Modulation of Bone Morphogenetic Protein (BMP) 2 gene expression by Sp1 transcription factors

In Silico Analysis: Genome-Wide Identification, Characterization and Evolutionary Adaptations of Bone Morphogenetic Protein (BMP) Gene Family in Homo sapiens

We systematically analyzed BMP gene family in H. sapiens to elucidate genetic structure, phylogenetic relationships, adaptive evolution and tissue-specific expression pattern. Total of 13 BMPs genes were identified in the H. sapiens genome. Bone morphogenetic proteins (BMPs) are composed of a variable number of exons ranging from 2 to 21. They exhibit a molecular weight ranging from 31,081.81 to 82,899.61 Da. These proteins possess hydrophilic characteristics, display thermostability, and exhibit a pH range from acidic to basic. We identified four segmental and two tandem duplication events in BMP gene family of H. sapiens. All of the vertebrate species that were studied show the presence of BMPs 1, 2, 3, 4, 5, 6, 7, 8A, and 15, however only Homo sapiens demonstrated the presence of BMP9 and BMP11. The pathway and process enrichment analysis of BMPs genes showed that these were considerably enriched in positive regulation of pathway-restricted SMAD protein phosphorylation (92%) and cartilage development (77%) biological processes. These genes exhibited positive selection signals that were shown to be conserved across vertebrate lineages. The results showed that BMP2/3/5/6/8a/15 proteins underwent adaptive selection at many amino acid locations and increased positive selection was detected in TGF-β propeptide and TGF-β super family domains which were involved in dorso-ventral patterning, limb bud development. More over the expression pattern of BMP genes revealed that BMP1 and BMP5; BMP4 and BMP6 exhibited substantially identical expression patterns in all tissues while BMP10, BMP15, and BMP3 showed tissue-specific expression.

Effectiveness of Combination of Chitosan Gel and Hydroxyapatite from Crabs Shells (Portunus pelagicus) Waste as Bonegraft on Periodontal Network Regeneration through IL-1 and BMP-2 Analysis

Background. Periodontitis can be treated by regenerating periodontal tissue using a bone graft. Several natural materials such as chitosan and minerals such as hydroxyapatite can be developed to increase periodontal tissue regeneration. Chitosan has a high potential in healing wounds. Hydroxyapatite has excellent properties such as biocompatibility, osteoconductive, osteoinductive, and osteogenesis, making it an ideal material for soft and hard tissue regeneration. Chitosan and hydroxyapatite can be obtained from the shells of crustaceans, such as crabs shells (Portunus pelagicus). Objective. To assess the effectiveness of the combination of chitosan gel and hydroxyapatite powder as a bone graft on periodontal tissue regeneration in experimental animals. Periodontal tissue regeneration was assessed by expressing inflammatory cytokine gene indicators IL-1 and BMP-2. Methods. Experimental laboratory research and clinical trials with posttest only control group design. Twenty-seven Wistar rats were divided into three groups. Then the femoral bone defect was made, the positive control group was given placebo gel, the positive control group was given BATAN hydroxyapatite, and the test group was given a combination of chitosan gel and hydroxyapatite crab shells. Wistar rats were sacrificed on days 7, 14, and 21, and the femur bone was then taken for immunohistochemical analysis to determine the levels of IL-1 and BMP-2. The Kolmogorov–Smirnov test, Levene test, and one-way ANOVA analyzed the data. Results. On days 7, 14, and 21, the expression levels of IL-1 and BMP2 were significantly different between the three groups. The group added with chitosan gel and crab shell HA showed a faster decrease in IL-1 expression than the control group. BMP-2 expression increased in the test group compared to the control group. Conclusion. The combination of chitosan gel and hydroxyapatite inhibited the production of proinflammatory cytokines and increased the production of BMP-2.

Identification of the specific microRNAs and competitive endogenous RNA mechanisms in osteoporosis

Objective

Osteoporosis and osteoarthritis are metabolic skeletal disorders. This study aimed to identify specific networks of competitive endogenous RNA (ceRNA) in osteoporosis that differ from those in osteoarthritis.

Methods

The dataset GSE74209 was downloaded from the Gene Expression Omnibus, and differentially expressed microRNAs (DEmiRNAs) in osteoporotic samples and osteoarthritic samples were identified. After predicting target genes and linked long noncoding (lnc)RNAs, ceRNA networks of DEmiRNAs were constructed. The nodes that overlapped between ceRNA networks and the Comparative Toxicogenomics Database were selected as key candidates.

