Noncollagenous Extracellular Matrix Proteins Research Articles

Cartilage Oligomeric Matrix Protein in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and life threatening disease with median survival of 2.5–3 years. The IPF lung is characterized by abnormal lung remodeling, epithelial cell hyperplasia, myofibroblast foci formation, and extracellular matrix deposition. Analysis of gene expression microarray data revealed that cartilage oligomeric matrix protein (COMP), a non-collagenous extracellular matrix protein is among the most significantly up-regulated genes (Fold change 13, p-value <0.05) in IPF lungs. This finding was confirmed at the mRNA level by nCounter® expression analysis in additional 115 IPF lungs and 154 control lungs as well as at the protein level by western blot analysis. Immunohistochemical analysis revealed that COMP was expressed in dense fibrotic regions of IPF lungs and co-localized with vimentin and around pSMAD3 expressing cells. Stimulation of normal human lung fibroblasts with TGF-β1 induced an increase in COMP mRNA and protein expression. Silencing COMP in normal human lung fibroblasts significantly inhibited cell proliferation and negatively impacted the effects of TGF-β1 on COL1A1 and PAI1. COMP protein concentration measured by ELISA assay was significantly increased in serum of IPF patients compared to controls. Analysis of serum COMP concentrations in 23 patients who had prospective blood draws revealed that COMP levels increased in a time dependent fashion and correlated with declines in force vital capacity (FVC). Taken together, our results should encourage more research into the potential use of COMP as a biomarker for disease activity and TGF-β1 activity in patients with IPF. Hence, studies that explore modalities that affect COMP expression, alleviate extracellular matrix rigidity and lung restriction in IPF and interfere with the amplification of TGF-β1 signaling should be persuaded.

Ameloblastin Inhibits Cranial Suture Closure by Modulating Msx2 Expression and Proliferation

Deformities of cranial sutures such as craniosynostosis and enlarged parietal foramina greatly impact human development and quality of life. Here we have examined the role of the extracellular matrix protein ameloblastin (Ambn), a recent addition to the family of non-collagenous extracellular bone matrix proteins, in craniofacial bone development and suture formation. Using RT-PCR, western blot and immunohistochemistry, Ambn was localized in mouse calvarial bone and adjacent condensed mesenchyme. Five-fold Ambn overexpression in a K14-driven transgenic mouse model resulted in delayed posterior frontal suture fusion and incomplete suture closure. Moreover, Ambn overexpressor skulls weighed 13.2% less, their interfrontal bones were 35.3% thinner, and the width between frontal bones plus interfrontal suture was 14.3% wider. Ambn overexpressing mice also featured reduced cell proliferation in suture blastemas and in mesenchymal cells from posterior frontal sutures. There was a more than 2-fold reduction of Msx2 in Ambn overexpressing calvariae and suture mesenchymal cells, and this effect was inversely proportionate to the level of Ambn overexpression in different cell lines. The reduction of Msx2 expression as a result of Ambn overexpression was further enhanced in the presence of the MEK/ERK pathway inhibitor O126. Finally, Ambn overexpression significantly reduced Msx2 down-stream target gene expression levels, including osteogenic transcription factors Runx2 and Osx, the bone matrix proteins Ibsp, ColI, Ocn and Opn, and the cell cycle-related gene CcnD1. Together, these data suggest that Ambn plays a crucial role in the regulation of cranial bone growth and suture closure via Msx 2 suppression and proliferation inhibition.

Osteopontin expression is an independent factor for poor survival in oral squamous cell carcinoma: a computer‐assisted analysis on TMA sections

Osteopontin (OPN) is non-collagenous extracellular matrix protein involved in various physiological and pathological events, including tumor progression. The aim of this study was to analyze the expression of OPN in normal oral mucosa and oral squamous cell carcinoma (OSCC) and to assess its prognostic significance. The expression of OPN was immunohistochemicaly analyzed in 86 OSCC and compared with clinicopathological variable such as tumor size, nodal stage, WHO clinical stage, Ki-67 proliferation index, and patients' outcome. OPN mRNA was analyzed using quantitative real-time PCR and compared with protein OPN expression and clinical outcome in 18 OSCC samples. The expression of OPN protein was found in OSCC tumor cells (t-OPN) and various stromal cells (s-OPN). High level of t-OPN expression was associated with higher nodal stage (P=0.045), higher WHO clinical stage (P=0.033), and poor clinical outcome (P=0.022). In multivariate analysis, t-OPN emerged as an adverse independent factor for survival (P=0.049). Although correlated with t-OPN (P=0.005), s-OPN was not significantly associated with clinical parameters, including patients' outcome. Also, there was no association between OPN and clinical parameters at the mRNA level. OPN is upregulated in tumor and stromal OSCC cells. Tumor cell-derived OPN is involved in tumor progression and can independently predict the clinical outcome. Stromal-derived OPN probably has a different function compared with OPN secreted from tumor cells.

