A deep insight into the male and female sialotranscriptome of adult Culex tarsalis mosquitoes

Previously, a Sanger-based sialotranscriptome analysis of adult female Culex tarsalis was published based on ∼2000 ESTs. During the elapsed 7.5 years, pyrosequencing has been discontinued and Illumina sequences have increased considerable in size and decreased in price. We here report an Illumina-based sialotranscriptome that allowed finding the missing apyrase from the salivary transcriptome of C. tarsalis, to determine several full-length members of the 34-62 kDa family, when a single EST has been found previously, in addition to identifying many salivary families with lower expression levels that were not detected previously. The use of multiple libraries including salivary glands and carcasses from male and female organisms allowed for an unprecedented insight into the tissue specificity of transcripts, and in this particular case permitting identification of transcripts putatively associated with blood feeding, when exclusive of female salivary glands, or associated with sugar feeding, when transcripts are found upregulated in both male and female glands.

Accelerated dentinogenesis by inhibiting the mitochondrial fission factor, dynamin related protein 1

Undifferentiated odontogenic epithelium and dental papilla cells differentiate into ameloblasts and odontoblasts, respectively, both of which are essential for tooth development. These differentiation processes involve dramatic functional and morphological changes of the cells. For these changes to occur, activation of mitochondrial functions, including ATP production, is extremely important. In addition, these changes are closely related to mitochondrial fission and fusion, known as mitochondrial dynamics. However, few studies have focused on the role of mitochondrial dynamics in tooth development. The purpose of this study was to clarify this role. We used mouse tooth germ organ cultures and a mouse dental papilla cell line with the ability to differentiate into odontoblasts, in combination with knockdown of the mitochondrial fission factor, dynamin related protein (DRP)1. In organ cultures of the mouse first molar, tooth germ developed to the early bell stage. The amount of dentin formed under DRP1 inhibition was significantly larger than that of the control. In experiments using a mouse dental papilla cell line, differentiation into odontoblasts was enhanced by inhibiting DRP1. This was associated with increased mitochondrial elongation and ATP production compared to the control. These results suggest that DRP1 inhibition accelerates dentin formation through mitochondrial elongation and activation. This raises the possibility that DRP1 might be a therapeutic target for developmental disorders of teeth.

The epigenetic regulators CBP and p300 facilitate leukemogenesis and represent therapeutic targets in acute myeloid leukemia

Growing evidence links abnormal epigenetic control to the development of hematological malignancies. Accordingly, inhibition of epigenetic regulators is emerging as a promising therapeutic strategy. The acetylation status of lysine residues in histone tails is one of a number of epigenetic post-translational modifications that alter DNA-templated processes, such as transcription, to facilitate malignant transformation. Although histone deacetylases are already being clinically targeted, the role of histone lysine acetyltransferases (KAT) in malignancy is less well characterized. We chose to study this question in the context of acute myeloid leukemia (AML), where, using in vitro and in vivo genetic ablation and knockdown experiments in murine models, we demonstrate a role for the epigenetic regulators CBP and p300 in the induction and maintenance of AML. Furthermore, using selective small molecule inhibitors of their lysine acetyltransferase activity, we validate CBP/p300 as therapeutic targets in vitro across a wide range of human AML subtypes. We proceed to show that growth retardation occurs through the induction of transcriptional changes that induce apoptosis and cell-cycle arrest in leukemia cells and finally demonstrate the efficacy of the KAT inhibitors in decreasing clonogenic growth of primary AML patient samples. Taken together, these data suggest that CBP/p300 are promising therapeutic targets across multiple subtypes in AML.

The effects of insulin and liraglutide on osteoprotegerin and vascular calcification in vitro and in patients with type 2 diabetes

OBJECTIVE

Vascular calcification (VC) is inhibited by the glycoprotein osteoprotegerin (OPG). It is unclear whether treatments for type 2 diabetes are capable of promoting or inhibiting VC. The present study examined the effects of insulin and liraglutide on i) the production of OPG and ii) the emergence of VC, both in vitro in human aortic smooth muscle cells (HASMCs) and in vivo in type 2 diabetes.

DESIGN/METHODS

HASMCs were exposed to insulin glargine or liraglutide, after which OPG production, alkaline phosphatase (ALP) activity and levels of Runx2, ALP and bone sialoprotein (BSP) mRNA were measured. A prospective, nonrandomised human subject study was also conducted, in which OPG levels and coronary artery calcification (CAC) were measured in a type 2 diabetes population before and 16 months after the commencement of either insulin or liraglutide treatment and in a control group that took oral hypoglycemics only.

RESULTS

Exposure to insulin glargine, but not liraglutide, was associated with significantly decreased OPG production (11 913±1409 pg/10(4) cells vs 282±13 pg/10(4) cells, control vs 10 nmol/l insulin, P<0.0001), increased ALP activity (0.82±0.06 IU/10(4) cells vs 2.40±0.16 IU/10(4) cells, control vs 10 nmol/l insulin, P<0.0001) and increased osteogenic gene expression by HASMCs. In the clinical study (n=101), insulin treatment was associated with a significant reduction in OPG levels and, despite not achieving full statistical significance, a trend towards increased CAC in patients.

CONCLUSION

Exogenous insulin down-regulated OPG in vitro and in vivo and promoted VC in vitro. Although neither insulin nor liraglutide significantly affected CAC in the present pilot study, these data support the establishment of randomised trials to investigate medications and VC in diabetes.

Chitosan/poly(DL,lactide-co-glycolide) scaffolds for tissue engineering

Chitosan/poly(DL-lactide-co-glycolide) (Ch/DL PLG) composite scaffolds were fabricated by freeze-drying lyophilization, and were evaluated and compared for use as a bone regeneration scaffold through measurements of the compression mechanical properties of the porous scaffolds. Also, In vitro cell culture of Sprague-Dawley rat's osteoblasts were used to evaluate the phenotype expression of cells in the scaffolds, characterizing the cellular adhesion, proliferation and alkaline phosphatase activity. The gene expression of osteocalcin, sialoprotein, alkaline phosphatase, Type I collagen and TGFβ1 were confirmed in the samples; moreover, it was confirmed, the mineralization by IR spectra and EDS analysis. Our results thus show that Ch/DL PLG scaffolds are suitable for biological applications.

Hypophosphatasia-associated deficiencies in mineralization and gene expression in cultured dental pulp cells obtained from human teeth

INTRODUCTION

Mutations in the gene ALPL in hypophosphatasia (HPP) reduce the function of tissue nonspecific alkaline phosphatase, and the resulting increase in pyrophosphate (PP(i)) contributes to bone and tooth mineralization defects by inhibiting physiologic calcium-phosphate (P(i)) precipitation. Although periodontal phenotypes are well documented, pulp/dentin abnormalities have been suggested in the clinical literature although reports are variable and underlying mechanisms remains unclear. In vitro analyses were used to identify mechanisms involved in HPP-associated pulp/dentin phenotypes.

METHODS

Primary pulp cells cultured from HPP subjects were established to assay alkaline phosphatase (ALP) activity, mineralization, and gene expression compared with cells from healthy controls. Exogenous P(i) was provided to the correct P(i)/PP(i) ratio in cell culture.

RESULTS

HPP cells exhibited significantly reduced ALP activity (by 50%) and mineral nodule formation (by 60%) compared with the controls. The expression of PP(i) regulatory genes was altered in HPP pulp cells, including reduction in the progressive ankylosis gene (ANKH) and increased ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). Odontoblast marker gene expression was disrupted in HPP cells, including reduced osteopontin (OPN), dentin matrix protein 1 (DMP1), dentin sialophosphoprotein (DSPP), and matrix extracellular phosphoprotein (MEPE). The addition of P(i) provided a corrective measure for mineralization and partially rescued the expression of some genes although cells retained altered messenger RNA levels for PP(i)-associated genes.

CONCLUSIONS

These studies suggest that under HPP conditions pulp cells have the compromised ability to mineralize and feature a disrupted odontoblast profile, providing a first step toward understanding the molecular mechanisms for dentin phenotypes observed in HPP.

