Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.3.1 (alkaline phosphatase)
 47,916 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Adiponectin, an adipose-derived hormone, exhibits various biological functions, such as increasing insulin sensitivity, protecting hypertension, and suppression of atherosclerosis, liver fibrosis, and tumor growth. Here, we report the role of adiponectin on bone metabolism. C57BL/6J mice were treated with adenovirus expressing lacZ or adiponectin, and their bones were analyzed by three-dimensional microcomputed tomography. Adiponectin-adenovirus treatment increased trabecular bone mass, accompanied by decreased number of osteoclasts and levels of plasma NTx, a bone-resorption marker. In vitro studies showed that adiponectin inhibited M-CSF- and RANKL-induced differentiation of mouse bone marrow macrophages and human CD14-positive mononuclear cells into osteoclasts and also suppressed the bone-resorption activity of osteoclasts. Furthermore, adiponectin enhanced mRNA expression of alkaline phosphatase and mineralization activity of MC3T3-E1 osteoblasts. Our results indicate that adiponectin exerts an activity to increase bone mass by suppressing osteoclastogenesis and by activating osteoblastogenesis, suggesting that adiponectin manipulation could be therapeutically beneficial for patients with osteopenia.
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PMID:Adiponectin increases bone mass by suppressing osteoclast and activating osteoblast. 1585 Jul 90

Osteoporosis is characterized by decreased bone mineral density and mechanistic imbalances of bone tissue that may result in reduced skeletal strength and an enhanced susceptibility to fractures. Osteoporosis in its most common form affects the elderly (both sexes) and all racial groups of human beings. Multiple environmental risk factors like acquired immune deficiency syndrome (AIDS) are believed to be one of the causes of osteoporosis. Recently a high incidence of osteoporosis has been observed in human immunodeficiency virus (HIV) infected individuals. The etiology of this occurrence in HIV infections is controversial. This problem seems to be more frequent in patients receiving potent antiretroviral therapy. In AIDS, the main suggested risk factors for the development of osteoporosis are use of protease inhibitors, longer duration of HIV infection, lower body weight before antiretroviral therapy, high viral load. Variations in serum parameters like osteocalcin, c-telopeptide, levels of elements like Calcium, Magnesium, Phosphorus, concentration of vitamin-D metabolites, lactate levels, bicarbonate concentrations, amount of alkaline phosphatase are demonstrated in the course of development of osteoporosis. OPG/RANKL/RANK system is final mediator of bone remodeling. Bone mineral density (BMD) test is of added value to assess the risk of osteoporosis in patients infected with AIDS. The biochemical markers also aid in this assessment. Clinical management mostly follows the lines of treatment of osteoporosis and osteopenia.
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PMID:An Increased Risk of Osteoporosis during Acquired Immunodeficiency Syndrome. 1591 94

When human blood monocytes were cocultured with stromal cells derived from human giant cell tumor of bone (GCTSC) and a Millipore filter (0.4 microm) was interposed between monocytes and GCTSC, multinucleated giant cell formation of monocytes was induced. The multinucleated giant cells have characters as osteoclast-like cells, indicating that a soluble osteoclast-inducing factor(s) is secreted from GCTSC expressing RANK, RANKL/ODF/OPGL and TACE mRNA. Furthermore, OCIF/OPG inhibited GCTSC-induced osteoclastogenesis, showing that the RANK-RANKL system is involved in GCTSC-induced osteoclastogenesis and that soluble form of ODF/RANKL induces osteoclasts from monocytes. GCTSC expressed the cytokine mRNAs such as M-CSF, GM-CSF, IL-3, IL-4, IL-6, and IFN-gamma mRNAs. None of IL-1ralpha, IL-1alpha, IL-1beta, IL-2, IL-4, IL-10, IL-18, TNF-alpha, G-CSF and IFN-gamma could be detected in all culture media. A significant amount of IL-6 could be detected in the culture media of all GCTSC. IL-8 was found in the culture media of two GCTSC and two osteosarcoma-derived cells. M-CSF was detected in all culture media. GCTSC express CaSR, and stimulation of GCTSC with either extracellular Ca(2+) or neomycin, agonist of CaSR, augmented the expression of RANKL. Some lines of GCTSC expressed alkaline phosphatase, osteocalcin and Cbfa1, suggesting that GCTSC are intimately related to osteoblastic lineage.
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PMID:Cytological properties of stromal cells derived from giant cell tumor of bone (GCTSC) which can induce osteoclast formation of human blood monocytes without cell to cell contact. 1602 7