MECHANICAL SIGNALS REGULATE THE ANCHORAGE OF COMP IN THE CHONDROCYTE MATRIX

The extracellular matrix (ECM) of chondrocytes is assembled in response to mechanical signals. The non-collagenous ECM protein COMP (cartilage oligomeric matrix protein) stabilizes the collagen network by binding to collagen II and other ECM components [Rosenberg, 1998; Zaucke, 2009]. COMP plays an important role in cartilage adaptation in response to mechanical signals. Serum levels of COMP are elevated after running [Niehoff, 2011] and dynamic loading of chondrocytes in 3D agarose scaffolds increased its expression resulting in altered mechanical properties of the engineered cartilage [Ng, 2009]. However, the cause effect relationship between COMP and mechanical loading is not well understood. Therefore, the aim of the study was to investigate the effect of cyclic tensile strain on the expression and localization of COMP.

The rhPTH treatment elevates plasma secreted protein acidic and rich in cysteine levels in patients with osteoporosis

The secreted protein acidic and rich in cysteine (SPARC), also known as osteonectin, plays an important role in osteoblast formation, maturation, and survival. Here, we report the effects of recombinant human parathyroid hormone (1-34) [rhPTH (1-34)], a bone formation-stimulating agent, and elcatonin on plasma SPARC levels in patients with osteoporosis. The rhPTH (1-34) treatment significantly increased plasma SPARC levels, and the change of plasma SPARC correlated positively with changes of lumbar bone mineral density (BMD) at L2-L4. These results unveil that SPARC may be a novel marker related to the regulation of bone formation. rhPTH (1-34) is known to influence osteoclast maturation and activity through modulation of osteoblast-derived cytokines. SPARC is the most abundant noncollagenous extracellular matrix protein in the bone. So far, however, no study has reported the effects of rhPTH (1-34) administration on plasma SPARC levels in patients with osteoporosis. The purpose of this study was to compare the response of SPARC and BMD to rhPTH (1-34) and elcatonin in postmenopausal women with osteoporosis. Women were randomized to either once-daily subcutaneous injection of rhPTH (1-34) (20 μg, N = 89) or once-weekly intramuscular injection of elcatonin (200 U, N = 35) for 12 months. Plasma biochemical markers of bone turnover and BMD were measured at baseline, 6 and 12 months after treatment. At baseline, plasma SPARC levels correlated positively with lumbar spine BMD in all patients (r = 0.45, p = 0.001). Compared with baseline, at 12 months, rhPTH (1-34) significantly increased lumbar spine BMD and plasma SPARC levels (p = 0.008 and p = 0.001, respectively), whereas elcatonin was ineffective. More importantly, the changes of plasma SPARC correlated positively with changes of lumbar BMD at L2-L4 (r = 0.47, p = 0.001) in the rhPTH (1-34)-treated group, but not in the elcatonin group. The increase in plasma SPARC levels during the rhPTH (1-34) treatment may have contributed to the anabolic effect on bone formation, and SPARC may be a novel marker related to the regulation of bone formation.

Hydrogen Sulfide Suppresses Mineralized Nodule Formation by Osteoblastic ROS17/2.8 Cells