Novel flow cytometric method for the detection of podocalyxin-positive elements in urine of patients with glomerulonephritides - first promising results

Glomerulonephritides together create a heterogenic group of supposedly immunologically mediated diseases of glomeruli. They still belong among the most frequent causes of chronic renal failure. Detection of podocytes in urine might serve as an important marker of glomerulonephritides activity. The aim of this study was to develop a novel flow cytometric method for the detection of podocyte fragments and podocytes in urine and assess its possible use in clinical practice. We placed emphasis on the improvement of pre-analytic phase. To suppress the autofluorescence of the background, blocking solutions and magnetic separation were used. An additional surface marker CD10 (nephrilysin) was used together with routinely used podocalyxin (PCX) in order to achieve better identification of podocytes. Based on the surface marker expression, three different element types were identified in the urine samples: PCX+/CD10+ elements (EL) (supposedly podocytes), PCX-/CD10+ EL (supposedly parietal epithelial cells) and PCX+ EL. We examined a total of 36 patients who underwent renal biopsy (non-glomerular nephropathy, MGN, FSGS, IgAN, AAV and MPGN) and 27 healthy controls. Negative results were found in non-glomerular nephropathy and in MGN. In patients with FSGS and IgAN, the levels of urine elements were slightly increased. The highest levels of all elements were found in AAV and MPGN. Our first results suggest that flow cytometric detection may distinguish between glomerular and nonglomerular diseases and that the levels of urine elements might correlate with the degree of glomerular destruction.

[Effect of Notch ligand Delta1-RNA interference by lentivirus on proliferation and differentiation of human dental pulp stem cells]

OBJECTIVE

To investigate the effects of specific RNA interference (RNAi) to Notch ligand Delta1 on proliferation and differentiation of human dental pulp stem cells (DPSC).

METHODS

DPSC were infected by lentivirus vectors carrying Delta1-RNAi. DPSC were divided into three groups, DPSC/Delta1-RNAi group, DPSC/wt group and DPSC/vector group as control. Cell counting kit-8 (CCK-8) assay and flow cytometry were used to evaluate the proliferation of DPSC. Expression of proliferating cell nuclear antigen (PCNA) was examined with immunohistochemical staining. All groups were cultured in an odonto-inductive medium and were observed under microscope. The number of mineralization nodules was counted after Alizarin red staining. Alkaline phosphatase (ALP) activity and the expression of dentin sialophosphoprotein (DSPP) were detected by ALP activity assay and Western blotting.

RESULTS

Compared with DPSC/wt or DPSC/vector separately, proliferating rate and S-cycle of DPSC/Delta1-RNAi was significantly lower. The S phase and proliferation index (PI) decreased markedly from 22.32 ± 2.35 and 33.68 ± 4.19 (DPSC/Delta1-RNAi) to 5.44 ± 0.91 and 16.00 ± 6.07 (DPSC/wt). The PCNA staining of DPSC/Delta1-RNAi was evidently weaker. DPSC/Delta1-RNAi group had more calcified cell nodules than the other two control groups, and ALP activity and DSPP expression of DPSC/Delta1-RNAi group increased markedly.

CONCLUSIONS

Delta1-RNAi induced by the lentivirus vectors may inhibit DPSC proliferation and differentiation. Notch-Delta signal pathway plays an important role in self-renewal and differentiation.

An insight into the sialotranscriptome and proteome of the coarse bontlegged tick, Hyalomma marginatum rufipes

Ticks are mites specialized in acquiring blood from vertebrates as their sole source of food and are important disease vectors to humans and animals. Among the specializations required for this peculiar diet, ticks evolved a sophisticated salivary potion that can disarm their host's hemostasis, inflammation, and immune reactions. Previous transcriptome analysis of tick salivary proteins has revealed many new protein families indicative of fast evolution, possibly due to host immune pressure. The hard ticks (family Ixodidae) are further divided into two basal groups, of which the Metastriata have 11 genera. While salivary transcriptomes and proteomes have been described for some of these genera, no tick of the genus Hyalomma has been studied so far. The analysis of 2084 expressed sequence tags (EST) from a salivary gland cDNA library allowed an exploration of the proteome of this tick species by matching peptide ions derived from MS/MS experiments to this data set. We additionally compared these MS/MS derived peptide sequences against the proteins from the bovine host, finding many host proteins in the salivary glands of this tick. This annotated data set can assist the discovery of new targets for anti-tick vaccines as well as help to identify pharmacologically active proteins.

Influence of the microenvironment on gene and protein expression of odontogenic-like and osteogenic-like cells

Progenitor cells play an important biological role in tooth and bone formation, and previous analyses during bone and dentine induction have indicated that they may be a good alternative for tissue engineering. Thus, to clarify the influence of the microenvironment on protein and gene expression, MDPC-23 cells (mouse dental papilla cell line) and KUSA/A1 cells (bone marrow stromal cell line) were used, both in vitro cell culture and in intra-abdominal diffusion chambers implanted in 4-week-old male immunodefficient mice (SCID mice). Our results indicate that KUSA/A1 cells differentiated into osteoblast-like cells and induced bone tissue inside the chamber, whereas, MDPC-23 showed odontoblast-like characteristics but with a low ability to induce dentin formation. This study shows that MDPC-23 cells are especial cells, which possess morphological and functional characteristics of odontoblast-like cells expressing dentin sialophosphoprotein in vivo. In contrast, dentin sialophosphoprotein gene and protein expression was not detected in both cell lines in vitro. The intra-abdominal diffusion chamber appears as an interesting experimental model for studying phenotypic expression of dental pulp cells in vivo.

Expression of E-selectin ligand-1 (CFR/ESL-1) on hepatic stellate cells: implications for leukocyte extravasation and liver metastasis

Leukocytes and tumor cells use E-selectin binding ligands to attach to activated endothelial cells expressing E-selectin during inflammation or metastasis. The cysteine-rich fibroblast growth factor receptor (CFR) represents the main E-selectin ligand (ESL-1) on granulocytes and its expression is exclusively modified by alpha(1,3)-fucosyltransferases IV or VII (FucT4 and FucT7). Hepatic stellate cells (HSC) are pericytes of liver sinusoidal endothelial cells. The activation of HSC and transdifferentiation into a myofibroblastic phenotype is involved in the repair of liver tissue injury, liver regeneration and angiogenesis of liver metastases. In the present study, we demonstrated that HSC expressed CFR together with FucT7 and exhibited a functional E-selectin binding activity on their cell surface. Since HSC appear to be oxygen-sensing cells, the expression of E-selectin binding activity was analyzed in HSC under a hypoxic atmosphere. While the expression of the glycoprotein CFR was unaffected by hypoxia, the cell-associated E-selectin binding activity decreased. However, under the same conditions, mRNA expression of the modifying enzyme FucT7 increased. The loss of E-selectin binding activity, therefore, appears to be neither the result of a reduced expression of the modifying transferase nor the expression of the backbone glycoprotein. After the transient transfection of HSC with CFR cDNA, the E-selectin binding activity (ESL-1) was efficiently released into the supernatant. Therefore, we hypothesize that under hypoxia, ESL-1 is shed from activated HSC. Our findings provide a novel perspective on the function of HSC in liver metastasis and inflammatory liver diseases.

A tryptamine derivative, SST-VEDI-1, inhibits apoptosis and stimulates mineralization in osteoblasts

SST-VEDI-1(VEDI-1) is a new synthetic compound that is synthesized from tryptamine, and has structural similarity to the SSH-BM family of compounds. However, the biological effects of VEDI-1 have yet to be well characterized. A recent report has demonstrated that SSH-BM-type compounds can stimulate osteoblast activity in cultured scales of goldfish. In this study, we examined the effects of VEDI-1 on osteoblastic differentiation as well as its effects on apoptosis, which is known to be closely related to osteoblastic differentiation. We found that VEDI-1 enhanced the formation of mineralized nodules in rat osteoblast cell lines, including ROS17/2.8 cells, and in mouse pre-osteoblast cell lines, including MC3T3-E1 cells, in a dose dependent manner, which was accompanied by increased expression of late osteoblast markers, bone sialoprotein (BSP) and osteocalcin (OC). Furthermore, VEDI-I inhibited apoptotic cell death and regulated the expression of proteins in the Bcl-2 family. These results suggest that VEDI-1 may facilitate late differentiation of osteoblasts and may have an inhibitory effect on apoptosis.

