Recruitment of nuclear factor Y to the inverted CCAAT element (ICE) by c-Jun and E1A stimulates basal transcription of the bone sialoprotein gene in osteosarcoma cells

Bone sialoprotein (BSP), a major protein in the extracellular matrix of bone, is expressed almost exclusively by bone cells and by cancer cells that have a propensity to metastasize to bone. Previous studies have shown that v-src stimulates basal transcription of bsp in osteosarcoma (ROS 17/2.8) cells by targeting the inverted CCAAT element (ICE) in the proximal promoter. To identify possible downstream effectors of Src we studied the effects of the proto-oncogene c-jun, which functions downstream of Src, on basal transcription of bsp using transient transfection assays. Increased expression of endogenous c-Jun induced by the tumor promoter 12-O-tetradecanoyl-phorbol 13-acetate and ectopic expression of c-Jun increased basal transcription of chimeric reporter constructs encompassing the proximal promoter by 1.5-3-fold in ROS 17/2.8 osteosarcoma cells, with more modest effects in a normal bone cell line, RBMC-D8. The effects of c-Jun were abrogated by mutations in the ICE box and by co-expression of dominant negative nuclear factor Y, subunit A (NF-YA). The increase in bsp transcription did not require phosphorylation of c-Jun and was not altered by trichostatin treatment or by ectopic expression of p300/CREB-binding protein (CBP) or mutated forms lacking histone acetyltransferase (HAT) activity. Similarly, ectopic expression of p300/CBP-associated factor (P/CAF), which transduces p300/CBP effects, or of HAT-defective P/CAF did not influence the c-jun effects. Surprisingly, E1A, which competes with P/CAF binding to p300/CBP, also stimulated BSP transcription through NF-Y independently of c-jun, p300/CBP, and P/CAF. Collectively, these studies show that c-Jun and E1A regulate basal transcription of bsp in osteosarcoma cells by recruiting the NF-Y transcriptional complex to the ICE box in a mechanism that is independent of p300/CBP and P/CAF HAT activities.

Potential markers that complement expression of CA125 in epithelial ovarian cancer

BACKGROUND

When ovarian carcinoma is diagnosed in stage I, up to 90% of patients can be cured with surgery and currently available chemotherapy. At present, less than 25% of cases are diagnosed at this stage. To increase the fraction of ovarian cancers detected at an early stage, screening strategies have been devised that utilize a rising serum CA125 level to trigger the performance of transvaginal sonography. One limitation of CA125 as an initial step in such a screening strategy is that up to 20% of ovarian cancers lack expression of the antigen. Serum tumor markers that can be detected in ovarian cancers that lack CA125 expression might improve the sensitivity for early detection.

METHODS

From 296 ovarian cancers, 65 (22%) were found to have weak or absent CA125 expression on immunoperoxidase staining. Tissue expression of CA125 was compared to serum CA125 levels. Using immunoperoxidase staining of tissue arrays, we have assessed expression of 10 potential serum tumor markers in the 65 epithelial ovarian cancers with little or no CA125 expression and in ovarian cystadenomas, tumors of low malignant potential, normal ovaries, and 16 other normal tissues.

RESULTS

Low or absent expression of CA125 in surgical specimens of epithelial ovarian cancer was associated with low levels of serum CA125 in pre-operative serum specimens. In ovarian cancers that lacked CA125, all specimens (100%) expressed human kallikrein 10 (HK10), human kallikrein 6 (HK6), osteopontin (OPN), and claudin 3. A smaller fraction of CA125-deficient ovarian cancers expressed DF3 (95%), vascular endothelial growth factor (VEGF) (81%), MUC1 (62%), mesothelin (MES) (34%), HE4 (32%), and CA19-9 (29%). When reactivity with normal tissues was considered, however, MES and HE4 showed the greatest specificity. Differential expression was also found for HK10, OPN, DF3, and MUC1.

CONCLUSIONS

At the level of tissue expression, each of 10 potential serum markers could be detected in 29-100% of ovarian cancers that had low or absent expression of CA125. Several markers exhibited more intense expression in cancers than in normal organs. Further investigation is needed to demonstrate complementary expression of markers in serum.

On-Column Refolding and Purification of Recombinant Human Interleukin-1 Receptor Antagonist (rHuIL-1ra) Expressed as Inclusion Body in Escherichia coli

Recombinant human interleukin-1 receptor antagonist (rHuIL-1ra) was produced in E. coli as an inclusion body. rHuIL-1ra was purified to Over 98% purity by anion exchange chromatography after on-column refolding. The optimized processes produced more than 2 g pure refolded rHuIL-1ra per 1 l culture, corresponding to a 44% recovery, without an intermediate dialysis step. Refolded rHuIL-1ra had full biological activity with the MTT assay. An intramolecular disulfide linkage in the oxidized recombinant protein was suggested by data from HPLC and non-reducing SDS-PAGE.

Pattern of expression of the podocalyxin gene in the mouse brain during development

We studied the expression pattern of the major renal protein Podocalyxin during the development of mouse brain using in situ hybridization. Podocalyxin mRNA was widely expressed at least from E14, the first age we studied, and expression remained high until adulthood. The highest levels of expression were postnatal. Podocalyxin expression was particularly elevated in the cortical plate, the hippocampus and cerebellum, and in several basal forebrain nuclei.

In vitro and in vivo effects of the overexpression of osteopontin on osteoblast differentiation using a recombinant adenoviral vector

Osteopontin (OPN) is a highly acidic secreted phosphoprotein that binds to cells via an RGD (arginine-glycine-aspartic acid) cell adhesion sequence that recognizes the alphaVbeta3 integrin. OPN may regulate the formation and remodeling of bone. To elucidate the function of OPN in bone tissue, we examined the overexpression of OPN in osteoblasts in vitro and in vivo using an adenoviral vector carrying an OPN cDNA (Adv-OPN). Rat bone marrow-derived osteoblasts infected with Adv-OPN were examined by Western blotting, immunofluorescence, nodule formation measurements, assay of alkaline phosphatase (ALP) activity, and Northern blotting. The results suggested that not only osteoblast differentiation markers such as osteocalcin and ALP, but nodule formation and ALP activity are markedly enhanced by OPN overexpression in the case of viral infection. On the contrary, when Adv-OPN and uninfected osteoblasts were implanted into subcutaneous sites with a porous ceramic scaffold, the ALP activity and calcium content of the OPN-infected composite were higher than in uninfected composites, however, the differences were smaller than expected from the in vitro experiments. We speculate that the difference in the result of in vitro and in vivo experiments originates from the inhibitory effect of secreted OPN on the crystal growth of apatite in vivo, which competes with the induced activity of osteoblasts.

Osteopontin Expression in Gestational Trophoblastic Diseases: Correlation With Expression of the Adhesion Molecule, CEACAM1

The human placenta is a complex tissue with multiple endocrine and nutritional functions and a unique capacity for rapid proliferation but tightly controlled invasion, differentiating it from malignant tumors. Osteopontin (OPN) is a glycoprotein of the extracellular matrix, which has been shown to mediate cellular migration and invasion and to contribute to tumorigenesis in several types of cancers. OPN also could be implicated in regulating implantation and placentation by promoting cellular migration and invasion in a placenta-specific fashion. We could demonstrate the expression pattern of OPN in the normal human placenta in which it is localized in the extravillous (intermediate) trophoblast and the villous cytotrophoblast. CEACAM1 is an adhesion molecule, which we have recently found to be expressed at the maternal-fetal interface of the normal placenta with a localization to the extravillous (invasive) trophoblast and in gestational trophoblastic disease (GTD) and also to be potentially implicated in trophoblast invasion and tumorigenesis. Both OPN and CEACAM1 have been shown to interact with integrin beta3. The purpose of this study was to investigate the expression pattern of OPN in GTD and to correlate it with the expression of CEACAM1. To analyze the expression of OPN, we performed immunohistochemistry on a total of 27 cases of GTD, including 21 hydatidiform moles and 6 choriocarcinomas, which had previously been characterized with respect to their CEACAM1 expression. Hydatidiform moles showed a positivity for OPN in villous cytotrophoblast and in the trophoblast proliferations on the villous surface. The strongest OPN expression could be observed in the choriocarcinomas with a heterogenous OPN expression pattern. CEACAM1 had shown similar results and was found to be expressed in choriocarcinoma. The expression pattern of osteopontin in gestational trophoblastic diseases indicates that it might play a role in the pathogenesis of GTD (possibly as a functional complex with CEACAM1 and integrin beta3) and might be useful as an additional diagnostic marker for such lesions.

