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Biomedical subjects

J M Wozney

Publications and source records attributed to J M Wozney.

At least 19 recordsLinked to original sources

The bone morphogenetic protein family and osteogenesis.

The BMPs (bone morphogenetic proteins) are a group of related proteins originally identified by their presence in bone-inductive extracts of demineralized bone. By molecular cloning, at least six related members of this family have been identified and are called BMP-2 through BMP-7. These molecules are part of the TGF-beta superfamily, based on primary amino acid sequence homology, including the absolute conservation of seven cysteine residues between the TGF-betas and the BMPs. The BMPs can be divided into subgroups with BMP-2 and BMP-4 being 92% identical, and BMP-5, BMP-6, and BMP-7 being an average of about 90% identical. To examine the individual activities of these molecules, we are producing each BMP in a mammalian expression system. In this system, each BMP is synthesized as a precursor peptide, which is glycosylated, processed to the mature peptide, and secreted as a homodimer. These reagents have been used to demonstrate that single molecules, such as BMP-2, are capable of inducing the formation of new cartilage and bone when implanted ectopically in a rodent assay system. Whether each of the BMPs possesses the same inductive activities in an animal is the subject of ongoing research. Based on the chondrogenic and osteogenic abilities of the BMPs in the adult animal, the expression of the mRNAs for the BMPs has been examined in the development of the embryonic skeleton by in situ hybridization. These studies demonstrate that the BMP mRNAs are spatially and temporally expressed appropriately for the proteins involved in the induction and development of cartilage and bone in the embryonic limb bud.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals

The gene for bone morphogenetic protein 2A (BMP2A) is localized to human chromosome 20p12 by radioactive and nonradioactive in situ hybridization.

Bone morphogenetic protein 2A (BMP2A), a member of the decapentaplegic-Vg-related family, belongs to the transforming growth factor beta superfamily and has a striking sequence similarity to the decapentaplegic locus in Drosophila melanogaster, a major determinant of pattern specification during embryogenesis. BMP2A is thought to be involved in cartilage and bone formation during embryogenesis, but may have additional functions in morphogenesis as implied by its expression in various organs and embryonic tissues of mice. Human BMP2A, assigned to chromosome 20 by the use of human-Chinese hamster ovary cell hybrids, is considered to be a reasonable candidate gene for the autosomal dominant disease of fibrodysplasia (myositis) ossificans progressiva. We have confirmed the localization of BMP2A to chromosome 20 and regionally assigned the locus to 20p12 by radioactive and nonradioactive in situ hybridization.

Bone Morphogenetic Proteins

A bone morphogenetic protein subfamily: chromosomal localization of human genes for BMP5, BMP6, and BMP7.

Bone morphogenetic proteins (BMPs) were originally identified by the ability of a demineralized bone extract to induce endochondral osteogenesis in vivo. Seven BMP cDNAs (BMP1 through BMP7) have been recovered through molecular cloning. Recombinant protein products from six of these clones (BMP2 through BMP7) are members of the transforming growth factor beta (TGF-beta) superfamily of regulatory molecules. Based upon a high degree of amino acid sequence homology, BMP5, BMP6, and BMP7 constitute a subfamily within the BMPs. Using human-rodent somatic cell hybrid lines and cDNA probes, we mapped the three members of this subfamily of genes to the human chromosomes. BMP5 and BMP6 are syntenic on human chromosome 6, while BMP7 is syntenic with previously localized BMP2 on human chromosome 20. This analysis reveals that BMP6 maps to a conserved region between the mouse and human genomes. Sequence analysis suggests that the Drosophila 60A gene is the dipteran homolog of this BMP subfamily and may provide clues to the physiologic functions of the products of these genes in human biology.

Animals

Bone morphogenetic proteins-2 and -4 are involved in the retinoic acid-induced differentiation of embryonal carcinoma cells.

Bone morphogenetic proteins-2 and -4 (BMPs-2 and -4) are transforming growth factor beta-related proteins that can induce bone formation in vivo. We observed that the level of endogenous BMP-2 mRNA increased an average of 11-fold on differentiation of F9 embryonal carcinoma cells into parietal endoderm after treatment with retinoic acid (RA) and cAMP, whereas the message for the closely related BMP-4 decreased 12-fold after this treatment. Therefore, the effects of exogenous recombinant BMP-2 protein on the RA-induced differentiation of F9 embryonal carcinoma cells were investigated. BMP-2 addition altered the growth and morphology of RA-treated but not untreated cells. Moreover, the abundance of several messages was affected by exogenous BMP-2 treatment. Notably, the BMP-2 and -4 messages themselves were reduced by the addition of exogenous BMP-2. The observations suggest that RA, which is known to affect bone morphogenesis, may regulate the osteoinductive proteins, BMP-2 and -4. Furthermore, BMP-2 and -4 may be involved in preimplantation embryogenesis.

