Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0005940 (bone disease)
 7,459 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Normal human skin fibroblast primary cell lines secrete over 50 proteins into culture medium. These have been mapped previously using two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) and this technique has now been used to investigate extracellular protein secretion by human osteoblasts in vitro. We report the mapping of a number of consistent markers specific to the osteoblast. In particular, one protein chain with posttranslational modifications was found to be unique to the osteoblast extracellular protein map. The absence of the N- and O-glycoforms of collagenase from the osteoblast profile in this study concurs with findings reported using the immunoprecipitation functional assay and Northern blot analysis. The use of 2-D PAGE in phenotypic assessment provides a more complete analysis than the standard range of single-parameter tests for osteoblasts. Mapping of extracellular and cellular proteins in addition to bone matrix protein analysis will allow a comprehensive analysis of normal osteoblast function. This technique may also be applied to the study of osteoblasts in relation to bone disease and in assessing the phenotypic shift within a normal osteoblast culture.
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PMID:Two-dimensional polyacrylamide gel electrophoresis reveals differences between osteoblast and fibroblast extracellular proteins. 139 27

The ability of low-dose tetracyclines to inhibit collagenase activity and inactivate osteoclasts suggests that these compounds have great potential as a prophylaxis for metabolic bone disease. However, the cellular mechanism by which tetracyclines interact with skeletal tissue is not yet clear. To better understand the effects of tetracyclines on bone metabolism, we examined their effect on osteoclast activity in vitro. Because tetracyclines can enter the cell and bind calcium and have been reported to directly interact with osteoclasts, we postulated that exposure to either of two tetracyclines, minocycline or doxycycline, would alter cytosolic Ca2+ regulation in rat osteoclasts. [Ca2+]i was measured in single rat osteoclasts utilizing fura-2. Addition of extracellular Ca2+ (5 mM CaCl2), a potent osteoclast inhibitor, increased [Ca2+]i in all osteoclasts, but 10(-6) M salmon calcitonin (sCT) did so only in a subpopulation of osteoclasts. Neither minocycline nor doxycycline (10 micrograms/ml) altered steady-state osteoclast [Ca2+]i. Further, neither minocycline nor doxycycline pretreatment affected the sCT-mediated increases in [Ca2+]i. However, tetracycline pretreatment significantly decreased the cytosolic Ca2+ response to extracellular CaCl2. Our results strongly suggest that tetracyclines have a specific effect on extracellular Ca(2+)-stimulated cytosolic Ca2+ mobilization in osteoclasts, which is not solely dependent on their ability to buffer Ca2+. Furthermore, these results point to the potential use of tetracyclines as probes to study cytosolic Ca2+ regulation. However, that tetracyclines attenuate a signal response associated with decreased osteoclastic resorption suggests that the reported antiresorptive attributes of tetracyclines must be achieved independently of an effect on osteoclastic cytosolic Ca2+.
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PMID:Regulation of cytoplasmic calcium concentration in tetracycline-treated osteoclasts. 146 56

The mechanism of aluminum-induced bone disease was studied by experiments in vitro and in rats. After decalcification femur sections were treated with 0.1 M AlCl3 and implanted with control bone matrices into weanling male rats. After 4 or 8 weeks of implantation the tissue values of calcium(Ca), phosphorus(P) and aluminum(Al) were measured. The results showed that both Ca and P values in Al-treated bones were obviously lower than those of the controls (P less than 0.01), Al level in these bones remained considerably high. Histological examination indicated that aluminum deposited diffusely in Al-treated bones, the bone formation rate and mineralization rate markedly decreased, osteoclastic and osteoblastic activities were also inhibited. In collagenase incubation test the bone matrices pretreated with different concentrations of AlCl3 showed different degrees of resistance to digestion of collagenase. It is considered that aluminum forms tight complexes with bone collagen causing cross linkage and destroying the inductive effect in bone matrix, thus leading to aluminum-induced bone disease. Our study also suggests that the usage of chelating agents can remove aluminum from matrix and recover its abilities of bone formation and mineralization.
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PMID:[Experimental study of the mechanism of aluminum-induced bone disease]. 208 19

