Noggin Gene Research Articles

Nucleotide Polymorphisms in the Canine Noggin Gene and Their Distribution Among Dog (Canis lupus familiaris) Breeds

Noggin (NOG) is an important regulator for the signaling of bone morphogenetic proteins. In this study, we sequenced the complete coding sequence of the canine NOG gene and characterized the nucleotide polymorphisms. The sequence length varied from 717 to 729 bp, depending on the number of a 6-bp tandem repeat unit (GGCGCG), an insertion that has not been observed in other mammalian NOG genes investigated to date. It results in extensions of (Gly–Ala)3–5 in the putative NOG protein. To survey the distribution of these tandem repeat polymorphisms, we analyzed 126 individuals in seven dog breeds. We identified only three alleles: (GGCGCG)3, (GGCGCG)4, and (GGCGCG)5. Although the allele frequencies were remarkably different among the breeds, the three alleles were present in all seven of the breeds and did not show any deviation from Hardy–Weinberg equilibrium.Electronic supplementary materialThe online version of this article (doi:10.1007/s10528-011-9453-5) contains supplementary material, which is available to authorized users.

Evo-devo: Hydra raises its Noggin

Noggin, along with other secreted bone morphogenetic protein (BMP) inhibitors, plays a crucial role in neural induction and neural tube patterning as well as in somitogenesis, cardiac morphogenesis and formation of the skeleton in vertebrates. The BMP signalling pathway is one of the seven fundamental pathways that drive embryonic development and pattern formation in animals. Understanding its evolutionary origin and role in pattern formation is, therefore, important to evolutionary developmental biology (evo-devo). We have studied the evolutionary origin of BMP-Noggin antagonism in hydra, which is a powerful diploblastic model to study evolution of pattern-forming mechanisms because of the unusual cellular dynamics during its pattern formation and its remarkable ability to regenerate. We cloned and characterized the noggin gene from hydra and found it to exhibit considerable similarity with its orthologues at the amino acid level. Microinjection of hydra Noggin mRNA led to duplication of the dorsoventral axis in Xenopus embryos, demonstrating its functional conservation across the taxa. Our data, along with those of others, indicate that the evolutionarily conserved antagonism between BMP and its inhibitors predates bilateral divergence. This article reviews the various roles of Noggin in different organisms and some of our recent work on hydra Noggin in the context of evolution of developmental signalling pathways.

Postnatal growth retardation, facial dysmorphism, spondylocarpal synostosis, cardiac defect, and inner ear malformation (cardiospondylocarpofacial syndrome?)—A distinct syndrome?

We report on two unrelated cases born to nonconsanguineous parents with a similar clinical presentation: hypotonia since the neonatal period, severe failure to thrive, postnatal growth retardation, facial dysmorphism, congenital cardiac defects (septal defect and non progressive multiple valve dysplasia), shortened extremities, carpal/tarsal and extensive vertebral synostosis, delayed carpal bone age, deafness, and inner ear malformations. Presently, both patients present with normal psychomotor development. Additional abnormal findings include extra oral frenulum, nasal speech, and vesico-ureteral reflux. Molecular analysis in one patient excluded the Noggin gene and Filamin B (FLNB) was excluded in the other patient. Although some features are similar to spondylocarpotarsal synostosis syndrome, the exclusion of FLNB and this constellation of findings suggest a new entity, closely similar to an autosomal dominant condition reported by Forney et al. 1966 in a unique family. Identification of similarly affected patients should aid in the further elucidation of this syndrome.

