Periostin is expressed within the developing teeth at the sites of epithelial-mesenchymal interaction

Periostin improves cell adhesion to implantable biomaterials and osteoblastic differentiation on implant titanium surfaces in a topography-dependent fashion

Periostin is a matricellular protein highly expressed in periodontal ligament and periostium and has been shown to be required for tissue development and maintenance. We showed that the adhesion of murine osteoblastic MC3T3 cells to thiolated hyaluronic acid/polyethyleneglycol hydrogels was greatly improved by enrichment with periostin. Polished or sand-blasted/acid-etched (SLA) commercially pure titanium surfaces were also coated with this protein and periostin ameliorated cell adhesion and dramatically affected cell morphology on both surfaces, as assessed at fluorescence microscopy, scanning electron microscopy, and chemiluminescence-based viability assay. Moreover, periostin increased the expression of alkaline phosphatase, osteoprotegerin, connective tissue growth factor, collagen 1a1, osteocalcin, Runx2, and osterix transcription factors on smooth surfaces. However, it did not affect, or even decreased, the expression of these genes on SLA discs. Transcript levels for connexin 43 were greatly increased on both surfaces in the presence of periostin. Taken together, these results show that periostin coatings can be a viable approach to improve cell adhesion and differentiation on implantable biomaterials.

Th2 cytokines efficiently stimulate periostin production in gingival fibroblasts but periostin does not induce an inflammatory response in gingival epithelial cells

OBJECTIVES

This study aims to clarify whether gingival fibroblasts produce periostin in response to Th2 cytokines which are elevated in periodontitis lesion and, if so, whether periostin affects the inflammatory response and matrix-protein metabolism.

DESIGN

Human gingival fibroblasts, periodontal ligament cells and the gingival epithelial cell line epi4 were stimulated with interleukin-4 (IL-4), IL-13, tumour necrosis factor-α (TNF-α) and Porphyromonas gingivalis lipopolysaccharide (LPS). Periostin expression was analysed by real-time polymerase chain-reaction (PCR) and Western blotting. The expression of the IL-4 receptor α-chain was evaluated by immunocytochemistry. The effect of periostin on the production of inflammatory cytokines and the expression of matrix protein-related genes was analysed by real-time PCR and enzyme-linked immunosorbent assay (ELISA).

RESULTS

While IL-4 and IL-13 significantly induced periostin production in gingival fibroblasts and periodontal ligament cells, no effect was observed in epi4 cells. No stimulatory effect of TNF-α or P. gingivalis LPS on the production of periostin was observed. The effect of periostin on the production of inflammatory cytokines was weak in gingival fibroblasts; however, little or no effect was observed on periodontal ligament cells or epi4 cells. No significant effect of periostin on the expression of matrix protein-related genes was found.

CONCLUSION

The results suggest that gingival fibroblasts may be a source of periostin in periodontitis lesions but periostin has only a limited role either in the inflammatory response or in matrix-protein metabolism. Thus, the role of periostin in the cellular interaction between epithelial and mesenchymal cells in gingiva may be distinct from that of skin.

Overexpression of periostin predicts poor prognosis in non-small cell lung cancer

The periostin protein, encoded by the POSTN gene, is a component of the extracellular matrix, which is expressed by fibroblasts and has been observed in a variety of human malignancies. The present study aimed to detect the expression of periostin in the tissues of non-small cell lung cancer (NSCLC) patients and benign lung tumors, and to correlate the results with the clinicopathological data of the subjects, in order to evaluate periostin as a potential prognostic marker. In total, 49 NSCLC patients and 6 benign lung tumors were included in this study. The protein level of periostin was detected in paired normal/paratumor/cancer tissues by a western blot analysis and the mRNA level in paired normal/cancer tissues was detected by quantitative polymerase chain reaction (qPCR). The results were then correlated with established biological and prognostic factors. Immunohistochemistry was used to confirm the location of periostin in the NSCLC tissues. Uni- and multivariate analyses were performed using Cox's proportional hazards regression model. The protein level of periostin was elevated in the cancer tissue of the NSCLC patients compared with the normal (P=0.017) and paratumor (P=0.000) tissues. The expression level in the male patients was much higher than in the female patients at the protein (P=0.001) and mRNA (P=0.010) levels. The mRNA level in the non-adenocarcinoma (non-ADC) patients was much higher than in the adenocarcinoma (ADC) patients (P=0.029). Periostin was demonstrated higher expression at the protein level in the pseudotumors and tuberculosis patients than in the adjacent (P=0.016) and surrounding tissues (P=0.001). Immunostaining indicated that high levels of periostin were present in the mesenchymal areas, but not in the cancer cells themselves. The patients with tumors exhibiting high-level periostin expression showed a significantly shorter survival time (P=0.036, log-rank test). The 3-year survival rate was 81.5% for patients with low-level periostin expression (periostin-L; n=27) and 45.4% for patients with high-level periostin expression (periostin-H; n=22). Similarly, pathological node (pN) status was a significant prognostic marker in the univariate Cox survival analysis. Notably, periostin-H expression was also identified as an independent prognostic factor by the multivariate analysis (P=0.011). These results showed that the overexpression of periostin predicts a poor prognosis, therefore it may be regarded as a novel molecule in the progression and development of NSCLC. The results provide an additional target for the adjuvant treatment of NSCLC.

Periostin downregulation is an early marker of inhibited neonatal murine lung alveolar septation

BACKGROUND

Extreme preterm birth exposes the saccular lung to multiple teratogens, which ultimately retard alveolar development. Specifically, therapeutic high level oxygen supplementation adversely affects the premature lungs and results in blunted alveolarization. Prolonged hyperoxic lung injury has previously been shown to upregulate the matricellular protein Periostin (Postn) and stimulate ectopic accumulation of alpha smooth muscle actin (αSMA) myofibroblasts. Therapies that promote lung septation are lacking largely due to a lack of reliable early biomarkers of injury. Thus, we determined if Postn expression correlated with the initial appearance of myofibroblasts in the saccular lung and was required for early alveolar development.

METHODS

Lung development in C57BL/6J mice following room-air (RA, 21%-O₂) or continuous hyperoxia (85%-O₂) from birth (P0) through postnatal day P14 was correlated with Postn and αSMA expression. Alveolarization in Postn knockout mice exposed to room-air, 60%-, and 85%-O₂ was also examined.

RESULTS

Postn was widely expressed in distal lung septa through P2 to P4 and peak expression coincided with accumulation of saccular myofibroblasts. Initially, 85%-O₂ prematurely downregulated Postn and αSMA expression and suppressed proliferation before the first evidence of distal lung simplification at P4. By P14, chronic 85%-O₂ resulted in secondary upregulation of Postn and αSMA in blunted septa. Myofibroblast differentiation and alveolar development was unaffected in Postn null mice and acute 85%-O₂ exposure equally inhibited septal formation in Postn null and wild-type littermates.

CONCLUSION

Postn expression is tightly correlated with the presence of αSMA-myofibroblasts and is a novel early biomarker of acutely inhibited alveolar septation during a crucial window of lung development.

Periostin-binding DNA aptamer inhibits breast cancer growth and metastasis

Periostin is an extracellular matrix (ECM) protein that is overexpressed in a variety of human cancers, and its functions appear to be linked to tumor growth, metastasis, and angiogenesis. Recent clinical evidence suggests that aberrant periostin expression is correlated with poor outcome in patients with breast cancer. To identify novel tools to regulate the functional role of periostin, we generated benzyl-d(U)TP-modified DNA aptamers that were directed against human periostin (PNDAs) and characterized their functional roles in breast cancer progression. PNDA-3 selectively bound to the FAS-1 domain of periostin with nanomolar affinity and disrupted the interaction between periostin and its cell surface receptors, αvβ3 and αvβ5 integrins. PNDA-3 markedly antagonized the periostin-induced adhesion, migration, and invasion of breast cancer cells and blocked the activation of various components of the αvβ3 and αvβ5 integrin signal transduction pathways. In a 4T1 orthotopic mouse model, PNDA-3 administration significantly reduced primary tumor growth and distant metastasis. Thus, our results demonstrated that periostin-integrin signaling regulates breast cancer progression at multiple levels in tumor cells and the tumor microenvironment. DNA aptamers targeting periostin may potentially be used to inhibit breast cancer progression.