Results

Fifteen DEmiRNAs (including 2 downregulated and 13 upregulated miRNAs) were identified in osteoporotic samples versus osteoarthritic samples; these targeted 161 genes and linked to 60 lncRNAs. The ceRNA network consisted of 6 DEmiRNAs, 63 target genes, and 53 lncRNAs. After searching the Comparative Toxicogenomics Database and mining the literature, 2 lncRNAs (MALAT1 and NEAT1), 2 DEmiRNAs (hsa-miR-32-3p, downregulated; and hsa-miR-22-3p, upregulated) and 6 genes (SP1, PTEN, ESR1, ERBB3, CSF1R, and CDK6) that relate to cell death, growth, and differentiation were identified as key candidates separating osteoporosis from osteoarthritis.

Conclusions

Two miRNA–ceRNA networks (including NEAT1/MALAT1-hsa-miR-32-3p-SP1/FZD6 and NEAT1/MALAT1-hsa-miR-22-3p-PTEN/ESR1/ERBB3/CSF1R/CDK6) might have crucial and specific roles in osteoporosis.

The Epstein-Barr Virus-Encoded EBNA1 Protein Activates the Bone Morphogenic Protein (BMP) Signalling Pathway to Promote Carcinoma Cell Migration

The Epstein-Barr virus (EBV)-encoded nuclear antigen 1 (EBNA1) protein is expressed in all virus-associated malignancies, where it performs an essential role in the maintenance, replication and transcription of the EBV genome. In recent years, it has become apparent that EBNA1 can also influence cellular gene transcription. Here, we demonstrate that EBNA1 is able to stimulate the expression of the Transforming growth factor-beta (TGFβ) superfamily member, bone morphogenic protein 2 (BMP2), with consequential activation of the BMP signalling pathway in carcinoma cell lines. We show that BMP pathway activation is associated with an increase in the migratory capacity of carcinoma cells, an effect that can be ablated by the BMP antagonist, Noggin. Gene expression profiling of authentic EBV-positive nasopharyngeal carcinoma (NPC) tumours revealed the consistent presence of BMP ligands, established BMP pathway effectors and putative target genes, constituting a prominent BMP “signature” in this virus-associated cancer. Our findings show that EBNA1 is the major viral-encoded protein responsible for activating the BMP signalling pathway in carcinoma cells and supports a role for this pathway in promoting cell migration and possibly, metastatic spread.

Sp1 Plays an Important Role in Vascular Calcification Both In Vivo and In Vitro

BACKGROUND

Vascular calcification and increased cardiovascular morbidity and mortality are closely related in patients with end-stage renal disease and diabetes mellitus. Specific protein 1 (Sp1) is a transactivation molecule that plays a crucial role in the regulation of apoptosis, fibrosis, angiogenesis, and other pathological disorders. There is evidence that specific protein 1 (Sp1) directly stimulates the transcription of bone morphogenetic protein 2 (BMP2) and that BMP2 plays a key role in the calcification process in the BMP2-expressing F9 cell model system. Here, we investigated whether Sp1 plays an important role in vascular calcification and its potential regulatory mechanism in vascular calcification.

METHODS AND RESULTS

In this study, vascular calcification was induced in male Wistar rats by administration of nicotine (25 mg/kg) and vitamin D3 (300 000 IU/kg). These rats were randomly selected for treatment with adenovirus harboring Sp1 knockdown gene or empty virus. The mechanism of Sp1 in vascular smooth muscle cells cultured in high phosphate medium was studied. Based on our findings, the Sp1 gene silencing or inhibition improved calcium deposition, which was partly achieved by inhibiting phenotype switch, apoptosis, and matrix vesicle release of vascular smooth muscle cells. Moreover, Sp1 can activate BMP2 transcription by binding to the Sp1-binding element of the BMP2 promoter.

CONCLUSIONS

Overall, elevated Sp1 exerts a pro-apoptotic effect, promoting BMP2 transcription and further accumulating vascular calcification. Proper and timely regulation of Sp1 expression may be a potential strategy for treatment of aging, end-stage renal disease, and diabetic-related macrovascular disease treatment.