Hydrogen sulfide (H2S), which is the main component of the volatile sulfur compounds (VSCs) produced by putrefactive bacteria, plays a role in not only oral malodor, but also the initiation and progress of periodontitis. The loss of alveolar bone associated with periodontitis appears to be related to local factors that change the balance between bone formation and resorption. Previous studies have indicated that VSCs, including H2S, induce bone resorption by stimulating the differentiation and activation of osteoclasts; however, there is little information about the effect of VSCs on bone formation by osteoblasts. Therefore, we examined the effect of H2S on cell proliferation, alkaline phosphatase (ALPase) activity, non-collagenous extracellular matrix protein (ECMP) expression, and mineralized nodule formation using ROS17/2.8 cells as osteoblasts. Cells were cultured with 0 (control), 10-4, 10-3, or 10-2 M sodium hydrogen sulfide (NaHS; H2S donor). Mineralized nodule formation was detected by alizarin red staining. The expression of non-collagenous ECMP, including bone sialoprotein (BSP) and osteopontin (OPN), was examined at the mRNA and protein levels using real-time PCR and Western blotting, respectively. Cell proliferation was suppressed by the addition of 10-2 M NaHS, but was unaffected by 10-3 and 10-4 M NaHS. ALPase activity and the expression of BSP and OPN at the mRNA and protein levels were decreased when cells were cultured with 10-4 and/or 10-3 M NaHS. In addition, mineralized nodule formation was strongly inhibited by 10-4 and 10-3 M NaHS. These results suggest that H2S suppresses mineralized nodule formation by decreasing ALPase activity and the production of BSP and OPN by osteoblasts.

Sympathetic control of bone mass regulated by osteopontin

The sympathetic nervous system suppresses bone mass by mechanisms that remain incompletely elucidated. Using cell-based and murine genetics approaches, we show that this activity of the sympathetic nervous system requires osteopontin (OPN), a cytokine and one of the major members of the noncollagenous extracellular matrix proteins of bone. In this work, we found that the stimulation of the sympathetic tone by isoproterenol increased the level of OPN expression in the plasma and bone and that mice lacking OPN (OPN-KO) suppressed the isoproterenol-induced bone loss by preventing reduced osteoblastic and enhanced osteoclastic activities. In addition, we found that OPN is necessary for changes in the expression of genes related to bone resorption and bone formation that are induced by activation of the sympathetic tone. At the cellular level, we showed that intracellular OPN modulated the capacity of the β2-adrenergic receptor to generate cAMP with a corresponding modulation of cAMP-response element binding (CREB) phosphorylation and associated transcriptional events inside the cell. Our results indicate that OPN plays a critical role in sympathetic tone regulation of bone mass and that this OPN regulation is taking place through modulation of the β2-adrenergic receptor/cAMP signaling system.

Unraveling the Human Bone Microenvironment beyond the Classical Extracellular Matrix Proteins: A Human Bone Protein Library

A characteristic feature of bone, differentiating it from other connective tissues, is the mineralized extracellular matrix (ECM). Mineral accounts for the majority of the bone tissue volume, being the remainder organic material mostly derived from collagen. This, and the fact that only a limited number of noncollagenous ECM proteins are described, provides a limited view of the bone tissue composition and bone metabolism, the more so considering the increasing understanding of ECM significance for cellular form and function. For this reason, we set out to analyze and extensively characterize the human bone proteome using large-scale mass spectrometry-based methods. Bone samples of four individuals were analyzed identifying 3038 unique proteins. A total of 1213 of these were present in at least 3 out of 4 bone samples. For quantification purposes, we were limited to noncollagenous proteins (NCPs) and we could quantify 1051 NCPs. Most classical bone matrix proteins mentioned in literature were detected but were not among the highly abundant ones. Gene ontology analyses identified high-abundance groups of proteins with a functional link to mineralization and mineral metabolism such as transporters, pyrophosphatase activity, and Ca(2+)-dependent phospholipid binding proteins. ECM proteins were as well overrepresented together with nucleosome and antioxidant activity proteins, which have not been extensively characterized as being important for bone. In conclusion, our data clearly demonstrates that human bone tissue is a reservoir of a wide variety of proteins. In addition to the classical osteoblast-derived ECM, we have identified many proteins from different sources and of unknown function in bone. Thus, this study represents an informative library of bone proteins forming a source for novel bone formation modulators as well as biomarkers for bone diseases such as osteoporosis.