Incremental evolution of the neural crest, neural crest cells and neural crest-derived skeletal tissues

Urochordates (ascidians) have recently supplanted cephalochordates (amphioxus) as the extant sister taxon of vertebrates. Given that urochordates possess migratory cells that have been classified as 'neural crest-like'- and that cephalochordates lack such cells--this phylogenetic hypothesis may have significant implications with respect to the origin of the neural crest and neural crest-derived skeletal tissues in vertebrates. We present an overview of the genes and gene regulatory network associated with specification of the neural crest in vertebrates. We then use these molecular data--alongside cell behaviour, cell fate and embryonic context--to assess putative antecedents (latent homologues) of the neural crest or neural crest cells in ascidians and cephalochordates. Ascidian migratory mesenchymal cells--non-pigment-forming trunk lateral line cells and pigment-forming 'neural crest-like cells' (NCLC)--are unlikely latent neural crest cell homologues. Rather, Snail-expressing cells at the neural plate of border of urochordates and cephalochordates likely represent the extent of neural crest elaboration in non-vertebrate chordates. We also review evidence for the evolutionary origin of two neural crest-derived skeletal tissues--cartilage and dentine. Dentine is a bona fide vertebrate novelty, and dentine-secreting odontoblasts represent a cell type that is exclusively derived from the neural crest. Cartilage, on the other hand, likely has a much deeper origin within the Metazoa. The mesodermally derived cellular cartilages of some protostome invertebrates are much more similar to vertebrate cartilage than is the acellular 'cartilage-like' tissue in cephalochordate pharyngeal arches. Cartilage, therefore, is not a vertebrate novelty, and a well-developed chondrogenic program was most likely co-opted from mesoderm to the neural crest along the vertebrate stem. We conclude that the neural crest is a vertebrate novelty, but that neural crest cells and their derivatives evolved and diversified in a step-wise fashion--first by elaboration of neural plate border cells, then by the innovation or co-option of new or ancient metazoan cell fates.

Prospective potency of TGF-β1 on maintenance and regeneration of periodontal tissue

Periodontal ligament (PDL) tissue, central in the periodontium, plays crucial roles in sustaining tooth in the bone socket. Irreparable damages of this tissue provoke tooth loss, causing a decreased quality of life. The question arises as to how PDL tissue is maintained or how the lost PDL tissue can be regenerated. Stem cells included in PDL tissue (PDLSCs) are widely accepted to have the potential to maintain or regenerate the periodontium, but PDLSCs are very few in number. In recent studies, undifferentiated clonal human PDL cell lines were developed to elucidate the applicable potentials of PDLSCs for the periodontal regenerative medicine based on cell-based tissue engineering. In addition, it has been suggested that transforming growth factor-beta 1 is an eligible factor for the maintenance and regeneration of PDL tissue.

Periostin is down-regulated during periodontal inflammation

Periostin, a matricellular adapter protein highly expressed by periodontal ligament fibroblasts, is implicated in the maintenance of periodontal integrity, which is compromised during periodontal diseases. The aim of this study was to explore the influence of chronic periodontal inflammation on tissue periostin levels. Periodontal breakdown was induced in a pre-clinical ligature periodontal inflammatory disease model. Periodontal tissue specimens were harvested at baseline, 2 weeks, and 4 weeks and prepared for histologic, immunofluorescence, and micro-CT examination. Statistical analyses were conducted by Kruskal-Wallis, Mann-Whitney, and Spearman's tests. Periostin detection levels were reduced over time in response to the inflammatory process (1 ± 0.05; 0.67 ± 0.03; 0.31 ± 0.02; p < 0.001; baseline, 2, and 4 weeks, respectively). Simultaneously, alveolar bone loss increased from baseline to the 2- and 4-week time-points (0.40 ± 0.02 mm; 1.39 ± 0.08 mm; 1.33 ± 0.15 mm; p < 0.001), which was inversely correlated with the levels of periostin (ρ = -0.545; p < 0.001). In conclusion, periostin PDL tissue levels significantly decrease under chronic inflammatory response and correlate with the detrimental changes to the periodontium over time.

The multiple facets of periostin in bone metabolism

Periostin is a matricellular glutamate-containing protein expressed during ontogenesis and in adult connective tissues submitted to mechanical strains including bone and, more specifically, the periosteum, periodontal ligaments, tendons, heart valves, or skin. It is also expressed in neoplastic tissues, cardiovascular and fibrotic diseases, and during wound repair. Its biological functions are extensively investigated in fields such as cardiovascular physiology or oncology. Despite its initial identification in bone, investigations of periostin functions in bone-related physiopathology are less abundant. Recently, several studies have analyzed the potential role of periostin in bone biology and suggest that periostin may be an important regulator of bone formation. The aim of this article is to provide an extensive review on the implications of periostin in bone biology and its potential use in benign and metabolic bone diseases.

Roles of collagen and periostin expression by cranial neural crest cells during soft palate development

The tissue in the palatal region can be divided into the hard and the soft palates, each having a specialized function such as occlusion, speech, or swallowing. Therefore, an understanding of the mechanism of palatogenesis in relation to the function of each region is important. However, in comparison with the hard palate, there is still a lack of information about the mechanisms of soft palate development. In this study, the authors investigated the contribution of cranial neural crest (CNC) cells to development of both hard and soft palates. They also demonstrated a unique pattern of periostin expression during soft palate development, which was closely related to that of collagen type I (Col I) in palatine aponeurosis. Furthermore, organ culture analysis showed that exogenous transforming growth factor-β (TGF-β) induced the expression of both periostin and Col I. These novel patterns of expression in the extracellular matrix (ECM) induced by CNC cells suggest that these cells may help to determine the character of both the hard and soft palates through ECM induction. TGF-β signaling appears to be one of the mediators of Col I and periostin expression in the formation of functional structures during soft palate development.

Periostin Expression is Altered in Aortic Valves in Smad6 Mutant Mice

Smad6 is known to predominantly inhibit BMP signaling by negatively regulating the BMP signaling process. Therefore, Smad6 mutation potentially provides an important genetic model for investigating the role of BMP signaling in vivo. Periostin is a 90-kDA secreted extracellular matrix (ECM) protein and implicated in cardiac valve progenitor cell differentiation, maturation and adult aortic valve calcification in mice. We have previously reported periostin expression patterns during AV valve development in mice. Because periostin can play critical roles in aortic valve interstitial cell differentiation and can be correlated with adult valve disease pathogenesis, in the present study we specifically focused on periostin expression during outflow tract (OT) development and its expression within the adult mouse valves. We previously reported that periostin expression in valve progenitor cells was altered by exogenously adding BMP-2 in culture. In this study, we investigated whether expression of periostin and other valvulogenic ECM proteins was altered in Smad6-mutant newborn mice in vivo. Periostin protein was localized within OT during embryonic development in mice. At embryonic day (ED) 13.5, robust periostin expression was detected within the developing pulmonary trunk and developing pulmonary and aortic valves. Periostin expression remained intense in pulmonary and aortic valves up to the adult stage. Our immunohistochemical and immunointensity analyses revealed that periostin expression was significantly reduced in the aortic valves in Smad6−/− neonatal hearts. Versican expression was also significantly reduced in Smad6−/− aortic valves, whereas, hyaluronan deposition was not significantly altered in the Smad6−/− neonatal valves. Expression of periostin and versican was less prominently affected in AV valves compared to the aortic valves, suggesting that a cell lineage/origin-dependent response to regulatory molecules may play a critical role in valve interstitial cell development and ECM protein expression.

Periostin: novel tissue and urinary biomarker of progressive renal injury induces a coordinated mesenchymal phenotype in tubular cells

BACKGROUND

Periostin acts as an adhesion molecule during bone formation. Knowledge of its expression in kidney injury is scant.

