Association of CDX1 binding site of periostin gene with bone mineral density and vertebral fracture risk

Serum Periostin Level and Genetic Polymorphisms Are Associated with Vertebral Fracture in Chinese Postmenopausal Women

Purposes: In order to investigate the association between serum periostin levels and the variation of its encoding gene POSTN and the prevalence of vertebral fractures and bone mineral density (BMD) in Chinese postmenopausal women, an association study was performed. Materials and Methods: 385 postmenopausal women were recruited. For participants without a history of vertebral fracture, lateral X-rays of the spine covering the fourth thoracic spine to the fifth lumbar spine were performed to detect any asymptomatic vertebral fractures. Ten tag-single nucleotide polymorphisms (SNP) of POSTN were genotyped. Serum periostin levels, biochemical parameters, and BMD were measured individually. Results: rs9603226 was significantly associated with vertebral fractures. Compared to allele G, the minor allele A carriers of rs9603226 had a 1.722-fold higher prevalence of vertebral fracture (p = 0.037). rs3923854 was significantly associated with the serum periostin level. G/G genotype of rs3923854 had a higher serum periostin level than C/C and C/G (67.26 ± 19.90 ng/mL vs. 54.57 ± 21.44 ng/mL and 54.34 ± 18.23 ng/mL). Furthermore, there was a negative correlation between the serum level of periostin and BMD at trochanter and total hip. Conclusion: Our study suggested that genetic variation of POSTN could be a predicting factor for the risk of vertebral fractures. The serum level of periostin could be a potential biochemical parameter for osteoporosis in Chinese postmenopausal women.

A combination of genome-wide association study and selection signature analysis dissects the genetic architecture underlying bone traits in chickens

The bones of chicken play an important role in supporting and protecting the body. The growth and development of bones have a substantial influence on the health and production performance in chickens. However, genetic architecture underlying chicken bone traits is not well understood. The objectives of this study are to dissect the genetic basis of bone traits in chickens and to identify valuable genes and genetic markers for chicken breeding. We performed a combination of genome-wide association study (GWAS) and selection signature analysis (fixation index values and nucleotide diversity ratios) in an F₂ crossbred experimental population with different genetic backgrounds (broiler × layer) to identify candidate genes and significant variants related to femur, shank, keel length, chest width, metatarsal claw weight, metatarsal length, and metatarsal circumference. A total of 545 individuals were genotyped based on the whole genome re-sequencing method (26 F₀ individuals were re-sequenced at 10 × coverage; 519 F₂ individuals were re-sequenced at 3 × coverage). A total of 2 028 112 single-nucleotide polymorphisms (SNPs) remained to carry out analysis after quality control and imputation. The integration of GWAS and selection signature analysis indicated that all significant SNPs responsible for bone traits were mainly localized on chicken chromosomes 1, 4, and 27. Finally, we identified 21 positional candidate genes that might regulate chicken bone growth and development, including LRCH1, RB1, FNDC3A, MLNR, CAB39L, FOXO1, LHFP, TRPC4, POSTN, SMAD9, RBPJ, PPARGC1A, SLIT2, NCAPG, NKX3-2, CPZ, SPOP, NGFR, SOST, ZNF652, and HOXB3. Additionally, an array of uncharacterized genes was identified. The findings provide an in-depth understanding of the genetic architecture of chicken bone traits and offer a molecular basis for applying genomics in practical chicken breeding.

Plasma periostin as a biomarker of osteoporosis in postmenopausal women with type 2 diabetes

INTRODUCTION

Periostin, as an emerging biomarker, is involved in multiple steps in bone metabolism. This study aimed to investigate the correlation between periostin levels and bone mineral density as well as bone turnover markers in postmenopausal women with type 2 diabetes (T2DM).

MATERIALS AND METHODS

This study was a cross-sectional study that included 164 postmenopausal women with T2DM as study subjects and 32 age-matched nondiabetic postmenopausal women with normal bone mineral density (BMD) as healthy control subjects. A total of 164 subjects with T2DM were then divided into three groups according to BMD: the normal BMD group (n = 29), the osteopenia group (n = 70), and the osteoporosis group (n = 65). The clinical data of all subjects along with the relevant biochemical parameter data were collected. Plasma periostin was detected using an enzyme-linked immunosorbent assay (ELISA).