Dentin Matrix Protein 1 (DMP1) Signals via Cell Surface Integrin

Dentin matrix phosphoprotein 1 (DMP1) is a non-collagenous, acidic extracellular matrix protein expressed chiefly in bone and dentin. We examined the DMP1 ability to engage cell-surface receptors and subsequently activate intracellular signaling pathways. Our data indeed show that the presence of extracellular DMP1 triggers focal adhesion point formation in human mesenchymal stem cells and osteoblast-like cells. We determine that DMP1 acts via interaction with αvβ3 integrin and stimulates phosphorylation of focal adhesion kinase. Further biochemical characterization confirms the activation of downstream effectors of the MAPK pathways, namely ERK and JNK, after DMP1 treatment. This activation is specifically inhibitable and can also be blocked by the addition of anti-αvβ3 integrin antibody. Furthermore, we show that extracellular treatment with DMP1 stimulates the translocation of phosphorylated JNK to the nucleus and a concomitant up-regulation of transcriptional activation by phosphorylated c-Jun. The evidence presented here indicates that DMP1 is specifically involved in signaling via extracellular matrix-cell surface interaction. Combined with the published DMP1-null data (Feng, J. Q., Ward, L. M., Liu, S., Lu, Y., Xie, Y., Yuan, B., Yu, X., Rauch, F., Davis, S. I., Zhang, S., Rios, H., Drezner, M. K., Quarles, L. D., Bonewald, L. F., and White, K. E. (2006) Nat. Genet. 38, 1310-1315) it can be hypothesized that DMP1 could be a key effector of ECM-osteocyte signaling.

Extracellular Matrix Dynamics in Hepatocarcinogenesis: a Comparative Proteomics Study of PDGFC Transgenic and Pten Null Mouse Models

We are reporting qualitative and quantitative changes of the extracellular matrix (ECM) and associated receptor proteomes, occurring during the transition from liver fibrosis and steatohepatitis to hepatocellular carcinoma (HCC). We compared two mouse models relevant to human HCC: PDGFC transgenic (Tg) and Pten null mice, models of disease progression from fibrosis and steatohepatitis to HCC. Using mass spectrometry, we identified in the liver of both models proteins for 26 collagen-encoding genes, providing the first evidence of expression at the protein level for 16 collagens. We also identified post-transcriptional protein variants for six collagens and lysine hydroxylation modifications for 14 collagens. Tumor-associated collagen proteomes were similar in both models with increased expression of collagens type IV, VI, VII, X, XIV, XV, XVI, and XVIII. Splice variants for Col4a2, Col6a2, Col6a3 were co-upregulated while only the short form of Col18a1 increased in the tumors. We also identified tumor specific increases of nidogen 1, decorin, perlecan, and of six laminin subunits. The changes in these non-collagenous ECM proteins were similar in both models with the exception of laminin β3, detected specifically in the Pten null tumors. Pdgfa and Pdgfc mRNA expression was increased in the Pten null liver, a possible mechanism for the similarity in ECM composition observed in the tumors of both models. In contrast and besides the strong up-regulation of integrin α5 protein observed in the liver tumors of both models, the expression of the six other integrins identified was specific to each model, with integrins α2b, α3, α6, and β1 up-regulated in Pten null tumors and integrins α8 and β5 up-regulated in the PDGFC Tg tumors. In conclusion, HCC–associated ECM proteins and ECM–integrin networks, common or specific to HCC subtypes, were identified, providing a unique foundation to using ECM composition for HCC classification, diagnosis, prevention, or treatment.

The Sox2 high mobility group transcription factor inhibits mature osteoblast function in transgenic mice

We have previously shown that in osteoblasts Sox2 expression can be induced by Fgfs, and can inhibit Wnt signaling and differentiation. Furthermore, in mice in which Sox2 is conditionally deleted in the osteoblastic lineage, bones are osteopenic, and Sox2 inactivation in cultured osteoblasts leads to a loss of proliferative ability with a senescent phenotype. To help understand the role of Sox2 in osteoblast development we have specifically expressed Sox2 in bone from a Col1α1 promoter, which extended Sox2 expression into more mature osteoblasts. In long bones, trabecular cartilage remodeling was delayed and the transition from endochondral to cortical bone was disrupted, resulting in porous and undermineralized cortical bone. Collagen deposition was disorganized, and patterns of osteoclast activity were altered. Calvarial bones were thinner and parietal bones failed to develop the diploic space. Microarray analysis showed significant up- or downregulation of a variety of genes coding for non-collagenous extracellular matrix proteins, with a number of genes typical of mature osteoblasts being downregulated. Our results position Sox2 as a negative regulator of osteoblast maturation in vivo.