Expression of Osterix in mechanical stress-induced osteogenic differentiation of periodontal ligament cells in vitro

Osterix (Osx) is an osteoblast-specific transcription factor required for the differentiation of pre-osteoblasts into functional osteoblasts. This study sought to examine the changes of Osx expression in periodontal ligament cells (PDLC) subjected to mechanical force, and to investigate whether Osx is involved in the mechanical stress-induced differentiation of PDLC. Human PDLC were exposed to centrifugal force for 1-12 h. Real-time polymerase chain reaction (PCR), western blot, and immunofluorescence assays were used to examine the mRNA and protein expression of Osx and its subcellular localization. Furthermore, PDLC were transfected with the expression vector pcDNA3.1 flag-Osx and subjected to mechanical force for 6 h. The changes in alkaline phosphatase (ALP) activity and in the expression of core-binding factor alpha1 (Cbfa1), ALP, osteopontin, bone sialoprotein, osteocalcin, and collagen I were measured. After the application of mechanical force, Osx was upregulated in a time-dependent manner at both mRNA and protein levels, and Osx protein was translocated from the cytosol into the cell nuclei. Overexpression of Osx did not affect the expression of Cbfa1, but it significantly enhanced the ALP activity and the mRNA expression of all the aforementioned osteogenic marker genes, all of which increased further under mechanical stress. These results suggest that Osx might play an important role in the mechanical stress-induced osteogenic differentiation of PDLC and therefore be involved in alveolar bone remodeling during orthodontic therapy.

Rapamycin inhibits osteoblast proliferation and differentiation in MC3T3-E1 cells and primary mouse bone marrow stromal cells

While the roles of the mammalian target of rapamycin (mTOR) signaling in regulation of cell growth, proliferation, and survival have been well documented in various cell types, its actions in osteoblasts are poorly understood. In this study, we determined the effects of rapamycin, a specific inhibitor of mTOR, on osteoblast proliferation and differentiation using MC3T3-E1 preosteoblastic cells (MC-4) and primary mouse bone marrow stromal cells (BMSCs). Rapamycin significantly inhibited proliferation in both MC-4 cells and BMSCs at a concentration as low as 0.1 nM. Western blot analysis shows that rapamycin treatment markedly reduced levels of cyclin A and D1 protein in both cell types. In differentiating osteoblasts, rapamycin dramatically reduced osteoblast-specific osteocalcin (Ocn), bone sialoprotein (Bsp), and osterix (Osx) mRNA expression, ALP activity, and mineralization capacity. However, the drug treatment had no effect on osteoblast differentiation parameters when the cells were completely differentiated. Importantly, rapamycin markedly reduced levels of Runx2 protein in both proliferating and differentiating but not differentiated osteoblasts. Finally, overexpression of S6K in COS-7 cells significantly increased levels of Runx2 protein and Runx2 activity. Taken together, our studies demonstrate that mTOR signaling affects osteoblast functions by targeting osteoblast proliferation and the early stage of osteoblast differentiation.

Androgen receptor stimulates bone sialoprotein (BSP) gene transcription via cAMP response element and activator protein 1/glucocorticoid response elements

Bone sialoprotein (BSP) is an early marker of osteoblast differentiation. Androgens are steroid hormones that are essential for skeletal development. The androgen receptor (AR) is a transcription factor and a member of the steroid receptor superfamily that plays an important role in male sexual differentiation and prostate cell proliferation. To determine the molecular mechanism involved in the stimulation of bone formation, we have analyzed the effects of androgens and AR effects on BSP gene transcription. AR protein levels were increased after AR overexpression in ROS17/2.8 cells. BSP mRNA levels were increased by AR overexpression. However, the endogenous and overexpressed BSP mRNA levels were not changed by DHT (10(-8) M, 24 h). Whereas luciferase (LUC) activities in all constructs, including a short construct (nts -116 to +60), were increased by AR overexpression, the basal and LUC activities enhanced by AR overexpression were not induced by DHT (10(-8)M, 24 h). The effect of AR overexpression was abrogated by 2 bp mutations in either the cAMP response element (CRE) or activator protein 1 (AP1)/glucocorticoid response element (GRE). Gel shift analyses showed that AR overexpression increased binding to the CRE and AP1/GRE elements. Notably, the CRE-protein complexes were supershifted by phospho-CREB antibody, and CREB, c-Fos, c-Jun, and AR antibodies disrupted the complexes formation. The AP1/GRE-protein complexes were supershifted by c-Fos antibody and c-Jun, and AR antibodies disrupted the complexes formation. These studies demonstrate that AR stimulates BSP gene transcription by targeting the CRE and AP1/GRE elements in the promoter of the rat BSP gene.

Odontoblast marker gene expression is enhanced by a CC-chemokine family protein MIP-3alpha in human mesenchymal stem cells

OBJECTIVE

Macrophage inflammatory protein-3 alpha (MIP-3alpha) is a major CC-chemokine family protein, which serves as a differentiation factor for mesenchymal cells, including osteoblasts and dental pulp cells. The purpose of this study was to investigate the influence of MIP-3alpha on human mesenchymal stem cell differentiation in vitro.

DESIGN

Human mesenchymal stem cells were maintained in Dulbecco's modified Eagle's medium in the presence or absence of MIP-3alpha and the presence or absence of osteogenic factors (dexamethasone, beta-glycerophoshate and ascorbic acid). Alkaline phosphatase (ALP) activity was measured, and expression of odontoblast and osteoblast markers were examined by RT-PCR and Western blotting.

RESULTS

MIP-3alpha alone did not increase ALP activity, as compared to controls. The combination of MIP-3alpha and osteogenic factors increased ALP activity beyond increases observed with osteogenic factors alone. mRNA expression of the odontoblast marker dspp was only detectable when MIP-3alpha was added together with osteogenic factors at day 7 in three out of four samples. DSP protein level was increased only in the samples treated with both MIP-3alpha and osteogenic factors until day 5. In contrast, MIP-3alpha did not influence levels of the osteoblast markers CBFA1 or BSP.

CONCLUSIONS

The present study demonstrated that MIP-3alpha enhanced gene expression and protein levels of odontoblast-related genes, without affecting levels of the osteogenic proteins CBFA1 or BSP.

[High glucose downregulates the expression of podocalyxin protein in glomerular podocytes of mice]

OBJECTIVE

To examine the expression of podocalyxin protein in glomerular podocytes by long-term high glucose exposure in vitro and in vivo.

METHODS

Immunohistochemical staining and computer image analysis were applied to detect the expression of podocalyxin protein in glomeruli from db/db mice and Wt mice. The effects of high glucose on the expression of podocalyxin protein were analyzed by Western blotting. The activation of MAPKS signaling pathway (ERK, p38 and JNK) by high glucose was also examined.

RESULTS

The expressions of podocalyxin protein in db/db mice were obviously less than that in Wt mice [(0.18+/-0.07) vs (0.25+/-0.05),P<0.05] assessed by immunostaining and semiquantitative analysis. Basal levels of podocalyxin protein were observed in cultured mouse podocytes. The level of podocalyxin protein declined at each time point by high glucose incubation, reached the lowest level on the 6th day (5.5% of control group, P<0.01), but no significant changes were observed in normal glucose and mannitol glucose incubation groups. High glucose medium induced phosphorylation of ERK1/2 as early as 30 minutes, reached the peak at hour 6; maintained the activation from hour 12 to 24, and declined to the basal level at hour 48. However, activation of ERK1/2 was not detected in normal glucose and mannitol glucose groups. Blockade of activation of ERK1/2 with PD98059, a specific ERK1/2 activation inhibitor, attenuated the high glucose-induced expression of podocalyxin protein on the 6th day.

CONCLUSION

High ambient glucose decreases the protein level of podocalyxin by podocyte in vitro and in vivo, and the decrease in podocalyxin protein is ERK1/2jdependent in cultured podocytes.

Tissue Engineering Bone Formation in Novel Recombinant Human Bone Morphogenic Protein 2–Atelocollagen Composite Scaffolds

BACKGROUND

Bone morphogenic proteins (BMPs) are important bone-induction factors, and the development of a suitable carrier for BMPs is a critical step to achieve osteoinductive function. The aims of the present study were to evaluate, at the cellular and molecular levels, the feasibility of recombinant human BMP-2 (rhBMP-2)-collagen composite scaffold and its efficiency for carrying BMP-2 in ectopic bone formation in rats.

METHODS

Scaffolds with (test) or without rhBMP-2 (control) were made and implanted into the calf muscle of 16 5-week-old rats. The tissue responses to the scaffolds were examined by histology. Masson's trichrome and von Kossa stainings were performed to examine collagen matrix deposition and calcification at 3, 7, 10, and 14 days. Expressions of bone phenotypic markers, alkaline phosphatase, osteocalcin, osteopontin, and bone sialoprotein were detected by reverse transcription-polymerase chain reaction and immunohistochemistry.