RESULTS

Plasma periostin levels were significantly increased in T2DM patients with normal BMD compared with healthy controls (p < 0.05). In the diabetic group, plasma periostin levels were significantly elevated with decreased BMD, were positively correlated with osteocalcin levels (r = 0.162, p = 0.039) and were inversely associated with femoral neck BMD (r = - 0.308, p < 0.001) and total femur BMD (r = - 0.295, p < 0.001). In the case of chronic complications, periostin levels were slightly increased in individuals with complications of diabetic retinopathy, diabetic nephropathy and fracture (p > 0.05).

CONCLUSIONS

The current study demonstrated that plasma periostin levels were significantly associated with BMD in patients with T2DM, and periostin might act as a novel biochemical marker of osteoporosis in postmenopausal women with type 2 diabetes.

Identification of key regulators in parathyroid adenoma using an integrative gene network analysis

Parathyroid adenoma (PA) is marked by a certain benign outgrowth in the surface of parathyroid glands. The transcriptome analysis of parathyroid adenomas can provide a deep insight into actively expressed genes and transcripts. Hence, we analyzed and compared the gene expression profiles of parathyroid adenomas and healthy parathyroid gland tissues from Gene Expression Omnibus (GEO) database. We identified a total of 280 differentially expressed genes (196 up-regulated, 84 down-regulated), which are involved in a wide array of biological processes. We further constructed a gene interaction network and analyzed its topological properties to know the network structure and its hidden mechanism. This will help to understand the molecular mechanisms underlying parathyroid adenoma development. We thus identified 13 key regulators (PRPF19, SMC3, POSTN, SNIP1, EBF1, MEIS2, PAX9, SCUBE2, WNT4, ARHGAP10, DOCK5, CAV1 and VSIR), which are deep-rooted from top to bottom in the gene interaction network forming a backbone for the network. The structural features of the network are probably maintained by crosstalk between important genes within the network along with associated functional modules.Thus, gene-expression profiling and network approach could be used to provide an independent platform to glen insights from available clinical data.

Prioritization of candidate metabolites for postmenopausal osteoporosis using multi-omics composite network

Risk metabolites of postmenopausal osteoporosis (PO) were explored to offer a theoretical basis for future therapy. The data E-GEOD-7429 were downloaded from ArrayExpress database. In total 20 samples deprived from postmenopausal women having low or high bone mineral density (BMD) were covered in this expression profile. After screening of differentially expressed genes (DEGs), gene-gene network was constructed taking the intersection between the DEGs and genes in the seed protein-protein interaction network. Then, the other five networks were established, including metabolite, phenotype, gene-metabolite, phenotype-gene, and phenotype-metabolite networks. Next, these 6 networks were integrated into one weighted multi-omics network to further identify the candidate metabolites using random walk with restart based on the PO-related seed genes, seed metabolites and phenotype. Using the score among nodes of the weighted composite network, the top 50 metabolites, and the top 100 co-expressed genes interacting with the top 50 metabolites were detected. A set of 601 DEGs between low BMD and high BMD samples were selected. Significantly, the top 5 metabolites were respectively glucosylgalactosyl hydroxylysine, all-trans-5,6-epoxyretinoic acid, tretinoin, colecalciferol, and rocaltrol. Moreover, 3 metabolites (estraderm, triphosadenine, and tretinoin) had a degree >50 in the co-expression network. Tretinoin was the member of the top 5 metabolites, and estraderm was a metabolite with the seventh interaction score. A series of metabolites, tretinoin and estraderm might be closely associated with the onset and progression of PO.

The Structure of the Periostin Gene, Its Transcriptional Control and Alternative Splicing, and Protein Expression

Although many studies have described the role of periostin in various diseases, the functions of periostin derived from alternative splicing and proteinase cleavage at its C-terminus remain unknown. Further experiments investigating the periostin structures that are relevant to diseases are essential for an in-depth understanding of their functions, which would accelerate their clinical applications by establishing new approaches for curing intractable diseases. Furthermore, this understanding would enhance our knowledge of novel functions of periostin related to stemness and response to mechanical stress .