METHODS

We investigated periostin function and expression in vivo in Sprague-Dawley rats after 5/6 nephrectomy (Nx), in DBA2J mice with streptozotocin-induced diabetic nephropathy (SZ-DN) and unilateral ureteral obstruction (UUO) and in vitro in mouse distal collecting tubular cells (MDCT) and in tissue and urine from chronic kidney disease (CKD) patients.

RESULTS

Periostin messenger RNA was increased after 5/6Nx and SZ-DN demonstrating generalizability of the increment in renal injury. Periostin was expressed predominantly in distal tubule (DT) epithelial cell cytoplasm in situ, in cells shed into the lumen, and, in lesser abundance, in glomeruli undergoing obsolescence, arterioles and in the tubulointerstitium in extracellular and intracellular locations. In affected DT after 5/6Nx, periostin expression appeared de novo, E-cadherin became undetectable and tubule cells displayed the mesenchymal marker proteins fibroblast-specific protein-1 (FSP1) and matrix metalloproteinase-9 (MMP9). Periostin overexpression in cultured MDCT cells dramatically induced MMP9 and FSP1 protein and suppressed E-cadherin. Periostin short interfering RNA blocked these changes. Urine periostin excretion increased over time after 5/6Nx, and it was also excreted in the urine of CKD patients. Urine periostin enzyme-linked immunosorbent assay at a cutoff of 32.66 pg/mg creatinine demonstrated sensitivity and specificity for distinguishing patients with CKD from healthy people (92.3 and 95.0%, respectively) comparing favorably with urine neutrophil gelatinase-associated lipocalin.

CONCLUSION

These data demonstrate that periostin is a mediator and marker of tubular dedifferentiation and a promising tissue and urine biomarker for kidney injury in experimental models and in clinical renal disease.

Characterization of periostin isoform pattern in non-small cell lung cancer

INTRODUCTION

The extracellular matrix N-glycoprotein periostin (OSF-2, POSTN) is a major constituent of the desmoplastic stroma around solid tumors. It promotes tumor invasion and metastasis via epithelial-mesenchymal transition (EMT). In this study we investigated periostin expression at both RNA and protein level as well as the expression pattern of its splice isoforms in non-small cell lung cancer (NSCLC).

METHODS

Thirty fresh frozen and corresponding formalin-fixed NSCLC tissues (adeno- and squamous cell carcinoma subtype, each n=15) and their matched non-neoplastic tissues were investigated. Periostin mRNA levels were analyzed by quantitative RT-PCR. The EMT-markers periostin and vimentin were analyzed by immunohistochemistry. Laser capture microdissection allowed for analysis of periostin expression in tumor epithelia and stroma, separately. Isoform patterns were investigated by isoform-specific PCR following sequencing in NSCLC, fetal and adult normal lung tissue.

RESULTS

The qRT-PCR analysis showed periostin mRNA up-regulation in NSCLC tissue in relation to normal lung, with significantly higher levels in the adeno-compared to the squamous cell subtype (p<0.05). However, protein levels in both tumor epithelia and stroma correlated with squamous cell carcinoma (p<0.001) and larger tumor size (p<0.05). Further, periostin tumor epithelia expression, correlated with higher tumor grade (p<0.05). Sequence analysis detected eight periostin isoforms in fetal lung, but only five in both NSCLC and matched normal lung tissue. Among the eight isoforms, four are new and were labelled 5, 7, 8 and 9. The exclusive presence of isoforms 1 and 9 in fetal tissue suggests splice-specific regulation during lung embryogenesis. Finally, laser capture microdissection demonstrated that both tumor epithelia and stromal cells can be a source of periostin production in NSCLC.

CONCLUSIONS

This study represents the first analysis of periostin isoform expression patterns in NSCLC and a characterization of periostin expression in cancer versus stromal cells at both RNA and protein level.

The haploinsufficient hematopoietic microenvironment is critical to the pathological fracture repair in murine models of neurofibromatosis type 1

Germline mutations in the NF1 tumor suppressor gene cause neurofibromatosis type 1 (NF1), a complex genetic disorder with a high predisposition of numerous skeletal dysplasias including short stature, osteoporosis, kyphoscoliosis, and fracture non-union (pseudoarthrosis). We have developed murine models that phenocopy many of the skeletal dysplasias observed in NF1 patients, including reduced bone mass and fracture non-union. We also show that the development of these skeletal manifestations requires an Nf1 haploinsufficient background in addition to nullizygous loss of Nf1 in mesenchymal stem/progenitor cells (MSCs) and/or their progenies. This is replicated in two animal models of NF1, PeriCre⁺;Nf1^flox/− and Col2.3Cre⁺;Nf1^flox/−mice. Adoptive transfer experiments demonstrate a critical role of the Nf1+/− marrow microenvironment in the impaired fracture healing in both models and adoptive transfer of WT bone marrow cells improves fracture healing in these mice. To our knowledge, this is the first demonstration of a non-cell autonomous mechanism in non-malignant NF1 manifestations. Collectively, these data provide evidence of a combinatory effect between nullizygous loss of Nf1 in osteoblast progenitors and haploinsufficiency in hematopoietic cells in the development of non-malignant NF1 manifestations.

Odontogenic differentiation of human dental pulp stem cells induced by preameloblast-derived factors

The differentiation of odontoblasts is initiated by the organization of differentiating ameloblasts during tooth formation. However, the exact roles of ameloblast-derived factors in odontoblast differentiation have not yet been characterized. We investigated the effects of preameloblast-conditioned medium (PA-CM) on the odontogenic differentiation of human dental pulp stem cells (hDPSCs) in vitro and in vivo. Furthermore, we analyzed the PA-CM by liquid chromatography-mass spectrometry to identify novel factors that facilitate odontoblast differentiation. In the co-culture of MDPC-23 cells or hDPSCs with mouse apical bud cells (ABCs), ABCs promoted differentiation of odontoblastic MDPC-23 cells and facilitated odontoblast differentiation of hDPSCs. PA-CM, CM from ABCs after 3 days culture, was most effective in increasing the dentin sialophosphoprotein promoter activity of odontoblastic MDPC-23 cells. When PA-CM-treated hDPSCs were transplanted into immunocompromised mice, they generated pulp-like structures lined with human odontoblast-like cells showing typical odontoblast processes. However, during recombinant human bone morphogenenetic protein 2-treated hDPSCs transplantation, some of the cells were entrapped in mineralized matrix possessing osteocyte characteristics. After proteomic analyses, we identified 113 types of proteins in PA-CM, of which we characterized 23. The results show that preameloblast-derived factors induce the odontogenic differentiation of hDPSCs and promote dentin formation.

A protective role for periostin and TGF-β in IgE-mediated allergy and airway hyperresponsiveness

Background

The pathophysiology of asthma involves allergic inflammation and remodelling in the airway and airway hyperresponsiveness (AHR) to cholinergic stimuli, but many details of the specific underlying cellular and molecular mechanisms remain unknown. Periostin is a matricellular protein with roles in tissue repair following injury in both the skin and heart. It has recently been shown to be up-regulated in the airway epithelium of asthmatics and to increase active TGF-β. Though one might expect periostin to play a deleterious role in asthma pathogenesis, to date its biological role in the airway is unknown.

Objective

To determine the effect of periostin deficiency on airway responses to inhaled allergen.

Methods

In vivo measures of airway responsiveness, inflammation, and remodelling were made in periostin deficient mice and wild-type controls following repeated intranasal challenge with Aspergillus fumigatus antigen. In vitro studies of the effects of epithelial cell-derived periostin on murine T cells were also performed.

Results

Surprisingly, compared with wild-type controls, periostin deficient mice developed increased AHR and serum IgE levels following allergen challenge without differences in two outcomes of airway remodelling (mucus metaplasia and peribronchial fibrosis). These changes were associated with decreased expression of TGF-β1 and Foxp3 in the lungs of periostin deficient mice. Airway epithelial cell-derived periostin-induced conversion of CD4⁺ CD25⁻ cells into CD25⁺, Foxp3⁺ T cells in vitro in a TGF-β dependent manner.

Conclusions and Clinical Relevance

Allergen-induced increases in serum IgE and bronchial hyperresponsiveness are exaggerated in periostin deficient mice challenged with inhaled aeroallergen. The mechanism of periostin's effect as a brake on allergen-induced responses may involve augmentation of TGF-β-induced T regulatory cell differentiation.