Ex Vivo Noggin Gene Therapy Inhibits Bone Formation in a Mouse Model of Postoperative Resynostosis

Resynostosis following surgical correction of primary craniosynostosis necessitates further surgical intervention, thereby increasing morbidity and mortality. Bone morphogenetic proteins are known to be expressed during normal bone healing. This study tested the hypothesis that treatment of suturectomy sites with Noggin, an extracellular antagonist of bone morphogenetic proteins, would inhibit postoperative resynostosis in a mouse suturectomy model. Healing of small interfrontal suturectomies was assessed in three groups of mice using radiographic, micro-computed tomographic, and histologic analyses. The groups were as follows: group 1, no treatment (n = 36); group 2, green fluorescent protein (GFP)-labeled cells in a collagen scaffold (n = 36); and group 3, Noggin/GFP-expressing cells in a collagen scaffold (n = 36). Radiographic analysis of defect area showed that Noggin-treated suturectomy sites were significantly larger than untreated sites 4 and 8 weeks postoperatively (p < 0.05). Analysis of defect volume showed that Noggin-treated defects were significantly larger than untreated defects at all time points after surgery. The GFP-treated defects demonstrated some inhibition of bone formation, but this inhibition was not significant compared with untreated controls 12 weeks after surgery. These findings suggest that Noggin is an effective inhibitor of bone formation within small suturectomy sites and that Noggin may be useful in avoiding postoperative resynostosis. Noggin treatment may be useful as an adjunct to traditional surgical intervention for the treatment of children with craniosynostosis.

Expression pattern of the expanded noggin gene family in the planarian Schmidtea mediterranea

Noggin genes are mainly known as inhibitors of the Bone Morphogenetic Protein (BMP) signalling pathway. Noggin genes play an important role in various developmental processes such as axis formation and neural differentiation. In vertebrates, inhibition of the BMP pathway is usually carried out together with other inhibitory molecules: chordin and follistatin. Recently, it has been shown in planarians that the BMP pathway has a conserved function in the maintenance and re-establishment of the dorsoventral axis during homeostasis and regeneration. In an attempt to further characterize the BMP pathway in this model we have undertaken an in silico search of noggin genes in the genome of Schmidtea mediterranea. In contrast to other systems in which between one and four noggin genes have been reported, ten genes containing a noggin domain are present in S. mediterranea. These genes have been classified into two groups: noggin genes (two genes) and noggin-like genes (eight genes). Noggin-like genes are characterized by the presence of an insertion of 50–60 amino acids in the middle of the noggin domain. Here, we report the characterization of this expanded family of noggin genes in planarians as well as their expression patterns in both intact and regenerating animals. In situ hybridizations show that planarian noggin genes are expressed in a variety of cell types located in different regions of the planarian body.

Identification and association analysis of single nucleotide polymorphisms in the human noggin (NOG) gene and osteoporosis phenotypes

Noggin, an extracellular bone morphogenic protein (BMP) antagonist, blocks BMP signaling and decreases osteoblastogenesis. The purpose of this study was to identify novel sequence variations in the human noggin gene and to perform association analyses of these variations with phenotypes related to osteoporosis. Novel single nucleotide polymorphisms (SNPs) were identified by resequencing 7 kb of the noggin gene region in 24 randomly selected Afro-Caribbean men without regard to their bone mineral density (BMD) level. We identified 22 SNPs in the 7 kb noggin gene region, only 2 of which were previously described in dbSNP (build 126). There were also 11 unvalidated SNPs from dbSNP that could not be verified in our sequence analysis. Ten of the 22 identified SNPs showed a minor allele frequency greater than 0.05. Seven of these common SNPs were genotyped in 2060 Afro-Caribbean men age 40 and older. None of the 7 SNPs were associated with BMD at the proximal femur or lumbar spine. Our analysis suggests that a common variation in the noggin gene is unlikely to have a major impact on BMD among older men of African ancestry.