Podocalyxin: a marker of blasts in acute leukemia

Podocalyxin is a CD34 family member expressed by podocytes, vascular endothelium, mesothelium, and a subset of hematopoietic progenitors. Podocalyxin expression was not observed in the hematopoietic cells of normal adult bone marrow samples. However, podocalyxin was expressed by blasts in 30 (77%) of 39 cases of acute myeloid leukemia (AML), 22 (81%) of 27 cases of acute lymphoblastic leukemia (ALL), and 13 (87%) of 15 cases of cutaneous myeloid sarcoma. No correlation with CD34 expression by immunohistochemical analysis was seen. Wilms tumor 1 (WT1) expression was detected in blasts in 17 AML cases (44%) and 21 ALL cases (78%). There was no correlation between WT1 and podocalyxin expression. We conclude that podocalyxin is expressed commonly by blasts in ALL and AML. Analysis of the expression of CD34 and podocalyxin increases sensitivity for the immunophenotypic detection of leukemic blasts compared with the analysis of CD34 alone. Therefore, podocalyxin seems to complement CD34 as a useful hematopoietic blast marker. The physiologic role of podocalyxin in leukemic blasts remains unknown.

[Effects of rotation on osteonectin and osteopontin mRNA level of cultured osteoblasts in rats]

Conditions of disuse such as bed rest, space flight, and immobilization result in decreased mechanical loading of bone, which is associated with reduced bone mineral density and increased fracture risk. Mechanisms involved in this process are not well understood except the suppression of osteoblast function. To investigate the effect of simulated weightlessness on mRNA level of extracellular matrix proteins, osteoblasts were rotated in horizontal plane as a model of simulated microgravity. Primordial osteoblasts of rats were grown for 2 d and then rotated for 24, 48 and 72 h, respectively. After isolating total RNA in cells, reverse transcription polymerase chain reaction (PT-PCR) was made to examine the mRNA level of osteopontin (OPN) and osteonectin (ON). Meanwhile, the levels of alkaline phosphatase (ALP) and osteocalcin (BGP) in the cultured medium were measured to evaluate the calcific function of cell. The expression of OPN and ON mRNA fell significantly after rotating for 24, 48 and 72 h, respectively. The contents of BGP descended significantly, meanwhile, the activity of ALP also showed a degressive tendency. Horizontal rotation decreased the expression of ON and OPN as well as diminished the secretion of BGP and ALP, which affected the calcific function of osteoblast. The results obtained suggest that depression of extracellular matrix proteins expression plays a key role in bone loss during weightlessness.

Osteoblast responsiveness to 1alpha,25-dihydroxyvitamin D3 during spaceflight

Rat osteoblasts were cultured aboard a space shuttle for 4 and 5 days. Cells were treated with 1 nM 1alpha,25-dihydroxyvitamin D(3) (VD) for the last 1 day. The conditioned media were harvested. Cells were solubilized with guanidine solution on board. We examined microgravity effects on the production/expression of osteocalcin, bone sialoprotein (BSP), and VD receptor (VD-R) in osteoblasts. Under VD treatment, the osteocalcin protein level was 243 +/- 117 and 1,718 +/- 534 pg/microg cellular DNA in flight cultures and ground controls, respectively. Without VD treatment, the osteocalcin protein level was not different between flight cultures and ground controls. The osteocalcin mRNA level in the VD-treated flight cultures was as low as 16% of that in ground controls. The VD-R mRNA level in the VD-treated flight cultures was also decreased to 16% of that in ground controls. Microgravity would suppress the VD-inducible production of osteocalcin but not the basal productivity. The BSP mRNA level was increased by microgravity. VD/VD-R binds to the vitamin D-responsive element (VDRE) on the target genes. The rat osteocalcin gene is positively regulated via "enhancer" VDRE, whereas the rat BSP gene is negatively regulated via "repressor " VDRE. Microgravity might modulate osteoblast responsiveness to VD through the suppression of VD-R.

In Vitro Growth and Differentiation of Osteoblast-Like Cells on Hydroxyapatite Ceramic Granule Calcified From Red Algae

PURPOSE

The purpose of this study was to analyze the interaction between osteoblast-like cells isolated from mandibular bone and hydroxyapatite ceramic bone substitute obtained from calcified red algae to assess the growth and differentiation of adherent cells on this biomaterial.

MATERIALS AND METHODS

The macroporous ceramic material C GRAFT/Algipore (The Clinician's Preference LLC, Golden, CO) is composed of 100% hydroxyapatite and possesses specific mechanical and physiochemical properties. Osteoblast-like cells were seeded on 200 mg of biomaterial and cultured for 6 and 21 days under osteogenic differentiation conditions. Specific alkaline phosphatase activity, DNA, and protein content of the proliferating cells were analyzed. The morphology of the cells in contact with the biomaterial was examined by scanning electron microscopy. The osteoblastic phenotype of the cells was confirmed by analysis of the expression of bone-specific genes (osteocalcin, osteopontin and collagen type I) by semi-quantitative reverse transcriptase polymerase chain reaction.

RESULTS

The DNA and protein content increased over the culture period. Scanning electron microscopy showed cells spreading on the surface of the biomaterials, covering the macropores, and colonizing the depth of the particles. The analysis of the expression patterns of bone-related genes confirmed the osteoblastic phenotype of the cultured cells.

CONCLUSION

The results of this study showed that hydroxyapatite ceramic bone substitute obtained from calcified red algae support the proliferation and differentiation of human osteoblast-like cells on its surface in vitro and might be suitable for use as scaffolds in tissue engineering strategies in vivo.

Up-regulation of osteopontin and alphaBeta-crystallin in the normal-appearing white matter of multiple sclerosis: an immunohistochemical study utilizing tissue microarrays

Tissue microarrays assembled from control and multiple sclerosis (MS) brain tissue have been used to assess the expression patterns and cellular distribution of two antigens, the proinflammatory cytokine osteopontin and the inducible heat shock protein alphaBeta-crystallin, which have previously been implicated in MS pathogenesis. Tissue cores were taken from paraffin-embedded donor blocks containing chronic active or chronic inactive plaques and normal-appearing white matter (NAWM) in seven MS cases, and white matter (WM) in five control cases. Expression patterns of both proteins were assessed against myelin density and microglial activation in the different tissue categories. Both proteins showed increased expression in all categories of MS tissue compared with control WM. The results indicate progressive up-regulation of expression of osteopontin with increased plaque activity, while elevation of alphaBeta-crystallin expression in MS tissue was independent of demyelination. In MS NAWM a significant correlation was observed between high levels of expression of osteopontin and alphaBeta-crystallin. Osteopontin expression was predominantly confined to astrocytes throughout MS tissues. alphaBeta-crystallin was expressed on astrocytes, oligodendrocytes and occasionally on demyelinated axons. Taken together, these data indicate a wider distribution of osteopontin and alphaBeta-crystallin in MS tissues than previously described and support their proposed role in MS pathogenesis.

The dioxin/aryl hydrocarbon receptor mediates downregulation of osteopontin gene expression in a mouse model of gastric tumourigenesis

The dioxin/aryl hydrocarbon receptor functions as a ligand-activated transcription factor regulating transcription of a battery of genes encoding primarily drug-metabolizing enzymes. Expression of a constitutively active mutant of the aryl hydrocarbon receptor (CA-AhR) in transgenic mice results in development of stomach tumours, correlating with increased mortality. We have used suppression subtractive hybridization techniques followed by macroarray analysis to elucidate which genes are differentially expressed during this process. In the glandular stomach of CA-AhR mice, we observed decreased mRNA expression of osteopontin (OPN), a noncollagenous protein of bone matrix that is also involved in several important functions including regulation of cytokine production, macrophage accumulation, cell motility and adhesion. Downregulated expression of OPN during tumour development was confirmed by RT-PCR and RNA blot analysis. Immunohistochemical analysis showed that this decrease was confined to the corpus region, correlating with the restricted localization of the tumours. Decreased OPN mRNA expression was also observed in other organs of CA-AhR mice. Taken together, these results show that OPN is negatively regulated by the dioxin receptor, and that downregulation of its expression correlates with development of stomach tumours in mice expressing a constitutively active mutant of dioxin receptor.

Weight loss regulates inflammation-related genes in white adipose tissue of obese subjects

Adipose tissue produces inflammation and immunity molecules suspected to be involved in obesity-related complications. The pattern of expression and the nutritional regulation of these molecules in humans are poorly understood. We analyzed the gene expression profiles of subcutaneous white adipose tissue from 29 obese subjects during very low calorie diet (VLCD) using cDNA microarray and reverse transcription quantitative PCR. The patterns of expression were compared with that of 17 non-obese subjects. We determined whether the regulated genes were expressed in adipocytes or stromavascular fraction cells. Gene expression profiling identified 100 inflammation-related transcripts that are regulated in obese individuals when eating a 28 day VLCD but not a 2 day VLCD. Cluster analysis showed that the pattern of gene expression in obese subjects after 28 day VLCD was closer to the profile of lean subjects than to the pattern of obese subjects before VLCD. Weight loss improves the inflammatory profile of obese subjects through a decrease of proinflammatory factors and an increase of anti-inflammatory molecules. The genes are expressed mostly in the stromavascular fraction of adipose tissue, which is shown to contain numerous macrophages. The beneficial effect of weight loss on obesity-related complications may be associated with the modification of the inflammatory profile in adipose tissue.

