrease in the mRNA expression of NFATc1, c-Jun, and MITF at the late stage. Our results suggest that tacrolimus or cyclosporine A acts directly on human osteoclast precursors in RA patients and exerts their immunosuppressive effects on human monocyte-osteoclast formation via targeting both the calcineurin-dependent NFAT pathway and activation pathway for c-Jun or MITF.
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PMID:Tacrolimus and cyclosporine A inhibit human osteoclast formation via targeting the calcineurin-dependent NFAT pathway and an activation pathway for c-Jun or MITF in rheumatoid arthritis. 1658 42

Calcium (Ca(2+)) signaling is essential for a variety of cellular responses and higher biological functions. Ca(2+)/calmodulin-dependent kinases (CaMKs) and the phosphatase calcineurin activate distinct downstream pathways that are mediated by the transcription factors cAMP response element (CRE)-binding protein (CREB) and nuclear factor of activated T cells (NFAT), respectively. The importance of the calcineurin-NFAT pathway in bone metabolism has been demonstrated in osteoclasts, osteoblasts and chondrocytes. However, the contribution of the CaMK-CREB pathway is poorly understood, partly because of the difficulty of dissecting the functions of homologous family members. Here we show that the CaMKIV-CREB pathway is crucial for osteoclast differentiation and function. Pharmacological inhibition of CaMKs as well as the genetic ablation of Camk4 reduced CREB phosphorylation and downregulated the expression of c-Fos, which is required for the induction of NFATc1 (the master transcription factor for osteoclastogenesis) that is activated by receptor activator of NF-kappaB ligand (RANKL). Furthermore, CREB together with NFATc1 induced the expression of specific genes expressed by differentiated osteoclasts. Thus, the CaMK-CREB pathway biphasically functions to regulate the transcriptional program of osteoclastic bone resorption, by not only enhancing induction of NFATc1 but also facilitating NFATc1-dependent gene regulation once its expression is induced. This provides a molecular basis for a new therapeutic strategy for bone diseases.
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PMID:Regulation of osteoclast differentiation and function by the CaMK-CREB pathway. 1712 69

Intercellular cross-talk between osteoblasts and osteoclasts is important for controlling bone remolding and maintenance. However, the precise molecular mechanism by which osteoblasts regulate osteoclastogenesis is still largely unknown. Here, we show that osteoblasts can induce Ca(2+) oscillation-independent osteoclastogenesis. We found that bone marrow-derived monocyte/macrophage precursor cells (BMMs) lacking inositol 1,4,5-trisphosphate receptor type2 (IP(3)R2) did not exhibit Ca(2+) oscillation or differentiation into multinuclear osteoclasts in response to recombinant receptor activator of NF-kappaB ligand/macrophage colony-stimulating factor stimulation. IP(3)R2 knockout BMMs, however, underwent osteoclastogenesis when they were cocultured with osteoblasts or in vivo in the absence of Ca(2+) oscillation. Furthermore, we found that Ca(2+) oscillation-independent osteoclastogenesis was insensitive to FK506, a calcineurin inhibitor. Taken together, we conclude that both Ca(2+) oscillation/calcineurin-dependent and -independent signaling pathways contribute to NFATc1 activation, leading to efficient osteoclastogenesis in vivo.
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PMID:Osteoblasts induce Ca2+ oscillation-independent NFATc1 activation during osteoclastogenesis. 1855 77

IL-27 was first discovered as a factor supporting initial Th1 immune responses. Subsequent studies revealed that this cytokine has pleiotropic effects, including inhibition of certain immune cells, a regulatory role in hemopoietic stem cell differentiation, and antitumor activities. However, the role of human IL (hIL)-27 in human osteoclast precursors and inflammatory bone disease is unclear. Here, we examined the direct effect of hIL-27 on human osteoclastogenesis. Human bone marrow cells cultured in MethoCult medium containing human (h) GM-CSF, human stem cell factor, and hIL-3 expressed Mac-1, c-kit, and c-Fms. These cells, called hCFU-GMs, also expressed the IL-27 receptor, an IL-27Ralpha (WSX-1)/gp130 heterodimer. Cultivation in hM-CSF and human receptor activator of NF-kappaB ligand induced the differentiation of tartrate-resistant acid phosphatase-positive multinucleated cells (osteoclasts) from hCFU-GMs, and hIL-27 inhibited this osteoclastogenesis in a dose-dependent manner. hIL-27 also repressed bone resorption by osteoclasts on a dentine slice. hIL-27 caused a remarkable increase in STAT1 phosphorylation and enhanced the STAT1 protein level. It also inhibited the expression of receptor activator of NF-kappaB ligand-induced c-Fos and cytoplasmic, calcineurin-dependent 1 NFAT (NFATc1), which are indispensable transcription factors for osteoclastogenesis. Fludarabine, a STAT1 inhibitor, and STAT1 small interfering RNA partially rescued the inhibition of osteoclastogenesis by IL-27. A WSX-1 deficiency caused severe inflammatory bone destruction primed by Escherichia coli cell wall lysate in vivo. Therefore, hIL-27 may act as an anti-inflammatory cytokine in human bone destruction, by inhibiting osteoclastogenesis from hCFU-GMs via STAT1-dependent down-regulation of the transcription factor c-Fos. Our results suggest that hIL-27 may prove useful as a therapeutic target for inflammatory bone destruction.
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PMID:IL-27 abrogates receptor activator of NF-kappa B ligand-mediated osteoclastogenesis of human granulocyte-macrophage colony-forming unit cells through STAT1-dependent inhibition of c-Fos. 1962 Mar 1