RESULTS

No detectable adverse responses were noted around the implanted scaffolds, and the area of the resorbed scaffold had been replaced by young connective tissue by 3 to 7 days in both groups. In the rhBMP-2 composite scaffold, collagen matrix deposition was found in the implanted site on day 7 and initial signs of endochondral differentiation also appeared. Mineralization and the expressions of key bone proteins were demonstrated in chondroblasts and osteoblasts at 7 to 14 days. Molecular cascades of bone induction were not shown in control specimens.

CONCLUSION

The rhBMP-2-atelocollagen scaffold showed excellent biocompatibility and possessed a bone-inducing capacity in rat within 2 weeks, and, thus, may provide a potential application in tissue engineering of bone tissue.

SIBLING expression patterns in duct epithelia reflect the degree of metabolic activity

The SIBLING (Small Integrin-Binding LIgand, N-linked Glycoprotein) family of secreted glycophosphoproteins includes bone sialoprotein (BSP), dentin matrix protein-1 (DMP1), dentin sialophosphoprotein (DSPP), osteopontin (OPN), and matrix extracellular phosphoglycoprotein (MEPE). For many years, they were thought in normal adults to essentially be limited to metabolically active mesenchymal cells that assembled the mineralized matrices of bones and teeth. Over the last decade they have also been upregulated in a variety of tumors. Three of these proteins (BSP, OPN, and DMP1) have been shown to interact with three matrix metalloproteinases (MMP-2, MMP-3, and MMP-9, respectively). Recently, all five SIBLINGs and their MMP partners when known were observed in specific elements of normal ductal epithelia in salivary gland and kidney. We have hypothesized that the SIBLINGs and their MMP partners may be expressed in ductal cells with high metabolic activity. In this paper, we show that all the SIBLINGs (except MEPE) and their MMP partners are expressed in the metabolically active epithelia of human eccrine sweat gland duct but not in the more passive ductal cells of the macaque (monkey) lacrimal gland. It is hypothesized that MEPE expression may be limited to cells involved in active phosphate transport. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials.

Surface-induced modulation of human mesenchymal progenitor cells. An in vitro model for early implant integration

Clinical experience indicates that the surface architecture of dental implants has an important impact on their integration. This has been related to the finding that differentially treated substrates can modulate the expression of osteogenic markers in various bone-related cell lines and primary cells. Here, we investigated the influence of surface architecture on the differentiation of human mesenchymal progenitor cells (HMPC) from adult bone marrow, i. e. the cells likely involved in initial bone synthesis at the bone-implant interface. Cells were seeded on machine surfaced (MS) or sandblasted/acid etched (SE) titanium discs in agarose-coated dishes, and on polystyrene (PS) controls. On all substrates cell densities did not change between days 7 and 14. Cell numbers were higher on SE, likely due to increased attachment to the rougher material. Alkaline phosphatase activity (ALP) was similar on all substrates, whereas mRNA expression of bone sialoprotein (BSP) at day 14 was about tenfold higher on SE (p < 0.05%). The SE-related increase of BSP in progenitor cells indicates an earlier differentiation of immigrated cells and could thus explain earlier implant integration and shorter time to functional loading observed in the clinic. The in vitro model and BSP quantification could be used to screen for changes in osteogenic cell differentiation induced by specific implant surfaces, with potential relevance on the prediction of bone-implant integration.

Platelet-rich plasma/osteoblasts complex induces bone formation via osteoblastic differentiation following subcutaneous transplantation

BACKGROUND AND OBJECTIVE

Platelet-rich plasma (PRP) has been shown to enhance the maturation of bone grafts following local application and to have biological effects on osteoblasts in vitro. However, PRP is not applied by itself clinically as a result of its poor benefits in large bone defects. The present study was undertaken to develop a clinical alternative to autologous bone, by investigating the application of PRP in combination with osteoblastic cells and evaluating its effects after transplantation.

MATERIAL AND METHODS

PRP and platelet-poor plasma (PPP) were prepared from blood, obtained from ddY mice, by two centrifugation steps. MC3T3-E1 cells were labeled with fluorescent carbocyanine just before transplantation. The combination of labeled cells and PRP gel was subcutaneously transplanted into the back of severe combined immunodeficient (SCID) mice, and the transplants were evaluated radiographically and immunohistologically after 4 wk. The effects of PRP were assessed by alkaline phosphatase (ALP) staining and von Kossa staining, and the expression of bone-related markers was analyzed by reverse transcription-polymerase chain reaction before transplantation.

RESULTS

Before transplantation, PRP enhanced the expression of Osterix and bone sialoprotein mRNAs compared with PPP. Furthermore, PRP elevated ALP activity and induced the formation of mineralized nodules. After transplantation, the combination of labeled cells and PRP gel formed mineralized tissue, and the transplanted cells visualized in the tissue using fluorescence microscopy expressed osteocalcin and type I collagen.

CONCLUSION

These results suggest that the application of a PRP/osteoblasts complex has beneficial effects for transplanting engineered cells into bone defects through the promotion of osteoblastic differentiation.

Podocalyxin is expressed in normal and leukemic monocytes

We have investigated the expression of podocalyxin in primary cultures of leukemic blast cells from 73 patients with acute myeloid leukemia. Podocalyxin was expressed at moderate levels in 15 patients and at high levels in 13 patients. The analysis of membrane markers showed that Podocalyxin expression in leukemic blasts was associated with a monocytic immunophenotype. Cases of podocalyxin-positive acute myelogenous leukemia had high blast cell counts at diagnosis and elevated CD123, CD135, VLA-4 and CXCR4 expression, features associated with poor prognosis. Podocalyxin expression in leukemic blasts was coupled with the concomitant expression of VEGF-R1, -R2, -R3 and Tie-2, the capacity to release VEGF-A and angiopoietin1 and the ability to differentiate into endothelial cells under appropriate culture conditions. These findings show that podocalyxin is a marker of acute myeloid leukemia with a monocytic phenotype and suggest that podocalyxin-positive cases of acute myeloid leukemia originate from the malignant transformation of progenitors common to the myeloid and endothelial lineages. These observations suggest a possible relationship between the monocytic lineage and podocytes.

Differentiation of Dental Pulp Stem Cells into Regular-Shaped Dentin-Pulp Complex Induced by Tooth Germ Cell Conditioned Medium

Investigations of the odontoblast phenotype are hindered by obstacles such as the limited number of odontoblasts within the dental pulp and the difficulty in purification of these cells. Therefore, it is necessary to develop a cell culture system in which the local environment is inductive and can promote dental pulp stem cells (DPSCs) to differentiate into odontoblast lineage. In this study, we investigated the effect of conditioned medium from developing tooth germ cells (TGCs) on the differentiation and dentinogenesis of DPSCs both in vitro and in vivo. DPSCs were enzymatically isolated from the lower incisors of 4-week-old Sprague-Dawley rats and co-cultured with TGC conditioned medium (TGC-CM). The cell phenotype of induced DPSCs presents many features of odontoblasts, as assessed by the morphologic appearance, cell cycle modification, increased alkaline phosphatase level, synthesis of dentin sialoprotein, type I collagen and several other noncollagenous proteins, expression of the dentin sialophosphoprotein and dentin matrix protein 1 genes, and the formation of mineralized nodules in vitro. The induced DPSC pellets in vivo generated a regular-shaped dentin-pulp complex containing distinct dentinal tubules and predentin, while untreated pellets spontaneously differentiated into bone-like tissues. To our knowledge, this is the first study to mimic the dentinogenic microenvironment from TGCs in vitro, and our data suggest that TGC-CM creates the most odontogenic microenvironment, a feature essential and effective for the regular dentinogenesis mediated by DPSCs.

Podocalyxin-like protein 1 expression in primary hepatic tumours and tumour-like lesions

AIMS

The differential diagnosis of benign hepatic lesions and well-differentiated hepatocellular carcinomas can be a challenge, especially in small biopsy specimens. Recently, novel proteins expressed by the neovasculature in hepatocellular carcinoma (HCC) have been identified. The aim of this study was to compare the expression of podocalyxin-like protein 1 (PODXL1), a CD34-related sialomucin, in HCC and benign liver tumours or tumour-like lesions.

METHODS AND RESULTS

Vascular marker expression was examined using tissue microarrays as well as standard paraffin sections from formalin fixed paraffin-embedded liver tissue samples. Expression of PODXL1 was compared with anti-CD34, CD31 and von Willebrand factor VIII staining by immunohistochemistry. PODXL1 is expressed in tumour-associated microvasculature endothelial cells in HCC, as well as in capillarized sinusoidal endothelium of focal nodular hyperplasia (FNH) and hepatic adenoma. Expression in cirrhotic nodules correlates with CD34 and highlights endothelium in the inflow area. In dysplastic nodules CD34 and PODXL1 are not or only focally expressed.