Behaviour of bone marrow osteoblast-like cells on mineral trioxide aggregate: morphology and expression of type I collagen and bone-related protein mRNAs

AIM

To investigate the in vitro behaviour of rat bone marrow cells (RBM) on mineral trioxide aggregate (MTA) (ProRoot, MTA Root Canal Repair Material; Dentsply Tulsa, Tulsa, OK, USA) compared with intermediate restorative materials (IRM) (Dentsply Caulk, Milford, DE, USA).

METHODOLOGY

RBM were obtained from rat femur and were primary cultured and then subcultured. Cells were then seeded on three dishes of each material, and cultured for 3 days, after which they were evaluated morphologically using scanning (SEM) and transmission (TEM) electron microscopy. Furthermore, the calcium released from hydrated material, the cell proliferation ratio and alkaline phosphatase (ALP) activity were analysed, and the expression of type I collagen and bone-related protein mRNAs were evaluated. The data were averaged and analysed via one-way analysis of variance (anova) and were then compared by the Scheffe's test.

RESULTS

SEM showed that RBM attached to MTA and had a flattened appearance without nuclear protrusions and microspikes. TEM showed that the cells attached in the same manner as the control group, but gaps larger than 2 microm were frequently seen. The calcium released from hydrated MTA was about 130 ppm after 3 days of immersion in saline. The ALP activity was similar to the control group. Cell proliferation and expression of type I collagen mRNA was significantly lower, while the expression of osteopontin mRNA was significantly higher than the control group at the third day of culture. In IRM groups, a few rounded cells were observed on the material but no living cells were seen.

CONCLUSIONS

MTA is a material of low toxicity which does not inhibit cell growth, but does suppress the differentiation of osteoblast-like cells.

Interleukin-1 levels in gingival crevicular fluid adjacent to restorations of calcium aluminate cement and resin composite

OBJECTIVES

The aim of this clinical study was to intra-individually compare Class V restorations of a calcium aluminate cement (CAC), resin composite and enamel with respect to the adjacent levels of interleukin (IL)-1alpha, IL-1beta and IL-1 receptor antagonist (IL-1ra) in gingival crevicular fluid (GCF). The hypothesis was that there are higher IL-1 levels adjacent to resin composite, compared with CAC and enamel.

MATERIALS AND METHODS

In 15 subjects, at least one set of two Class V restorations with subgingival margins, one CAC and one universal hybrid resin composite, and one control surface of enamel were included. In a cross-sectional study and on days 0, 3 and 7 of an experimental gingivitis study, GCFs were collected with Periopaper for 30 s. The GCF concentrations of IL-1alpha, IL-1beta and IL-1ra were quantified with enzyme linked immunosorbent assays.

RESULTS

Neither the cross-sectional study nor the experimental gingivitis study showed any significant differences in the levels of IL-1alpha, IL-1beta and IL-1ra between CAC, resin composite and enamel sites (p>0.05). In the cross-sectional study, low IL-1 concentrations were observed. The IL-1 levels increased significantly during the experimental gingivitis.

CONCLUSION

Regardless of CAC or resin composite, the restorations per se did not affect the GCF levels of IL-1 and IL-1ra, neither at healthy gingiva, nor at initiation of plaque-related gingival inflammation.

Activation of pro-inflammatory and anti-inflammatory cytokines in host organs during chronic allograft rejection: role of endothelin receptor signaling

This study investigated whether allograft rejection is associated with local inflammatory activation in host organs and whether endothelin ET(A) receptor signaling is involved. Expression of IL-1beta, IL-1ra, IL-6, IL-10 and TNF-alpha was investigated in host liver, lung and native heart in a rat model of chronic rejection 8 weeks after heterotopic cardiac transplantation in the absence of immunosuppression. In the presence of rejection, circulating levels of cytokines increased, while tissue level activation was dependent on the organ involved. Similarly, tissue-specific regulatory patterns were observed regarding transcriptional activation. Although chronic ET(A) receptor blockade did not reduce transplant vasculopathy or tissue protein expression, treatment had pronounced effects on plasma levels and transcriptional regulation of chemokines. These data provide evidence for distinct pro-inflammatory local activation in host organs during chronic rejection and suggest a role for ET(A) receptors contributing to regulation of cytokine plasma levels and transcriptional activity.

Human osteocalcin and bone sialoprotein mediating osteomimicry of prostate cancer cells: role of cAMP-dependent protein kinase A signaling pathway

Osteocalcin and bone sialoprotein are the most abundant noncollagenous bone matrix proteins expressed by osteoblasts. Surprisingly, osteocalcin and bone sialoprotein are also expressed by malignant but not normal prostate epithelial cells. The purpose of this study is to investigate how osteocalcin and bone sialoprotein expression is regulated in prostate cancer cells. Our investigation revealed that (a) human osteocalcin and bone sialoprotein promoter activities in an androgen-independent prostate cancer cell line of LNCaP lineage, C4-2B, were markedly enhanced 7- to 12-fold in a concentration-dependent manner by conditioned medium collected from prostate cancer and bone stromal cells. (b) Deletion analysis of human osteocalcin and bone sialoprotein promoter regions identified cyclic AMP (cAMP)-responsive elements (CRE) as the critical determinants for conditioned medium-mediated osteocalcin and bone sialoprotein gene expression in prostate cancer cells. Consistent with these results, the protein kinase A (PKA) pathway activators forskolin and dibutyryl cAMP and the PKA pathway inhibitor H-89, respectively, increased or repressed human osteocalcin and bone sialoprotein promoter activities. (c) Electrophoretic mobility shift assay showed that conditioned medium-mediated stimulation of human osteocalcin and bone sialoprotein promoter activities occurs through increased interaction between CRE and CRE-binding protein. (d) Conditioned medium was found to induce human osteocalcin and bone sialoprotein promoter activities via increased CRE/CRE-binding protein interaction in a cell background-dependent manner, with marked stimulation in selected prostate cancer but not bone stromal cells. Collectively, these results suggest that osteocalcin and bone sialoprotein expression is coordinated and regulated through cAMP-dependent PKA signaling, which may define the molecular basis of the osteomimicry exhibited by prostate cancer cells.

Sequence of protein expression of bone sialoprotein and osteopontin at the developing interface between repair cementum and dentin in human deciduous teeth

Experimental periodontal regeneration studies have revealed the weak binding of repair cementum to the root surface, whereas attachment of cementum to dentin preconditioned by odontoclasts appears to be superior. The aim of this study has been, therefore, to analyze the structural and partial biochemical nature of the interface that develops between resorbed dentin and repair cementum by using human deciduous teeth as a model. Aldehyde-fixed and decalcified tooth samples were embedded in acrylic or epoxy resins and sectioned for light and transmission electron microscopy. Antibodies against bone sialoprotein (BSP) and osteopontin (OPN), two noncollagenous proteins accumulating at hard tissue interfaces in bone and teeth, were used for protein A-gold immunocytochemistry. Light microscopy revealed a gradually increasing staining intensity of the external dentin matrix starting after the withdrawal of the odontoclast. Labeling for both BSP and OPN was first detected among the exposed collagen fibrils and in the intratubular dentin matrix when odontoclasts had withdrawn but mesenchymal cells were present. Subsequently, collagen fibrils of the repair cementum were deposited concomitantly with the appearance of labeling for BSP and OPN over the intratubular, intertubular, and peritubular dentin matrix. Labeled mineralization foci indicated the advancing mineralization front, and the collagenous repair matrix became integrated in an electron-dense organic material that showed labeling for BSP and OPN. Thus, no distinct planar interfacial matrix layer lies between the resorbed dentin and the repair cementum. The results suggest that odontoclasts precondition the dentin matrix such that the repair cementum becomes firmly attached.

Protein kinase Cbeta inhibition attenuates osteopontin expression, macrophage recruitment, and tubulointerstitial injury in advanced experimental diabetic nephropathy

Tubulointerstitial macrophage accumulation is an important marker of prognosis that correlates closely with declining renal function in a range of human and experimental diseases, including diabetic nephropathy. These inflammatory cells are rich in the profibrotic growth factor TGF-beta such that their presence in areas of injury is frequently associated with tissue fibrosis. The migration of macrophages occurs in response to the site-specific production of chemokines, with osteopontin closely associated with their trafficking into the tubulointerstitium of the kidney. Although cell culture studies indicate that protein kinase C (PKC) mediates the expression of osteopontin, its role in the in vivo setting is unknown. Accordingly, Ren-2 control and diabetic rats that were treated with or without the specific PKC-beta isoform inhibitor ruboxistaurin (10 mg/kg per d) were examined. After 12 wk, diabetic rats showed increases in osteopontin expression in tubular epithelial cells of the cortex in association with macrophage infiltration, interstitial fibrosis, and activity of TGF-beta as indicated by the expression of its receptor activated protein phospho-Smad2 (P < 0.05 for all parameters). Ruboxistaurin treatment significantly attenuated these parameters (P < 0.05) in diabetic rats without affecting either BP or glycemic control. These findings suggest that osteopontin and macrophage accumulation may play a role in the tubulointerstitial injury in diabetic nephropathy and that inhibition of osteopontin expression may be one of the mechanisms by which inhibition of the beta-isoform of PKC confers a renoprotective effect.