Bone samples from the iliac crest of patients with no signs of bone disorder were treated with collagenase to remove the collagen component and so allow detailed observation of the mineral hydroxyapatite. Both polished and unpolished surfaces were studied in the scanning electron microscope and they showed that the mineral component of bone is composed of small rounded units about 10 nm across which are fused together to form larger spheroidal units roughly 100 nm in diameter. In the unpolished surfaces these 100 nm units are seen to aggregate to form columns approximately parallel to their neighbours and with numerous interconnections forming a continuous mineral phase. The polished sections also show the hydroxyapatite as a continuous phase of contiguous spheroids and the holes from which the collagen fibres were removed are clearly revealed. Lamellations in the surface are interpreted as resulting from adjacent layers of collagen fibres having orientations approximately perpendicular to each other.
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PMID:Human bone microstructure studied by collagenase etching. 254 41

A structural defect in the alpha 2(I) chain of type I collagen was characterized in a new case of the Ehlers-Danlos syndrome type VII. The patient's skin, fascia, and bone collagens all showed an abnormal additional chain, pN-alpha 2(I)s, running slower than the alpha 2(I) chain on electrophoresis. The extension was shown to be on the amino-terminal fragment of pN-alpha (I)s by cleavage with human collagenase, but pepsin was unable to convert pN-alpha 2(I)s to alpha 2(I). Skin collagen was 4-fold more extractable and contained fewer beta-dimers and a lower concentration of cross-linking amino acids than control skin collagen. Electron micrographs of both dermis and bone showed markedly irregular ragged outlines of the collagen fibrils in cross-section, although the patient had no clinical signs of bone disease. Procollagen secreted by her skin fibroblasts in culture showed equal amounts of the normal and abnormal alpha 2(I) chains on pepsin digestion. Before pepsin, the pN-alpha 2(I) component ran as a doublet on electrophoresis; pepsin removed only the normal slower chain. The suspected deletion in pN-alpha 2(I)s was traced by CNBr peptide analysis to the N-propeptide fragment, which behaved on electrophoresis about 15-20 residues smaller than that from the normal pN-alpha 2(I) chain. The simplest genetic explanation is a spontaneous heterozygote in which one normal and one abnormal allele for the pro-alpha 2(I) gene are expressed, the protein defect being a deletion of the junction domain that spans the N-propeptidase cleavage site and the N-telopeptide cross-linking sequence.
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PMID:A heterozygous collagen defect in a variant of the Ehlers-Danlos syndrome type VII. Evidence for a deleted amino-telopeptide domain in the pro-alpha 2(I) chain. 299 7

Osteoporosis is a metabolic bone disease that is characterized by heightened state of bone resorption accompanied by diminished bone formation, leading to a reduction of bone mineral density (BMD) and deterioration of bone quality, thus increasing the risk of developing fractures. Molecular insight into bone biology identified cathepsin K (CatK) as a novel therapeutic target. CatK is a lysosomal cysteine protease secreted by activated osteoclasts during bone resorption, whose primary substrate is type I collagen, the major component of organic bone matrix. Available anti-resorptive drugs affect osteoclast survival and influence both resorption and formation of bone. CatK inhibitors are distinct from the existing anti-resorptives as they only target the resorption process itself without impairing osteoclast differentiation and do not interfere with bone formation. An inhibitor of CatK, odanacatib, robustly increased both trabecular and cortical BMD in postmenopausal osteoporosis patients. The phase III fracture prevention trial with odanacatib ended early due to good efficacy and a favorable benefit/risk profile, thus, enhancing the opportunity for CatK as a pharmacological target for osteoporosis. So far, all the inhibitors that reached to the stage of clinical trial targeted active site of CatK to abrogate the entire proteolytic activity of the enzyme in addition to the desired blockage of excessive elastin and collagen degradation, and could thus pose safety concerns with long term use. Identification of selective exosite inhibitors that inhibit CatK's elastase and/or collagenase activity but do not affect the hydrolysis of other physiologically relevant substrates of CatK would be an improved strategy to inhibit this enzyme.
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PMID:Pharmacological inhibition of cathepsin K: A promising novel approach for postmenopausal osteoporosis therapy. 2710 79