Expression patterns and roles of periostin during kidney and ureter development

PURPOSE

Periostin is a secreted extracellular matrix protein that is differentially expressed in the developing kidney. We analyzed the temporal-spatial expression of periostin in the developing kidney and ureter as well as its roles in ureter branching morphogenesis, nephrogenesis and ureter development.

MATERIALS AND METHODS

RNA in situ hybridization and immunofluorescence histochemistry were used to investigate the expression of periostin, αv integrin and α-smooth muscle actin during mouse renal and ureteral development. Metanephric explants were cultured in the presence of recombinant periostin, and ureteral branch points/tips and the glomerular number were quantified. Explants were also cultured in the presence of exogenous bone morphogenetic protein 4 and the effect on periostin mRNA levels was determined by quantitative real-time polymerase chain reaction.

RESULTS

Periostin expression was observed in the mesenchyme surrounding the kidney and ureter, renal stroma, metanephric mesenchyme, ureter epithelium and developing nephrons. At embryonic day 15.5 periostin and αv integrin, a common subunit of periostin receptors, were co-expressed in smooth muscle cells of the ureter, renal artery and intrarenal arteries. Bone morphogenetic protein 4 up-regulated periostin mRNA expression and exogenous periostin inhibited branching morphogenesis and glomerular number.

CONCLUSIONS

Bone morphogenetic protein 4 which inhibits ureteral branching morphogenesis and promotes smooth muscle cell migration in the ureter up-regulated periostin mRNA expression in the developing kidney. Ureteral smooth muscle cells express periostin and αv integrin. Periostin inhibited ureteral branching morphogenesis and glomerular number. Together these results suggest that periostin and bone morphogenetic protein 4 may have a role in branching morphogenesis, nephrogenesis and possibly smooth muscle cell migration.

Relevance of periostin splice variants in renal cell carcinoma

The extracellular matrix N-glycoprotein periostin is thought to enhance tumor invasion. In this study, the expression patterns of periostin and its splice isoforms were investigated in renal cell carcinoma (RCC). Periostin mRNA expression patterns were characterized in 30 fresh-frozen RCCs in normal fetal and adult renal tissues by both isoform-specific and nonspecific RT-PCR and by gene expression array analysis. Its protein expression was analyzed by immunohistochemistry, using tissue microarrays with tissue from 1007 RCC patients. Periostin mRNA in RCC was increased, as observed in both RT-PCR and gene microarray analyses, with significantly higher expression in the clear cell than in the papillary subtype. Four of eight periostin isoforms, identified in fetal kidney by direct sequencing, have not been described to date. Three isoforms could be detected in both RCC and matched non-neoplastic tissue, and one of them was expressed more frequently in RCC. Periostin protein was detected in both mesenchymal cells of the tumor stroma and epithelial tumor cells. Greater amounts of periostin in tumor epithelia correlated with the presence of sarcomatoid differentiation, higher tumor stage, lymph node metastases, and poor overall survival in the clear cell subtype. In conclusion, periostin expression in tumor epithelia may contribute to sarcomatoid differentiation and more aggressive behavior of RCC. The presence of a tumor-associated periostin isoform suggests splice-specific regulation in RCC tissue.

Periostin as a heterofunctional regulator of cardiac development and disease

Periostin (Postn) is a heterofunctional secreted extracellular matrix (ECM) protein comprised of four fasciclin domains that promotes cellular adhesion and movement, as well as collagen fibrillogenesis. Postn is expressed in unique growth centers during embryonic development where it facilitates epithelial-mesenchymal transition (EMT) of select cell populations undergoing reorganization. In the heart, Postn is expressed in the developing valves, cardiac fibroblasts and in regions of the outflow track. In the adult, Postn expression is specifically induced in areas of tissue injury or areas with ongoing cellular re-organization. In the adult heart Postn is induced in the ventricles following myocardial infarction, pressure overload stimulation, or generalized cardiomyopathy. Here we will review the functional consequences associated with Postn induction in both the developing and adult heart. The majority of data collected to date suggest a common function for Postn in both development and disease as a potent inducible regulator of cellular reorganization and extracellular matrix homeostasis, although some alternate and controversial functions have also been ascribed to Postn, the validity of which will be discussed here.

Periostin gene polymorphisms, protein levels and risk of incident coronary artery disease

Vascular endothelial growth factor and its receptor the kinase domain receptor play critical roles in the pathogenesis of coronary artery disease. Periostin is an up-regulator of kinase domain receptor expression. The purpose of this study was to determine whether polymorphisms in periostin are associated with the risk of coronary artery disease. Two single nucleotide polymorphisms (SNP C-33G, SNP A-953T) within the promoter region were chosen for further analyses. A case-control study was carried out with patients of Han Chinese ethnicity, which consisted of 492 coronary artery disease cases and 498 controls. Genotyping was performed by means of PCR and restriction fragment length polymorphism (PCR-RFLP) and the plasma level of periostin was measured by enzyme-linked immunosorbent assay (ELISA). In our study, the TT genotype of SNP-A953T was present in the general Chinese population (3.5%), but not in the Han Chinese from Beijing Project (HAPMAP CHB). Plasma periostin concentrations were elevated significantly in patients with coronary artery disease (7.96±8.33 nmol/l) compared with those in healthy volunteers (3.93±1.71 nmol/l) (P=0.005). There was a significant correlation between the 953T genotype and the plasma level of periostin (r2=-0.490, P=0.039). The prevalence of the TT genotype in patients was associated with a slightly lower risk of coronary artery disease (OR=0.443, 95% CI=0.200-0.982), but was not significant after correction (OR=0.427, 95% CI=0.146-1.250). The periostin-33G allele frequency was not significantly different in cases versus controls. Our data suggest that plasma periostin level may serve as a biomarker for the risk of coronary artery disease, but the periostin polymorphisms SNPC-33G and SNPA-953T were not significantly associated with the risk of coronary artery disease in this Chinese population. Although a major effect of the SNPs in the periostin genes on coronary artery disease susceptibility was excluded, the effect of the A-953T SNP on susceptibility and protein expression needs further investigation.

In vitro requirement for periostin in B lymphopoiesis

B lymphopoiesis arrests in rabbits by 4 months of age. To identify molecules that contribute to this arrest, cDNA-representational difference analysis on BM stromal cells from young and adult rabbits showed that expression of Postn that encodes for the extracellular matrix protein periostin dramatically reduced with age. Postn-small interfering RNA OP9 cells lost their capacity to support B-cell development from rabbit or murine BM cells, and reexpression of periostin restored this potential, indicating an in vitro requirement for periostin in B lymphopoiesis. In our system, we determined that periostin deficiency leads to increased cell death and decreased proliferation of B-lineage progenitors. Further, RGD peptide inhibition of periostin/α(v)β(3) interaction resulted in a marked decrease in B lymphopoiesis in vitro. Microarray analysis of the Postn-small interfering RNA OP9 cells showed decreased expression of key B-lymphopoietic factors, including IL-7 and CXCL12. In vivo, unidentified molecule(s) probably compensate periostin loss because Postn(-/-) mice had normal numbers of B-cell progenitors in BM. We conclude that the decline in periostin expression in adult rabbit BM does not solely explain the arrest of B lymphopoiesis. However, the interaction of periostin with α(v)β(3) on lymphoid progenitors probably provides both proliferative and survival signals for cells in the B-cell development pathway.