Expression of Phosphophoryn Is Sufficient for the Induction of Matrix Mineralization by Mammalian Cells

Mineralized tissues such as dentin and bone assemble extracellular matrices uniquely rich in a variety of acidic phosphoproteins. Although these proteins are presumed to play a role in the process of biomineralization, key questions regarding the nature of their contributions remain unanswered. First, it is not known whether highly phosphorylated proteins alone can induce matrix mineralization, or whether this activity requires the involvement of other bone/dentin non-collagenous proteins. Second, it remains to be established whether the protein kinases that phosphorylate these acidic proteins are unique to cells responsible for producing mineralized tissues. To begin to address these questions, we consider the case of phosphophoryn (PP), due to its high content of phosphate, high affinity for Ca(2+), and its potential role in hydroxyapatite nucleation. We have created a model system of biomineralization in a cellular environment by expressing PP in NIH3T3 fibroblasts (which do not produce a mineralized matrix); as a positive control, PP was expressed in MC3T3-E1 osteoblastic cells, which normally mineralize their matrices. We show that expression of PP in NIH3T3 cells is sufficient for the induction of matrix mineralization. In addition, assessment of the phosphorylation status of PP in these cells reveals that the transfected NIH3T3 cells are able to phosphorylate PP. We suggest that the phosphorylation of PP is essential for mineral formation. The principle goal of this study is to enrich the current knowledge of mineralized tissue phosphorylation events by analyzing them in the context of a complete cellular environment.

Intrafibrillar collagen mineralization produced by biomimetic hierarchical nanoapatite assembly.

Biomineralization templated by non-collagenous proteins is an example how nature uses nanotechnology to strengthen the load-bearing skeletons of vertebrates.[1–3] Mineralized collagen fibrils are responsible for the second level of hierarchy of bone structure[4] and account for its strength and toughness.[5] Calcium-deficient apatites are deposited in nanocrystalline form at the intrafibrillar and extrafibrillar spaces associated with the collagen fibrillar assembly.[6] Regulation of calcium phosphate phases during biomineralization is believed to exhibit two major characteristics.[7–9] The first is the sequestration of the calcium and phosphate ions into nanoscopic entities known as amorphous calcium phosphate (ACP). The second is the templating of mineral nucleation and growth through noncollagenous extracellular matrix proteins. These protein molecules contain polyanionic domains that are rich in polycarboxylic acid and phosphate function groups that bind to the collagen substrates at specific sites such as the gap zones of the collagen molecular assembly.[1,10] The immobilized proteins contain anionic charge sites wherein calcium binding and apatite nucleation occur at the aforementioned intrafibrillar locations. As a highly ordered manner of intrafibrillar mineralization at the nanoscale is responsible for the biomechanical properties of mineralized collagen,[11] this intricate biological process has inspired scientists to mimic its mechanism for creating mineralized type I collagen scaffolds to repair existing bone defects and/or generate new bone. Here, we demonstrate that the use of two phosphate-based templating analogs of matrix proteins in the presence of a polycarboxylic acid sequestration analog of ACPs results in a highly ordered intrafibrillar nanoapatite assembly that recapitulates the gap and overlap arrangement of collagen molecules within a collagen fibril. Adoption of a dual analog biomimetic strategy provides a means to produce advanced mineralized collagen scaffolds for tissue engineering applications.

Laminin database: a tool to retrieve high-throughput and curated data for studies on laminins

The Laminin(LM)-database, hosted at http://www.lm.lncc.br, is the first database focusing a non-collagenous extracellular matrix protein family, the LMs. Part of the knowledge available in this website is automatically retrieved, whereas a significant amount of information is curated and annotated, thus placing LM-database beyond a simple repository of data. In its home page, an overview of the rationale for the database is seen and readers can access a tutorial to facilitate navigation in the website, which in turn is presented with tabs subdivided into LMs, receptors, extracellular binding and other related proteins. Each tab opens into a given LM or LM-related molecule, where the reader finds a series of further tabs for ‘protein’, ‘gene structure’, ‘gene expression’ and ‘tissue distribution’ and ‘therapy’. Data are separated as a function of species, comprising Homo sapiens, Mus musculus and Rattus novergicus. Furthermore, there is specific tab displaying the LM nomenclatures. In another tab, a direct link to PubMed, which can be then consulted in a specific way, in terms of the biological functions of each molecule, knockout animals and genetic diseases, immune response and lymphomas/leukemias. LM-database will hopefully be a relevant tool for retrieving information concerning LMs in health and disease, particularly regarding the hemopoietic system.