CONCLUSIONS

Expression patterns of CD34 and PODXL1 are almost identical in primary hepatic tumours and tumour-like lesions. The presence of CD34+ and PODXL1+ sinusoidal endothelial cells aids in the diagnosis of HCC. Sinusoidal expression of PODXL1 is also seen in a less diffuse pattern in FNH and adenoma.

Involvement of the alpha2,8-polysialyltransferases II/STX and IV/PST in the biosynthesis of polysialic acid chains on the O-linked glycoproteins in rainbow trout ovary

Polysialoglycoprotein (PSGP) in salmonid fish egg is a unique glycoprotein bearing alpha2,8-linked polysialic acid (polySia) on its O-linked glycans. Biosynthesis of the polySia chains is developmentally regulated and only occurs at later stage of oogenesis. Two alpha2,8-polysialyltransferases (alpha2,8-polySTs), PST (ST8Sia IV) and STX (ST8Sia II), responsible for the biosynthesis of polySia on N-glycans of glycoproteins, are known in mammals. However, nothing has been known about which alpha2,8-polySTs are involved in the biosynthesis of polySia on O-linked glycans in any glycoproteins. We thus sought to identify cDNA encoding the alpha2,8-polyST involved in polysialylation of PSGP. A clone for PST orthologue, rtPST, and two clones for the STX orthologue, rtSTX-ov and rtSTX-em, were identified in rainbow trout. The deduced amino acid sequence of rtPST shows a high identity (72-77%) to other vertebrate PSTs, while that of rtSTX-ov shows 92% identity with rtSTX-em and a significant identity (63-76%) to other vertebrate STXs. The rtPST exhibited the in vivo alpha2,8-polyST activity, although its in vitro activity was low. However, the rtSTXs showed no in vivo and very low in vitro activities. Interestingly, co-existence of rtPST and rSTX-ov in the reaction mixture synergistically enhanced the alpha2,8-polyST activity. During oogenesis, rtPST was constantly expressed, while the expression of rtSTX-ov was not increased until polySia chain is abundantly biosynthesized in the later stage. rtSTX-em was not expressed in ovary. These results suggest that the enhanced expression of rtSTX-ov under the co-expression with rtPST may be important for the biosynthesis of polySia on O-linked glycans of PSGP.

Transcriptomic and genomic analysis of human hepatocellular carcinomas and hepatoblastomas

This study analyzed gene expression patterns and global genomic alterations in hepatocellular carcinomas (HCC), hepatoblastomas (HPBL), tissue adjacent to HCC and normal liver tissue derived from normal livers and hepatic resections. We found that HCC and adjacent non-neoplastic cirrhotic tissue have considerable overlap in gene expression patterns compared to normal liver. Several genes including Glypican 3, spondin-2, PEG10, EDIL3 and Osteopontin are over-expressed in HCC vs. adjacent tissue whereas Ficolin 3 is the most consistently under-expressed gene. HCC can be subdivided into three clusters based on gene expression patterns. HCC and HPBL have clearly different patterns of gene expression, with genes IGF2, Fibronectin, DLK1, TGFb1, MALAT1 and MIG6 being over-expressed in HPBL versus HCC. In addition, specific areas of the genome appear unstable in HCC, with the same regions undergoing either deletion or increased gene dosage in all HCC. In conclusion, a set of specific genes and areas of genomic instability are found across the board in liver neoplasia.

Humanization of yeast to produce complex terminally sialylated glycoproteins

Yeast is a widely used recombinant protein expression system. We expanded its utility by engineering the yeast Pichia pastoris to secrete human glycoproteins with fully complex terminally sialylated N-glycans. After the knockout of four genes to eliminate yeast-specific glycosylation, we introduced 14 heterologous genes, allowing us to replicate the sequential steps of human glycosylation. The reported cell lines produce complex glycoproteins with greater than 90% terminal sialylation. Finally, to demonstrate the utility of these yeast strains, functional recombinant erythropoietin was produced.

Papilloma development is delayed in osteopontin-null mice: implicating an antiapoptosis role for osteopontin

Osteopontin is a secreted, adhesive glycoprotein, whose expression is markedly elevated in several types of cancer and premalignant lesions, implicating its association with carcinogenesis. To test the hypothesis that induced osteopontin is involved in tumor promotion in vivo, osteopontin-null and wild-type (WT) mice were subjected to a two-stage skin chemical carcinogenesis protocol. Mice were initiated with 7,12-dimethylbenz(a)anthracene (DMBA) applied on to the dorsal skin followed by twice weekly application of 12-O-tetradecanoylphorbol-13-acetate (TPA) for 27 weeks. Osteopontin-null mice showed a marked decrease both in tumor/papilloma incidence and multiplicity compared with WT mice. Osteopontin is minimally expressed in normal epidermis, but on treatment with TPA its expression is highly induced. To determine the possible mechanism(s) by which osteopontin regulates tumor development, we examined cell proliferation and cell survival. Epidermis from osteopontin-null and WT mice treated with TPA thrice or with DMBA followed by TPA for 11 weeks showed a similar increase in epidermal hyperplasia, suggesting that osteopontin does not mediate TPA-induced cell proliferation. Bromodeoxyuridine staining of papillomas and adjacent epidermis showed no difference in cell proliferation between groups. However, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling analyses indicated a greater number of apoptotic cells in DMBA-treated skin and papillomas from osteopontin-null versus WT mice. These studies are the first to show that induction of the matricellular protein osteopontin facilitates DMBA/TPA-induced cutaneous carcinogenesis most likely through prevention of apoptosis.

Macrophages and giant cell proliferation associated with bone protein synthesis and calcification in the trachea and bronchi of rabbits intoxicated with Solanum glaucophyllum

A histopathologic, immunohistochemical, and ultrastructural study of the trachea and the bronchi of 6 rabbits experimentally intoxicated with the calcinogenic plant Solanum glaucophyllum was performed. Histologically, infiltration of the mucosa and the submucosa of the trachea and the bronchi by macrophages, multinucleated giant cells, a few lymphocytes and mast cells, and calcium deposits in the basal lamina of the epithelium and in elastic fibers were observed. Expression of osteocalcin, osteonectin, and osteopontin was detected in the mucosa, lamina propria, and epithelium. Electron microscopic study of the corresponding areas showed numerous macrophages in the process of fusion to form multinucleated giant cells, activated mesenchymal cells, and calcium precipitation in the basal lamina of epithelium and in elastic fibers. It is suggested that the high levels of 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) in the plant induces macrophage proliferation, multinucleated giant-cell formation, mesenchymal cell activation, bone-protein synthesis, and calcification. In addition, the synthesis of 1,25(OH)2D3 by local macrophages may have contributed to the calcification.

The crucial role of cyclooxygenase-2 in osteopontin-induced protein kinase C alpha/c-Src/IkappaB kinase alpha/beta-dependent prostate tumor progression and angiogenesis

The regulation of tumor progression towards its malignancy needs the interplay among several cytokines, growth factors, and enzymes, which are controlled in the tumor microenvironment. Here, we report that osteopontin, a small integrin-binding ligand N-linked glycoprotein family of calcified extracellular matrix-associated protein, regulates prostate tumor growth by regulating the expression of cyclooxygenase-2 (COX-2). We have shown that osteopontin stimulates the activation of protein kinase C alpha/nuclear factor-inducing kinase/nuclear factor-kappaB-dependent signaling cascades that induces COX-2 expression, which in turn regulates the prostaglandin E(2) production, matrix metalloproteinase-2 activation, and tumor progression and angiogenesis. We have revealed that suppression of osteopontin-induced COX-2 expression by the nonsteroidal anti-inflammatory drug celecoxib or blocking the EP2 receptor by its blocking antibody resulted in significant inhibition of cell motility and tumor growth and angiogenesis. The data also showed that osteopontin-induced mice PC-3 xenograft exhibits higher tumor load, increased tumor cell infiltration, nuclear polymorphism, and neovascularization. Interestingly, use of celecoxib or anti-EP2 blocking antibody drastically suppressed osteopontin-induced tumor growth that further indicated that suppression of COX-2 or its metabolites could significantly inhibit osteopontin-induced tumor growth. Human clinical prostate cancer specimen analysis also supports our in vitro and animal model studies. Our findings suggest that blockage of osteopontin and/or COX-2 is a promising therapeutic approach for the inhibition of prostate tumor progression and angiogenesis.