Animals

Recombinant human bone morphogenetic protein-2 induces osteoblastic differentiation in W-20-17 stromal cells.

To better understand the in vivo bone-inductive properties of recombinant human (rh) BMP-2, we examined the ability of the protein to alter the phenotype of a bone marrow stromal cell line. W-20-17. rhBMP-2 increased alkaline phosphatase activity in W-20-17 cells in a dose-responsive manner in the absence of an effect on proliferation. The induction of alkaline phosphatase activity was not apparent until 12 h after rhBMP-2 treatment had begun and was effectively eliminated by cotreatment with cycloheximide, suggesting a requirement for protein synthesis. Continued treatment of W-20-17 cells with rhBMP-2 for 8 days resulted in a significant increase, compared to control cultures, in the production of cellular cAMP in response to a PTH challenge. In addition, 4-day treatment with rhBMP-2 induced osteocalcin levels in W-20-17 cells. These results indicate that rhBMP-2 induces the expression of several markers associated with the osteoblast phenotype in W-20-17 cells and raises the possibility that BMP-2 may be involved in the differentiation of osteoblasts from progenitor cells resident in bone marrow.

Alkaline Phosphatase

Effects of dentin proteins, transforming growth factor beta 1 (TGF beta 1) and bone morphogenetic protein 2 (BMP2) on the differentiation of odontoblast in vitro.

We have studied the effects of dentin proteins, of Transforming Growth Factor beta 1 (TGF beta 1) and Bone Morphogenetic Protein (BMP2) on the differentiation of odontoblasts in vitro. The total EDTA-soluble fraction of dentin proteins, prepared from rabbit incisors was further separated by chromatography on DEAE-Cellulose and heparin-agarose columns. While the total EDTA-soluble fraction of dentin had no effect on cultured dental papillae, fractions retained on both columns were able to initiate functional differentiation of preodontoblasts of isolated day-17 first lower mouse molar dental papillae cultured in vitro. TGF beta 1 and BMP2, both stimulated the matrix secretion by dental papillae cells. TGF beta 1 and BMP2, combined with the inactive total EDTA-soluble fraction, stimulated odontoblast differentiation. An active fraction retained on DEAE-Cellulose completely lost the inductive activity after incubation with a neutralizing anti-TGF beta antibody. These results demonstrate that a TGF beta-like molecule present in dentin could interact with some component which acts as a modulator of its activity on the initiation of the cytological and functional differentiation of odontoblasts.

Animals

The healing of segmental bone defects, induced by recombinant human bone morphogenetic protein (rhBMP-2). A radiographic, histological, and biomechanical study in rats.

Subcutaneous implants of a recombinant human form of the bone-inducing protein rhBMP-2 (recombinant human bone morphogenetic protein-2) in rats have resulted in the local induction of endochondral bone formation. To test the osteoinductive activity of rhBMP-2 in an osseous location, we created five-millimeter segmental defects in the femora of forty-five adult male Sprague-Dawley rats. Two doses of lyophilized rhBMP-2 (1.4 or 11.0 micrograms) were implanted in each defect, together with guanidine-hydrochloride extracted demineralized rat-bone matrix as a carrier, and the results were compared with those in rats that had implantation of guanidine-hydrochloride extracted demineralized rat-bone matrix only. The formation and healing of bone were determined by radiographic, histological, and mechanical analysis. Both doses of rhBMP-2 induced formation of endochondral bone in the osseous defects in a dose-related manner. Implantation of 11.0 micrograms of rhBMP-2 yielded significant (p less than 0.05) bone formation, resulting in radiographic, histological, and mechanical evidence of union. Despite new-bone formation in the defects that had received 1.4 micrograms of rhBMP-2, no instances of union were observed.

Animals

Bone morphogenetic protein-2 stimulates alkaline phosphatase activity and collagen synthesis in cultured osteoblastic cells, MC3T3-E1.

The activities of three bone morphogenetic proteins (BMPs), BMP-1, BMP-2 and BMP-3, on alkaline phosphatase activity, collagen synthesis and DNA synthesis were studied in cultured osteoblastic cells, MC3T3-E1. Treatment of cells with BMP-2 for 48 h induces an increase in cellular alkaline phosphatase activity. This stimulatory effect is evident at a concentration as low as 20 ng/ml of BMP-2 and becomes greater with increasing doses of BMP-2. The BMP-2-induced increase in alkaline phosphatase activity is enhanced by the presence of beta-estradiol, dexamethasone or 1 alpha, 25(OH)2D3. BMP-2 and BMP-3 slightly but significantly stimulate collagen synthesis. None of the BMPs stimulates DNA synthesis in MC3T3-E1 cells at doses tested. These results indicate that BMPs act directly on osteoblastic cells and stimulate the expression of the osteoblastic phenotypes.