Osteoclast function is important in the development of renal osteodystrophy (ROD). Osteoclast activity is modulated by the osteoprotegerin ligand-osteoprotegerin (OPGL/OPG) system. In the present study, we checked levels of serum OPG and soluble OPGL in dialyzed patients and correlated those levels with routinely measured parameters of bone metabolism. The study was carried out in 39 patients on hemodialysis (HD) and 29 on peritoneal dialysis (PD). The control group included 13 healthy volunteers. Patients on HD had lower OPGL (p = 0.027) and higher OPG (p = 0.000) levels than control subjects did [OPGL: 0.6 pmol/L (median) and 0.0 - 10.0 pmolL (range) vs. 1.9 pmo1/L (median) and 0.0 - 10.5 pmol/L (range); OPG: 7.7 pmol/L (median) and 0.9 - 16.5 pmol/L (range) vs. 2.2 pmol/L (median) and 1.0- 3.9 pmol/L (range)]. Patients on PD differed from controls only in OPG level [4.0 pmol/L (median) and 2.1 - 13.4 pmol/L (range), p = 0.043]. Patients on HD and on PD both had a lower OPGL/OPG ratio than did the control subjects [HD: 0.09 (median) and 0.00 - 1.45 (range), p = 0.000; PD: 0.35 (median) and 0.00 - 3.89 (range), p = 0.018; controls: 1.07 (median) and 0.00 - 5.14 (range)]. Patients on HD did not differ from patients on PD in levels of OPGL and OPGL/OPG, but they had a higher OPG level (p = 0.001). Patients on HD also showed significantly higher total alkaline phosphatase (ALP) activity and higher inorganic phosphate (iP), but lower total calcium and blood pH. In PD patients, OPGL and OPG both correlated with pH (OPGL positively and OPG negatively). In HD patients, OPGL showed a positive correlation with ALP and a negative correlation with calcium; OPG correlated positively with iP In 36 patients on HD (92.3%) and 15 patients on PD (51.7%), OPG was elevated above the normal value. Differences in serum OPG and OPGL/OPG ratio between groups of dialyzed patients and of control subjects indicate that ROD is more advanced in HD patients than in PD patients. Higher serum OPG and lower serum OPGL in the HD group is probably an effect of higher osteoclast activity. In about 50% of PD patients, osteoclast function is also disturbed, as indicated by elevated OPG levels.
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PMID:Using the ratio of serum osteoprotegerin ligand to osteoprotegerin to evaluate renal osteodystrophy in dialysis patients. 1668 16

The osteogenic growth peptide (OGP) is a naturally occurring tetradecapeptide that has attracted considerable clinical interest as a bone anabolic agent and hematopoietic stimulator. In vivo studies on animals have demonstrated that the synthetic peptide OGP (10-14), reproducing the OGP C-terminal active portion [H-Tyr-Gly-Phe-Gly-Gly-OH] increases bone formation, trabecular bone density and fracture healing. In vitro studies performed on cellular systems based on osteoblastic-like cell lines or mouse stromal cells, have demonstrated that OGP (10-14) increases osteoblast proliferation, alkaline phosphatase (ALKP) activity and matrix synthesis and mineralization. In view of a potential application of OGP (10-14) in clinical therapy, we have tested different concentrations of OGP (10-14) on primary human osteoblast (hOB) cultures. We have observed significant increases of hOB proliferation (+35%), ALKP activity (+60%), osteocalcin secretion (+50%), and mineralized nodules formation (+49%). Our experimental model based on mature hOBs was used to investigate if OGP (10-14) could prevent the effects on bone loss induced by sustained glucocorticoid (GC) treatments. A strong decrease in bone formation has been attributed to the effects of GCs on osteoblastogenesis and osteocyte apoptosis, while an increase in bone resorption was due to a transient osteoblastic stimulation, mediated by the OPG/RANKL/RANK system, of osteoclasts recruitment and activation. Moreover, GCs act on hOBs decreasing the release of osteoprotegerin (OPG) a regulator of the RANKL/RANK interaction. Here, we provide evidences that OGP (10-14) inhibits hOB apoptosis induced by an excess of dexamethasone (-48% of apoptotic cells). Furthermore, we show that OGP (10-14) can increase OPG secretion (+20%) and can restore the altered expression of OPG induced by GCs to physiological levels. Our results support the employment of OGP (10-14) in clinical trials addressed to the treatment of different bone remodeling alterations including the GC-induced osteoporosis.
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PMID:Osteogenic growth peptide effects on primary human osteoblast cultures: potential relevance for the treatment of glucocorticoid-induced osteoporosis. 1679 77

