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At least 343 records · Page 19Linked to original sources
PubMed2000

SPARC gene expression is increased in diabetes-related mesenteric vascular hypertrophy.

The anti-adhesive extracellular matrix protein SPARC (secreted protein and rich in cysteine; osteonectin or BM-40) has been implicated in the regulation of matrix turnover, cell migration, and proliferation. The present study sought to examine whether modulation in the expression of this protein may play a role in diabetes-associated vascular remodeling. SPARC mRNA and protein were measured in mesenteric vessels of diabetic rats and controls. Hypertrophy of mesenteric vessels was noted after 3 and 32 weeks of diabetes as revealed by the increase in mesenteric vessel wet weight and an increased wall/lumen ratio. SPARC mRNA was sparsely present in intima and adventitia of control vessels. There was a marked increase in SPARC gene expression in the intima and adventitia of mesenteric vessels after 1, 3, and 32 weeks of diabetes. SPARC protein was demonstrated in the vessel wall in control animals and was increased in the mesenteric vessels of diabetic rats after 1 and 32 weeks of diabetes. Administration of the inhibitor of advanced glycation end-product formation, aminoguanidine, to diabetic rats attenuated both the hypertrophic response in mesenteric vessels and the overexpression of SPARC mRNA and protein without affecting glycemic control or food intake. In summary, diabetes-related mesenteric vascular hypertrophy is associated with an increase in SPARC expression in the vessel wall. The modulation of SPARC expression in mesenteric vessels of diabetic rats might be of pathogenetic significance in the development of vascular remodeling in diabetes.

Animals↗
PubMed1992

Affinity of bone sialoprotein and several other bone and dentin acidic proteins to collagen fibrils.

Bone and dentin contain several kinds of mineral-binding proteins and cell-attachment proteins. The authors examined the affinity of these proteins to type I collagen, a major matrix protein of the tissue. Bone sialoprotein (BSP), bone Gla protein (BGP), bone small proteoglycan II (PG II), osteonectin (ON), and dentin phosphophoryn (DPP) were labeled with fluorescein isothiocyanate and incubated with reconstituted type I collagen fibril. DPP, BGP, BSP, and PG II were absorbed significantly to the collagen fibril at physiological ionic strength with dissociation constants of 10(-6)-10(-7) M. BSP and PG II enhanced the fibrillogenesis of collagen. These acidic proteins can affect the surface properties of collagen fibril, and BSP, having the cell-attachment sequence Arg-Gly-Asp, possibly mediates interaction between collagen fibril and cells.

Amino Acid Sequence↗
PubMed1992

Establishment of an osteogenic cell line derived from adult mouse bone marrow stroma by use of a recombinant retrovirus.

In order to characterize fibroblastic colony-forming units (CFU-F) from murine bone marrow in relation to osteogenesis, adherent cells of 7-day-old BALB/c mouse bone marrow cultures were infected with a recombinant retrovirus (N2/ delta fosB) containing the bacterial neomycin resistance gene. One of the G418-resistant clones, MN7, was selected for further analysis on the basis of its high expression of the bone-specific alkaline phosphatase. The cells have now been in culture for more than 1 year and maintain a stable phenotype. The osteogenic nature of the immortalized clone MN7 was demonstrated as follows: (1) Mineralization was detected by 85Sr uptake and with the Von Kossa staining method only after in vitro cultivation on a collagen type I matrix. (2) Osteoblastic phenotype markers, including the synthesis of type I collagen, osteonectin, and the bone-specific isoenzyme of alkaline phosphatase were expressed in vitro. (3) MN7 cells responded to bone effectors such as parathyroid hormone and 1,25-dihydroxyvitamin D3. (4) Intraperitoneal injection of MN7 cells into 1-day-old BALB/c mice produced typical osteosarcomas in all animals. We conclude that MN7, derived entirely in vitro from a stromal CFU-F colony, represents a stable murine osteosarcoma cell line expressing the osteoblastic phenotype and provides the first direct evidence needed to establish adult mouse marrow-derived, nonhematopoietic stromal cells as osteoprogenitors.

Alkaline Phosphatase↗
PubMed1993

Immobilized DPP and other proteins modify OCP formation.