The production of IL-1 receptor antagonist in IFN-beta-stimulated human monocytes depends on the activation of phosphatidylinositol 3-kinase but not of STAT1

IFN-beta induces the production of secreted IL-1R antagonist (sIL-1Ra) without triggering synthesis of the agonist IL-1beta in human monocytes. This might account for its anti-inflammatory properties. Canonically, IFN-beta signals through activation of JAK/STAT pathway, although PI3K and MAPK have also been involved. In this study, the role of PI3K, MEK1, and STAT1 in IFN-beta-induced sIL-1Ra production is investigated in freshly isolated human blood monocytes. PI3K, but not MEK1 activation is essential for sIL-1Ra production in monocytes treated with IFN-beta, as demonstrated by using the respective inhibitors of PI3K and MEK1, Ly294002 and PD98059. The use of cycloheximide and actinomycin D shows that sIL-1Ra was an immediate early gene induced by IFN-beta and that PI3K was controlling sIL-1Ra gene transcription. Although both inhibitors of PI3K and MEK1 diminished the Ser(727) phosphorylation of STAT1 induced by IFN-beta, only Ly294002 inhibited sIL-1Ra production. Furthermore, the inhibition of STAT1-Ser(727) phosphorylation by Ly294002 did not affect STAT1 translocation, suggesting that STAT1 was not involved in sIL-1Ra gene induction. This was confirmed in monocytes that were transfected with small interfering RNA specifically targeting STAT1. Indeed, monocytes in which effective STAT1 gene knockdown was achieved were fully responsive to IFN-beta in terms of sIL-1Ra production. Taken together, the present data demonstrate that the induction of sIL-1Ra transcription and production by IFN-beta in human monocytes involved PI3K, but not STAT1 activation.

Colocalization of dentin matrix protein 1 and dentin sialoprotein at late stages of rat molar development

Dentin matrix protein 1 (DMP1) and dentin sialophosphoprotein (DSPP) are acidic proteins found in the extracellular matrices of bones and teeth. Recent data from gene knockouts, along with those of gene mutations, indicate that these two phosphoproteins are critical for bone and tooth development and/or maintenance. However, the precise functions of the two proteins have not been elucidated. In order to gain insights into their functions in tooth formation, we performed systematic, comparative investigations on the immunolocalization of DMP1 and dentin sialoprotein (DSP, a cleaved fragment of DSPP), using the rat first molar at different developmental stages as a model. Immunohistochemistry (IHC) was performed with specific, monoclonal antibodies against the COOH-terminal fragments of DMP1 and against DSP. In 1-day- and 1-week-old rats, weak immunoreactions for DMP1 were observed in dentinal tubules while stronger reactions for DSP were seen in the tubules and predentin. In rats older than 2 weeks, immunoreactions for DMP1 were found in dentinal tubules, predentin and odontoblasts. In 5-week- and 8-week-old rats, strong immunoreactions for DMP1 were widely distributed in odontoblasts and predentin. The distribution pattern of DSP was strikingly similar to that of DMP1 after 2 weeks and the localization of each was distinctly different from that of bone sialoprotein (BSP). The unique colocalization of DMP1 and DSPP in tooth development suggests that the two proteins play complementary and/or synergistic roles in formation and maintenance of healthy teeth.

Aberrant expressions of annexin A10 short isoform, osteopontin and alpha-fetoprotein at chromosome 4q cooperatively contribute to progression and poor prognosis of hepatocellular carcinoma

Chromosome 4q exhibits high frequency of allelic loss in hepatocellular carcinoma (HCC). This study aimed to elucidate the interaction of the frequent aberrant mRNA expression of alpha-fetoprotein (AFP), osteopontin (OPN) and a novel short isoform of annexin A10 (ANXA10S) at 4q in the tumor progression among 294 patients who received surgical resection of unifocal primary HCC. AFP overexpression, OPN overexpression and ANXA10S down-regulation correlated with high-grade and high-stage tumors, early tumor recurrence (all P<0.0001), and lower 10-year survival (all P=0.000001). The AFP overexpression correlated with OPN overexpression (P=0.0026) and ANXA10S down-regulation (P=0.00001), while OPN overexpression correlated with ANXA10S down-regulation (P=0.00001). Pair-wise combinations revealed interactive effects between these genetic variants for tumor grade, tumor stage and early recurrence (all P<0.0001). HCCs with more genetic aberrations had more frequent high tumor grade, portal vein invasion (stage IIIB-IV) and early recurrence (all P<0.0001). The 10-year survival rate for HCCs with all three genetic alterations was the lowest (7%), followed by those with two (22%) or one event (29%), and the highest for those without these changes (43%), P=0.000001. The prognostic stratification using these molecular factors was similar to that of histopathological staging. These three genetic alterations also helped to identify different subgroups of patients of stage II HCC but with different prognosis (P=0.015). In conclusion, the aberrant expressions of AFP, OPN and ANXA10S cooperatively contribute to tumor progression and poor prognosis, and are useful for molecular staging of HCC and the subclassification of stage II HCC without vascular invasion.

Osteopontin expression in ulcerative colitis is distinctly different from that in Crohn's disease and diverticulitis

BACKGROUND

The aim of the present work was to assess osteopontin (OPN) expression in the colon tissues of ulcerative colitis (UC), Crohn's disease (CD), and diverticulitis (Div) patients.

METHODS

This study included three groups: the UC group, CD group, and Div group. Immunohistochemical staining was performed, using an immunoperoxidase method.

RESULTS

Regarding OPN expression in intestinal epithelial cells, no difference was noted among the three groups. However, in the submucosa of the UC group, the ratio of two types of large cells (oval and spindle-shaped) expressing OPN was 61.2 +/- 14.4% (mean +/- SD), which was significantly higher than that in the CD group (14.9 +/- 7.0%; P < 0.05) and that in the Div group (11.2 +/- 6.1%; P < 0.05). In addition, in the UC group, the ratio of these cells in the subserosa (50.1 +/- 15.0%; mean +/- SD) was significantly higher than that in the CD group (16.9 +/- 6.2%; P < 0.05) and that in the Div group (12.6 +/- 5.7%; P < 0.05). In a serial section study, the oval-shaped cells were stained for anti-CD 68, while the spindle-shaped cells were stained for anti-vimentin.

CONCLUSIONS

OPN in two types of large colon-infiltrating cells is possibly related to one of the pathogenic factors of UC.

Effect of TNF-alpha on human osteosarcoma cell line Saos2--TNF-alpha regulation of bone sialoprotein gene expression in Saos2 osteoblast-like cells

Tumor necrosis factor-alpha (TNF-alpha) is a major mediator of inflammatory response in many diseases. It inhibits bone formation and stimulates bone resorption. To determine the molecular mechanisms involved in the regulation of gene expression of osteoblast-like cells, we analyzed the effects of TNF-alpha on the human osteosarcoma cell line Saos2. We used RT-PCR to examine the effects of TNF-alpha on bone sialoprotein (BSP), core binding factor a1 (Cbfa1), osterix, alpha 1 (I) collagen, cyclooxygenase-2 (COX-2), interleukin-6 (IL-6), cathepsin B, cathepsin L and tissue inhibitors of metalloproteinase-1 (TIMP-1). TNF-alpha (10ng/ml) increased BSP, IL-6 and COX-2 mRNA levels after 3h, reaching maximal levels at 12 h. Cbfa1 mRNA levels increased after 3 h, but decreased by 24 h. Osterix, cathepsin B, cathepsin L and TIMP-1 mRNA levels did not change after stimulation with TNF-alpha. On the other hand, alpha 1 (I) collagen mRNA expression was suppressed by TNF-alpha at 24 h. Transient transfection analyses were performed using chimeric constructs of the rat BSP gene promoter linked to a luciferase reporter gene. TNF-alpha (10 ng/ml) had no effect on the promoter activities of BSP transfected into Saos2 cells. The results of gel mobility shift assays using radiolabeled double-stranded cAMP response element (CRE) and FGF2 response element (FRE) oligonucleotides in the proximal promoter of the rat BSP gene showed increased binding of nuclear proteins at 6 h. Gel mobility shift assays with radiolabelled COX-2-CRE and COX-2-NF kappa B oligonucleotides revealed an increase in the binding of nuclear proteins from TNF-alpha-stimulated Saos2 cells. These studies, therefore, showed that TNF-alpha indirectly increased BSP expression, and that it could be mediated through COX-2 and Cbfa1 expression in Saos2 osteoblast-like cells.