Circulating cytokine/inhibitor profiles reshape the understanding of the SIRS/CARS continuum in sepsis and predict mortality

Mortality in sepsis remains unacceptably high and attempts to modulate the inflammatory response failed to improve survival. Previous reports postulated that the sepsis-triggered immunological cascade is multimodal: initial systemic inflammatory response syndrome (SIRS; excessive pro-, but no/low anti-inflammatory plasma mediators), intermediate homeostasis with a mixed anti-inflammatory response syndrome (MARS; both pro- and anti-inflammatory mediators) and final compensatory anti-inflammatory response syndrome (CARS; excessive anti-, but no/low proinflammatory mediators). To verify this, we examined the evolution of the inflammatory response during the early phase of murine sepsis by repetitive blood sampling of septic animals. Increased plasma concentrations of proinflammatory (IL-6, TNF, IL-1beta, KC, MIP-2, MCP-1, and eotaxin) and anti-inflammatory (TNF soluble receptors, IL-10, IL-1 receptor antagonist) cytokines were observed in early deaths (days 1-5). These elevations occurred simultaneously for both the pro- and anti-inflammatory mediators. Plasma levels of IL-6 (26 ng/ml), TNF-alpha (12 ng/ml), KC (33 ng/ml), MIP-2 (14 ng/ml), IL-1 receptor antagonist (65 ng/ml), TNF soluble receptor I (3 ng/ml), and TNF soluble receptor II (14 ng/ml) accurately predicted mortality within 24 h. In contrast, these parameters were not elevated in either the late-deaths (day 6-28) or survivors. Surprisingly, either pro- or anti-inflammatory cytokines were also reliable in predicting mortality up to 48 h before outcome. These data demonstrate that the initial inflammatory response directly correlates to early but not late sepsis mortality. This multifaceted response questions the use of a simple proinflammatory cytokine measurement for classifying the inflammatory status during sepsis.

Effect of titanium surface roughness on human osteoblast proliferation and gene expression in vitro

PURPOSE

Cell proliferation and extracellular matrix formation are primary events in bone formation. At the dental implant-tissue interface, implant surface roughness modulates osteoblast functions. The aim of the present in vitro study was to investigate the effect of varying surface roughness of titanium implant material on cell proliferation and mRNA expression of specific markers of osteoblast phenotype.

MATERIALS AND METHODS

Primary cultures of osteoblasts derived from human mandibular bone were cultured on titanium surfaces. Three titanium surfaces were studied: machined titanium, microsandblasted titanium, and macro-sandblasted titanium (average surface roughnesses of 0.5 and 3 microm, respectively). Cell morphology was estimated by scanning electron microscope analysis and cell proliferation by measuring the amount of 3H-thymidine incorporation into DNA. mRNA expression of osteonectin, osteopontin, bone sialoprotein (BSP), and Runx2, which are markers of osteoblastic phenotype, were determined by reverse transcriptase polymerase chain reaction (RT-PCR) analysis.

RESULTS

Human osteoblasts cultured on machined titanium spread more and were flatter than cells cultured on rough titanium. All blasted surfaces showed significantly higher DNA synthesis than the machined surfaces. Osteonectin mRNA expression was similar on all surfaces. Other mRNA transcripts were increased in osteoblasts cultured on rough titanium surfaces, particularly the macrosandblasted surface.

CONCLUSIONS

An average surface roughness of 3 microm (macro-sandblasted titanium) is more suitable than an average surface roughness of 0.5 microm (micro-sandblasted titanium) in favoring osteoblast differentiation in vitro.

Diagnostic value of markers M2A, OCT3/4, AP-2γ, PLAP and c-KIT in the detection of extragonadal seminomas

AIMS

To compare the suitability of new seminoma markers including transcription factors AP-2gamma, OCT3/4 and M2A for detection of metastatic and extragonadal seminomas with the two well-known markers c-KIT and PLAP.

MATERIALS AND METHODS

The immunohistochemical distribution of PLAP, c-KIT, M2A, AP-2gamma and OCT3/4 was examined in two pineal germinomas, 28 metastatic seminomas and 10 of their testicular primaries. Evaluation of specificity was achieved by additional tissue array studies on 75 malignancies other than germ cell tumours (GCT). Clinical data including serum PLAP were available in 18 patients.

RESULTS

Compared with other markers, significantly better staining results were observed with antibodies to M2A and AP-2gamma in all seminomatous GCT. In contrast, the staining pattern with antibodies to c-KIT, PLAP and OCT3/4 was variable or absent. The lowest specificity was obtained with c-KIT, which was expressed in a variety of non-GCT. The only M2A+ mesothelioma expressed no other seminoma markers. No correlation between serum PLAP level and tissue PLAP expression was found.

CONCLUSIONS

M2A and AP-2gamma are the most sensitive markers for seminoma metastases or primary extragonadal seminomas. Combination of these markers provides highly specific and clear results for detection of a seminomatous GCT.

Apoptosis resistance downstream of eIF4E: posttranscriptional activation of an anti-apoptotic transcript carrying a consensus hairpin structure

Aberrant activation of the translation initiation machinery is a common property of malignant cells, and is essential for breast carcinoma cells to manifest a malignant phenotype. How does sustained activation of the rate limiting step in protein synthesis so fundamentally alter a cell? In this report, we test the post transcriptional operon theory as a possible mechanism, employing a model system in which apoptosis resistance is conferred on NIH 3T3 cells by ectopic expression of eIF4E. We show (i) there is a set of 255 transcripts that manifest an increase in translational efficiency during eIF4E-mediated escape from apoptosis; (ii) there is a novel prototype 55 nt RNA consensus hairpin structure that is overrepresented in the 5′-untranslated region of translationally activated transcripts; (iii) the identified consensus hairpin structure is sufficient to target a reporter mRNA for translational activation under pro-apoptotic stress, but only when eIF4E is deregulated; and (iv) that osteopontin, one of the translationally activated transcripts harboring the identified consensus hairpin structure functions as one mediator of the apoptosis resistance seen in our model. Our findings offer genome-wide insights into the mechanism of eIF4E-mediated apoptosis resistance and provide a paradigm for the systematic study of posttranscriptional control in normal biology and disease.

Co-Expression of Vascular Endothelial Growth Factor and Interleukin-1 Receptor Antagonist Improves Human Islet Survival and Function

PURPOSE

Ex vivo gene therapy approaches can improve the outcome of islet transplantation for treating type I diabetes. We have previously shown the improvement in islet function and vascularization following ex vivo transfection for human vascular endothelial growth factor (hVEGF) gene expression. In this study, we tested the hypothesis that co-expression of two genes, which target different challenges faced by islets post-transplantation, supplement each other to improve the survival and function of islets. We determined whether there is an additive effect of hVEGF and human interleukin-1 receptor antagonist (hIL-1Ra) gene expression in human islets.

MATERIALS AND METHODS

Human islets were co-infected with adenoviral vectors encoding hVEGF and hIL-1Ra. Islets were then incubated with a cocktail of inflammatory cytokines (IL-1beta+TNFalpha+IFNgamma), and islet viability and function were determined. In vivo function was evaluated by transplanting islets under the kidney capsules of streptozotocin-induced non-obese diabetic severe combined immunodeficient (NOD-SCID) mice.

RESULTS

Infection of human islets with Adv-hVEGF and/or Adv-hIL-1Ra inhibited expression of inducible nitric oxide synthase (iNOS), decreased the production of nitric oxide (NO), and prevented the loss of in vitro glucose-stimulated insulin response and viability. Moreover, co-expression of hVEGF and hIL-1Ra reduced the blood glucose level of mice, and increased the level of blood insulin and c-peptide upon glucose challenge.

CONCLUSIONS

Our results indicated that co-expression of genes that target different insults to transplanted islets can improve the outcome of islet transplantation better than either gene alone.