Defective Tbx2-dependent patterning of the atrioventricular canal myocardium causes accessory pathway formation in mice

Ventricular preexcitation, a feature of Wolff-Parkinson-White syndrome, is caused by accessory myocardial pathways that bypass the annulus fibrosus. This condition increases the risk of atrioventricular tachycardia and, in the presence of atrial fibrillation, sudden death. The developmental mechanisms underlying accessory pathway formation are poorly understood but are thought to primarily involve malformation of the annulus fibrosus. Before birth, slowly conducting atrioventricular myocardium causes a functional atrioventricular activation delay in the absence of the annulus fibrosus. This myocardium remains present after birth, suggesting that the disturbed development of the atrioventricular canal myocardium may mediate the formation of rapidly conducting accessory pathways. Here we show that myocardium-specific inactivation of T-box 2 (Tbx2), a transcription factor essential for atrioventricular canal patterning, leads to the formation of fast-conducting accessory pathways, malformation of the annulus fibrosus, and ventricular preexcitation in mice. The accessory pathways ectopically express proteins required for fast conduction (connexin-40 [Cx40], Cx43, and sodium channel, voltage-gated, type V, α [Scn5a]). Additional inactivation of Cx30.2, a subunit for gap junctions with low conductance expressed in the atrioventricular canal and unaffected by the loss of Tbx2, did not affect the functionality of the accessory pathways. Our results suggest that malformation of the annulus fibrosus and preexcitation arise from the disturbed development of the atrioventricular myocardium.

Stem cells isolated from human dental follicles have osteogenic potential

OBJECTIVE

Stem cells isolated from human dental follicles as a potential cell source for bone-tissue engineering were examined for correcting a critical bone defect.

STUDY DESIGN

Impacted third molars were collected and single cell-derived cell populations were cultivated in growth medium. Single cell-derived cell lines were examined in terms of cell shape, gene expression patterns, differentiation capacity in vitro, and osteogenic potential in vivo.

RESULTS

Three distinct cell populations were identified with different morphologies, patterns of gene expression, and differentiation capacity. All 3 cell populations promoted bone formation when transplanted into surgically created critical-size defects in immunodeficient rat calvaria, compared with control animals without cell transplantation, although one of these populations showed a weak capacity for osteogenetic differentiation in vitro.

CONCLUSIONS

Human dental follicle can derive at least 3 unique cell populations in culture, all of which promote bone formation in vivo.

A novel role of periostin in postnatal tooth formation and mineralization

Periostin plays multiple functions during development. Our previous work showed a critical role of this disulfide-linked cell adhesion protein in maintenance of periodontium integrity in response to occlusal load. In this study, we attempted to address whether this mechanical response molecule played a direct role in postnatal tooth development. Our key findings are 1) periostin is expressed in preodontoblasts, and odontoblasts; and the periostin-null incisor displayed a massive increase in dentin formation after mastication; 2) periostin is also expressed in the ameloblast cells, and an enamel defect is identified in both the adult-null incisor and molar; 3) deletion of periostin leads to changes in expression profiles of many non-collagenous protein such as DSPP, DMP1, BSP, and OPN in incisor dentin; 4) the removal of a biting force leads to reduction of mineralization, which is partially prevented in periostin-null mice; and 6) both in vitro and in vivo data revealed a direct regulation of periostin by TGF-β1 in dentin formation. In conclusion, periostin plays a novel direct role in controlling postnatal tooth formation, which is required for the integrity of both enamel and dentin.

Spatiotemporal localization of periostin and its potential role in epithelial-mesenchymal transition during palatal fusion

The medial epithelial seam (MES) between the palatal shelves degrades during palatal fusion to achieve the confluence of palatal mesenchyme. Cellular mechanisms underlying the degradation of MES have been proposed, such as apoptosis, epithelial-mesenchymal transition (EMT) and migration of medial edge epithelia (MEE). Extracellular matrix components have been shown to play an important role in EMT in many model systems. Periostin (also known as osteoblast-specific factor-2) is a secreted mesenchymal extracellular matrix component that affects the ability of cells to migrate and/or facilitates EMT during both embryonic development and pathologic conditions. In this study, we evaluated the spatiotemporal expression patterns of periostin during mouse palatal fusion by in situ hybridization and immunofluorescence. Periostin mRNA and protein were present in the palatal mesenchyme, the protein being distributed in a fine fibrillar network and in the basement membrane, but absent from the epithelium. During MES degradation, the protein was strongly expressed in the basement membrane underlying the MES and in some select MEE. Confocal microscopic analysis using an EMT marker, twist1, and an epithelial marker, cytokeratin 14, provided evidence that select MEE were undergoing EMT in association with periostin. Moreover, the major extracellular matrix molecules in basement membrane, laminin and collagen type IV were degraded earlier than periostin. The result is that select MEE establish interactions with periostin in the mesenchymal extracellular matrix, and these new cell-matrix interactions may regulate MEE transdifferentiation during palatal fusion.

Increased expression and serum levels of the stromal cell-secreted protein periostin in breast cancer bone metastases

Periostin, a matricellular protein, is overexpressed in the stroma of several cancers. The aim of our study was to investigate more specifically whether periostin expression is associated with bone metastases from breast cancer and to determine its source in the affected bone. Nude mice were inoculated with human MDA-B02 breast cancer cells. Bone metastases-bearing mice were treated with zoledronic acid-an antiresorptive drug-or vehicle. Bone metastases were examined for tumor- and stroma-derived periostin expression by quantitative polymerase chain reaction with human- and mouse-specific primers and immunohistochemistry. Serum periostin and conventional bone turnover markers were also measured. MDA-B02 cells did not express periostin both in vitro and in vivo. However, mouse-derived periostin was markedly overexpressed (eightfold) in metastatic legs compared to noninoculated mice. Serum periostin levels were also markedly increased in metastatic mice and correlated with in situ expression levels. Immunostaining showed that periostin derived from the environing stromal cells of bone metastasis. Bone turnover blockade by zoledronic acid markedly decreased osteolytic lesions but only slightly modulated serum periostin levels. Bone metastases from breast cancer induce overexpression of periostin by surrounding stromal cells. Periostin could be a biochemical marker of the early stromal response associated to breast cancer bone metastasis formation.

Development of a new ELISA for serum periostin: evaluation of growth-related changes and bisphosphonate treatment in mice

Periostin is a gamma-carboxyglutamic acid protein preferentially expressed in periosteum and bone mesenchymal stem cells. Lack of a precise assay for measuring circulating levels impairs the investigation of its biological significance. We developed a new ELISA and studied changes of periostin levels both locally at the bone site and systemically in circulating blood during growth and after bisphosphonate-induced inhibition of bone remodeling in the mouse. The ELISA we developed is based on an affinity-purified polyclonal antibody that was raised against the C-terminal sequence of mouse periostin. Reproducibility, repeatability, precision, and accuracy tests met standards of acceptance. Serum periostin and levels of the bone turnover markers osteocalcin, PINP, CTX-I, and TRAP5b were measured in (1) 4-, 6-, 8-, 10-, and 12-week-old wild-type female Balb/c mice and (2) adult ovariectomized female Balb/c mice treated with zoledronic acid or vehicle. Serum periostin decreased during growth and stabilized from 8 weeks and older, its levels correlating with bone turnover markers. Immunohistochemistry in bones from different growth stages showed that periostin localized specifically at the sites of endochondral and intramembranous ossification, especially at the periosteal envelopes. Zoledronic acid induced a marked decrease in bone remodeling markers but did not alter serum periostin levels or periostin immunostaining pattern. The novel ELISA is highly specific and allows accurate and precise measurements of serum periostin levels in mice.

Cardiac fibrosis in mice with hypertrophic cardiomyopathy is mediated by non-myocyte proliferation and requires Tgf-β

Mutations in sarcomere protein genes can cause hypertrophic cardiomyopathy (HCM), a disorder characterized by myocyte enlargement, fibrosis, and impaired ventricular relaxation. Here, we demonstrate that sarcomere protein gene mutations activate proliferative and profibrotic signals in non-myocyte cells to produce pathologic remodeling in HCM. Gene expression analyses of non-myocyte cells isolated from HCM mouse hearts showed increased levels of RNAs encoding cell-cycle proteins, Tgf-β, periostin, and other profibrotic proteins. Markedly increased BrdU labeling, Ki67 antigen expression, and periostin immunohistochemistry in the fibrotic regions of HCM hearts confirmed the transcriptional profiling data. Genetic ablation of periostin in HCM mice reduced but did not extinguish non-myocyte proliferation and fibrosis. In contrast, administration of Tgf-β-neutralizing antibodies abrogated non-myocyte proliferation and fibrosis. Chronic administration of the angiotensin II type 1 receptor antagonist losartan to mutation-positive, hypertrophy-negative (prehypertrophic) mice prevented the emergence of hypertrophy, non-myocyte proliferation, and fibrosis. Losartan treatment did not reverse pathologic remodeling of established HCM but did reduce non-myocyte proliferation. These data define non-myocyte activation of Tgf-β signaling as a pivotal mechanism for increased fibrosis in HCM and a potentially important factor contributing to diastolic dysfunction and heart failure. Preemptive pharmacologic inhibition of Tgf-β signals warrants study in human patients with sarcomere gene mutations.