Effect of genetic variants of OPTN in the pathophysiology of Paget's disease of bone

Paget's disease of bone (PDB) is the second most frequent metabolic bone disease after osteoporosis. Genetic factors play an important role in PDB, but to date PDB causing mutations were identified only in the Sequestosome 1 gene at the PDB3 locus. OPTN has been recently associated with PDB, however little is known about the effect of genetic variants in this gene in PDB pathophysiology. By sequencing OPTN in SQSTM1 non-carriers PDB patients we found 16 SNPs in regulatory, coding and non-coding regions. One of those was found to be associated with PDB in our cohort - rs2234968. Our results show that rs2238968 effect may be explained by a change in OPTN splicing that give rise to a predicted truncated protein. We also performed functional studies on the variants located in OPTN promoter - rs3829923 and the rare variant -9906 - to investigate putative regulators of OPTN. Our results show that OPTN expression seems to be regulated by SP1, RXR, E47, and the E2F family. In conclusion, our work suggests a potential pathophysiological role of SNPs in OPTN, giving a new perspective about the regulatory mechanisms of this gene. Ultimately we discovered a new variant associated with PDB in OPTN, reinforcing the relevance of this gene for the development of this bone disease.

Turning Bone Morphogenetic Protein 2 (BMP2) on and off in Mesenchymal Cells

The concentration, location, and timing of bone morphogenetic protein 2 (BMP2, HGNC:1069, GeneID: 650) gene expression must be precisely regulated. Abnormal BMP2 levels cause congenital anomalies and diseases involving the mesenchymal cells that differentiate into muscle, fat, cartilage, and bone. The molecules and conditions that influence BMP2 synthesis are diverse. Understandably, complex mechanisms control Bmp2 gene expression. This review includes a compilation of agents and conditions that can induce Bmp2. The currently known trans-regulatory factors and cis-regulatory elements that modulate Bmp2 expression are summarized and discussed. Bone morphogenetic protein 2 (BMP2, HGNC:1069, GeneID: 650) is a classical morphogen; a molecule that acts at a distance and whose concentration influences cell behavior. In mesenchymal cells, the concentration of BMP2 influences myogenesis, adipogenesis, chondrogenesis, and osteogenesis. Because the amount, timing, and location of BMP2 synthesis influence the allocation of cells to muscle, fat, cartilage, and bone, the mechanisms that regulate the Bmp2 gene are crucial. Key early mesodermal events that require precise Bmp2 regulation include heart specification and morphogenesis. Originally named for its osteoinductive properties, healing fractures requires BMP2. The human Bmp2 gene also has been linked to osteoporosis and osteoarthritis. In addition, all forms of pathological calcification in the vasculature and in cardiac valves involve the pro-osteogenic BMP2. The diverse tissues, mechanisms, and diseases influenced by BMP2 are too numerous to list here (see OMIM: 112261). However, in all BMP2-influenced pathologies, changes in the behavior and differentiation of pluripotent mesenchymal cells are a recurring theme. Consequently, much effort has been devoted to identifying the molecules and conditions that influence BMP2 synthesis and the complex mechanisms that control Bmp2 gene expression. This review begins with an overview of the Bmp2 gene's chromosomal neighborhood and then summarizes and evaluates known regulatory mechanisms and inducers.

A common atopy-associated variant in the Th2 cytokine locus control region impacts transcriptional regulation and alters SMAD3 and SP1 binding

BACKGROUND

Type 2 immune responses directed by Th2 cells and characterized by the signature cytokines IL4, IL5, and IL13 play major pathogenic roles in atopic diseases. Single nucleotide polymorphisms in the human Th2 cytokine locus in particular in a locus control region within the DNA repair gene RAD50, containing several RAD50 DNase1-hypersensitive sites (RHS), have been robustly associated with atopic traits in genome-wide association studies (GWAS). Functional variants in IL13 have been intensely studied, whereas no causative variants for the IL13-independent RAD50 signal have been identified yet. This study aimed to characterize the functional impact of the atopy-associated polymorphism rs2240032 located in the human RHS7 on cis-regulatory activity and differential binding of transcription factors.

METHODS

Differential transcription factor binding was analyzed by electrophoretic mobility shift assays (EMSAs) with Jurkat T-cell nuclear extracts. Identification of differentially binding factors was performed using mass spectrometry (LC-MS/MS). Reporter vector constructs carrying either the major or minor allele of rs2240032 were tested for regulating transcriptional activity in Jurkat and HeLa cells.