Interaction between LRP5 and periostin gene polymorphisms on serum periostin levels and cortical bone microstructure

We investigated the interaction between periostin SNPs and the SNPs of the genes assumed to modulate serum periostin levels and bone microstructure in a cohort of postmenopausal women. We identified an interaction between LRP5 SNP rs648438 and periostin SNP rs9547970 on serum periostin levels and on radial cortical porosity.

PURPOSE

The purpose of this study is to investigate the interaction between periostin gene polymorphisms (SNPs) and other genes potentially responsible for modulating serum periostin levels and bone microstructure in a cohort of postmenopausal women.

METHODS

In 648 postmenopausal women from the Geneva Retirees Cohort, we analyzed 6 periostin SNPs and another 149 SNPs in 14 genes, namely BMP2, CTNNB1, ESR1, ESR2, LRP5, LRP6, PTH, SPTBN1, SOST, TGFb1, TNFRSF11A, TNFSF11, TNFRSF11B and WNT16. Volumetric BMD and bone microstructure were measured by high-resolution peripheral quantitative computed tomography at the distal radius and tibia.

RESULTS

Serum periostin levels were associated with radial cortical porosity, including after adjustment for age, BMI, and years since menopause (p = 0.036). Sixteen SNPs in the ESR1, LRP5, TNFRSF11A, SOST, SPTBN1, TNFRSF11B and TNFSF11 genes were associated with serum periostin levels (p range 0.03-0.001) whereas 26 SNPs in 9 genes were associated with cortical porosity at the radius and/or at the tibia. WNT 16 was the gene with the highest number of SNPs associated with both trabecular and cortical microstructure. The periostin SNP rs9547970 was also associated with cortical porosity (p = 0.04). In particular, SNPs in LRP5, ESR1 and near the TNFRSF11A gene were associated with both cortical porosity and serum periostin levels. Eventually, we identified an interaction between LRP5 SNP rs648438 and periostin SNP rs9547970 on serum periostin levels (interaction p = 0.01) and on radial cortical porosity (interaction p = 0.005).

CONCLUSION

These results suggest that periostin expression is genetically modulated, particularly by polymorphisms in the Wnt pathway, and is thereby implicated in the genetic variation of bone microstructure.

Introductory review: periostin-gene and protein structure

Although many studies have described the role of periostin in various diseases, the function of the periostin protein structures derived from alternative splicing and proteinase cleavage at the C-terminal remain unknown. Further experiments revealing the protein structures that are highly related to diseases are essential to understand the function of periostin in depth, which would accelerate its clinical application by establishing new approaches for curing intractable diseases. Furthermore, this understanding would enhance our knowledge of novel functions of periostin related to stemness and response to mechanical stress.

Circulating periostin levels increase in association with bone density loss and healing progression during the early phase of hip fracture in Chinese older women

The present study shows that hip fracture women had higher serum periostin (sPostn) levels. The elevation of sPostn is associated with bone density loss, yet fracture itself may even increase sPostn levels during early healing phase.

INTRODUCTION

The study aims to quantify the associations of sPostn levels with bone density loss and the possible effect on the fracture healing.

METHODS

This study enrolled 261 older women with osteoporotic hip fracture and 106 age-matched women without fracture serving as controls. Clinical features, bone mineral density (BMD), and bone turnover markers including sPostn level were measured after fracture within 2 days. Follow-up sPostn levels during 1 year after 2 days were available for 128 patients.

RESULTS

Initial levels of sPostn after fracture were significantly higher in patients than controls. sPostn was correlated with BMD of femoral neck (r = -0.529, P < 0.001), β-isomerized C-terminal crosslinking of type I collagen (β-CTX) (r = 0.403, P = 0.008), and N-terminal procollagen of type I collagen (PINP) (r = 0.236, P = 0.042) in the entire cohort. After multivariate analysis, sPostn remained as an independent risk factor for femoral neck BMD, which explained 19.1% of the variance in BMD. sPostn sampled within 7 days after fracture were acutely increasing from day 2 and then decreased and maintained at slightly high levels at 360 days. The percentage changes of sPostn positively correlated with the variation in β-CTX (r = 0.396, P = 0.002) and PINP (r = 0.180, P = 0.033) at day 7 after fracture.

CONCLUSIONS

High sPostn levels were an independent predictor of femoral neck BMD in older women presenting with an acute hip fracture. Increased sPostn levels during early healing phase may imply that Postn play a role in bone repair.