Periostin promotes ovarian cancer angiogenesis and metastasis

OBJECTIVE

Perostin (PN) has been found to be overexpressed in a variety of human malignancies including ovarian cancer. In the present study, we investigated PN expression status in a large cohort of ovarian tumors with the focus on biological influence of PN related on ovarian tumor angiogenesis and metastasis.

METHODS

PN expression was determined by cDNA microarray, PN northern blot and PN IHC tissue array analyses. Exogenous PN expression in ovarian cancer cells OVCAR-3 and OV2008 were achieved through retroviral transfection and confirmed by PN western blot and ELISA. The effects of exogenous PN expression on tumor angiogenesis and metastatic growth were accessed in orthotopic mouse models. The in vitro cell adhesion, migration and invasion assays were performed to investigate the potential mechanisms involved in PN's in vivo effects.

RESULTS

PN was frequently overexpressed in ovarian tumors. Higher PN levels significantly correlated with clinical late stages (III/IV) and cancer recurrence. PN was produced by engineered PN-overexpressing cells at levels comparable to that of A2780 cells, an ovarian carcinoma cell line with endogenous PN expression. PN overexpression did not change cell growth rates in vitro; however it significantly promoted intraperitoneal tumor metastatic growth in immunodeficient mice, which was associated with increased tumor angiogenesis and decreased tumor cell apoptosis. In vitro purified PN promoted cell adhesion, migration, and invasion of both human umbilical endothelial cells (HUVECs) and/or ovarian cancer cells.

CONCLUSIONS

Our data indicate PN plays a critical role in both ovarian tumor angiogenesis and metastasis. Thus PN may represent a clinically effective new target for therapy of ovarian cancer.

Periostin is up-regulated in high grade and high stage prostate cancer

BACKGROUND

Expression of periostin is an indicator of epithelial-mesenchymal transition in cancer but a detailed analysis of periostin expression in prostate cancer has not been conducted so far.

METHODS

Here, we evaluated periostin expression in prostate cancer cells and peritumoural stroma immunohistochemically in two independent prostate cancer cohorts, including a training cohort (n = 93) and a test cohort (n = 325). Metastatic prostate cancers (n = 20), hormone refractory prostate cancers (n = 19) and benign prostatic tissues (n = 38) were also analyzed.

RESULTS

In total, strong epithelial periostin expression was detectable in 142 of 418 (34.0%) of prostate carcinomas and in 11 of 38 benign prostate glands (28.9%). Increased periostin expression in carcinoma cells was significantly associated with high Gleason score (p < 0.01) and advanced tumour stage (p < 0.05) in the test cohort. Whereas periostin expression was weak or absent in the stroma around normal prostate glands, strong periostin expression in tumour stroma was found in most primary and metastatic prostate cancers. High stromal periostin expression was associated with higher Gleason scores (p < 0.001). There was a relationship between stromal periostin expression and shortened PSA relapse free survival times in the training cohort (p < 0.05).

CONCLUSIONS

Our data indicate that periostin up-regulation is related to increased tumour aggressiveness in prostate cancer and might be a promising target for therapeutical interventions in primary and metastatic prostate cancer.

Spatiotemporal expression of periostin during skin development and incisional wound healing: lessons for human fibrotic scar formation

Differentiation of fibroblasts to myofibroblasts and collagen fibrillogenesis are two processes essential for normal cutaneous development and repair, but their misregulation also underlies skin-associated fibrosis. Periostin is a matricellular protein normally expressed in adult skin, but its role in skin organogenesis, incisional wound healing and skin pathology has yet to be investigated in any depth. Using C57/BL6 mouse skin as model, we first investigated periostin protein and mRNA spatiotemporal expression and distribution during development and after incisional wounding. Secondarily we assessed whether periostin is expressed in human skin pathologies, including keloid and hypertrophic scars, psoriasis and atopic dermatitis. During development, periostin is expressed in the dermis, basement membrane and hair follicles from embryonic through neonatal stages and in the dermis and hair follicle only in adult. In situ hybridization demonstrated that dermal fibroblasts and basal keratinocytes express periostin mRNA. After incisional wounding, periostin becomes re-expressed in the basement membrane within the dermal-epidermal junction at the wound edge re-establishing the embryonic deposition pattern present in the adult. Analysis of periostin expression in human pathologies demonstrated that it is over-expressed in keloid and hypertrophic scars, atopic dermatitis, but is largely absent from sites of inflammation and inflammatory conditions such as psoriasis. Furthermore, in vitro we demonstrated that periostin is a transforming growth factor beta 1 inducible gene in human dermal fibroblasts. We conclude that periostin is an important ECM component during development, in wound healing and is strongly associated with pathological skin remodeling.

SUMMARY

Periostin is a fibrogenic protein that mediates fibroblast differentiation and extracellular matrix synthesis. Here, we show that periostin is dynamically and temporally expressed during skin development, is induced by TGF-beta1 in vitro and is significantly upregulated during wound repair as well as cutaneous pathologies.

Whole genome microarray analysis of chicken embryo facial prominences

The face is one of the three regions most frequently affected by congenital defects in humans. To understand the molecular mechanisms involved, it is necessary to have a more complete picture of gene expression in the embryo. Here, we use microarrays to profile expression in chicken facial prominences, post neural crest migration and before differentiation of mesenchymal cells. Chip-wide analysis revealed that maxillary and mandibular prominences had similar expression profiles while the frontonasal mass chips were distinct. Of the 3094 genes that were differentially expressed in one or more regions of the face, a group of 56 genes was subsequently validated with quantitative polymerase chain reaction (QPCR) and a subset examined with in situ hybridization. Microarrays trends were consistent with the QPCR data for the majority of genes (81%). On the basis of QPCR and microarray data, groups of genes that characterize each of the facial prominences can be determined.

Periostin shows increased evolutionary plasticity in its alternatively spliced region

Background

Periostin (POSTN) is a secreted extracellular matrix protein of poorly defined function that has been related to bone and heart development as well as to cancer. In human and mouse, it is known to undergo alternative splicing in its C-terminal region, which is devoid of known protein domains. Differential expression of periostin, sometimes of specific splicing isoforms, is observed in a broad range of human cancers, including breast, pancreatic, and colon cancer. Here, we combine genomic and transcriptomic sequence data from vertebrate organisms to study the evolution of periostin and particularly of its C-terminal region.

Results

We found that the C-terminal part of periostin is markedly more variable among vertebrates than the rest of periostin in terms of exon count, length, and splicing pattern, which we interpret as a consequence of neofunctionalization after the split between periostin and its paralog transforming growth factor, beta-induced (TGFBI). We also defined periostin's sequential 13-amino acid repeat units - well conserved in teleost fish, but more obscure in higher vertebrates - whose secondary structure is predicted to be consecutive beta strands. We suggest that these beta strands may mediate binding interactions with other proteins through an extended beta-zipper in a manner similar to the way repeat units in bacterial cell wall proteins have been reported to bind human fibronectin.

Conclusions

Our results, obtained with the help of the increasingly large collection of complete vertebrate genomes, document the evolutionary plasticity of periostin's C-terminal region, and for the first time suggest a basis for its functional role.