RESULTS

The variant rs2240032 impacts transcriptional activity and allele-specific binding of SMAD3, SP1, and additional putative protein complex partners. We further demonstrate that rs2240032 is located in an RHS7 subunit which itself encompasses repressor activity and might be important for the fine-tuning of transcription regulation within this region.

CONCLUSION

The human RHS7 critically contributes to the regulation of gene transcription, and the common atopy-associated polymorphism rs2240032 impacts transcriptional activity and transcription factor binding.

CRABP2 promotes myoblast differentiation and is modulated by the transcription factors MyoD and Sp1 in C2C12 cells

Cellular retinoic acid binding protein 2 (CRABP2), a member of a family of specific carrier proteins for Vitamin A, belongs to a family of small cytosolic lipid binding proteins. Our previous study suggested that CRABP2 was involved in skeletal muscle development; however, the molecular function and regulatory mechanism of CRABP2 in myogenesis remained unclear. In this study, we found that the expression of the CRABP2 gene was upregulated during C2C12 differentiation. An over-expression assay revealed that CRABP2 promotes myogenic transformation by regulating the cell cycle during C2C12 differentiation. The region from -459 to -4 bp was identified as the core promoter and contains a TATA box, a GC box and binding sites for the transcription factors MyoD and Sp1. Over-expression, site-directed mutagenesis and EMSA assays indicated that the transcription factors MyoD and Sp1 regulate CRABP2 expression and promote myoblast differentiation in C2C12 cells.

A conserved post-transcriptional BMP2 switch in lung cells

An ultra-conserved sequence in the bone morphogenetic protein 2 (BMP2) 3' untranslated region (UTR) markedly represses BMP2 expression in non-transformed lung cells. In contrast, the ultra-conserved sequence stimulates BMP2 expression in transformed lung cells. The ultra-conserved sequence functions as a post-transcriptional cis-regulatory switch. A common single-nucleotide polymorphism (SNP, rs15705, +A1123C), which has been shown to influence human morphology, disrupts a conserved element within the ultra-conserved sequence and altered reporter gene activity in non-transformed lung cells. This polymorphism changed the affinity of the BMP2 RNA for several proteins including nucleolin, which has an increased affinity for the C allele. Elevated BMP2 synthesis is associated with increased malignancy in mouse models of lung cancer and poor lung cancer patient prognosis. Understanding the cis- and trans-regulatory factors that control BMP2 synthesis is relevant to the initiation or progression of pathologies associated with abnormal BMP2 levels.

Vitamin A upregulates matrix metalloproteinase-9 activity by murine myeloid dendritic cells through a nonclassical transcriptional mechanism

Myeloid dendritic cells (DC) are specialized antigen-presenting immune cells. Upon activation in peripheral tissues, DC migrate to lymph nodes to activate T lymphocytes. Matrix metalloproteinase (MMP)-9 is a gelatinase essential for DC migration. We have previously shown that all-trans retinoic acid (atRA), a bioactive metabolite of vitamin A, significantly augmented DC MMP-9 mRNA and protein production. We investigated the mechanisms by which atRA increased MMP-9 activity in vitro. Mouse myeloid DC cultured with atRA demonstrated increased gelatinase activity compared with cells cultured with retinoic acid receptor (RAR)-alpha antagonist. Adding MMP-9 inhibitor significantly blocked DC gelatinase activity and increased adherence of DC in a dose-dependent manner. AtRA-induced Mmp-9 gene expression in DC was blocked by transcriptional inhibition. Because the Mmp-9 promoter contains no canonical retinoic acid response element (RARE), we performed additional studies to determine how atRA regulated DC Mmp-9 transcription. Electrophoretic mobility shift assays for the consensus Sp1, activating protein-1, and nuclear factor-kappaB binding sites located in the Mmp-9 promoter did not indicate greater nuclear protein binding in response to atRA. Chromatin immunoprecipitation assays indicated RARalpha and histone acetyltransferase p300 recruitment to, and acetylation of, histone H3 at the Mmp-9 promoter was greater after atRA treatment. These data suggest that atRA regulated DC adhesion in vitro partly through MMP-9 gelatinase activity. Mmp-9 expression was enhanced through a transcriptional mechanism involving greater RARalpha promoter binding, recruitment of p300, and subsequent histone H3 acetylation, despite the absence of a consensus RARE.