Modulation of Proliferation and Differentiation of Human Anterior Cruciate Ligament–Derived Stem Cells by Different Growth Factors

We have previously isolated and identified stem cells from human cruciate ligaments. The goal of this study was to evaluate the proliferation and differentiation abilities of ligament-derived stem cells (LSCs) cultured with growth factors, including fibroblast growth factor 2 (FGF-2), epidermal growth factor, and transforming growth factor-beta 1 (TGF-b1). The ligament tissues were obtained from patients with anterior cruciate ligament injuries receiving arthroscopic surgeries. LSCs were obtained by collagenase digestion and plating as previously reported. Surface immunophenotype and the potential for trilineage differentiation into osteoblasts, chondrocytes, and adipocytes were confirmed. It was found that proliferation of the cells was enhanced with the addition of FGF-2 and TGF-b1. Upon TGF-b1 treatment, expression of collagen type I and type III, tenascin-c, fibronectin, and a-smooth muscle actin were significantly upregulated. Additionally, LSCs treated with TGF-b1 and FGF-2 increased the production of collagenous and noncollagenous extracellular matrix protein. Together, these results demonstrate that LSCs respond differently to various cytokines, and the results further validate the potential of using cruciate ligament tissue as a stem cell source for tissue engineering purposes.

The Role of Cartilage Oligomeric Matrix Protein (COMP) in Skeletal Disease

Cartilage oligomeric matrix protein is a non-collagenous extracellular matrix protein expressed primarily in cartilage, ligament, and tendon. Cartilage oligomeric matrix protein has been studied extensively because mutations in the gene cause two skeletal dysplasias, pseudoachondroplasia and multiple epiphyseal dysplasia. Pseudoachondroplasia is a disproportionate dwarfing condition associated with joint abnormalities, while multiple epiphyseal dysplasia is less severe. Both of these skeletal dysplasias have a characteristic chondrocyte pathology that consists of intracellular retention of cartilage oligomeric matrix protein and other extracellular matrix proteins in an enlarged rough endoplasmic reticulum. This toxic intracellular retention of extracellular matrix proteins causes chondrocyte cell death thereby decreasing linear bone growth. Additionally, when cartilage oligomeric matrix protein and the other co-retained proteins are not exported to the extracellular matrix, the resulting matrix is abnormal and easily erodes with normal physical activity. Cartilage oligomeric matrix protein is also a marker for joint destruction associated osteoarthritis, rheumatoid arthritis, joint trauma, and intense activity. Serum cartilage oligomeric matrix protein levels are higher in aggressive cases of arthritis and levels are used to predict future disease progression. Recent studies have identified molecular functions of cartilage oligomeric matrix protein that may contribute to its role in skeletal disease. These molecular functions include: binding other ECM proteins, catalyzing polymerization of type II collagen fibrils, and regulation of chondrocyte proliferation. Here, we review cartilage oligomeric matrix protein's role in skeletal disease and potential molecular mechanisms.

The effect of stromelysin-1 (MMP-3) on non-collagenous extracellular matrix proteins of demineralized dentin and the adhesive properties of restorative resins

Dentin non-collagenous matrix components (NCPs) are structural proteins involved in the formation, the architecture and the mineralization of the extracellular matrix (ECM). We investigated here how recombinant metalloproteinase stromelysin-1, also termed MMP-3, initiates the release of ECM molecules from artificially demineralized human dentin. Analysis of the supernatants by Western blotting reveals that MMP-3 extracts PGs (decorin, biglycan), and also a series of phosphorylated proteins: dentin sialoprotein (DSP), osteopontin (OPN), bone sialoprotein (BSP) and MEPE, but neither dentin matrix protein-1 (DMP1), another member of the SIBLING family, nor osteocalcin (OC), a non-phosphorylated matrix molecule. After treatment of dentin surfaces by MMP-3, scanning electron microscope (SEM) examination of resin replica shows an increased penetration of the resin into the dentin tubules when compared to surfaces only treated by demineralizing solutions. This preclinical investigation suggests that MMP-3 may be used to improve the adhesive properties of restorative materials.

Suppression of NFkappaB and its regulated gene products by oral administration of green tea polyphenols in an autochthonous mouse prostate cancer model.