Gene expression profile on chitosan/rhBMP-2 films: A novel osteoinductive coating for implantable materials

This study focusses on the gene expression profile related to a new rhBMP-2 carrier material, chitosan film. This film could be suitable for use as an osteoinductive coating of commercially available titanium implants. The developed material was characterized, biocompatibility was tested and the cellular response was extensively characterized by transcriptional expression studies. Finally, in vivo studies were carried out to confirm the osteoinductivity of the developed coating. Results show good material properties for cell adhesion and proliferation. Presented data show cellular differentiation to the osteoblastic phenotype due to rhBMP-2, with a 90% common transcriptional response between the control rhBMP-2 treatment and the developed chitosan/rhBMP-2 film. The growing surface also had an influence on the observed cellular response and was quantified as 7% of the total. These results indicate that both the growth factor and the material induce a cell response, but this is mainly driven by the osteoinductor factor. In vivo, new bone formation and early vascularization was observed around chitosan/rhBMP-2 coated titanium pieces implanted in mouse muscle. In contrast, control implants did not induce this reaction. This work, therefore, shows both in vitro and in vivo that chitosan/rhBMP-2 film is a promising osteoinductive coating for titanium implantable materials.

Expression of periostin in the serum of NSCLC and its function on proliferation and migration of human lung adenocarcinoma cell line (A549) in vitro

Periostin is over expressed in many epithelial malignant cancers, including lung cancer, breast cancer, ovarian cancer and colon cancer. It is related with the progression and migration of breast and ovarian cancer cells in vitro. The aim of this study was to investigate the serum level of periostin in non-small cell lung cancer (NSCLC) and its relationship with established biological and prognostic factors by enzyme-linked-immunosorbent serologic assay. We also observe the function of periostin on the proliferation and migration of human lung adenocarcinoma cell line (A549) and discuss the mechanism. The mean value for serum periostin (POSTN) was elevated in NSCLC patients (242.84 + or - 5.33 pg/ml) compared to the normal healthy volunteers (215.66 + or - 11.67 pg/ml) (p = 0.030). The serum level of periostin of NSCLC patients had no connection with gender, age, pathological type, TNM stage, lymph node status, tumor size and invasiveness. We constructed a plasmid named pEGFP-N1/POSTN expressing full-length human periostin. Transfecting the plasmid to A549 cells and periostin was efficiently expressed in transfected A549 cells. Our data showed that periostin could promote the proliferation and migration of A549 cells by inducing vimentin and N-cadherin expression and downregulating E-cadherin expression. These results strongly suggest that periostin is a novel molecular which play an important role during the progression and development of NSCLC.

The KK-Periome database for transcripts of periodontal ligament development

The periodontal ligament (PDL) is a strong connective tissue that surrounds the tooth root, absorbs occlusal forces, and functions as a sense organ. PDL originated from dental follicle (DF), which possessed mesenchymal progenitors in the developing tooth germ. However, as specific marker genes for PDL and DF are currently unavailable, the molecular mechanisms of PDL development are yet to be clarified. To facilitate the identification of such genes, we have previously established a transcriptome database of the human PDL (the KK-Periome database) and screened for specific genes expressed during PDL development. Initial screening of the database revealed two marker genes for distinguishing DF and PDL. The KK-Periome database thus appears to offer a useful resource for investigating genes involved in PDL development.

Autoreactivity of serum immunoglobulin to periodontal tissue components: a pilot study

BACKGROUND

Periodontal diseases are inflammatory diseases resulting in the destruction of tissues of the periodontium. Although bacteria must be present for periodontal disease to occur, a susceptible host is also required, which is determined by genetic, environmental, and acquired factors. One such factor, autoimmunity, may play a role in the tissue destruction. Data indicate that some antibodies that occur in the gingival lesion are directed to host tissue components, such as type I collagen, although investigations of other periodontal autoimmune targets are limited.

METHODS

Histologic sections and extracts from periodontally healthy teeth and the associated soft tissues were probed with serum from localized aggressive periodontitis (LAgP), chronic periodontitis (CP), and periodontally healthy subjects to determine autoreactivity to components of the periodontium. Any autoreactivity observed was characterized further by mass spectrometry and enzyme-linked immunosorbent assay.

RESULTS

Autoreactivity to components of the periodontium was observed in CP and LAgP. Known autoimmune targets, such as collagen and heat shock protein, were identified along with multiple potential autoimmune targets, including members of the extracellular matrix, such as vimentin, spectrin, filamin, actin, lamin, keratin, and tubulin. Finally, it was determined that the autoreactivity observed in LAgP was more severe and diverse than that observed in CP.

CONCLUSION

These data demonstrated that autoimmune reactivity can play a role in the tissue destruction of periodontal disease but that the nature of the autoreactivity may differ based on the type and/or stage of periodontal disease.

The multifaceted role of periostin in tumorigenesis

Periostin, also called osteoblast-specific factor 2 (OSF-2), is a member of the fasciclin family and a disulfide-linked cell adhesion protein that has been shown to be expressed preferentially in the periosteum and periodontal ligaments, where it acts as a critical regulator of bone and tooth formation and maintenance. Furthermore, periostin plays an important role in cardiac development. Recent clinical evidence has also revealed that periostin is involved in the development of various tumors, such as breast, lung, colon, pancreatic, and ovarian cancers. Periostin interacts with multiple cell-surface receptors, most notably integrins, and signals mainly via the PI3-K/Akt and other pathways to promote cancer cell survival, epithelial-mesenchymal transition (EMT), invasion, and metastasis. In this review, aspects related to the function of periostin in tumorigenesis are summarized.

Gene expression profiling of the forming atrioventricular node using a novel tbx3-based node-specific transgenic reporter

The atrioventricular (AV) node is a recurrent source of potentially life-threatening arrhythmias. Nevertheless, limited data are available on its developmental control or molecular phenotype. We used a novel AV nodal myocardium-specific reporter mouse to gain insight into the gene programs determining the formation and phenotype of the developing AV node. In this reporter, green fluorescent protein (GFP) expression was driven by a 160-kbp bacterial artificial chromosome with Tbx3 and flanking sequences. GFP was selectively active in the AV canal of embryos and AV node of adults, whereas the Tbx3-positive AV bundle and sinus node were devoid of GFP, demonstrating that distinct regulatory sequences and pathways control expression in the components of the conduction system. Fluorescent AV nodal and complementary Nppa-positive chamber myocardial cell populations of embryonic day 10.5 embryos and of embryonic day 17.5 fetuses were purified using fluorescence-activated cell sorting, and their expression profiles were assessed by genome-wide microarray analysis, providing valuable information concerning their molecular identities. We constructed a comprehensive list of sodium, calcium, and potassium channel genes specific for developing nodal or chamber myocardium. Furthermore, the data revealed that the AV node and the chamber (working) myocardium phenotypes diverge during development but that the functional gene classes characterizing both subtypes are maintained. One of the repertoires identified in the AV node-specific gene profiles consists of multiple neurotrophic factors and semaphorins, not yet appreciated to play a role in nodal development, revealing shared characteristics between nodal and nervous system development.

Periostin-like-factor and Periostin in an animal model of work-related musculoskeletal disorder

Work-related musculoskeletal disorders (WMSDs), also known as overuse injuries, account for a substantial proportion of work injuries and workers' compensation claims in the United States. However, the pathophysiological mechanisms underlying WMSDs are not well understood, especially the early events in their development. In this study we used an animal model of upper extremity WMSD, in which rats perform a voluntary repetitive reaching and pulling task for a food reward. This innovative model provides us an opportunity to investigate the role of molecules which may be used either as markers of early diagnosis of these disorders, and/or could be targeted for therapeutic purposes in the future. Periostin-like-factor (PLF), and Periostin were examined in this study. Both belong to a family of vitamin K-dependent gamma carboxylated proteins characterized by the presence of conserved Fasciclin domains and not detected in adult tissues except under conditions of chronic overload, injury, stress or pathology. The spatial and temporal pattern of PLF and Periostin localization was examined by immunohistochemistry and western blot analysis in the radius and ulna of animals performing a high repetition, high force task for up to 12 weeks and in controls. We found that PLF was present primarily in the cellular periosteum, articular cartilage, osteoblasts, osteocytes and osteoclasts at weeks 3 and 6 in all distal bone sites examined. This increase coincided with a transient increase in serum osteocalcin in week 6, indicative of adaptive bone formation at this time point. PLF immunoexpression decreased in the distal periosteum and metaphysis by week 12, coincided temporally with an increase in serum Trap5b, thinning of the growth plate and reduced cortical thickness. In contrast to PLF, once Periostin was induced by task performance, it continued to be present at a uniformly high level between 3 and 12 weeks in the trabeculae, fibrous and cellular periosteum, osteoblasts and osteocytes. In general, the data suggest that PLF is located in tissues during the early adaptive stage of remodeling but not during the pathological phase and therefore might be a marker of early adaptive remodeling.