Alkaline Phosphatase

Bone morphogenetic protein: chromosomal localization of human genes for BMP1, BMP2A, and BMP3.

Bone morphogenetic protein (BMP) induces endochondral bone formation in vivo. The human genes have been cloned for a group of proteins containing BMP activity (BMP1, BMP2A, and BMP3). Two of the proteins are members of the transforming growth factor-beta supergene family (BMP2A and BMP3), while BMP1 is a novel regulatory protein. Using somatic cell hybrid lines, cDNA probes were used to map BMP1 to chromosome 8, BMP2A to chromosome 20, and BMP3 to the p14-q21 region of chromosome 4. This analysis reveals that the BMP2A and BMP3 genes map to conserved regions between mouse and human, while the BMP1 gene does not. The locations of the BMP genes were found to overlap with the loci for several disorders of cartilage and bone formation.

Bone Diseases

Recombinant human bone morphogenetic protein-2 stimulates osteoblastic maturation and inhibits myogenic differentiation in vitro.

The in vitro effect of recombinant human bone morphogenetic protein-2 (rhBMP-2) on osteogenic and myogenic differentiation was examined in two clonal cell lines of rat osteoblast-like cells at different differentiation stages, ROB-C26 (C26) and ROB-C20 (C20). The C26 is a potential osteoblast precursor cell line that is also capable of differentiating into muscle cells and adipocytes; the C20 is a more differentiated osteoblastic cell line. Proliferation was stimulated by rhBMP-2 in C26 cells, but inhibited in C20 cells. rhBMP-2 greatly increased alkaline phosphate (ALP) activity in C26 cells, but not in C20 cells. The steady-state level of ALP mRNA was also increased by rhBMP-2 in C26 cells, but not in C20 cells. Production of 3',5'-cAMP in response to parathyroid hormone (PTH) was dose-dependently enhanced by adding rhBMP-2 in both C26 and C20 cells, though the stimulatory effect was much greater in the former. There was neither basal expression of osteocalcin mRNA nor its protein synthesis in C26 cells, but they were strikingly induced by rhBMP-2 in the presence of 1 alpha,25-dihydroxyvitamin D3. rhBMP-2 induced no appreciable changes in procollagen mRNA levels of type I and type III in the two cell lines. Differentiation of C26 cells into myotubes was greatly inhibited by adding rhBMP-2. The inhibitory effect of rhBMP-2 on myogenic differentiation was also observed in clonal rat skeletal myoblasts (L6). Like BMP-2, TGF-beta 1 inhibited myogenic differentiation. However, unlike BMP-2, TGF-beta 1 decreased ALP activity in both C26 and C20 cells. TGF-beta 1 induced neither PTH responsiveness nor osteocalcin production in C26 cells, but it increased PTH responsiveness in C20 cells. These results clearly indicate that rhBMP-2 is involved, at least in vitro, not only in inducing differentiation of osteoblast precursor cells into more mature osteoblast-like cells, but also in inhibiting myogenic differentiation.

Alkaline Phosphatase

The non-osteogenic mouse pluripotent cell line, C3H10T1/2, is induced to differentiate into osteoblastic cells by recombinant human bone morphogenetic protein-2.

The possibility that the non-osteogenic mouse pluripotent cell line, C3H10T1/2 (10T1/2), could be induced to differentiate into osteogenic cells by various hormones and cytokines was examined in vitro. Of a number of agents tested, recombinant human bone morphogenetic protein-2 (rhBMP-2) and retinoic acid induced alkaline phosphatase (ALP) activity in 10T1/2 cells. rhBMP-2 also induced mRNA expression of ALP in the cells. Dexamethasone, 1 alpha, 25-dihydroxyvitamin D3, transforming growth factor-beta 1 and insulin-like growth factor-I did not stimulate ALP activity. Treatment with rhBMP-2 greatly induced cAMP production in response to parathyroid hormone in 10T1/2 cells. No ALP activity was induced in NIH3T3 fibroblasts treated with rhBMP-2 or retinoic acid. These results indicate that 10T1/2 cells have a potential to differentiate into osteogenic cells under the control of BMP-2.

1-Methyl-3-isobutylxanthine

Identification of transforming growth factor beta family members present in bone-inductive protein purified from bovine bone.