This study examines the role of cell survival/apoptosis related proteins involved in NFkappaB signaling pathways and its associated events in GTP-induced chemoprevention of prostate cancer in TRAMP mice. Mice were given 0.1% GTP as drinking fluid. Western blot and immunohistochemical analysis performed to examine NFkappaB and its regulated pathway in response to GTP. Our data demonstrated increased expression of NFkappaB, IKKalpha, IKKbeta, RANK, NIK and STAT-3 in dorso-lateral prostate of TRAMP mice as a function of age and tumor growth and continuous GTP infusion for 32 weeks resulted in substantial reduction in these proteins. The levels of transcription factor osteopontin, a non-collagenous extracellular matrix protein, were also downregulated. Inhibition of NFkappaB signaling is known to activate apoptotic and inhibit anti-apoptotic proteins. Therefore, we analyzed Bax and Bcl2 levels in the dorsolateral prostate of TRAMP mice fed GTP and observed a shift in balance between Bax and Bcl2 favoring apoptosis. Based on the data we suggest that oral consumption of GTP might inhibit osteopontin and NFkappaB signaling that may contribute to induction of apoptosis observed in GTP fed TRAMP mice.

The Heat Is on

It is common knowledge that atherosclerosis is a multifactorial disease, and the disease-promoting role of classic risk factors for atherosclerosis, such as high serum cholesterol levels, diabetes, hypertension, smoking, and various types of infections, has been proven in innumerable clinical studies. Despite the fact that we are dealing with a chronic disease, however, there is a surprising scarcity of reports dealing with the very first stages of atherogenesis, ie, those that are not yet leading to clinical symptoms. It is now evident that inflammatory/immunologic processes play a major role in the development of atherosclerosis. The correlation between the presence and amount of inflammatory surrogate markers and the occurrence of sonographically demonstrable early arterial changes becomes more significant the earlier in the course of the disease that these analyses are performed. Although complicated atherosclerotic lesions, as the name implies, are composed of many different cellular and extracellular constituents, the earliest lesions are characterized by intimal infiltration by mononuclear cells often still without the presence of foam cells, especially in those instances in which risk factors other than high serum cholesterol levels are operative. In this context, it is important to remember that the first intima-infiltrating cells in early, clinically nonapparent lesions are lymphoid cells, followed by blood-borne monocytes, and finally smooth muscle cells immigrating from the media.1 Later, both the scavenger receptor–expressing macrophages and smooth muscle cells may transform into foam cells accompanied by fibroblast and myofibroblast proliferation with collagenous and noncollagenous extracellular matrix protein deposition leading to the paradigmatic hardening of the arterial wall. The antigenic specificity of early intima-infiltrating lymphoid cells is still to be determined. Article p 886 In this issue of Circulation , Park et al2 address the possible role of heat shock protein (HSP) 27 in atherogenesis. HSPs have risen to prominence in atherosclerosis …

Functional Knockout of the Matrilin-3 Gene Causes Premature Chondrocyte Maturation to Hypertrophy and Increases Bone Mineral Density and Osteoarthritis

Mutations in the gene encoding matrilin-3 (MATN3), a noncollagenous extracellular matrix protein, have been reported in a variety of skeletal diseases, including multiple epiphyseal dysplasia, which is characterized by irregular ossification of the epiphyses and early-onset osteoarthritis, spondylo-epimetaphyseal dysplasia, and idiopathic hand osteoarthritis. To assess the role of matrilin-3 in the pathogenesis of these diseases, we generated Matn3 functional knockout mice using embryonic stem cell technology. In the embryonic growth plate of the developing long bones, Matn3 null chondrocytes prematurely became prehypertrophic and hypertrophic, forming an expanded zone of hypertrophy. This expansion was attenuated during the perinatal period, and Matn3 homozygous null mice were viable and showed no gross skeletal malformations at birth. However, by 18 weeks of age, Matn3 null mice had a significantly higher total body bone mineral density than Matn1 null mice or wild-type littermates. Aged Matn3 null mice were much more predisposed to develop severe osteoarthritis than their wild-type littermates. Here, we show that matrilin-3 plays a role in modulating chondrocyte differentiation during embryonic development, in controlling bone mineral density in adulthood, and in preventing osteoarthritis during aging. The lack of Matn3 does not lead to postnatal chondrodysplasia but accounts for higher incidence of osteoarthritis.