Inhibition of osteopontin expression and function in oral cancer cell lines by antisense oligonucleotides

We examined expression and function of osteopontin (OPN) in oral cancer cell lines using antisense oligonucleotide (AS). Quantitative real-time RT-PCR showed that expression in BSC-OF cells was significantly higher (10-fold) than that in KB cell. AS-study showed that foci of AS-treated BSC-OF cells possessed thin processes and radiated morphologically, although BSC-OF cells showed round foci. Cell growth in AS-group was lower (<80%) than the control. Invasion ability in AS-group became significantly lower (P<0.01). These results suggest that BSC-OF cell is useful for over-expression of OPN, and that OPN contributes to morphology, growth and invasion.

Osteopontin (Eta-1) is present in the rat basal ganglia

Osteopontin (OPN) is a secreted glycosylated phosphoprotein that is responsive to oxidative stress and inflammation and controls cytokine production, inducible nitric oxide synthase (iNOS) expression and apoptotic cell death. In this study, we demonstrate the presence of OPN in the rat basal ganglia. Using reverse transcriptase polymerase chain reaction (RT-PCR), OPN cDNA was found in the substantia nigra, and striatum. The presence of OPN mRNA was demonstrated in the same areas of the basal ganglia, using in situ hybridisation. OPN protein was found in the SN, using Western blotting and confirmed by immunohistochemistry. The protein was localised to neurones but not to microglia or astroglia. This is the first report of the presence of OPN in the basal ganglia where it may be involved in the maintenance of neuronal viability.

Elevation of plasma osteopontin concentration is correlated with disease activity in patients with systemic lupus erythematosus

BACKGROUND

Osteopontin (OPN) is an extracellular matrix cell adhesion phosphoprotein with immunological activities including stimulation of macrophage chemotaxis, T-helper type 1 lymphocyte response and B-cell antibody synthesis. Overexpression of OPN has been associated with the development of the autoimmune/lymphoproliferative syndrome.

METHODS

We measured the plasma concentration and ex vivo production of OPN, and the plasma proinflammatory IL-18 concentration in 54 SLE patients with or without renal impairment (RSLE group and SLE group, respectively) and 26 sex- and age-matched control (NC) subjects using an enzyme-linked immunoabsorbent assay.

RESULTS

Plasma OPN concentrations were significantly higher in RSLE and SLE patients than in the NC group (both P<0.001). Increase in OPN concentration correlated positively and significantly with SLEDAI score in all SLE patients (r = 0.308, P = 0.023). The ex vivo production of OPN upon mitogen activation of peripheral blood mononuclear cells was significantly higher in the RSLE and SLE groups than in the NC group (both P<0.001). In RSLE patients, plasma OPN concentration showed a significant positive correlation with proinflammatory cytokine IL-18 concentration (r = 0.404, P = 0.037).

CONCLUSION

The above results suggest that the production of OPN is associated with the inflammatory process and SLE development, and may serve as a potential disease marker of SLE.

Tumour-expressed CD43 (sialophorin) mediates tumourmesothelial cell adhesion

Mesothelial cell intercellular adhesion molecule-1 (ICAM-1) has recently been shown to play a role in tumour cell adherence to the peritoneum. However, solid tumours poorly express its most ubiquitous ligand, beta2 integrin. The aim of this study was to investigate the role of the beta2 integrin subunit and CD43, a known ligand for ICAM-1, in the development of peritoneal metastases. beta2 Integrin subunit and CD43 expression was assessed on a number of tumour cell lines. Adhesion of SW1222 and PSN-1 cells to human peritoneal mesothelial cells was investigated using a fluorometric assay incorporating an inhibitory antibody to beta2 integrin and CD43. beta2 Integrin expression was not inducible on these tumour cell lines, but Western blotting demonstrated CD43 expression in all the cancer cell lines examined and cell surface expression was confirmed by flow cytometry. The anti-CD43 antibody significantly reduced adhesion of PSN-1 and SW1222 cells to HPMC, however beta2 integrin inhibition did not reduce tumour cell adhesion. CD43 is expressed by a variety of carcinoma cell lines, and plays a role in tumour cell-peritoneal adhesion probably via interactions with its putative ligand ICAM-1.

Detection of prothrombin and osteopontin in a renal stone found in a hyperuricemic patient using 2D-PAGE and LC-MS analysis

The liquid chromatography-mass spectrometry (LC-MS) following on from the two-dimensional polyacrylamide gel electrophoresis (2D-PAGE) technique was applied for the analysis of proteins in a renal stone found in a hyperuricemic patient. This technique was sensitive enough to detect small quantities of proteins even in a renal stone.

Polymerized bonding agents and the differentiation in vitro of human pulp cells into odontoblast-like cells

OBJECTIVES

Odontoblasts are highly differentiated post-mitotic cells, which under pathological conditions such as carious lesions and dental injuries may degenerate and be replaced by other pulp cells. We have recently shown that this physiological event can be reproduced in an in vitro assay system, but is highly modified by the presence of unpolymerized resinous monomers. Our hypothesis was that the photopolymerization of the monomers in the bonding agents might abolish these negative effects. The purpose of this study was to evaluate the effects of polymerized dentin bonding agents, through dentin slices, on odontoblast differentiation in vitro.

METHODS

Pulp cells were obtained from human third molars. They were used to study the effects of four dentin bonding agents through 0.7 mm dentin slices which served as a barrier between the bonding agents and the culture medium. The media containing the bonding agents' extracts were added at non-toxic concentrations onto the cultured cells. Immunohistochemistry was performed to study the differentiation of pulp fibroblasts into odontoblasts under these conditions by evaluating the expression of several odontoblast specific genes.

RESULTS

Pulp fibroblasts cultivated under these conditions synthesized type I collagen, osteonectin, dentin sialoprotein and nestin at the same level as in control cultures. Moreover, pulp cells synthesized a mineralized nodular extracellular matrix. Expression of these proteins was higher in the cells contributing to the nodule formation. In addition, except nestin, all these proteins were expressed in the mineral nodules.

SIGNIFICANCE

This work shows the lack of effects of photopolymerized bonding agents, through dentin slices, on cytodifferentiation of secondary odontoblasts.

Characterization of epithelial cells derived from periodontal ligament by gene expression patterns of bone-related and enamel proteins

The cells of epithelial rests of Malassez (ERM) are thought to play a number of roles, such as protection against root resorption and cementoblast differentiation. However, little is known about characteristics of these cells. In the present study, we compared the expression patterns of the bone-related proteins osteopontin (OPN), osteonectin/secreted protein, acidic and rich in cysteine (SPARC), osteoprotegerin (OPG), bone morphogenetic proteins (BMP-2 and BMP-4) and the enamel matrix proteins amelogenin and tuftelin in epithelial cells derived from human periodontal ligament (ECHPL) with those of human gingival epithelial cells (HGEC) and oral mesenchymal cells (human gingival fibroblasts, human periodontal ligament fibroblasts and human pulp cells). The mRNA expression patterns were determined by the reverse-transcription polymerase chain reaction (RT-PCR). Cytokeratin 8 mRNA was expressed by oral epithelial cells but not oral mesenchymal cells. The OPN mRNA levels in ECHPL were by far the highest in the five cell types investigated. ECHPL and oral mesenchymal cells expressed OPG mRNA, whereas HGEC did not. BMP-2, SPARC and tuftelin mRNAs were detected in ECHPL and the other cells examined. The oral mesenchymal cells expressed BMP-4 mRNA much more strongly than did the oral epithelial cells. Amelogenin mRNA expression could not be detected in any of the cells. These findings suggest that cultured ERM cells are characterized by expression of the cytokeratin 8, OPG and OPN genes.

Hyaluronic acid induces osteopontin via the phosphatidylinositol 3-kinase/Akt pathway to enhance the motility of human glioma cells

Hyaluronic acid (HA) binds to cell-surface receptors such as CD44, and seems to be involved in cell adhesion, motility, and tumor progression in brain. To identify gene expression changes that are initiated by HA, we explored human cytokine arrays in U87MG glioma cells and identified osteopontin, a secreted matrix protein, as a transcriptional target of HA. Interestingly, expression of osteopontin was induced by HA in glioma cells lacking functional PTEN, a tumor suppressor gene (U87MG, U251MG, and U373MG), but not in wild-type (wt)-PTEN-harboring cells (LN18 and LN428). To confirm the role of PTEN, adenoviral (Ad)-wt-PTEN was used to induce ectopic expression of wt-PTEN in U87MG cells, leading to reduced HA-mediated osteopontin induction. Reciprocally, transfection with dominant-negative Akt repressed HA-induced osteopontin expression. Furthermore, HA promoted the motility of glioma cells, and down-regulation of induced osteopontin activity via a neutralizing anti-osteopontin antibody repressed HA-induced motility in vitro. Together, these results strongly suggest that induction of osteopontin expression by HA is dependent on activation of the phosphatidylinositol 3-kinase/Akt pathway. Furthermore, our data indicate that PTEN can effectively modulate the expression of osteopontin, and HA-induced osteopontin plays an important role in the motility response induced by HA in human glioma cells.