Growth and Skeletal Development in Families with NOGGIN Gene Mutations

Introduction: There is a scarcity of data on height as well as bone densitometry in humans with NOGGIN mutations. Methods: In 2 families with symphalangism, anthropometry, bone densitometry and genetic analysis of the NOGGIN gene were performed. Results: In family A, the height standard deviation scores of the affected father and son were –0.4 and 3.5, respectively. In family B, the height standard deviation scores of the affected father, twin daughters and another daughter were 1.7, 1.8, 2.4 and 1.8, respectively. In the children, percentage predicted bone mineral content (BMC) for height at the appendicular sites (total femur, femoral neck) was lower than at an axial site lumbar spine. In the 2 fathers, median bone mineral density at total femur and femoral neck was –0.3 standard deviation scores (–0.7, 0.2) and at lumbar spine the scores were –0.4 and 0.9. The children had median tibial and radial speed of sound velocities of –2.1 (–0.9 to –6.4) and –1.4 (–0.2 to –4.9), respectively. DNA analysis revealed a novel missense mutation in family A and family B, resulting in a Met190Val substitution and a Pro42Arg substitution, respectively. Conclusion: Heterozygous gene mutations in NOGGIN are associated with tall stature in children but not necessarily in adults. The appendicular BMC and speed of sound may be low in affected children but normalises by adulthood. However, axial BMC seems normal in childhood and is high in adulthood.

Noggin heterozygous mice: an animal model for congenital conductive hearing loss in humans

Conductive hearing loss occurs when sound waves are not relayed efficiently to the inner ear. Mutations of the NOGGIN (NOG) gene in humans are associated with several autosomal dominant disorders such as proximal symphalangism and multiple synostoses. These syndromes are characterized by skeletal defects and synostoses, which include conductive hearing loss. Noggin is an antagonist of bone morphogenetic proteins (BMPs), and balanced levels of BMPs and Noggin are required for proper skeletal formation. Depending on the genetic background, some of the Nog(+/-) mice display mild hearing loss, that is, conductive in nature. Since Noggin is a single exon gene, this data strongly suggest that the autosomal dominant disorders associated with NOG mutations are due to haploinsufficiency of NOGGIN. The conductive hearing loss in Nog(+/-) mice is caused by an ectopic bone bridge located between the stapes and the posterior wall of the tympanum, which affects the normal mobility of the ossicle. Our analyses suggest that the ectopic bone formation is caused by a failure of the stapes and styloid process to separate completely during development. This failure of bone separation in the Nog(+/-) mice reveals another consequence of chondrocyte hyperplasia due to unopposed Bmp activities in these mutants such as Bmp4 and Bmp14 (Gdf5). More importantly, these results establish Nog(+/-) mice as the first animal model for the study of conductive rather than neurosensory hearing loss that has direct relevance to human genetic disorders.

Craniectomy and noggin application in an infant model

Noggin is an antagonist of bone morphogenetic proteins (BMP)-2, -4 and -7. Little data are available regarding its clinical utility. Two hypotheses were put forward: firstly, that spontaneous regeneration of calvarial defects with noggin protein would result in diminished bone volume when compared with calvarial defects not so treated. Secondly, that centrifugal cranial expansion would remain undisturbed whether noggin was applied or not. A unilateral defect of the frontal and parietal bones (2x4cm) was generated by excising the right coronal suture in 2-month-old minipigs (n=10) and in group 1 (n=5) no further intervention was undertaken. In the second group (n=5), a collagen type I tissue fleece and noggin protein (1.05mg/ml) were applied. After 4 months the coronal suture regions of frontal sides were examined in each animal by computed tomography and non-decalcified histology. Bony gaps of equivalent size remained in animals of both groups. The differences in bone volumes of the experimental sides of group 1 were not statistically significantly different (p=0.117) when compared with those of group 2. A significant difference in the bone volumes of the experimental versus control (unoperated) sides was found in both group 1 (p=0.043) and group 2 (p=0.043). Internal skull diameters increased by 16.4% in both groups but the physiological centrifugal cranial expansion remained undisturbed. Bone densities of the experimental and control sides of groups 1 and 2 were not statistically significantly different (both p>0.05). The first hypothesis was contradicted: the quantity and quality of spontaneous bone regenerates was not altered by application of noggin protein. The second hypothesis was confirmed: no disruption of subsequent cranial development was seen. It may be that a single application of noggin protein in this study was insufficient. However, it may well be suggested that the continuous supplementation of noggin, for example by adenoviral noggin gene transfer may significantly reduce the quantity of spontaneous bone regeneration in a similar experiment.