RANKL (receptor activator of NF-kappaB ligand) induces osteoclastogenesis by activating multiple signaling pathways in osteoclast precursor cells, chief among which is induction of long lasting oscillations in the intracellular concentration of Ca(2+) ([Ca(2+)](i)). The [Ca(2+)](i) oscillations activate calcineurin, which activates the transcription factor NFATc1. The pathway by which RANKL induces [Ca(2+)](i) oscillations and osteoclastogenesis is poorly understood. Here we report the discovery of a novel pathway induced by RANKL to cause a long lasting increase in reactive oxygen species (ROS) and [Ca(2+)](i) oscillations that is essential for differentiation of bone marrow-derived monocytes into osteoclasts. The pathway includes RANKL-mediated stimulation of Rac1 to generate ROS, which stimulate phospholipase Cgamma1 to evoke [Ca(2+)](i) oscillations by stimulating Ca(2+) release from the inositol 1,4,5-trisphosphate pool and STIM1-regulated Ca(2+) influx. Induction and activation of the pathway is observed only after 24-h stimulation with RANKL and lasts for at least 3 days. The physiological role of the pathway is demonstrated in mice with deletion of the Peroxiredoxin II gene and results in a mark increase is ROS and, consequently, a decrease in bone density. Moreover, bone marrow-derived monocytes in PrxII(-/-) primary culture show increased ROS and spontaneous [Ca(2+)](i) oscillations. These findings identify the primary RANKL-stimulated pathway to trigger the late stages of osteoclastogenesis and regulate bone resorption.
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PMID:RANKL-mediated reactive oxygen species pathway that induces long lasting Ca2+ oscillations essential for osteoclastogenesis. 2004 68

Caldecrin/chymotrypsin C is a novel secretory-type serine protease that was originally isolated as a serum calcium-decreasing factor from the pancreas. Previously, we reported that caldecrin suppressed the bone-resorbing activity of rabbit mature osteoclasts (Tomomura, A., Yamada, H., Fujimoto, K., Inaba, A., and Katoh, S. (2001) FEBS Lett. 508, 454-458). Here, we investigated the effects of caldecrin on mouse osteoclast differentiation induced by macrophage-colony stimulating factor and the receptor activator of NF-kappaB ligand (RANKL) from the monocyte/macrophage cell lineage of bone marrow cells. Wild-type and protease-deficient mutant caldecrin dose-dependently inhibited RANKL-stimulated tartrate-resistant acid phosphatase-positive osteoclast formation from bone marrow cells. Caldecrin did not affect macrophage colony formation from monocyte/macrophage lineage cells or osteoclast progenitor generation in cultures of bone marrow cells. Caldecrin inhibited accumulation of the RANKL-stimulated nuclear factor of activated T-cells, cytoplasmic 1 (NFATc1) mRNA in bone marrow cells, which is a key transcription factor for the differentiation of osteoclasts. Caldecrin also suppressed RANKL-induced differentiation of the RAW264.7 monocyte/macrophage cell line into osteoclasts. Caldecrin reduced the transcriptional activity of NFATc1 in RAW264.7 cells, whereas those of NF-kappaB and c-Fos, which are also transcription factors involved in osteoclast differentiation, were unaffected. Caldecrin inhibited RANKL-stimulated nuclear translocation of NFATc1 and the activity of the calcium/calmodulin-dependent phosphatase, calcineurin. Caldecrin inhibited phospholipase Cgamma1-mediated Ca(2+) oscillation evoked by RANKL stimulation. RANKL-stimulated phosphorylation of spleen tyrosine kinase (Syk) was also attenuated by caldecrin. Taken together, these results indicate that caldecrin inhibits osteoclastogenesis, without its protease activity, by preventing a phospholipase Cgamma1-mediated Ca(2+)oscillation-calcineurin-NFATc1 pathway.
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PMID:Serum calcium-decreasing factor, caldecrin, inhibits osteoclast differentiation by suppression of NFATc1 activity. 2054 67

Trimethylation of histone H3 lysine 4 and lysine 27 (H3K4me3 and H3K27me3) at gene promoter regions critically regulates gene expression. Key developmental genes tend to exhibit changes in histone modification patterns from the H3K4me3/H3K27me3 bivalent pattern to the H3K4me3 monovalent pattern. Using comprehensive chromatin immunoprecipitation followed by sequencing in bone marrow-derived macrophages (BMMs) and mature osteoclasts, we found that cell surface adhesion molecule 1 (Cadm1) is a direct target of nuclear factor of activated T cells 1 (NFATc1) and exhibits a bivalent histone pattern in BMMs and a monovalent pattern in osteoclasts. Cadm1 expression was upregulated in BMMs by receptor activator of nuclear factor kappa B ligand (RANKL), and blocked by a calcineurin/NFATc1 inhibitor, FK506. Cadm1-deficient mice exhibited significantly reduced bone mass compared with wild-type mice, which was due to the increased osteoclast differentiation, survival and bone-resorbing activity in Cadm1-deficient osteoclasts. These results suggest that Cadm1 is a direct target of NFATc1, which is induced by RANKL through epigenetic modification, and regulates osteoclastic bone resorption in a negative feedback manner.
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PMID:Negative feedback loop of bone resorption by NFATc1-dependent induction of Cadm1. 2841 95

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