Pharmacological Inhibition and Genetic Deficiency of Plasminogen Activator Inhibitor-1 Attenuates Angiotensin II/Salt-Induced Aortic Remodeling

OBJECTIVE

To test the hypothesis that pharmacological plasminogen activator inhibitor (PAI)-1 inhibition protects against renin-angiotensin-aldosterone system-induced cardiovascular injury, the effect of a novel orally active small-molecule PAI-1 inhibitor, PAI-039, was examined in a mouse model of angiotensin (Ang) II-induced vascular remodeling and cardiac fibrosis.

METHODS AND RESULTS

Uninephrectomized male C57BL/6J mice were randomized to vehicle subcutaneus, Ang II (1 mug/h) subcutaneous, vehicle+PAI-039 (1 mg/g chow), or Ang II+PAI-039 during high-salt intake for 8 weeks. Ang II caused significant medial, adventitial, and aortic wall thickening compared with vehicle. PAI-039 attenuated Ang II-induced aortic remodeling without altering the pressor response to Ang II. Ang II increased heart/body weight ratio and cardiac fibrosis. PAI-039 did not attenuate the effect of Ang II on cardiac hypertrophy and increased fibrosis. The effect of PAI-039 on Ang II/salt-induced aortic remodeling and cardiac fibrosis was comparable to the effect of genetic PAI-1 deficiency. Ang II increased aortic mRNA expression of PAI-1, collagen I, collagen III, fibronectin, osteopontin, monocyte chemoattractant protein-1, and F4/80; PAI-039 significantly decreased the Ang II-induced increase in aortic osteopontin expression at 8 weeks.

CONCLUSIONS

This study demonstrates that pharmacological inhibition of PAI-1 protects against Ang II-induced aortic remodeling. Future studies are needed to determine whether the interactive effect of Ang II/salt and reduced PAI-1 activity on cardiac fibrosis is species-specific. In this study, the effect of pharmacological PAI-1 inhibition in a mouse model of Ang II-induced vascular remodeling and cardiac fibrosis was examined. PAI-1 inhibition significantly attenuated Ang II-induced aortic medial and wall thickening, but not cardiac hypertrophy, and enhanced Ang II/salt-induced cardiac fibrosis.

Simvastatin Promotes Cell Metabolism, Proliferation, and Osteoblastic Differentiation in Human Periodontal Ligament Cells

BACKGROUND

Simvastatin is one of the cholesterol lowering drugs. Recent studies demonstrated that it has a bone stimulatory effect. Periodontal ligament (PDL) cells are believed to play an important role in periodontal regeneration; that is, they may differentiate into specific cells which make cementum, bone, and attachment apparatus. It would be of interest whether simvastatin has a positive effect on PDL cells. Therefore, effects of simvastatin on cell proliferation and osteoblastic differentiation in PDL cells were analyzed.

METHODS

Human PDL cells were cultured in monolayer with simvastatin for 24 and 72 hours and cell metabolism and proliferation were determined. To analyze osteoblastic differentiation, human PDL cells were cultured in organoid culture for 7, 14, and 21 days and alkaline phosphatase (ALP) activity, osteopontin (OPN), bone morphogenetic protein (BMP) -2, osteocalcin (OCN), and calcium contents were measured. They were co-treated by simvastatin and mevalonate.

RESULTS

Simvastatin enhanced cell proliferation and metabolism dose-dependently after 24 hours. Simvastatin also stimulated ALP activity of human PDL cells dose-dependently, and maximum effect was obtained at the concentration of 10(8) M. In time dependent analysis, 10(8) M simvastatin stimulated ALP activity and osteopontin content after 7 days and calcium contents after 21 days. BMP-2 and OCN contents were not detected. Moreover this statin-enhanced ALP activity was abolished by mevalonate.

CONCLUSION

These results suggest that at low concentration, simvastatin exhibits positive effect on proliferation and osteoblastic differentiation of human PDL cells, and these effects may be caused by the inhibition of the mevalonate pathway.

Upregulation of osteopontin by osteocytes deprived of mechanical loading or oxygen

The pathway(s) by which disuse is transduced into locally mediated osteoclastic resorption remain unknown. We found that both acute disuse (in vivo) and direct hypoxia (in vitro) induced rapid upregulation of OPN expression by osteocytes. Within the context of OPN's role in osteoclast migration and attachment, hypoxia-induced osteocyte OPN expression may serve to mediate disuse-induced bone resorption.

INTRODUCTION

We have recently reported that disuse induces osteocyte hypoxia. Because hypoxia upregulates osteopontin (OPN) in nonconnective tissue cells, we hypothesized that both disuse and hypoxia would rapidly elevate expression of OPN by osteocytes.

MATERIALS AND METHODS

The response of osteocytes to 24 h of disuse was explored by isolating the left ulna diaphysis of adult male turkeys from loading (n = 5). Cortical osteocytes staining positive for OPN were determined using immunohistochemistry and confocal microscopy. In vitro experiments were performed to determine if OPN expression was altered in MLO-Y4 osteocytes by direct hypoxia (3, 6, 24, and 48 h) or hypoxia (3 and 24 h) followed by 24 h of reoxygenation. A final in vitro experiment explored the potential of protein kinase C (PKC) to regulate hypoxia-induced osteocyte OPN mRNA alterations.

RESULTS

We found that 24 h of disuse significantly elevated osteocyte OPN expression in vivo (145% versus intact bones; p = 0.02). We confirmed this finding in vitro, by observing rapid and significant upregulation of OPN protein expression after 24 and 48 h of hypoxia. Whereas 24 h of reoxygenation after 3 h of hypoxia restored normal osteocyte OPN expression levels, 24 h of reoxygenation after 24 h of hypoxia did not mitigate elevated osteocyte OPN expression. Finally, preliminary inhibitor studies suggested that PKC serves as a potent upstream regulator of hypoxia-induced osteocyte OPN expression.

CONCLUSIONS

Given the documented roles of OPN as a mediator of environmental stress (e.g., hypoxia), an osteoclast chemotaxant, and a modulator of osteoclastic attachment to bone, we speculate that hypoxia-induced osteocyte OPN expression may serve to mediate disuse-induced osteoclastic resorption. Furthermore, it seems that a brief window of time exists in which reoxygenation (as might be achieved by reloading bone) can serve to inhibit this pathway.

Alphavbeta integrins play an essential role in BMP-2 induction of osteoblast differentiation

Both integrins and BMP-2 exert similar effects on osteoblasts. We examined the relationship between the alphav-containing integrins (alphavbeta) and BMP-2 in osteoblast function. BMP-2 stimulates alphavbeta expression. BMP-2 receptors co-localize/overlap with alphavbeta integrins, and the intact function of alphavbeta is essential in BMP-2 activity.

INTRODUCTION

Bone morphogenetic protein (BMP)-2 not only induces osteoblast differentiation and bone matrix mineralization, but also stimulates osteoblast migration on and adhesion to bone matrix proteins. The alphavbeta- and beta1- (alphabeta1) containing integrins mediate osteoblast interaction with many bone matrix proteins and play important roles in osteoblast adhesion, migration, and differentiation. Because alphavbeta integrins and BMP-2 share common effects on osteoblasts, we analyzed their relationship in osteoblast function.

MATERIALS AND METHODS

The effects of BMP-2 on integrin expression were determined by surface labeling/immunoprecipitation and cell adhesion to matrix proteins. Confocal analysis of the immunostained cells and co-immunoprecipitation of cell extracts were used to study the spatial relationship between integrins and BMP-2 receptors. A function-blocking anti-alphavbeta integrin antibody (L230) was employed to investigate the roles of alphavbeta integrins in BMP-2 function.

RESULTS

Human osteoblasts (HOBs) express alphabeta1, alphavbeta3, alphavbeta5, alphavbeta6, and alphavbeta8 integrins at focal adhesion sites. BMP-2 increases the levels of these integrins on osteoblast surface and enhances HOB adhesion to osteopontin and vitronectin. Immunoprecipitation and immunostaining analyses show that BMP-2 receptors co-localize or overlap with alphavbeta and alphabeta1 integrins. Incubation of HOBs with L230 abolishes the antiproliferative effect of BMP-2 and reduces the capacity of BMP-2 to stimulate alkaline phosphatase activity and the expression of osteocalcin, osteopontin, and bone sialoprotein. Furthermore, L230 prevents BMP-2 induction of matrix mineralization. Although BMP-2 retains its receptor-binding capability in the presence of L230, BMP-2 stimulation of Smad signaling is abolished by L230.

CONCLUSION

BMP-2 upregulates the expression of alphavbeta integrins, and these integrins, in turn, play a critical role in BMP-2 function in osteoblasts.