Genome-wide QTL mapping results for regional DXA body composition and bone mineral density traits in pigs

Abstract. In a previous study, genome-wide mapping of quantitative trait loci (QTL) for five body composition traits, three bone mineral traits and live weight was performed using whole-body dual-energy X-ray absorptiometry (DXA) data. Since QTL for bone mineral traits were rare, the current study aimed to clarify whether the mapping results were influenced by the analysed body regions. Thus, the same material (551 pigs) and methods as in the whole-body QTL mapping study were used. However, for evaluation of the DXA scans, we manually defined two body regions: (i) from the last ribs to the pelvis (A) and (ii) including the pelvis and the hind limbs (P). Since live weight was not affected by the regional analysis, it was omitted from the QTL mapping design. Our results show an overall high consistency of mapping results especially for body composition traits. Two thirds of the initial whole-body QTL are significant for both A and P. Possible causes for the still low number of bone mineral QTL and the lower consistency found for these traits are discussed. For body composition traits, the data presented here show high genome-wide Pearson correlations between mapping results that are based on DXA scans with the time-saving whole-body standard setting and mapping results for DXA data that were obtained by time-consuming manual definition of the regions of interest. However, our results also suggest that whole-body or regional DXA scans might generally be less suitable for mapping of bone mineral traits in pigs. An analysis of single reference bones could be more useful.

Computational Characterization of Osteoporosis Associated SNPs and Genes Identified by Genome-Wide Association Studies

OBJECTIVES

Genome-wide association studies (GWASs) have revealed many SNPs and genes associated with osteoporosis. However, influence of these SNPs and genes on the predisposition to osteoporosis is not fully understood. We aimed to identify osteoporosis GWASs-associated SNPs potentially influencing the binding affinity of transcription factors and miRNAs, and reveal enrichment signaling pathway and "hub" genes of osteoporosis GWAS-associated genes.

METHODS

We conducted multiple computational analyses to explore function and mechanisms of osteoporosis GWAS-associated SNPs and genes, including SNP conservation analysis and functional annotation (influence of SNPs on transcription factors and miRNA binding), gene ontology analysis, pathway analysis and protein-protein interaction analysis.

RESULTS

Our results suggested that a number of SNPs potentially influence the binding affinity of transcription factors (NFATC2, MEF2C, SOX9, RUNX2, ESR2, FOXA1 and STAT3) and miRNAs. Osteoporosis GWASs-associated genes showed enrichment of Wnt signaling pathway, basal cell carcinoma and Hedgehog signaling pathway. Highly interconnected "hub" genes revealed by interaction network analysis are RUNX2, SP7, TNFRSF11B, LRP5, DKK1, ESR1 and SOST.

CONCLUSIONS

Our results provided the targets for further experimental assessment and further insight on osteoporosis pathophysiology.

Chondrocytes Cocultured with Stromal Vascular Fraction of Adipose Tissue Present More Intense Chondrogenic Characteristics Than with Adipose Stem Cells

Partial replacement of chondrocytes by stem cells has been proposed to improve the performance of autologous chondrocyte implantation (ACI). Our previous studies showed that the increased cartilage production in pellet cocultures of chondrocytes and mesenchymal stem cells (MSCs) is due to a trophic role of the MSCs by stimulating chondrocyte proliferation and matrix production rather than MSCs actively undergoing chondrogenic differentiation. The aim of this study is to compare the trophic effects of stromal vascular fraction cells (SVF) and in vitro expanded adipose stem cells (ASC). SVF and culture-expanded ASC (n = 9) were cocultured with primary human chondrocytes in pellets. By glycosaminoglycan (GAG) and DNA assays, we showed that coculture pellets of SVF and chondrocytes have more GAG deposition than that of ASC and chondrocytes. Results of the short tandem repeats analysis indicated that the increase in the chondrocyte proportion in the coculture pellets is more pronounced in the SVF coculture group than in the ASC coculture group. Using flow cytometry and microarray, we demonstrated that SVF and ASC have different characteristics in cell surface markers and gene expression profiles. SVF is more heterogeneous than ASC, whereas ASC is more enriched in cells from the mesenchymal lineage than SVF. By subcutaneous implantation into nude mice, we showed that constructs of SVF and chondrocytes are better in depositing cartilage matrix than the mixture of ASC and chondrocytes. Taken together, SVF is better than ASC in terms of forming cartilage matrix in pellet coculture and in coimplantation models omitting the need for prior cell expansion. Our study suggests that the SVF in combination with primary human chondrocytes may be a good cell combination for one-stage cartilage repair.