Osteonectin, gamma-carboxyglutamic acid-containing (Gla) protein, and dentin phosphoprotein were covalently attached to sepharose beads and inoculated in solutions at two different degrees of supersaturation with respect to both octacalcium phosphate (OCP) and hydroxyapatite. In both solutions, the inhibitory activity towards de novo formation of calcium phosphate that these proteins display when freely dissolved in solution was completely eliminated when they were immobilized on the sepharose at concentrations of up to 5 micrograms/mg wet beads. In the solution that was more highly supersaturated with respect to OCP, the immobilized dentin phosphoprotein, moreover, was found to induce de novo formation of OCP in proportion to the concentration of the protein immobilized. For example, at 10 micrograms/ml of the immobilized dentin phosphoprotein, the induction period was reduced more than 50%. However, in the solution considerably less supersaturated with respect to OCP, none of the immobilized proteins were capable of inducing OCP or apatite deposition. These findings suggest that the immobilized dentin phosphoprotein could work as a nucleating substrate for the OCP phase in solutions where calcium and phosphate concentrations are sufficiently higher than equilibrium saturation levels for the OCP phase.

Animals↗
PubMed1987

Psammous desmo-osteoblastoma. Ultrastructural and immunohistochemical evidence for an osteogenic histogenesis.

Fibro-osteo-cemental lesions of the jaw bones are a heterogeneous group of diseases which present problems in classification. Psammous desmo-osteoblastoma is one of four newly proposed entities (Makek 1983) and has until now been characterized by its light microscopic, clinical and radiological features. On electron microscopy this tumour exhibits fibroblastic (preosteoblastic), osteoblastic and osteocytic cells and a globular mineralization unlike the mineralization of the psammoma bodies. Immunohistological investigations with anti-osteonectin, a bone specific protein linking mineral to collagen, showed positive intracellular staining in all tumour cells and extracellular staining in the osteoid. The psammoma bodies were, however, not stained. These results confirm the view of the osteogenic histogenesis of psammous desmo-osteoblastoma, with an osteogenic differentiation of the tumour cells, bone formation and association of psammoma bodies which are not of bone origin. This combination of findings supports the view that psammous desmo-osteoblastoma represents a new and distinct entity occurring in desmal preformed cranio-facial bones which should be incorporated in a revised WHO-classification.

Adolescent↗
PubMed1997

Phalangeal intraosseous well-differentiated osteosarcoma of the hand.

A case of intraosseous well-differentiated osteosarcoma in one phalanx of the hand is reported. A 78-year-old man noticed swelling in the little finger of his right hand approximately 7 years before referral. Imaging disclosed a tumour with a "ground glass" appearance and irregular mottled calcification occupying almost all of the phalanx marrow and suggested slight invasion into the soft tissue. Open biopsy suggested a diagnosis of well-differentiated fibroblastic osteosarcoma. The finger and its metacarpal bone were amputated and a tumour measuring 3.5 x 2.2 x 2.0 cm and with an indistinct soft tissue margin was found in the bone marrow. Histologically, the tumour was composed of fibroblastic cells with few mitoses, and neoplastic bone formation was apparent. Although the tumour appeared to be a fibrous dysplasia, the presence of nuclear atypia, hypercellularity, and the absence of a typical woven bone pattern in addition to the soft tissue invasion indicated otherwise. Ultrastructural examination showed focal myofibroblastic differentiation, and immunohistochemistry revealed smooth muscle actin, vimentin, osteocalcin, osteonectin and MIBI in the tumour cells. This ultrastructural and immunohistochemical study is believed to be the first detailed report of an intraosseous well-differentiated osteosarcoma of phalangeal bone.

Actins↗
PubMed1984

Identification of the noncollagenous proteins of bovine bone by two-dimensional gel electrophoresis.

We have characterized the noncollagenous proteins of bovine bone using two high-resolution gel electrophoretic techniques. Proteins were extracted from bone tissue by extended dialysis against 0.5 M EDTA. In some cases, a preextraction was done in guanidine HCl. Bovine plasma was also examined to identify the proteins in bone that might also be present in blood. We have scored 160 major, reproducible spots on our standard preparation bone map. These comprise about 40 individual protein groups. There are many more minor spots present which puts the total number present over 200. Of these groups, 15 are not present on plasma maps. Bone proteins identified in this way include actin, bone Gla-protein, and osteonectin. The remainder are unknown. Bone Gla-protein is present in bovine bone in four isoelectric forms, pI = 3.95-4.50. Electroblotting analysis of EDTA and guanidine HCl extracted material failed to reveal any higher molecular weight immunologically reactive species. The plasma proteins found in bone include, but are not limited to albumin, apo A-I lipoprotein, IgG, IgM, transferrin, alpha-2-HS-glycoprotein, and hemoglobin. Extraction with guanidine HCl plus EDTA significantly enriches the yield for the nonplasma proteins but does not appear to extract any additional bone proteins.