Early membrane events in polymorphonuclear cell (PMN) apoptosis: membrane blebbing and vesicle release, CD43 and CD16 down-regulation and phosphatidylserine externalization

CD43 down-regulation during the apoptosis of PMN (polymorphonuclear cells) is not caused by proteolysis or internalization. Could it be released with bleb-derived membrane vesicles? Membrane blebbing was followed by microscopy on PMN 'synchronized' by an overnight incubation at 15 degrees C before their spontaneous apoptosis at 37 degrees C. Released vesicles were quantified by flow cytometry. Membrane blebbing, release of bleb-derived membrane vesicles, decrease of CD43/CD16 expression and phosphatidylserine externalization occurred simultaneously. However, caspase and PKC inhibition prevented annexin binding but not blebbing, vesicle release or CD43 expression decrease; myosin light chain kinase inhibition prevented cell blebbing and vesicle release but had no effect on CD43/CD16 down-regulation or annexin V binding. By electron microscopy, CD43 appeared poorly expressed on membrane blebs and concentrated at bleb 'necks'. In conclusion, CD43 down-regulation is not caused by cell blebbing. Cell blebbing, phospholipid 'flip-flop' and CD43/CD16 down-regulation are independent membrane events.

Modulation of chondrocytic properties of fat-derived mesenchymal cells in co-cultures with nucleus pulposus

Human subcutaneous fat-derived mesenchymal cells recently have been shown to have the potential to differentiate in vitro into a variety of cell types, including adipocytes, osteoblasts, chondrocytes, and myoblasts. This effect suggests that fat tissue may serve as an abundant and easily acquired source of multipotent cells for tissue engineering. The multipotential characteristics of fat-derived mesenchymal cells from the inguinial fat pad of rabbit have not been clearly defined. In this study we have isolated a population of mesenchymal cells from inguinal fat from adult New Zealand white rabbits. The cells that were maintained under various differentiation conditions were shown to differentiate in vitro into adipocytes, osteoblasts, or chondrocytes; this differentiation was demonstrated using gene expression for tissue-specific proteins. We also co-cultured the cells with intervertebral disk tissue from the nucleus pulpous or from the annulus fibrosus. The fat-derived cells co-cultured with nucleus pulposus showed an increase in expression of type II collagen and aggrecan genes, compared with cells in alginate alone and cells co-cultured with annulus fibrosus. The data suggest that the fat-derived mesenchymal cells responded to soluble mediators from the disk. Future studies on intervertebral disk reconstruction could be based on our findings with fat-derived multipotential cells from the inguinal region of the rabbit that were co-cultured with disk tissue and may prove useful in tissue engineering strategies.

Osteopontin and related SIBLING glycoprotein genes are expressed by Sertoli cells during mouse testis development

Matrix proteins play important roles in tissue morphogenesis. We have studied the expression of genes encoding the related SIBLING glycoproteins osteopontin (OPN), bone sialoprotein (BSP), and dentin matrix protein (DMP) during the development of male and female gonads during mouse embryogenesis. Opn mRNA was expressed specifically by Sertoli cells of the developing testis cords, in the mesonephric tubules of both sexes, and, transiently, in the Müllerian ducts of both sexes, as determined by whole-mount and section in situ hybridization. OPN protein was detected in the cytoplasm of Sertoli cells and luminal cells of the mesonephric tubules, with small amounts associated with the plasma membrane of germ cells. We found no defects in developing testes of Opn-/- mice using a range of cell type-specific markers, suggesting that other SIBLING proteins may function in testis development. Dmp and Bsp mRNA was also expressed in the developing testis cords, supporting the view that all three SIBLING proteins may contribute to testis differentiation.

Molecular and cell biological properties of mouse osteogenic mesenchymal progenitor cells, Kusa

A cell line of murine osteogenic progenitor cells, Kusa, was established from femoral bone marrow stromal cells with other types of mesenchymal progenitor cells. We characterized two sublines of Kusa (Kusa-A1 and Kusa-O) from several aspects, including the use of an expression profiling system, a cDNA microarray. The original Kusa subline (Kusa-A1) had high alkaline phosphatase activity and high accumulation of calcium deposits in a condition inducing mineralization, with ascorbic acid and beta-glycerophosphate. Kusa-O, a low osteogenic subline of Kusa, had high alkaline phosphatase activity but slow accumulation of calcium deposits even in the inducing condition. These two Kusa sublines differed in the expression of the osteogenic marker genes, osteocalcin and osteopontin, during mineralization. A type of cDNA microarray revealed marked downregulation of gene expression in the inducing condition in both Kusa-A1 and Kusa-O. Another type of high-throughput microarray was performed to examine the difference in gene expression patterns between Kusa-A1 and Kusa-O. By this analysis, periostin, which would be involved in a stage of osteogenesis, was low in Kusa-A1. On the contrary, Myocyte enhancer factor 2C (MEF2C), a myogenic transcriptional factor, was high in Kusa-A1, although no expression of any other myogenic genes was shown.

Endogenous brain protection: models, gene expression, and mechanisms

Almost all injurious stimuli, when applied below the threshold of producing injury, activate endogenous protective mechanisms that significantly decrease the degree of injury after subsequent injurious stimuli. For example, a short duration of ischemia (i.e., ischemic preconditioning [PC]) can provide significant brain protection to subsequent long-duration ischemia (i.e., ischemic tolerance [IT]). PC/IT has recently been shown in human brain, suggesting that learning more about these endogenous neuroprotective mechanisms could help identify new approaches to treat patients with stroke and other central nervous system disorders/injury. This chapter provides a brief overview of PC/IT research, illustrates the types of data that can be generated from in vivo and in vitro models to help us understand gene and protein expression related to induced neuroprotective mechanisms, and emphasizes the importance of future research on this phenomenon to help discover new mechanisms and targets for the medical treatment of brain and other end-organ injuries.

BMP-9-transduced prefabricated muscular flaps for the treatment of bony defects

Autologous bone grafting techniques involve the use of tissues that need to be extracted from healthy sites. This can lead to significant donor site morbidity that causes a one-site defect to become a two-site defect. Bone grafts can be especially difficult to manipulate, because bone is a relatively nonmoldable tissue. Furthermore, the inability of a bone graft to contain a transplantable vascular supply also limits the possible size that such a bone graft can be. Because of these limitations, a graft that was moldable with a vascular supply would possess significant advantages in reconstructive applications. In this research, gene therapy techniques were used to create such a graft. An adenovirus expressing BMP-9 was injected into the latissimus dorsi of a nude animal to cause bony differentiation of that muscle. Differentiation of the muscle to cartilage in bone was measured by reverse transcription polymerase chain reaction and immunohistochemistry to determine the optimal time of flap elevation. After injection of the BMP-9 virus, the animals were biopsied weekly over a 3-week period. Both bone and cartilage markers were discovered in these tissues over the study period. Optimal flap elevation time was established to be 2 weeks after injection of the virus.

Col1a1 promoter-targeted expression of p20 CCAAT enhancer-binding protein beta (C/EBPbeta), a truncated C/EBPbeta isoform, causes osteopenia in transgenic mice

CCAAT enhancer-binding protein (C/EBP) transcription factors regulate adipocyte differentiation, and recent evidence suggests that osteoblasts and adipocytes share a common pluripotent progenitor in bone marrow. However, little is known about the role of C/EBP transcription factors in the control of osteoblast differentiation or function. In this study, the function of C/EBP transcription factors was disrupted in osteoblast lineage cells by overexpressing a naturally occurring dominant negative C/EBP isoform. Expression of FLp20C/EBPbeta was driven by a 3.6-kb Col1a1 promoter/first intron construct, and four transgenic (TG) mouse lines were established. Northern blotting and reverse transcription-PCR indicated that the transgene was targeted to bone, with lower levels of expression in lung, skin, and adipose tissue. TG mice from two lines showed reduced body weight compared with wild type littermates. All TG lines showed evidence of osteopenia, ranging from mild to severe, as evidenced by reduced trabecular bone volume. Severely affected lines also showed reduced cortical bone width. Dynamic histomorphometry demonstrated an associated decrease in mineral apposition and bone formation rates. Long bones and calvariae of TG mice showed reduced COL1A1 and osteocalcin mRNA levels and increased bone sialoprotein mRNA, consistent with an inhibition of terminal osteoblast differentiation. Ex vivo analysis of primary osteoblast differentiation showed similar effects on marker expression and reduced expression of the mature osteoblast marker Col2.3-green fluorescent protein, demonstrating a cell-autonomous effect of the transgene. These data suggested that C/EBP transcription factors may be important determinants of osteoblast function and bone mass.