Gene expression profiles induced by growth factors in in vitro cultured osteoblasts

Objectives

Effects of insulin-like growth factor 1 (IGF1), fibroblast growth factor 2 (FGF2) and bone morphogenetic protein 2 (BMP2) on the expression of genes involved in the proliferation and differentiation of osteoblasts in culture were analysed. The best sequence of growth factor addition that induces expansion of cells before their differentiation was sought.

Methods

Primary human osteoblasts in in vitro culture were treated with IGF1, BMP2 or FGF2 (10 ng/ml) for 24 hours (IGF1) or 48 hours (BMP2 and FGF2). Experiments were performed during the exponential growth phase with approximately 1e7 cells per 75 cm² flask. mRNA was reverse transcribed directly and analysed using RT-PCR Taqman assays. Expression levels of key genes involved in cell growth and differentiation (CDH11, TNFRSF11B, RUNX2, POSTN, ALP, WNT5A, LEF1, HSPA5, FOS, p21) were monitored using RT-PCR with gene-specific Taqman probes.

Results

Autocrine expression of BMP2 is stimulated by FGF2 and BMP2 itself. BMP2 and FGF2 act as proliferative factors as indicated by reduced expression of ALP and POSTN, whereas IGF1 exhibits a more subtle picture: the Wingless und Int-1 (Wnt) signalling pathway and the Smad pathway, but not p38 mitogen-activated protein (MAP) kinase signalling, were shown to be activated by IGF1, leading to proliferation and differentiation of the cells.

Conclusions

For future use of autologous bone cells in the management of bony defects, new treatment options take advantage of growth factors and differentiation factors. Thus, our results might help to guide the timely application of these factors for the expansion and subsequent differentiation of osteoblastic cells in culture.

Cite this article: Bone Joint Res 2014;3:236–40.

Serum periostin is associated with fracture risk in postmenopausal women: a 7-year prospective analysis of the OFELY study

PURPOSE

Periostin (POSTN) is a secreted γ-carboxyglutamic acid-containing protein expressed mainly in the periosteum in adult individuals. POSNT deficient mice develop periodontis and osteoporosis with decreased bone strength. The relationship between serum POSTN and bone metabolism and fracture risk in postmenopausal women is unknown.

SUBJECTS AND METHODS

Serum POSTN was measured in 607 postmenopausal women (mean age 66.6 ± 8.4 y) from the Os des Femmes de Lyon cohort at the ninth annual follow-up visit (baseline visit of the current analysis). Nonvertebral and clinical vertebral incident fragility fractures were reported annually during 7 years. Areal bone mineral density (BMD; measured by dual energy X-ray absorptiometry) of the hip and bone markers (intact N-terminal propeptide of type I collagen, osteocalcin, and serum type I collagen C-telopeptide) were also measured.

RESULTS

At baseline, serum POSTN did not correlate with age, bone markers, and BMD. After a median of 7 years of follow-up, 75 women sustained an incident clinical vertebral or nonvertebral fragility fracture. The proportion of women who had an incident fracture was significantly higher in women with levels of POSTN in the highest quartile than that of women in the three other quartiles (19.5% vs 10.1%, P = .018) after adjustment for age and prevalent fracture. The highest quartile of POSTN was associated with an increased risk of incident fracture with a relative risk (95% confidence interval) of 1.88 (1.1-3.2) after adjustment for age, prevalent fracture, and hip BMD T-score. Patients with both low hip BMD (T-score < -2.5) and high levels of POSTN (fourth quartile) had a relative risk of fracture of 7.1 (95% confidence interval 2.4-21.8) after adjustment for age.

CONCLUSION

High serum POSTN levels are independently associated with increased fracture risk in postmenopausal women. These data suggest that serum POSTN could be useful to improve fracture risk assessment.