Osteopontin is an oncogenic Vav1- but not wild-type Vav1-responsive gene: implications for fibroblast transformation

Mammalian wild-type Vav1 (wtVav1) encodes a specific GDP/GTP nucleotide exchange factor that is exclusively expressed in the hematopoietic system. Despite numerous studies, the mechanism underlying transformation of fibroblasts by oncogenic Vav1 (oncVav1) is not well defined. We identified osteopontin, a marker for tumor aggressiveness, as an oncVav1-inducible gene. Osteopontin is highly expressed in oncVav1-transformed NIH3T3 cells (NIH/oncVav1) but is barely detected in NIH3T3 expressing wtVav1 (NIH/wtVav1) even following epidermal growth factor stimulation, which normally induces osteopontin. Depleting oncVav1 in NIH/oncVav1 using small interfering RNA led to a considerable decrease in osteopontin, whereas reducing osteopontin expression did not affect oncVav1 expression, suggesting that oncVav1 operates upstream of osteopontin. Vav1-depleted NIH/oncVav1 cells, but not osteopontin-depleted NIH/oncVav1 cells, exhibited impaired extracellular signal-regulated kinase (ERK) and c-Jun NH2-terminal kinase phosphorylation. Inhibition of ERK phosphorylation in NIH/oncVav1 cells led to a decrease in osteopontin expression, implying that the elevated osteopontin expression in these cells is dependent on ERK phosphorylation. Vav1-depleted or osteopontin-depleted NIH/oncVav1 cells lost their tumorigenic properties as judged by the soft agar and invasion assays, although loss of osteopontin expression had a less dramatic effect. Suppression of Vav1 expression in NIH/oncVav1 cells led to reversion to "normal" morphology, whereas when only osteopontin expression was diminished cells retained their transformed morphology. This work strongly supports a role for oncVav1 as a master oncogene and provides clues to the molecular mechanism underlying oncVav1 transformation.

Bone sialoprotein mediates the tumor cell-targeted prometastatic activity of transforming growth factor beta in a mouse model of breast cancer

Transforming growth factor betas (TGF-beta) play a dual role in carcinogenesis, functioning as tumor suppressors early in the process, and then switching to act as prometastatic factors in late-stage disease. We have previously shown that high molecular weight TGF-beta antagonists can suppress metastasis without the predicted toxicities. To address the underlying mechanisms, we have used the 4T1 syngeneic mouse model of metastatic breast cancer. Treatment of mice with a monoclonal anti-TGF-beta antibody (1D11) significantly suppressed metastasis of 4T1 cells to the lungs. When metastatic 4T1 cells were recovered from lungs of 1D11-treated and control mice, the most differentially expressed gene was found to be bone sialoprotein (Bsp). Immunostaining confirmed the loss of Bsp protein in 1D11-treated lung metastases, and TGF-beta was shown to regulate and correlate with Bsp expression in vitro. Functionally, knockdown of Bsp in 4T1 cells reduced the ability of TGF-beta to induce local collagen degradation and invasion in vitro, and treatment with recombinant Bsp protected 4T1 cells from complement-mediated lysis. Finally, suppression of Bsp in 4T1 cells reduced metastasis in vivo. We conclude that Bsp is a plausible mediator of at least some of the tumor cell-targeted prometastatic activity of TGF-beta in this model and that Bsp expression in metastases can be successfully suppressed by systemic treatment with anti-TGF-beta antibodies.

Production of IL-1Ra by human mononuclear blood cells in vitro: influence of serum factors

In vitro cell culture models that measure cytokine production can be of great value when analyzing regulatory mechanisms underlying various pathological conditions. However, testing the function of peripheral blood cells has to take into consideration that serum factors are likely to be of importance in maintaining their function. Interleukin-1 receptor antagonist (IL-1Ra) is a cytokine of key importance in immune regulation and is believed to be involved in numerous pathological processes, such as autoimmunity and cancer. We investigated the influence of normal, human serum on spontaneous production of IL-1Ra by human peripheral blood mononuclear cells (PBMC) in vitro. IL-1Ra production in vitro spanned over a wide range of concentrations, which could be attributed to a combined effect of both cellular parameters and properties of the serum used. The production of IL-1Ra in vitro could be correlated to the level of immobilized IgG, especially IgG1 and IgG3, which is adsorbed from the serum and bound to the tissue culture wells during culture. However, the amount of serum IgG adsorbed to the tissue culture wells could not necessarily be predicted based on the serum concentration of IgG.

A critical role for the inflammatory response in a mouse model of preneoplastic progression

The tumor microenvironment, which includes inflammatory cells, vasculature, extracellular matrix, and fibroblasts, is a critical mediator of neoplastic progression and metastasis. Using an inducible transgenic mouse model of preneoplastic progression in the mammary gland, we discovered that activation of inducible fibroblast growth factor receptor-1 (iFGFR1) in the mammary epithelium rapidly increased the expression of several genes involved in the inflammatory response. Further analysis revealed that iFGFR1 activation induced recruitment of macrophages to the epithelium and continued association with the alveolar hyperplasias that developed following long-term activation. Studies using HC-11 mammary epithelial cells showed that iFGFR1-induced expression of the macrophage chemoattractant osteopontin was required for macrophage recruitment in vitro. Finally, conditional depletion of macrophages inhibited iFGFR1-mediated epithelial cell proliferation and lateral budding. These findings show that inflammatory cells, specifically macrophages, are critical for mediating early events in an inducible transgenic mouse model of preneoplastic progression.

Cooperative cell transformation by Myc/Mil(Raf) involves induction of AP-1 and activation of genes implicated in cell motility and metastasis

Avian fibroblasts transformed simultaneously by the v-myc and v-mil(raf) oncogenes of acute leukemia and carcinoma virus MH2 contain elevated levels of c-Fos and c-Jun, major components of the transcription factor complex AP-1. To define specific transcriptional targets in these cells, subtractive hybridization techniques were employed leading to the identification of strongly upregulated genes including OPN (osteopontin), 126MRP, and rac2. OPN is a cytokine and cell attachment protein which has been implicated in human tumor progression and metastasis, the calcium binding 126MRP protein is related to the human S100 protein family involved in invasive cell growth, and the Rac2 protein belongs to the Rho family of small GTPases regulating actin reorganization and cell migration. Promoter analysis indicated that OPN activation is mediated by a non-consensus AP-1 binding site located close to the transcription start site. Electrophoretic mobility shift assays, chromatin immunoprecipitation and transcriptional reporter gene analyses showed that c-Fos and c-Jun bind specifically to this site and that c-Fos efficiently transactivates the OPN promoter. High-level expression of OPN, 126MRP, or Rac2 proteins from a retroviral vector led to partial cell transformation, documented by morphological changes and anchorage-independent growth. The specific activation in v-myc/v-mil(raf)-transformed cells of target genes with intrinsic oncogenic potential may provide an explanation for the longstanding observation that concomitant expression of these oncogenes leads to strongly enhanced oncogenicity in vivo and in vitro compared to cell transformation by v-myc or v-mil(raf) alone.

Ti-6Al-7Nb promotes cell spreading and fibronectin and osteopontin synthesis in osteoblast-like cells

The purpose of this study was to compare the early response of human osteoblast-like cells (SaOS-2) on commercially pure titanium (cpTi) and titanium-6-aluminium-7-niobium (Ti-6Al-7Nb) using glass slide as a control. In terms of cell attachment, no significance was observed when cells were seeded on the materials. However, morphological analysis by scanning electron microscope revealed that cells on Ti-6Al-7Nb showed better spreading after 4 hrs. After 48 hrs, both Western analysis and reverse transcription polymerase chain reaction analyses showed that cells cultured on Ti-6Al-7Nb synthesized a higher amount of fibronectin and osteopontin as compared to cells seeded on cpTi or on glass slide. These results suggest that Ti-6Al-7Nb possess a good potential to support SaOS-2 cells on spreading and fibronectin and osteopontin synthesis, therefore, this material may be one of a candidate material used in implant dentistry.

Transient suppression of PPARgamma directed ES cells into an osteoblastic lineage

Osteoblasts and adipocytes are believed to share a common progenitor. Peroxisome proliferator-activated receptor gamma (PPARgamma) plays a key role in the switching of these two cell lineages. Here, we demonstrated the differentiation of ES cells into an osteoblastic lineage using siRNA against PPARgamma without the addition of any osteogenic factors. We found that PPARgamma-siRNA downregulated the expression of aP2 mRNA and lipid accumulation, whereas it upregulated the expression of osteocalcin and calcium deposition. These results suggested that ES cells were directed into an osteoblastic lineage. Therefore, transient suppression using PPARgamma-siRNA may be a novel tool to induce differentiation of ES cells into osteoblasts.