Actins↗
PubMed1991

Diverse forms of stress result in changes in cellular levels of osteonectin/SPARC without altering mRNA levels in osteoligament cells.

The osteonectin/SPARC gene has been shown to possess motifs for a heat shock element and metal responsiveness. Also, the expression of the protein has been associated with culture stress in endothelial cells. In the present study, osteoligament (OL) cells derived from the patellar ligament were subjected to diverse forms of stress that included (a) exposure to sodium arsenite, (b) heat shock, (c) cadmium ion, and (d) the amino acid analog, AZC. Osteonectin/SPARC levels in OL cells were determined by Western blot analyses, and immunoprecipitation using antiosteonectin antibodies. Expression of osteonectin/SPARC mRNA was determined by Northern analysis using a 1.5 kb EcoRI restriction fragment of bovine osteonectin cDNA. These studies reveal that osteonectin/SPARC is produced following diverse forms of stress, however, the levels are lower than observed in unchallenged OL cells. In all instances, the mRNA levels were comparable to control cells. These studies indicate that expression of osteonectin/SPARC mRNA is tightly controlled in OL cells and that the protein may be regulated at the level of protein translation.

Animals↗
PubMed1986

Mineralized tissue protein profiles in the Australian form of bovine osteogenesis imperfecta.

Noncollagenous proteins and proteoglycan from the bone and dentin of affected and normal half-siblings neonatal calves with the Australian variant of bovine osteogenesis imperfecta (BOI-A) were quantitated. In contrast to a clinically similar syndrome of BOI in the progeny of a second progenitor bull identified in Texas (BOI-T), osteonectin and bone sialoprotein levels were normal in the affected BOI-A bone, and dentin phosphophoryn levels were normal in affected BOI-A teeth. However, bone proteoglycan in the affected BOI-A calves was depleted to one-third of the level found in normal siblings, a finding qualitatively similar to the depletion of bone proteoglycan in the BOI-T syndrome. These results suggest that quantitation of noncollagenous proteins and proteoglycans may be a useful technique for differentiating clinically similar syndromes of OI in man.

Animals↗
PubMed1986

Mineralized bone nodules formed in vitro from enzymatically released rat calvaria cell populations.

Single-cell suspensions obtained from sequential enzymatic digestions of fetal rat calvaria were grown in long-term culture in the presence of ascorbic acid, Na beta-glycerophosphate, and dexamethasone to determine the capacity of these populations to form mineralized bone. In cultures of osteoblastlike cells grown in the presence of ascorbic acid and beta-glycerophosphate or ascorbic acid alone, three-dimensional nodules (approximately 75 micron thick) covered by polygonal cells resembling osteoblasts could be detected 3 days after confluency. The nodules became macroscopic (up to 3 mm in diameter) after a further 3-4 days. Only in the presence of organic phosphate did they mineralize. Nodules did not develop without ascorbic acid in the medium. Dexamethasone caused a significant increase in the number of nodules. Histologically, nodules resembled woven bone and the cells covering the nodules stained strongly for alkaline phosphatase. Immunolabeling with specific antibodies demonstrated intense staining for type I collagen that was mineral-associated, a weaker staining for type III collagen and osteonectin, and undetectable staining for type II collagen. Nodules did not develop from population I and the number of nodules formed by populations II-V bore a linear relationship to the number of cells plated (r = .99). The results indicate that enzymatically released calvaria cells can form mineralized bone nodules in vitro in the presence of ascorbic acid and organic phosphate.

Animals↗
PubMed1993

Human bone marrow stromal cells express an osteoblastic phenotype in culture.

This study reports the selection and characterization of osteogenic precursors from human bone marrow which were isolated by two "clonings" and successive subculturing. These cell lines express alkaline phosphatase activity. Gel electrophoresis of [3H]-proline labeled cultures showed that the cloned cells produce only type I collagen. They synthetize osteocalcin and osteonectin. They respond to 1,25 dihydroxy vitamin D3 by increasing osteocalcin synthesis and secretion, and to parathyroid hormone by increasing cyclic AMP synthesis. After the third subculture in the absence of beta-glycerophosphate, these cell lines formed lots of clusters which exhibit high alkaline phosphatase activity and positive von Kossa staining. X-ray energy spectrum shows that these cells are surrounded by "budding" structures containing calcium and phosphorus with a ratio Ca:P identical to those of pure hydroxyapatite. This process was associated with 45Ca uptake into the cells. All these data support the selection of osteogenic cells which may be of considerable clinical importance.