The Bone Morphogenetic Protein Antagonist Noggin Regulates Mammalian Cardiac Morphogenesis

Bone morphogenetic proteins (BMPs) play many roles in mammalian cardiac development. Here we address the functions of Noggin, a dedicated BMP antagonist, in the developing mouse heart. In early cardiac tissues, the Noggin gene is mainly expressed in the myocardial cells of the outflow tract, atrioventricular canal, and future right ventricle. The major heart phenotypes of Noggin mutant embryos are thicker myocardium and larger endocardial cushions. Both defects result from increased cell number. Cell proliferation is increased and cell cycle exit is decreased in the myocardium. Although we find evidence of increased BMP signal transduction in the myocardium and endocardium, we show that the cardiac defects of Noggin mutants are rescued by halving the gene dosage of Bmp4. In culture, BMP increases the epithelial-to-mesenchymal transformation (EMT) of endocardial explant cells. Increased EMT likely accounts for the enlarged atrioventricular cushion. In the outflow tract cushion, we observed an increased contribution of cardiac neural crest cells to the mutant cushion mesenchyme, although many cells of the cushion were not derived from neural crest. Thus the enlarged outflow tract cushion of Noggin mutants likely arises by increased contributions both of endocardial cells that have undergone EMT as well as cells that have migrated from the neural crest. These data indicate that antagonism of BMP signaling by Noggin plays a critical role in ensuring proper levels of cell proliferation and EMT during cardiac morphogenesis in the mouse.

Noggin haploinsufficiency differentially affects tissue responses in destructive and remodeling arthritis

The balance between destruction and homeostatic or reparative responses determines the outcome of arthritis. Increasing evidence suggests a role for signaling pathways, essential for development and growth, in the maintenance of tissue homeostasis and attempts at repair. Inappropriate activation of such pathways may also have a role in disease progression. We undertook this study to determine the effect of shifting the balance in bone morphogenetic protein (BMP) signaling in different mouse models of arthritis. Endogenous levels of noggin, a BMP antagonist, were reduced using heterozygous noggin(+/LacZ) mice in a model of inflammation-driven destruction (methylated bovine serum albumin [mBSA]-induced monarthritis), a model of systemic autoimmune arthritis (collagen-induced arthritis [CIA]), and a model of joint ankylosis (spontaneous arthritis in DBA/1 mice). In addition, we studied BMP inactivation by adenoviral noggin overexpression in destructive arthritis. Cartilage damage and activation of BMP signaling were studied by digital image analysis using Safranin O sulfated glycosaminoglycan staining and immunohistochemistry for phosphorylated Smads (Smads 1, 5, and 8), respectively. Noggin haploinsufficiency provided protection for articular cartilage against destruction in mBSA-induced arthritis. Antagonist overexpression rendered cartilage more vulnerable in this model. Noggin gene transfer in knees affected by CIA also enhanced cartilage damage. Haploinsufficiency did not affect CIA, but noggin(+/LacZ) mice had an increased number of CD4-positive cells with normal immune responses. In noggin(+/LacZ) DBA/1 mice with spontaneous arthritis, we observed delayed progression from cartilage to bone formation. Tight spatiotemporal control of BMP signaling appears to be critical in the response of joint tissues in models of arthritis.