Characterization of the polypeptides present in bone-inductive protein extracts from bovine bone has led to the cloning of seven regulatory molecules, six of which are distantly related to transforming growth factor beta. The three human bone morphogenetic proteins (BMPs) we describe herein, BMP-5, BMP-6, and BMP-7, show extensive sequence similarity to BMP-2, a molecule that by itself is sufficient to induce de novo bone formation in vivo. The additive or synergistic contribution of these BMP-2-related molecules to the osteogenic activity associated with demineralized bone is strongly implicated by the presence of these growth factors in the most active fractions of highly purified bone extract.

Amino Acid Sequence

Growth factors influencing bone development.

We have approached the study of growth factors affecting cartilage and bone development by investigating those factors present in bone which are able to initiate new cartilage and bone formation in vivo. This has led to the identification and molecular cloning of seven novel human factors which we have named BMP-1 through BMP-7. Six of these molecules are related to each other, and are also distantly related to TGF-beta. The presence of one of these molecules, recombinant human BMP-2 (rhBMP-2) is sufficient to produce the complex developmental system of cartilage and bone formation when implanted subcutaneously in a rat assay system. In this model, administration of rhBMP-2 ultimately results in the formation of a piece of trabecular bone, which is filled with mature bone marrow. While our studies demonstrate that rhBMP-2 by itself has the ability to induce cartilage and bone formation in vivo, we find other BMP molecules present along with BMP-2 in our highly purified nonrecombinant bone-inductive material. These results suggest that the bone inductive capacity of bone-derived proteins may reside in the combinatorial or synergistic activities of this set of BMP-2 related molecules.

Animals

Bone morphogenetic proteins.

Bone Morphogenetic Protein (BMP) refers to an activity derived from bone that induces the formation of cartilage and bone in vivo. This activity leads to a series of developmental processes including chemotaxis, proliferation, and differentiation, which result in the transient formation of cartilage and the production of living bone tissue, complete with hematopoietic marrow. The determination of the factor or factors responsible for this activity has clear significance both for our understanding of bone biology and for the clinical application of cartilage and bone replacement. Several newly discovered factors, BMP-1, BMP-2 (BMP-2A), BMP-3 (osteogenin), BMP-4 (BMP-2B), BMP-5, BMP-6, BMP-7, and osteoinductive factor (OIF) have been implicated in the BMP process. BMP-2 through BMP-7 are all in the TGF-beta superfamily of molecules, and are closely related to two factors (Vg1 and dpp) which are involved in a variety of developmental processes during embryogenesis. A recently discovered factor, OIF, exhibits BMP activity only in the presence of TGF-beta. BMP-2, expressed as a recombinant protein, is the only molecule described to data that has been shown to clearly induce by itself the entire cartilage and bone formation process seen with bone-derived BMP. Evidence is accumulating that the BMP effect is a result of the combined actions of a set of BMP-2-like molecules. Definitive examination of the activities of the other factors will require expression of the recombinant proteins and testing of these in vivo alone and in combinations.

Amino Acid Sequence

Purification and molecular cloning of a novel group of BMPs and localization of BMP mRNA in developing bone.

Using a novel purification scheme, we have characterized BMP as a 30kD fraction. After reduction, which destroys biological activity, this fraction was shown to be comprised of individual polypeptides with molecular weights of 30kD, 18kD and 16kD. Molecular cloning of these polypeptides resulted in the identification of 4 previously undescribed genes (BMP-1, BMP-2A, BMP-2B, and BMP-3) each of which is capable of directing de novo cartilage formation in vivo. While BMP-1 appears to be unrelated to other known growth factors, the derived amino acid sequence of BMP-2A, 2B, and 3 indicate that they are new members of the TGFb gene family. BMP-1, 2A and 2B are expressed in rat embryos during morphogenesis and can be localized by in situ hybridization to developing limb buds. BMP-3 localizes to neural ectoderm and later on in development to newly forming periosteum. Comparisons to other members of the TGFb family suggest that these newly identified BMPs are involved in pattern formation during early skeletal development.

Amino Acid Sequence

Novel regulators of bone formation: molecular clones and activities.

Protein extracts derived from bone can initiate the process that begins with cartilage formation and ends in de novo bone formation. The critical components of this extract, termed bone morphogenetic protein (BMP), that direct cartilage and bone formation as well as the constitutive elements supplied by the animal during this process have long remained unclear. Amino acid sequence has been derived from a highly purified preparation of BMP from bovine bone. Now, human complementary DNA clones corresponding to three polypeptides present in this BMP preparation have been isolated, and expression of the recombinant human proteins have been obtained. Each of the three (BMP-1, BMP-2A, and BMP-3) appears to be independently capable of inducing the formation of cartilage in vivo. Two of the encoded proteins (BMP-2A and BMP-3) are new members of the TGF-beta supergene family, while the third, BMP-1, appears to be a novel regulatory molecule.

Amino Acid Sequence