Adult↗
PubMed1996

Bone chondroadherin promotes attachment of osteoblastic cells to solid-state substrates and shows affinity to collagen.

Chondroadherin, which is reported to be synthesized by chondrocytes and to promote their attachment, was purified from bovine bone. It was a minor component of bone organic matrix, and was present in the 4 M guanidine extract of demineralized bone. Chondroadherin promoted attachment of osteoblastic cells to solid-state substrates, and bound to collagen. Binding of chondroadherin to collagen was significantly higher than that of osteonectin or decorin. These findings imply that chondroadherin may play a role in maintaining bone cells on the collagen matrices of bone.

Amino Acid Sequence↗
PubMed1999

Expression of bone matrix proteins in urolithiasis model rats.

Urinary calcium stones are a pathological substance, and they show similarities to physiological mineralization and other pathological mineralizations. The expression of messenger (m) RNAs of osteopontin (OPN), matrix Gla protein (MGP), osteonectin (ON) and osteocalcin (OC) in bones and teeth has been described. We previously identified OPN as an important stone matrix protein. In addition, the spontaneous calcification of arteries and cartilage in mice lacking MGP was recently reported, a finding which indicates that MGP has a function as an inhibitor of mineralization. Here, we examined the mRNA expressions of OPN, MGP, ON, and OC in the kidneys of stone-forming model rats administered an oxalate precursor, ethylene glycol (EG) for up to 28 days. The Northern blotting showed that the mRNA expressions of OPN and MGP were markedly increased with the administration of EG, but their expression patterns differed. The OPN mRNA expression reached the maximal level at day 7 after the initiation of the EG treatment and showed no significant difference after 14 and 28 days, whereas the MGP mRNA expression rose gradually to day 28. The in situ hybridization demonstrated that the cell type expressing OPN mRNA was different from that expressing MGP. We suggest that OPN acts on calcification and MGP acts on suppression.

Animals↗
PubMed2002

Immunohistochemical examination on intracranial calcification in neurodegenerative diseases.

Fahr-type calcification is a relatively common finding in the elderly, and in younger patients with Alzheimer's disease, calcification in the basal ganglia is not uncommon. However, as far as we know, an immunohistochemical study of intracranial calcification in neurodegenerative diseases has not been performed. In this study, we examined intracranial calcification of the basal ganglia and cerebellum with antibodies against noncollagenous bone matrix proteins. Nineteen brains were employed. The diagnoses were diffuse neurofibrillary tangles with calcification in five, Alzheimer's disease in five, Pick's disease in one, progressive supranuclear palsy in one, Parkinson's disease in one, and six controls. By conventional histology, three patterns of calcium (Ca) deposition were recognized: diffuse deposition within the tunica media of small and medium-sized vessels (type 1 deposition), free spherical or lobulated concretions (type 2 deposition) in the parenchyma, and rows of small calcospherites lying along capillaries (type 3 deposition). Type 3 deposition is relatively rare, and may be a hallmark of severe intracranial calcification. Immunohistochemistry demonstrated that osteopontin was present diffusely in all Ca deposition types. Osteocalcin was present chiefly in the peripheral region of type 2 and 3 depositions, as well as in only the rims of type 1 deposition. Bone sialoprotein and osteonectin were found only in the core portions of type 2 and 3 depositions. In brief, type 1 deposition shows a different staining pattern from type 2 and 3. Different Ca deposition patterns of noncollagenous bone matrix proteins may suggest their separate roles in the pathogenesis of intracranial calcification.

Aged↗
PubMed1999

In situ hybridization with polymerase chain reaction-derived single-stranded DNA probe and S1 nuclease.