GDF5 Is a Second Locus for Multiple-Synostosis Syndrome

Multiple-synostosis syndrome is an autosomal dominant disorder characterized by progressive symphalangism, carpal/tarsal fusions, deafness, and mild facial dysmorphism. Heterozygosity for functional null mutations in the NOGGIN gene has been shown to be responsible for the disorder. However, in a cohort of six probands with multiple-synostosis syndrome, only one was found to be heterozygous for a NOGGIN mutation (W205X). Linkage studies involving the four-generation family of one of the mutation-negative patients excluded the NOGGIN locus, providing genetic evidence of locus heterogeneity. In this family, polymorphic markers flanking the GDF5 locus were found to cosegregate with the disease, and sequence analysis demonstrated that affected individuals in the family were heterozygous for a novel missense mutation that predicts an R438L substitution in the GDF5 protein. Unlike mutations that lead to haploinsufficiency for GDF5 and produce brachydactyly C, the protein encoded by the multiple-synostosis-syndrome allele was secreted as a mature GDF5 dimer. These data establish locus heterogeneity in multiple-synostosis syndrome and demonstrate that the disorder can result from mutations in either the NOGGIN or the GDF5 gene.

The Noggin null mouse phenotype is strain dependent and haploinsufficiency leads to skeletal defects

Noggin is a secreted peptide that binds and inactivates Bone Morphogenetic Proteins, members of the transforming growth factor beta superfamily of secreted signaling molecules. In vertebrate limbs, Noggin is expressed in condensing cartilage and immature chondrocytes. Inactivation of the Noggin gene has been reported in an inbred 129X1/SvJ mouse genetic background. The null allele was lethal at 18.5 dpc and resulted in severe hyperplasia of the cartilage together with multiple joint fusions. In order to investigate the effect of the genetic background on the phenotypic manifestation of Noggin inactivation, we crossed the Noggin null allele into the outbred CD1 and inbred DBA1 and C57BL/6 mouse strains. We describe here skeletal phenotypes of Noggin null mice, such as accelerated or delayed mineralization of different bones suggestive of a complex tissue response to the perturbations in BMP balances. Additionally, we found that in the absence of Noggin, early specification of myogenic differentiation was unaffected, whereas terminal stages of myogenesis were delayed. Furthermore, we have discovered Noggin haploinsufficiency leading to carpal and tarsal fusions reminiscent of some phenotypes reported for NOGGIN haploinsufficiency in humans.

A tribute to our teacher, Dr. Judith Hall: A child with the trait of the Earl of Shrewsbury

"Organized human endeavor can be lifted an order of magnitude through teaching if it is inspiring" (Editor, Am J Dis Child, 1972). The benevolent influence of Dr. Judy Hall's inspiring clinical teaching in the field of genetic syndromes and birth defects is illustrated through the eventual surgical remediation of conductive hearing loss for a 4-year-old girl with unusual knuckles. The fascinating history of this child's syndrome has been further explored in the descendents of the first Earl of Shrewsbury. The legends of his story and his role in the Hundred Years War were immortalized by William Shakespeare in his play Henry VI Part I, but neither Shakespeare nor historians documented that the Earl actually had abnormal finger joints. Heterozygous mutations in the human noggin gene (NOG) cause a spectrum of joint fusions, including this child's traits. On behalf of practitioners of medicine, pediatrics, clinical genetics, and dysmorphology, as well as research scientists in the many domains of genetics, thank you, Judy, for your inspiration, enthusiasm, and teaching.

Multiple noggins in vertebrate genome: cloning and expression of noggin2 and noggin4 in Xenopus laevis

Noggin is a neural inducer secreted by cells of the Spemann organizer. A single noggin gene was identified until very recently in all tested vertebrates. The only exception was zebrafish, in which two close homologs of noggin, named noggin1 and noggin3, and one gene more diverged from them, noggin2, were cloned. Nevertheless, finding of three zebrafish noggins was attributed exclusively to specific genomic duplications in the fish evolutionary branch. However, very recently it was shown that Xenopus tropicalis have additional noggin homolog, called noggin2 [Fletcher, R.B., Watson, A.L., Harland, R.M. (2004). Expression of Xenopus tropicalis noggin1 and noggin2 in early development: two noggin genes in a tetrapod. Gene Expr. Patterns 5, 225–230], which indicates at least two independent noggin genes in vertebrate phylum. Now we report identification of two novel noggin homologs in each of so evolutionary distant species as Xenopus laevis, chicken and fugu. One of these noggins is ortholog of the X. tropicalis and zebrafish noggin2, whereas another, named noggin4, was not known previously. In the X. laevis embryos, the expression of noggin2 very resembles that of its counterpart in X. tropicalis: it begins with neurulation at the anterior margin of the neural plate and, afterward, continues mainly in the forebrain and dorsal hindbrain. At the same time, noggin4 is expressed starting from the beginning of gastrulation, throughout the ectoderm, with a local expression maximum in the prospective anterior neurectoderm. Later, it is widely expressed on the dorsal side of embryo, including neural tube, eyes, otic vesicles, cranial placodes, branchial arches, and somites. The data presented here demonstrate that the vertebrate phylum contains at least three distinct noggin genes.