Functional differentiation of uterine stromal cells involves cross-regulation between bone morphogenetic protein 2 and Kruppel-like factor (KLF) family members KLF9 and KLF13

The inability of the uterine epithelium to enter a state of receptivity for the embryo to implant is a significant underlying cause of early pregnancy loss. We previously showed that mice null for the progesterone receptor (PGR)-interacting protein Krüppel-like factor (KLF) 9 are subfertile and exhibit reduced uterine progesterone sensitivity. KLF9 expression is high in predecidual stroma, undetectable in decidua, and enhanced in uteri of mice with conditional ablation of bone morphogenetic protein 2 (BMP2). Given the individual importance of KLF9 and BMP2 for implantation success, we hypothesized that the establishment of uterine receptivity involves KLF9 and BMP2 functional cross-regulation. To address this, we used early pregnant wild-type and Klf9 null mice and KLF9 small interfering RNA-transfected human endometrial stromal cells (HESCs) induced to differentiate under standard conditions. Loss of KLF9 in mice and HESCs enhanced BMP2 expression, whereas recombinant BMP2 treatment of HESCs attenuated KLF9 mRNA levels. IGFBP1 and KLF9-related KLF13 expression were positively associated with BMP2 and inversely associated with KLF9. Prolonged, but not short-term, knockdown of KLF9 in HESCs reduced IGFBP1 expression. Mouse uterine Igfbp1 expression was similarly reduced with Klf9 ablation. PGR-A and PGR-B expression were positively associated with KLF9 in predecidual HESCs but not decidualizing HESCs. KLF13 knockdown attenuated BMP2 and PGR-B and abrogated BMP2-mediated inhibition of KLF9 expression. Results support cross-regulation among BMP2, KLF9, and KLF13 to maintain progesterone sensitivity in stromal cells undergoing differentiation and suggest that loss of this regulatory network compromises establishment of uterine receptivity and implantation success.

Repressive BMP2 gene regulatory elements near the BMP2 promoter

The level of bone morphogenetic protein 2 (BMP2) profoundly influences essential cell behaviors such as proliferation, differentiation, apoptosis, and migration. The spatial and temporal pattern of BMP2 synthesis, particular in diverse embryonic cells, is highly varied and dynamic. We have identified GC-rich sequences within the BMP2 promoter region that strongly repress gene expression. These elements block the activity of a highly conserved, osteoblast enhancer in response to FGF2 treatment. Both positive and negative gene regulatory elements control BMP2 synthesis. Detecting and mapping the repressive motifs is essential because they impede the identification of developmentally regulated enhancers necessary for normal BMP2 patterns and concentration.

Differences in fat and muscle mass associated with a functional human polymorphism in a post-transcriptional BMP2 gene regulatory element

A classic morphogen, bone morphogenetic protein 2 (BMP2) regulates the differentiation of pluripotent mesenchymal cells. High BMP2 levels promote osteogenesis or chondrogenesis and low levels promote adipogenesis. BMP2 inhibits myogenesis. Thus, BMP2 synthesis is tightly controlled. Several hundred nucleotides within the 3' untranslated regions of BMP2 genes are conserved from mammals to fishes indicating that the region is under stringent selective pressure. Our analyses indicate that this region controls BMP2 synthesis by post-transcriptional mechanisms. A common A to C single nucleotide polymorphism (SNP) in the BMP2 gene (rs15705, +A1123C) disrupts a putative post-transcriptional regulatory motif within the human ultra-conserved sequence. In vitro studies indicate that RNAs bearing the A or C alleles have different protein binding characteristics in extracts from mesenchymal cells. Reporter genes with the C allele of the ultra-conserved sequence were differentially expressed in mesenchymal cells. Finally, we analyzed MRI data from the upper arm of 517 healthy individuals aged 18-41 years. Individuals with the C/C genotype were associated with lower baseline subcutaneous fat volumes (P = 0.0030) and an increased gain in skeletal muscle volume (P = 0.0060) following resistance training in a cohort of young males. The rs15705 SNP explained 2-4% of inter-individual variability in the measured parameters. The rs15705 variant is one of the first genetic markers that may be exploited to facilitate early diagnosis, treatment, and/or prevention of diseases associated with poor fitness. Furthermore, understanding the mechanisms by which regulatory polymorphisms influence BMP2 synthesis will reveal novel pharmaceutical targets for these disabling conditions.