Chemokines are now known to play an important role in cancer growth and metastasis. Here we report that differentiating osteoclasts constitutively produce CCL22 (also called macrophage-derived chemokine) and potentially promote bone metastasis of lung cancer expressing its receptor CCR4. We first examined expression of chemokines by differentiating osteoclasts. CCL22 was selectively upregulated in osteoclast-like cells derived from RAW264.7 cells and mouse bone marrow cells upon stimulation with RANKL (receptor activator of nuclear factor-kappaB ligand). In addition, a human lung cancer cell line SBC-5 that efficiently metastasized to bone when intravenously injected into NK cell-depleted SCID mice was found to express CCR4. Stimulation of SBC-5 cells with CCL22 induced cell migration and also enhanced phosphorylation of protein kinase B/Akt and extracellular signal-regulated kinase (ERK). Furthermore, immunohistochemical analysis of bone metastasis lesions demonstrated close co-localization of tartrate-resistant alkaline phosphatase (TRAP)-positive osteoclasts expressing CCL22 and SBC-5 cells expressing CCR4. Collectively, these results suggest that osteoclasts may promote bone metastasis of cancer cells expressing CCR4 in the bone marrow by producing its ligand CCL22.
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PMID:RANKL-induced CCL22/macrophage-derived chemokine produced from osteoclasts potentially promotes the bone metastasis of lung cancer expressing its receptor CCR4. 1682 Nov 25

Skeletal demineralization and mineral metabolism derangement are well-recognized features of untreated celiac disease (CD). Although treatment with a gluten-free diet appears to prevent bone loss while correcting skeletal demineralization in childhood, there is evidence that bone mineral density does not return to normal in celiacs diagnosed in adulthood. Osteoprotegerin (OPG), a member of the tumor necrosis factor receptor family, and ligand of receptor activator of NFkB (RANKL) are involved in the process of bone turnover and have been implicated in the pathogenesis of osteoporosis and other metabolic bone diseases. We measured OPG, RANKL, bone mineral density (BMD), and biochemical markers of bone turnover in 32 adult female premenopausal celiac patients on a gluten-free diet, and thirty age-matched healthy women. We correlated the OPG/RANKL ratio with the severity of bone loss. Celiac patients had a mean BMD lower than controls in lumbar spine and in the femoral neck. Serum levels of bone alkaline phosphatase (BAP, marker of bone formation), and urinary excretion of telopeptides of type I collagen (a marker of bone resorption) were significantly higher than in controls. Serum OPG and RANKL levels were significantly higher in CD patients than in controls, while the OPG/RANKL ratio was significantly lower in CD patients than in controls and was positively correlated with BMD at the spine. The role of elevated OPG in CD patients is unclear, but it might represent a compensatory mechanism against other factors that promote bone damage. Further studies are required to assess a possible therapeutic potential of osteoprotegerin in optimally treated celiacs with persistent osteopenia.
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PMID:Altered osteoprotegerin/RANKL ratio and low bone mineral density in celiac patients on long-term treatment with gluten-free diet. 1682 25

The cause of the polyneuropathy, organomegaly, endocrinopathy, monoclonal plasma cell disorder and skin changes (POEMS) syndrome is currently unknown, but increased levels of vascular endothelial growth factor (VEGF) appear to play a pathogenetic role. Osteosclerotic bone lesions are a characteristic finding in POEMS, but there are no data about the specific role of various molecules that control bone remodeling in patients with POEMS. Serum levels of angiogenic cytokines (VEGF, angiogenin, angiopoietin-2, and basic fibroblast growth factor) along with a series of bone remodeling indices (C-telopeptide of type I collagen, bone-alkaline phosphatase [bALP], osteocalcin [OC], soluble receptor activator of nuclear factor-kappaB ligand [RANKL], osteoprotegerin [OPG], and macrophage inflammatory protein-1alpha) were measured in 2 patients with POEMS before and after high-dose therapy (HDT) with autologous stem cell transplantation and in age- and sex-matched controls. Increased VEGF levels before HDT were reduced significantly after treatment, although levels of the other angiogenetic factors did not differ from that of controls and were less influenced by HDT. Serum RANKL levels were increased before HDT, whereas OPG levels were within the levels of healthy controls, resulting in an abnormal soluble RANKL to OPG ratio. Levels of bone resorption markers (C-telopeptide of type I collagen) were very low or undetectable before HDT, although bALP and OC levels were similar to that of controls. After HDT, soluble RANKL levels decreased, OPG remained rather stable, bone resorption markers increased to levels of normal individuals, bALP levels were rather unchanged, and OC levels increased. Decreasing VEGF levels parallel clinical improvement, and the restoration of normal bone metabolism follows HDT.
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PMID:Angiogenetic factors and biochemical markers of bone metabolism in POEMS syndrome treated with high-dose therapy and autologous stem cell support. 1687 74