Molecular signaling in intervertebral disk development

The purpose of this investigation is to identify and study the expression pattern of pertinent molecular factors involved in the differentiation of the intervertebral disk (IVD). It is likely that hedgehog genes and the BMP inhibitors are key factors involved in spinal joint formation. Radioactive in situ hybridization with mRNA probes for pax-1, SHH, IHH and Noggin gene was performed on mouse embryo and adult tissue. Immunohistochemistry was performed to localize hedgehog receptor, “patched” (ptc). From 14.5 dpc until birth pax-1 mRNA was expressed in the developing anulus fibrosus (AF). During the same developmental period Noggin mRNA is highly expressed throughout the spine, in the developing AF, while ptc protein and SHH mRNA were expressed in the developing nucleus pulposus (NP). IHH mRNA was expressed by condensing chondrocytes of the vertebral bodies and later becomes confined to the vertebral endplate. We show for the first time that pax-1 is expressed in the adult intervertebral disk. Ptc expression in the NP is an indicator of hedgehog protein signaling in the developing IVD. The expression pattern of the BMP inhibitor Noggin appears to be important for the normal formation of the IVD and may prove to play a role in its segmental pattern formation.

Developmental Anomalies of the Cervical Spine in Patients With Fibrodysplasia Ossificans Progressiva Are Distinctly Different From Those in Patients With Klippel-Feil Syndrome

A radiographic analysis of the cervical spine of 70 patients diagnosed with fibrodysplasia ossificans progressiva (FOP) and 33 diagnosed with Klippel-Feil (KF) syndrome was conducted. The objectives of this study were to describe cervical spine abnormalities in patients with FOP, to compare and contrast those findings with the malformations in patients with KF syndrome, and to examine the possible etiology of these abnormalities. Congenital features of diseases often provide seminal clues to underlying etiology and developmental pathways. While progressive metamorphosis of connective tissue to heterotopic bone is the most dramatic and disabling feature of FOP, less severe congenital anomalies of the skeleton are also present. Vertebral fusions observed in KF are consistent with defects in embryonic segmentation. The cervical spine plain films of 70 FOP patients and 33 KF patients with documented congenital abnormalities were reviewed. Generalized neck stiffness and decreased range of motion were noted in most children with FOP. In the FOP patient group, characteristic anomalies, including large posterior elements, tall narrow vertebral bodies,and fusion of the facet joints between C2 and C7, were observed. Most notably, these characteristic anomalies of the cervical spine in patients with FOP were distinctly different from those of 33 patients with KF that were examined but were strikingly similar to those seen in mice with homozygous deletions of the gene-encoding noggin, a bone morphogenetic protein (BMP) antagonist. FOP patients exhibit a characteristic set of congenital spine malformations. While the noggin gene (NOG) is not mutated in patients who have FOP, these findings extend a growing body of evidence implicating overactivity of the BMP signaling pathway in the molecular pathogenesis of FOP.