Proteomic analysis of human osteoarthritis synovial fluid

Background

Osteoarthritis is a chronic musculoskeletal disorder characterized mainly by progressive degradation of the hyaline cartilage. Patients with osteoarthritis often postpone seeking medical help, which results in the diagnosis being made at an advanced stage of cartilage destruction. Sustained efforts are needed to identify specific markers that might help in early diagnosis, monitoring disease progression and in improving therapeutic outcomes. We employed a multipronged proteomic approach, which included multiple fractionation strategies followed by high resolution mass spectrometry analysis to explore the proteome of synovial fluid obtained from osteoarthritis patients. In addition to the total proteome, we also enriched glycoproteins from synovial fluid using lectin affinity chromatography.

Results

We identified 677 proteins from synovial fluid of patients with osteoarthritis of which 545 proteins have not been previously reported. These novel proteins included ADAM-like decysin 1 (ADAMDEC1), alanyl (membrane) aminopeptidase (ANPEP), CD84, fibulin 1 (FBLN1), matrix remodelling associated 5 (MXRA5), secreted phosphoprotein 2 (SPP2) and spondin 2 (SPON2). We identified 300 proteins using lectin affinity chromatography, including the glycoproteins afamin (AFM), attractin (ATRN), fibrillin 1 (FBN1), transferrin (TF), tissue inhibitor of metalloproteinase 1 (TIMP1) and vasorin (VSN). Gene ontology analysis confirmed that a majority of the identified proteins were extracellular and are mostly involved in cell communication and signaling. We also confirmed the expression of ANPEP, dickkopf WNT signaling pathway inhibitor 3 (DKK3) and osteoglycin (OGN) by multiple reaction monitoring (MRM) analysis of osteoarthritis synovial fluid samples.

Conclusions

We present an in-depth analysis of the synovial fluid proteome from patients with osteoarthritis. We believe that the catalog of proteins generated in this study will further enhance our knowledge regarding the pathophysiology of osteoarthritis and should assist in identifying better biomarkers for early diagnosis.

Wnt-related genes and large-joint osteoarthritis: association study and replication

Osteoarthritis (OA) has a strong genetic component, and experimental evidence suggests the involvement of the Wnt pathway in its pathogenesis. Hence, we explored the association of common single nucleotide polymorphisms (SNPs) related to the Wnt pathway with hip and knee OA. Seventy-eight SNPs were analyzed in 606 patients undergoing joint replacement and in 680 control subjects. SNPs were located in WNT1, WNT10A, WNT16, DVL2, FZD5, BCL9, SFRP1, TCF7L1 and SFRP4 genes. SNPs significantly associated with OA were genotyped in an independent group of 369 patients and 407 controls. One SNP in WNT10A, rs3806557, was associated with hip OA in men (OR 0.65, 95% CI 0.46-0.93; p = 0.017), but the association was not confirmed in the replication phase. The TCF7L1 polymorphism rs11547160 was also associated with hip OA in the discovery set, but not in the replication set. Similarly, the SFRP4 SNP rs1052981 was associated with knee OA in women with OR of 2.73 (95% CI 1.29-5.8; p = 0.006), but the association was not replicated. The BCL9 polymorphism rs2353525 was associated with knee OA in women, both in the unadjusted and in the age- and BMI-adjusted analysis (OR 2.01; 95% CI 1.34-2.98; p = 0.0006). A similar, but not statistically significant, trend was observed in the replication phase. In the combined analysis, OR was 3.13 (1.34-7.28; p = 0.009). These data suggest that some SNPs of genes related to the Wnt pathway and, specifically BCL9, influence the genetic predisposition to osteoarthritis of the large joints in a sex- and joint-specific way.

The association of single nucleotide polymorphisms in the calcitonin gene with primary osteoarthritis of the knee in Mexican mestizo population