Periostin is essential for the integrity and function of the periodontal ligament during occlusal loading in mice

BACKGROUND

The ability of the periodontal ligament (PDL) to absorb and distribute forces is necessary for periodontal homeostasis. This adaptive response may be determined, in part, by a key molecule, periostin, which maintains the integrity of the PDL during occlusal function and inflammation. Periostin is primarily expressed in the PDL and is highly homologous to betaig-H3 (transforming growth factor-beta [TGF-beta] inducible gene). Cementum, alveolar bone, and the PDL of periostin-null mice dramatically deteriorate following tooth eruption. The purpose of this study was to determine the role of periostin in maintaining the functional integrity of the periodontium.

METHODS

The periodontia from periostin-null mice were characterized followed by unloading the incisors. The effect of substrate stretching on periostin expression was evaluated using a murine PDL cell line. Real-time reverse transcription-polymerase chain reaction was used to quantify mRNA levels of periostin and TGF-beta. TGF-beta1 neutralizing antibodies were used to determine whether the effects of substrate stretching on periostin expression are mediated through TGF-beta.

RESULTS

Severe periodontal defects were observed in the periostin-null mice after tooth eruption. The removal of masticatory forces in periostin-null mice rescue the periodontal defects. Periostin expression was increased in strained PDL cells by 9.2-fold at 48 hours and was preceded by a transient increase in TGF-beta mRNA in vitro. Elevation of periostin in response to mechanical stress was blocked by the addition of 2.5 ng/ml neutralizing antibody to TGF-beta1, suggesting that mechanical strain activates TGF-beta to have potential autocrine effects and to increase periostin expression.

CONCLUSION

Mechanical loading maintains sufficient periostin expression to ensure the integrity of the periodontium in response to occlusal load.

Functional role of periostin in development and wound repair: implications for connective tissue disease

Integrity of the extracellular matrix (ECM) is essential for maintaining the normal structure and function of connective tissues. ECM is secreted locally by cells and organized into a complex meshwork providing physical support to cells, tissues, and organs. Initially thought to act only as a scaffold, the ECM is now known to provide a myriad of signals to cells regulating all aspects of their phenotype from morphology to differentiation. Matricellular proteins are a class of ECM related molecules defined through their ability to modulate cell-matrix interactions. Matricellular proteins are expressed at high levels during development, but typically only appear in postnatal tissue in wound repair or disease, where their levels increase substantially. Members of the CCN family, tenascin-C, osteopontin, secreted protein acidic rich in cysteine (SPARC), bone sialoprotein, thrombospondins, and galectins have all been classed as matricellular proteins. Periostin, a 90 kDa secreted homophilic cell adhesion protein, was recently added to matricellular class of proteins based on its expression pattern and function during development as well as in wound repair. Periostin is expressed in connective tissues including the periodontal ligament, tendons, skin and bone, and is also prominent in neoplastic tissues, cardiovascular disease, as well as in connective tissue wound repair. This review will focus on the functional role of periostin in tissue physiology. Fundamentally, it appears that periostin influences cell behaviour as well as collagen fibrillogenesis, and therefore exerts control over the structural and functional properties of connective tissues in both health and disease. Periostin is a novel matricellular protein with close homology to Drosophila fasciclin 1. In this review, the functional role of periostin is discussed in the context of connective tissue physiology, in development, disease, and wound repair.

Periostin is expressed in pericryptal fibroblasts and cancer-associated fibroblasts in the colon

Periostin is a unique extracellular matrix protein, deposition of which is enhanced by mechanical stress and the tissue repair process. Its significance in normal and neoplastic colon has not been fully clarified yet. Using immunohistochemistry and immunoelectron microscopy with a highly specific monoclonal antibody, periostin deposition was observed in close proximity to pericryptal fibroblasts of colonic crypts. The pericryptal pattern of periostin deposition was decreased in adenoma and adenocarcinoma, preceding the decrease of the number of pericryptal fibroblasts. Periostin immunoreactivity appeared again at the invasive front of the carcinoma and increased along the appearance of cancer-associated fibroblasts. ISH showed periostin signals in cancer-associated fibroblasts but not in cancer cells. Ki-67-positive epithelial cells were significantly decreased in the colonic crypts of periostin-/- mice (approximately 0.6-fold) compared with periostin+/+ mice. In three-dimensional co-culture within type I collagen gel, both colony size and number of human colon cancer cell line HCT116 cells were significantly larger ( approximately 1.5-fold) when cultured with fibroblasts derived from periostin+/+ mice or periostin-transfected NIH3T3 cells than with those from periostin-/- mice or periostin-non-producing NIH3T3 cells, respectively. Periostin is secreted by pericryptal and cancer-associated fibroblasts in the colon, both of which support the growth of epithelial components.

Periostin is required for maturation and extracellular matrix stabilization of noncardiomyocyte lineages of the heart

The secreted periostin protein, which marks mesenchymal cells in endocardial cushions following epithelial-mesenchymal transformation and in mature valves following remodeling, is a putative valvulogenesis target molecule. Indeed, periostin is expressed throughout cardiovascular morphogenesis and in all 4 adult mice valves (annulus and leaflets). Additionally, periostin is expressed throughout the fibrous cardiac skeleton and endocardial cushions in the developing heart but is absent from both normal and/or pathological mouse cardiomyocytes. Periostin (peri(lacZ)) knockout mice exhibit viable valve disease, with neonatal lethality in a minority and latent disease with leaflet abnormalities in the viable majority. Surviving peri(lacZ)-null leaflets are truncated, contain ectopic cardiomyocytes and smooth muscle, misexpress the cartilage proteoglycan aggrecan, demonstrate disorganized matrix stratification, and exhibit reduced transforming growth factor-beta signaling. Neonatal peri(lacZ) nulls that die (14%) display additional defects, including leaflet discontinuities, delamination defects, and deposition of acellular extracellular matrix. Assessment of collagen production, 3D lattice formation ability, and transforming growth factor-beta responsiveness indicate periostin-deficient fibroblasts are unable to support normal valvular remodeling and establishment of a mature cardiac skeleton. Furthermore, pediatric stenotic bicuspid aortic valves that have lost normal extracellular matrix trilaminar stratification have greatly reduced periostin. This suggests that loss of periostin results in inappropriate differentiation of mesenchymal cushion cells and valvular abnormalities via a transforming growth factor-beta-dependent pathway during establishment of the mature heart. Thus, peri(lacZ) knockouts provide a new model of viable latent valve disease.

Periostin regulates atrioventricular valve maturation

Cardiac valve leaflets develop from rudimentary structures termed endocardial cushions. These pre-valve tissues arise from a complex interplay of signals between the myocardium and endocardium whereby secreted cues induce the endothelial cells to transform into migratory mesenchyme through an endothelial to mesenchymal transformation (EMT). Even though much is currently known regarding the initial EMT process, the mechanisms by which these undifferentiated cushion mesenchymal tissues are remodeled "post-EMT" into mature fibrous valve leaflets remains one of the major, unsolved questions in heart development. Expression analyses, presented in this report, demonstrate that periostin, a component of the extracellular matrix, is predominantly expressed in post-EMT valve tissues and their supporting apparatus from embryonic to adult life. Analyses of periostin gene targeted mice demonstrate that it is within these regions that significant defects are observed. Periostin null mice exhibit atrial septal defects, structural abnormalities of the AV valves and their supporting tensile apparatus, and aberrant differentiation of AV cushion mesenchyme. Rescue experiments further demonstrate that periostin functions as a hierarchical molecular switch that can promote the differentiation of mesenchymal cells into a fibroblastic lineage while repressing their transformation into other mesodermal cell lineages (e.g. myocytes). This is the first report of an extracellular matrix protein directly regulating post-EMT AV valve differentiation, a process foundational and indispensable for the morphogenesis of a cushion into a leaflet.