Unusual phenotype with progressive vertebral fusion in a girl with an apparently balanced t(10;20)(p11;p13) translocation

We report the case of a girl presenting with an unusual form of multiple joint fusion. Skeletal abnormalities consisted of radioulnar synostosis and vertebral fusions without any carpal, digital or tarsal involvement, and broad ribs and clavicles. Spinal X-rays were available from age 4 to 21, demonstrating that the spinal involvement was progressive and led to a complete anterior and lateral fusion of vertebrae. A complete sequencing of the NOGGIN gene failed to find any mutation. In addition, this girl was carrier of an apparently balanced reciprocal translocation t(10;20)(p11;p13). We investigated the role of the BMP2A gene as a potential candidate gene. Fluorescence in situ hybridization with YAC probes from chromosome 20 showed that the BMP2A gene was not disrupted by the translocation breakpoint.

Effects of FGF-2/-9 in calvarial bone cell cultures: differentiation stage-dependent mitogenic effect, inverse regulation of BMP-2 and noggin, and enhancement of osteogenic potential

Systemically administered fibroblast growth factors (FGFs) show anabolic effects on bone formation in animals, whereas in vitro cell culture studies have demonstrated that FGFs block mineralized bone nodule formation. These apparently contradictory outcomes indicate that the nature of FGF action is complex and that the biological effect of FGFs may depend on the differentiation stage of osteoblasts, interaction with other cytokines, or the length and mode of exposure to factors. Thus, we have utilized primary calvarial bone cell populations at different maturation phases to determine their responses to 2, FGF-9, and BMP-2, the factors expressed in bone. FGF-2 and FGF-9 stimulated proliferation of the cell populations consisting of more mature osteoblasts, but not those with undifferentiated precursor cells. Continuous treatment with FGF-2/-9 inhibited expression of several osteoblast marker genes and mineralization. However, brief pretreatment with FGF-2/-9 or sequential treatment with FGF-2/-9 followed by BMP-2 led to marked stimulation of mineralization, suggesting that FGFs enhance the intrinsic osteogenic potential. Furthermore, FGF-2 and FGF-9 increased expression of other osteogenic factors BMP-2 and TGFβ-1. Meanwhile, blocking endogenous FGF signaling, using a virally transduced dominant-negative FGF receptor (FgfR), resulted in drastically reduced expression of the BMP-2 gene, demonstrating for the first time that endogenous FGF/FgfR signaling is a positive upstream regulator of the BMP-2 gene in calvarial osteoblasts. In contrast, expression of a BMP antagonist noggin was inhibited by FGF-2 and FGF-9. Thus, collective data from this study suggest that FGF/FgfR signaling enhances the intrinsic osteogenic potential by selectively expanding committed osteogenic cell populations as well as inversely regulating BMP-2 and noggin gene expression.

1678 Construction of neuron specific expression vector for human noggin gene

Objective To construct an eukaryotic expression vector with specificity toneurons for human Noggin gene for further study on the role of Noggin in development and functioning in the nerve system. Methods According to human Noggin cDNA sequence, a pair of specific primers with the digestion site of HindIII and XbaI on the 5' end were designed and synthesized to clone Noggin cDNA from human fetus with reverse transcription polymorase chain reaction (RT-PCR). The purified product of RT-PCR was ligated into the pMD18 simple T clone vector to be identified with HindIII and XbaI and DNA sequence analysis. The pCS2+〔Tα1〕-GFP plasmid contained the alpha1-tubulin promoter, a tissue-specific promoter to neurons. The Hind III-XbaI fragments recycled from the two plasmids, which contained the full length of human Noggin cDNA and the tissue-specific promoter, were ligated with T4 DNA ligase. The recombinant pCS2+〔Tα1〕-Noggin plasmid was identified by DNA sequence analysis. Results The product of RT-PCR contained the human Noggin gene. The recombinant pMD18-Noggin plasmid contained the correct nucleotide sequence for human Noggin cDNA by DNA sequence analysis, the recombinant pCS2+〔Tα1〕-Noggin plasmid contained cDNA sequence of human Noggin gene and alpha1-tubulin promoter. Conclusions The specific expression vector to neurons of human Noggin gene, pCS2+〔Tα1〕-Noggin plasmid was successfully constructed.