Mechanical unloading causes detrimental effects on the skeleton, but the underlying mechanisms are still unclear. We investigated the effect of microgravity on osteoblast ability to regulate osteoclastogenesis. Mouse osteoblast primary cultures were grown for 24 h at unit gravity or under simulated microgravity, using the NASA-developed Rotating Wall Vessel bioreactor. Conditioned media (CM) from osteoblasts subjected to microgravity increased osteoclastogenesis and bone resorption in mouse bone marrow cultures. In these osteoblasts, the RANKL/OPG ratio was higher relative to 1g. Consistently, treatment with high concentrations of OPG-inhibited osteoclastogenesis and bone resorption in the presence of CM arising from osteoblasts cultured under microgravity. Microgravity failed to affect osteoblast differentiation and function in the time frame of the experiment, as we found no effect on alkaline phosphatase mRNA and activity, nor on Runx2, osteocalcin, osteopontin, and collagen1A2 mRNA expression. In contrast, microgravity induced a time dependent increase of ERK-1/2 phosphorylation, while phospho-p38 and phospho-JNK remained unchanged. Apoptosis, revealed by bis-benzimide staining, was similar among the various gravity conditions, while it was increased under microgravity after treatment with the MEK-1/2 inhibitor, PD98059, suggesting a protection role by ERK-1/2 against cell death. In conclusion, microgravity is capable to indirectly stimulate osteoclast formation and activity by regulating osteoblast secretion of crucial regulatory factors such as RANKL and OPG. We hypothesize that this mechanism could contribute to bone loss in individuals subjected to weightlessness and other unloading conditions.
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PMID:Modeled microgravity stimulates osteoclastogenesis and bone resorption by increasing osteoblast RANKL/OPG ratio. 1692 71

Tumour necrosis factor (TNF)-like weak inducer of apoptosis (TWEAK), a member of the TNF family, is a multifunctional cytokine that regulates cell growth, migration, and survival principally through a TWEAK receptor, fibroblast growth factor-inducible 14 (Fn14). However, its physiological roles in bone are largely unknown. We herein report various effects of TWEAK on mouse osteoblastic MC3T3-E1 cells. MC3T3-E1 cells expressed Fn14 and produced RANTES (regulated upon activation, healthy T cell expressed and secreted) upon TWEAK stimulation through PI3K-Akt, but not nuclear factor-kappaB (NF-kappaB), pathway. In addition, TWEAK inhibited bone morphogenetic protein (BMP)-2-induced expression of osteoblast differentiation markers such as alkaline phosphatase through mitogen-activated protein kinase (MAPK) Erk pathway. Furthermore, TWEAK upregulated RANKL (receptor activation of NF-kappaB ligand) expression through MAPK Erk pathway in MC3T3-E1 cells. All these effects of TWEAK on MC3T3-E1 cells were abolished by mouse Fn14-Fc chimera. We also found significant TWEAK mRNA or protein expression in osteoblast- and osteoclast-lineage cell lines or the mouse bone tissue, respectively. Finally, we showed that human osteoblasts expressed Fn14 and induced RANTES and RANKL upon TWEAK stimulation. Collectively, TWEAK/Fn14 interaction regulates RANTES production, BMP-2-induced differentiation, and RANKL expression in MC3T3-E1 cells. TWEAK may thus be a novel cytokine that regulates several aspects of osteoblast function.
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PMID:TWEAK/Fn14 interaction regulates RANTES production, BMP-2-induced differentiation, and RANKL expression in mouse osteoblastic MC3T3-E1 cells. 1694 57


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