A rapid and simplified protocol for in situ hybridization (ISH) with polymerase chain reaction (PCR)-derived single-stranded DNA probes and S1 nuclease revealed transcripts of bone matrix proteins on decalcified skeletal bone specimens. Mouse bone tissue was fixed with 4% paraformaldehyde, decalcified with 20% EDTA, and embedded in paraffin. Each pair of primers for reverse transcriptase -PCR was designed to amplify a 280-bp DNA fragment from the coding region of the mature protein of mouse osteonectin (ON) and a 320-bp fragment from the coding region of mouse osteopontin (OP). Initial PCR products were eluted, purified, and reamplified by unidirectional PCR in the presence of the digoxigenin (DIG)-labeled dUTP. ISH was carried out by proteinase K treatment, hybridization, and washing. The unhybridized single-stranded DNA probe was selectively removed by S1 nuclease treatment. Hybridized probes were visualized with the alkaline phosphatase-conjugated anti-DIG antibody. The transcripts of ON and OP were clearly detected on the thin sections of the decalcified bone. Because this protocol does not require cloning or in vitro transcription, reliable and stable ISH can be done in an ordinary laboratory equipped with a thermal cycler.

Animals↗
PubMed2001

Expression of the novel transcription factor OASIS, which belongs to the CREB/ATF family, in mouse embryo with special reference to bone development.

The OASIS gene, which encodes a novel CREB/ATF family member, was isolated from long-term cultured astrocytes that were employed as an in vitro gliosis model. In the present study, we examined the expression pattern of the OASIS gene in the developing mouse embryo by in situ hybridization histochemistry and compared it with the expression of osteogenesis markers. OASIS mRNA expression was most strongly detected in preosteoblasts of the outer bony cortex of the ribs. Alveolar bone also showed strong signals for OASIS gene expression. OASIS mRNA was also localized to the preodontoblast of tooth buds. Expression began at embryonic day 12 (D12.5), peaked around D14.5-16.5, and continued to D18.5. The pattern of expression was very similar to that of hXBP-1 mRNA, which encodes another CREB/ATF family member. Spatiotemporal patterns of OASIS partly overlapped that of osteopontin, osteonectin, and alpha1 type I procollagen genes. Among these, the time course of OASIS mRNA expression was most similar to that of osteopontin mRNA expression, suggesting that the OASIS protein is involved in the late phase of osteoblast differentiation, as compared to the Cbfa1 that regulates early phases of osteoblast differentiation.

Animals↗
PubMed2002

Evolutionary conservation and association of SPARC with the basal lamina in Drosophila.

SPARC (secreted protein, acidic, rich in cysteine, also called BM40 and osteonectin) is a multifunctional calcium-binding glycoprotein whose modular organization has been highly conserved between invertebrates and vertebrates, indicating a conservation of function during metazoan evolution. Genome analysis has revealed a single copy of the DrosophilaSPARC ( dSPARC) gene. As a first step towards investigating the function of SPARC in Drosophila, we examined its spatiotemporal distribution during development. During embryogenesis, dSPARC mRNA transcripts are restricted to mesoderm derivatives, hemocytes, and the fat body. Immunostaining with anti- DrosophilaSPARC antibodies indicates that dSPARC secreted by the hemocytes and fat body cells is concentrated in basal laminae surrounding internal organs. During oogenesis, dSPARC transcripts are restricted to the somatic cells of the germarium and follicles. Consistent with embryonic development, the resultant protein is concentrated in basal laminae. Mutations in type IV collagen are associated with a dramatic decrease in dSPARC protein immunostaining in hemocytes. The data suggest that the production and assembly of dSPARC in the basal lamina is dependent on type IV collagen, and raise the possibility that dSPARC and type IV collagen interactions are a prerequisite to the assembly and structural integrity of basal laminae in Drosophila.

Amino Acid Sequence↗
PubMed2006

Lung osteoma--a new benign lung lesion.

Extraskeletal osteomas have not been described in the lung. Tumors with osseous elements can be found, such as hamartoma and amyloid tumor, and reactive lesions such as osseous metaplasia. A 39-year-old male patient was treated for multiple myeloma and got a bone marrow transplantation 2 years and a few months before he presented with a solitary well-circumscribed tumor in the right middle lobe. The patient underwent surgical resection. The tumor presented with a fibrous capsule and consisted of mature bone trabecules. Within the tumor, fatty tissue was seen. There were small bone spicules interpreted as areas of new bone formation and appositional growth. No amyloid deposition, no immature epithelial tubules as in hamartomas, and no normal lung structure as in osseous metaplasia were seen. Within the osseous elements, a positive reaction was seen with antibodies for osteonectin, whereas the reaction for calcitonin was negative. To the best of our knowledge, this is the first case of an osteoma being reported in the lung looking like any other extraskeletal osteoma. This tumor might have been induced by circulating stem cells; however, due to autologous bona marrow transplantation, this cannot be proven.

Adult↗