Primary osteoarthritis (OA) is a multifactorial disorder with several genetics factors involved. Calcitonin (CT) has been suggested to possess chondroprotective effects and could play an important role in the pathogenesis of OA. The aim of this study was to investigate whether genetic variations in or adjacent to the CT gene may be associated with primary OA of the knee in Mexican mestizo population. We conducted a case-control study to investigate the association between six single nucleotide polymorphisms at the CT locus and OA of the knee in 107 cases and 106 controls. Cases were patients >40 years of age, with a body mass index (BMI) ≤ 27 and a radiologic score for OA of the knee ≥ 2. Controls were subjects >40 years of age with a radiologic score <2. Non-conditional logistic regression was developed to evaluate risk magnitude. The G allele and GT genotype frequencies of the G-706T polymorphism and the C allele and CC genotype of the C-778T polymorphism were significantly higher in patients with OA than in control subjects. The GG genotype of the G-706T was associated with lower risk of the development of OA of the knee. According to the results, the G-706T and the C-778T polymorphisms were related to the Cdx1 and Mzf1 transcription factor binding sites, respectively. Therefore, these could be related to regulation sequences in the CT gene promoter. In conclusion, G-706T and C-778T polymorphisms in the CT gene are significantly associated with the development of primary OA of the knee.

Regulation of beta catenin signaling and parathyroid hormone anabolic effects in bone by the matricellular protein periostin

Periostin (Postn) is a matricellular protein preferentially expressed by osteocytes and periosteal osteoblasts in response to mechanical stimulation and parathyroid hormone (PTH). Whether and how periostin expression influences bone anabolism, however, remains unknown. We investigated the skeletal response of adult Postn(-/-) and Postn(+/+) mice to intermittent PTH. Compared with Postn(+/+), Postn(-/-) mice had a lower bone mass, cortical bone volume, and strength response to PTH. PTH-stimulated bone-forming indices were all significantly lower in Postn(-/-) mice, particularly at the periosteum. Furthermore, in vivo stimulation of Wnt-β-catenin signaling by PTH, as evaluated in TOPGAL reporter mice, was inhibited in the absence of periostin (TOPGAL;Postn(-/-) mice). PTH stimulated periostin and inhibited MEF2C and sclerostin (Sost) expression in bone and osteoblasts in vitro. Recombinant periostin also suppressed Sost expression, which was mediated through the integrin αVβ3 receptor, whereas periostin-blocking antibody prevented inhibition of MEF2C and Sost by PTH. In turn, administration of a Sost-blocking antiboby partially restored the PTH-mediated increase in bone mass in Postn(-/-) mice. In addition, primary osteoblasts from Postn(-/-) mice showed a lower proliferation, mineralization, and migration, both spontaneously and in response to PTH. Osteoblastic gene expression levels confirmed a defect of Postn(-/-) osteoblast differentiation with and without PTH, as well as an increased osteoblast apoptosis in the absence of periostin. These data elucidate the complex role of periostin on bone anabolism, through the regulation of Sost, Wnt-β-catenin signaling, and osteoblast differentiation.

Regulation of beta catenin signaling and parathyroid hormone anabolic effects in bone by the matricellular protein periostin

Periostin (Postn) is a matricellular protein preferentially expressed by osteocytes and periosteal osteoblasts in response to mechanical stimulation and parathyroid hormone (PTH). Whether and how periostin expression influences bone anabolism, however, remains unknown. We investigated the skeletal response of adult Postn −/− and Postn +/+ mice to intermittent PTH. Compared with Postn +/+ , Postn −/− mice had a lower bone mass, cortical bone volume, and strength response to PTH. PTH-stimulated bone-forming indices were all significantly lower in Postn −/− mice, particularly at the periosteum. Furthermore, in vivo stimulation of Wnt-β-catenin signaling by PTH, as evaluated in TOPGAL reporter mice, was inhibited in the absence of periostin ( TOPGAL;Postn −/− mice). PTH stimulated periostin and inhibited MEF2C and sclerostin (Sost) expression in bone and osteoblasts in vitro. Recombinant periostin also suppressed Sost expression, which was mediated through the integrin αVβ3 receptor, whereas periostin-blocking antibody prevented inhibition of MEF2C and Sost by PTH. In turn, administration of a Sost-blocking antiboby partially restored the PTH-mediated increase in bone mass in Postn −/− mice. In addition, primary osteoblasts from Postn −/− mice showed a lower proliferation, mineralization, and migration, both spontaneously and in response to PTH. Osteoblastic gene expression levels confirmed a defect of Postn −/− osteoblast differentiation with and without PTH, as well as an increased osteoblast apoptosis in the absence of periostin. These data elucidate the complex role of periostin on bone anabolism, through the regulation of Sost, Wnt-β-catenin signaling, and osteoblast differentiation.