Particle Size of Hydroxyapatite Granules Calcified from Red Algae Affects the Osteogenic Potential of Human Mesenchymal Stem Cells in vitro

Hydroxyapatite (HA) microparticles as a carrier in an injectable tissue-engineered bone filler are considered promising candidates for the treatment of small bone defects in the craniomaxillofacial region. HA granules calcified from red algae, varying in size, were evaluated in vitro for their suitability to be used as a carrier for human mesenchymal stem cells (hMSCs). Three groups of granules were produced in grain sizes of 10-100, 200-500 and 600-1,000 mum. After seeding and culturing hMSCs under osteogenic differentiation conditions onto HA particles for 3, 6 and 9 days, cellular proliferation (tetrazolium salt, XTT), alkaline phosphatase (ALP)-specific activity and total protein synthesis were investigated. The osteoblastic phenotype of the cells was evaluated by assaying the bone-specific genes osteocalcin, osteopontin and collagen type I. XTT assay revealed significantly higher (p < 0.01) proliferation of cells grown on the smallest grain size after 9 days of culture. Regarding ALP-specific activity, significantly higher levels of activity were detected in cells grown on the smallest grain size. Different grain sizes had no significant effects on the secretion of osteocalcin and osteopontin. Collagen type I production was significantly higher (p < 0.05) in cells grown on the biggest grain size in comparison with the two other grain sizes. These results show that the particle size of HA microparticles affects the osteogenic potential of cultured hMSCs and lead to the conclusion that particle size has differential effects on ALP-specific activity and collagen type I production.

Chemical and hormonal determinants of vascular calcification in vitro

Vascular calcification is a complex process that is dependent not only on the physicochemical effects of Ca, PO(4), and pH, but also on smooth muscle factors that may be regulated by these ions as well as by 1,25-dihydroxyvitamin D(3) (calcitriol) and parathyroid hormone (PTH). These minerals and hormones were tested in a model of medial calcification in rat aorta maintained in culture for 9 days. Calcification was quantitated as incorporation of (45)Ca, alkaline phosphatase activity was measured in aortic homogenates, and osteopontin production was measured from immunoblots of culture medium. At 1.8 mM Ca (1.46 mM free), calcification occurred at or above 2.8 mM PO(4). At 3.8 mM PO(4), calcification occurred at or above 1.10 mM free [Ca]. At a constant [Ca] x [PO(4)], calcification varied directly with [Ca] and inversely with [PO(4)]. Calcification was directly related to pH between 7.19 and 7.50 but not altered by PTH or calcitriol. Alkaline phosphatase activity and osteopontin production were increased by Ca, PO(4), calcitriol, and PTH. We conclude that calcification of rat aorta in vitro requires elevation of both [Ca] and [PO(4)], and that [Ca] rather than [PO(4)] or the product of the two is the dominant determinant. The induction of alkaline phosphatase and osteopontin indicates that Ca and PO(4) have effects in addition to simple physicochemical actions. Although PTH and calcitriol did not increase calcification in vivo, they have effects on smooth muscle that could influence calcification in vivo. Calcification is enhanced by alkalinity within the range produced during hemodialysis.

Glucocorticoid-induced osteogenesis is negatively regulated by Runx2/Cbfa1 serine phosphorylation

Glucocorticoid hormones have complex stimulatory and inhibitory effects on skeletal metabolism. Endogenous glucocorticoid signaling is required for normal bone formation in vivo, and synthetic glucocorticoids, such as dexamethasone, promote osteoblastic differentiation in several in vitro model systems. The mechanism by which these hormones induce osteogenesis remains poorly understood. We demonstrate here that the coordinate action of dexamethasone and the osteogenic transcription factor Runx2/Cbfa1 synergistically induces osteocalcin and bone sialoprotein gene expression, alkaline phosphatase activity, and biological mineral deposition in primary dermal fibroblasts. Dexamethasone decreased Runx2 phosphoserine levels, particularly on Ser125, in parallel with the upregulation of mitogen-activated protein kinase (MAPK) phosphatase-1 (MKP-1) through a glucocorticoid-receptor-mediated mechanism. Inhibition of MKP-1 abrogated the dexamethasone-induced decrease in Runx2 serine phosphorylation, suggesting that glucocorticoids modulate Runx2 phosphorylation via MKP-1. Mutation of Ser125 to glutamic acid, mimicking constitutive phosphorylation, inhibited Runx2-mediated osteoblastic differentiation, which was not rescued by dexamethasone treatment. Conversely, mutation of Ser125 to glycine, mimicking constitutive dephosphorylation, markedly increased osteoblastic differentiation, which was enhanced by, but did not require, additional dexamethasone supplementation. Collectively, these results demonstrate that dexamethasone induces osteogenesis, at least in part, by modulating the phosphorylation state of a negative-regulatory serine residue (Ser125) on Runx2. This work identifies a novel mechanism for glucocorticoid-induced osteogenic differentiation and provides insights into the role of Runx2 phosphorylation during skeletal development.

Genomic identification of potential risk factors during acetaminophen-induced liver disease in susceptible and resistant strains of mice

Drug-induced liver disease (DILD) continues to cause significant morbidity and mortality and impair new drug development. Mounting evidence suggests that DILD is a complex, multifactorial disease in which no one factor is likely to be an absolute indicator of susceptibility. As an approach to better understand the multifactorial basis of DILD, we recently compared the hepatic proteomes of mice that were resistant (SJL) and susceptible (C57Bl/6) to APAP-induced liver disease (AILD) wherein we identified potential risk factors and mechanistic pathways responsible for DILD. In this study, we have uncovered additional potential risk factors by comparing hepatic mRNA expression profiles of the same two strains of mice with that of SJLxB6-F1 hybrid (F1) mice, which were found to be of intermediate susceptibility to AILD. Global hepatic gene expression profiling over a 24 h period following APAP treatment revealed elevated patterns in the mRNA expression of cytoprotective genes in resistant SJL mice as compared to susceptible B6 mice, while F1 mice had intermediate mRNA expression levels of these genes. One of these genes encoded for heat shock protein (HSP) 70 whose relative protein expression among the three strains of mice was found to parallel that of their mRNA levels, suggesting that this protein had a protective role against AILD. However, there was no difference in the susceptibility of HSP70 knockout (KO) mice to AILD as compared to wild-type (WT) mice. There were also protoxicant genes, such as osteopontin (OPN), with elevated mRNA expression levels in the B6 mice as compared to the SJL mice and with intermediate levels in the F1 mice, suggesting that they may play a role in exacerbating liver injury after APAP treatment. In support of this hypothesis, OPN KO mice were found to be more resistant to AILD than WT mice. Additionally, the results from both the proteomic and the genomic studies were compared. The two approaches were found to be complementary to each other and not simply overlapping. Our findings suggest that comparative gene expression analysis of susceptible and resistant mouse strains may lead to the identification of factors that could have a role in determining the susceptibility of individuals to DILD.

Augmentation of osteopontin expression in renal tubuli is independent of a histopathological type of glomerular lesions in mouse lupus nephritis

Augmentation of osteopontin (OPN) expression in renal tubuli is often observed in lupus nephritis. To investigate whether this might depend on histopathological type of glomerular lesions, comparative studies of the distribution and levels of OPN expression in kidneys were performed by in situ hybridization and real-time polymerase chain reaction in mouse lupus nephritis manifesting inflammatory (endocapillary proliferative) and deposit (wire loop) types of glomerular lesions. These glomerular lesions were developed in C.B-17/Inc-scid/scid mice by injection of IgG3 antibody producing hybridoma clones, 2B11.3 and 7B6.8, respectively, which are derived from an MRL/Mp-lpr/lpr (MRL/lpr) lupus mouse. Both clones significantly augmented OPN expression in renal tubuli, but a non-nephritogenic IgG3 clone, 1G3, derived from the same MRL/lpr mouse, did not. The OPN augmentation was prominent in the renal cortex and the inner stripe of the outer medulla. These results indicate that OPN augmentation in renal tubuli is not associated with a histopathological type of glomerular lesion in lupus nephritis, at least not with an inflammatory or a deposit type.

Osteopontin participates in Th1-mediated host resistance against nonlethal malaria parasite Plasmodium chabaudi chabaudi infection in mice

Osteopontin (OPN) knockout mice (OPN-KO mice) died of Plasmodium chabaudi chabaudi infection, although wild-type (WT) mice had self-limiting infections. OPN was detected in the WT mice at 2 days postinfection. OPN-KO mice produced significantly smaller amounts of interleukin-12 and gamma interferon than WT mice produced. These results suggested that OPN is involved in Th1-mediated immunity against malaria infection.