Species-specific cis-regulatory elements in the 3'-untranslated region direct alternative polyadenylation of bone morphogenetic protein 2 mRNA

BMP2 (bone morphogenetic protein 2) is a multifunctional member of the transforming growth factor-beta family of growth factors. Disruption of BMP2 signaling results in developmental defects, cancers, and other diseases. BMP2 mRNAs are alternatively polyadenylated, resulting in mRNAs with distinct 3'-untranslated regions. The longer mRNA contains additional putative binding sites for post-transcriptional regulatory factors, including micro-RNAs. We combined functional assays with computational analyses of emerging genome data to define site- and species-specific polyadenylation determinants. In all mouse and human cell lines tested, shorter mRNAs resulting from using the first polyadenylation signal (PA1) were more abundant than mRNAs from the second signal (PA2). However, the PA1/PA2 usage ratios were 2-3-fold higher in human than in mouse cells. Expression of human BMP2 constructs in mouse cells and mouse constructs in human cells showed that cis-regulatory elements direct species-specific 3' processing of BMP2 transcripts. A 72-nucleotide region downstream of PA2 in the mouse sequence contains two novel cis-acting elements previously hypothesized to regulate polyadenylation in a bioinformatics analysis. Mutations that humanized the mouse-specific elements lowered the affinity for cleavage stimulation factor CstF64 and significantly weakened the PA2 signal relative to the PA1 signal. Thus, we have experimentally defined for the first time cis-regulatory elements that control a species-specific difference in the 3'-end processing of BMP2 and potentially of other genes.

Glial aromatization increases the expression of bone morphogenetic protein-2 in the injured zebra finch brain

In songbirds, brain injury upregulates glial aromatase. The resulting local estrogen synthesis mitigates apoptosis and enhances cytogenesis by poorly understood mechanisms. Bone morphogenetic proteins (BMPs), long studied for their role in neural development, are also neuroprotective and cytogenic in the adult brain. BMPs remain uncharacterized in songbirds, as do the mechanisms regulating their post-injury expression. We first established the expression of BMPs 2, 4, 6, and 7 in the adult zebra finch brain using RT-PCR. Next, we determined the effect of neural insult on BMP expression, by comparing BMP transcripts between injured and uninjured telencephalic hemispheres using semi-quantitative PCR. The expression of BMPs 2 and 4, but not 6 and 7, increased 24 h post-injury. To determine the influence of aromatase on BMP expression, we compared BMP expression following delivery of the aromatase inhibitor Fadrozole or vehicle into contralateral hemispheres. Fadrozole decreased BMP2, but not BMP4, expression, suggesting that aromatization may induce BMP2 expression following injury. Since BMPs are gliogenic and neurotrophic, future studies will test if the neuroprotective and cytogenic effects of aromatase upregulation are mediated by BMP2. Songbirds may be excellent models towards understanding the role of local estrogen synthesis and its downstream mechanisms on neuroprotection and repair.

Emodin accelerates osteoblast differentiation through phosphatidylinositol 3-kinase activation and bone morphogenetic protein-2 gene expression

Emodin is a naturally occurring anthraquinone present in the roots and bark of numerous plants of the genus Rhamnus. Here, we identified emodin as one of compounds activating the mRNA expression of bone morphogenetic protein (BMP)-2 in the differentiation process of mouse osteoblastic MC3T3-E1 subclone 4 cells. Without any effect on cell growth, the low concentration (up to 5 microM) of emodin highly induced the mRNA expression of BMP-2, the expression of alkaline phosphatase (an early marker of osteoblast differentiation), and the mineralization. Interestingly, emodin induced the activation of phosphatidylinositol 3-kinase (PI3K), Akt and mitogen-activated protein (MAP) kinases, but those inductions by emodin were completely inhibited by the PI3K inhibitor, LY294002, suggesting that the up-regulation of BMP-2 by emodin could be mediated through the activation of both Akt and MAP kinases by activating PI3K. Additionally, emodin-induced activation of NF-kappaB suggested that NF-kappaB might be required for its anabolic activity in part. In conclusion, the use of natural compounds with anabolic activity such as emodin could have a beneficial effect on bone health and this kind of studies further elucidate the pharmacological roles of natural compounds in the prevention of osteoporosis and provide the initiative in the early drug discovery and development for osteoporosis.