FGF-2 potently induces both proliferation and DSP expression in collagen type I gel cultures of adult incisor immature pulp cells

We investigated the effects of both cytokines and extracellular matrices on the proliferation and differentiation of immature adult rat incisor dental pulp cells. These immature cells, which have a high-proliferative potency in vitro and do not express mRNAs for dentin non-collagenous proteins such as dentin sialoprotein (DSP), bone sialoprotein (BSP), and osteocalcin, exist in the root regions of adult rat incisors. Fibroblast growth factor-2 (FGF-2) stimulated the proliferation of these immature cells and the subsequent production of mineralized calcium was induced by beta-glycerophosphate treatment. Additionally, FGF-2 dramatically induced the expression of DSP and BSP mRNAs, but only in collagen type I gel cultures, whereas neither plate-coated collagen type I nor fibronectin, laminin or collagen type IV cultures could produce this effect and generate sufficient physiological levels of these transcripts. Although bone morphogenetic protein-4 could not induce the proliferation of immature dental pulp cells nor upregulate DSP mRNA expression, it had a synergistic effect upon DSP transcript levels in conjunction with FGF-2. These results suggest that both the presence of FGF-2 and the three-dimensional formation of immature dental pulp cells in collagen type I gel cultures are essential for both DSP expression and odontoblast differentiation. These observations provide valuable information concerning the study of the commitment and differentiation of odontoblast lineages, and also provide a basis for the rational design of cytokine and extracellular matrix based compounds for regenerative therapies in new dental treatments.

UTP induces osteopontin expression through a coordinate action of NFkappaB, activator protein-1, and upstream stimulatory factor in arterial smooth muscle cells

Osteopontin (OPN) is an important chemokinetic agent for several cell types. Our earlier studies have shown that its expression is essential for uridine triphosphate (UTP)-mediated migration of vascular smooth muscle cells. We demonstrated previously that the activation of an AP-1 binding site located 76 bp upstream of the transcription start in the rat OPN promoter is involved in the induction of OPN expression. In this work, using a luciferase promoter deletion assay, we identified a new region of the rat OPN promoter (-1837 to -1757) that is responsive to UTP. This region contains an NFkappaB site located at -1800 and an Ebox located at -1768. Supershift electrophoretic mobility shift assay and chromatin immunoprecipitation assays identified NFkappaB and USF-1/USF-2 as the DNA binding proteins induced by UTP, respectively, for these two sites. Using dominant negative mutants of IkappaB kinase and USF transcription factors, we confirmed that NFkappaB and USF-1/USF-2 are involved in the UTP-mediated expression of OPN. Using a pharmacological approach, we demonstrated that USF proteins are regulated by the extracellular signal-regulated kinase (ERK)1/2 pathway, just as the earlier discovered AP-1 complex, whereas NFkappaB is up-regulated through PKCdelta signals. Finally, our work suggests that the UTP-stimulated OPN expression involves a coordinate regulation of PKCdelta-NFkappaB, ERK1/2-USF, and ERK1/2/NAD(P)H oxidase AP-1 signaling pathways.

Maximum Immunobioactivity of Murine Small Intestinal Intraepithelial Lymphocytes Resides in a Subpopulation of CD43+ T Cells

CD43 has been linked to many function-associated T cell activities. Using mAbs that recognize two different CD43 determinants, we show that, although mouse small intestinal intraepithelial lymphocytes (IELs) expressed the CD43 core molecule reactive with mAb R2/60, only about one-half of the total IELs-including some but not all of the TCRalphabeta and TCRgammadelta cells-expressed the CD43 S7(-) reactive determinant. CD43 S7(+) IELs secreted more IL-2, IL-4, IL-10, IL-17, and IFN-gamma following anti-CD3 stimulation, and were >4-fold more cytotoxic in fresh isolates and >16-fold more cytotoxic after anti-CD3 stimulation, than S7(-) IELs. S7(+) but not S7(-) IELs from the ileum of IL-10(-/-) mice spontaneously produced IFN-gamma. In vivo BrdU uptake by IELs in non-Ag-primed mice was greatest in the S7(+) population, indicating that significantly more S7(+) IELs than S7(-) IELs undergo cell expansion under normal homeostatic conditions. DNA microarray analyses showed that S7(+) IELs expressed higher levels of genes associated with activated T cells, whereas S7(-) IELs expressed genes used in the regulation of NK cells. These findings define two functionally distinct populations of IELs based on CD43 expression independent of TCR class, and they identify a subset of IELs that may serve as a target to better control intestinal inflammation.

Expression and characterization of recombinant osteopontin peptides representing matrix metalloproteinase proteolytic fragments

Osteopontin (OPN) is a secreted, arginine-glycine-aspartic acid (RGD)-containing phosphoprotein proteolytically modified by members of the matrix metalloproteinase (MMP) family. We previously defined the MMP-3 and MMP-7 cleavage sites in OPN and found increased adhesive and migratory activity of a pool of MMP-cleaved fragments compared to full-length OPN. In the present study, we performed mutational analysis of recombinant full-length OPN and generated recombinant OPN fragments corresponding to the MMP-cleaved fragments, which have apparent molecular weights of 40, 32, and 25 kD by SDS-PAGE. Single residue mutations in 167L and 211L do not abrogate MMP cleavage although processing of the putative C-terminal fragment appears to be affected by a 167L to 167A mutation. The N-terminal 40-kD fragment was a stronger adhesive substrate compared to full-length OPN despite the observation that full-length OPN displayed greater binding in soluble phase to endothelial cell surfaces. While the 32-kD fragment showed significant binding to endothelial cell surfaces, the C-terminal 25-kD fragment did not interact with cell surface. Our data indicate that the increased adhesive activity of MMP-cleaved OPN was accountable by the N-terminal 40-kD fragment. We further analyzed receptor binding, using competition with peptides representing the alpha4beta1 and alpha9beta1 binding sites in the 40-kD N-terminal fragment. Using Jurkat cells, we found that a peptide corresponding to 131ELVTDFPTDLPATE144 had no effect on cell adhesion, whereas the peptide SVVYGLR competitively inhibited cell adhesion. These results suggest that a shorter motif that is found in MMP-cleaved OPN, 162SVVYG166, is sufficient to mediate cell adhesion of Jurkat cells to receptors, including the beta1 integrins, which have been previously characterized to bind the SVVYGLR sequence.

Upregulation of osteopontin in Schwann cells of the sciatic nerves of Lewis rats with experimental autoimmune neuritis

We examined the expression of osteopontin (OPN) in the sciatic nerves of rats with experimental autoimmune neuritis (EAN), using immunohistochemistry and immunoblotting, to study its involvement in the pathogenesis of autoimmune peripheral nervous system diseases. Constitutive OPN expression was detected in some Schwann cells; expression was increased after immunization with adjuvant alone. At day 14 after induction of EAN, many Schwann cells had a granular pattern of immunoreactivity, whereas very few inflammatory cells were OPN-positive. Even after recovery from hindlimb paralysis, at 24 days post-immunization, OPN expression remained elevated in the Schwann cells. The results suggest that OPN expression in Schwann cells is easily induced by immunostimulation, and further enhanced by the inflammatory reaction in EAN. Continued elevation of OPN after recovery may represent a functional recovery after a transient inflammatory insult.

Leucine-rich amelogenin peptide: a candidate signaling molecule during cementogenesis

BACKGROUND

Cementum is a critical mineralized tissue; however, control of its formation remains undefined. One hypothesis is that enamel matrix proteins/peptides secreted by ameloblasts and/or epithelial rest cells contribute to the control of cementum formation via epithelial-mesenchymal interactions. Here, we focused on determining whether or not leucine-rich amelogenin peptide (LRAP), translated from an alternatively spliced amelogenin RNA, altered cementoblast behavior.

METHODS

Immortalized murine cementoblasts (OCCM-30) were exposed to LRAP and evaluated for: 1) proliferative activity; 2) gene expression using Northern blot for Cbfal (core binding factor alpha-1); OCN (osteocalcin), OPN (osteopontin), and real-time reverse transcription-polymerase chain reaction (RT-PCR) for OPG (osteoprotegerin); and RANKL (receptor activator of NF-kappaB ligand); 3) signaling pathway using inhibitors of PKA (THFA), PKC (GF109203X), and MAPK (UO126); and 4) mineralization evaluated by von Kossa and Alizarin-red.

RESULTS

LRAP had no effect on cell proliferation up to 6 days, with a decrease in cell growth observed at the highest dose by 9 days versus untreated cells. LRAP down regulated OCN and up regulated OPN in a dose- and time-response fashion, and inhibited the capacity of mineral nodule formation. Transcripts for OPG were increased in LRAP-treated cells compared to control, but RANKL mRNA levels were not affected. Core binding factor alpha (Cbfa) mRNA, expressed constitutively, was not affected by LRAP. Signaling pathway assays suggested involvement of the MAPK pathway, since the addition of the MAPK inhibitor suppressed OPN expression in LRAP-treated cells.

CONCLUSION

Leucine-rich amelogenin peptide appears to have a direct effect on cementoblast activity that may prove significant during development as well as in regeneration of periodontal tissues.