Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:2.7.7.49 (reverse transcriptase)
31,746 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Similarities between primitive neuroectodermal tumors and central nervous system (CNS) progenitor cells have evoked interest in the response of these tumors to endogenous growth factors. The bone morphogenetic proteins (BMPs) have recently been found to regulate survival and differentiation of CNS progenitor cell populations. In this study, we investigated the effects of BMP-2, BMP-4, and BMP-6 on the undifferentiated cerebellar primitive neuroectodermal tumor or medulloblastoma cell line DAOY. Analysis by reverse transcriptase-polymerase chain reaction showed that mRNAs for type IA and type II BMP receptors were present in control cultures. In cultures treated with BMP-2, mRNAs for BMP receptor type IB and the activin R-I receptor became evident. Cultures were analyzed for total cell counts, proliferating cell nuclear antigen (PCNA), and apoptotic DNA fragmentation. There was a significant increase in total cell number in the BMP-2 and BMP-4 treatment groups, without any change in PCNA reactivity, and a dramatic decrease in the proportion of apoptotic nuclei at concentrations of BMP-2 and BMP-4 above 5 ng/ml (P<0.001). These effects were not observed with BMP-6, TGF-beta1 or GDNF. These results suggest that the increase in total cell number is due to the attenuation of apoptosis by BMP-2 and BMP-4. The anti-apoptotic effect of BMP-2 and BMP-4 on this neuroectodermal cell line has potential clinical implications for neuroectodermal tumors.
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PMID:Bone morphogenetic proteins-2 and -4 attenuate apoptosis in a cerebellar primitive neuroectodermal tumor cell line. 1033 54

We studied differences in ectopic osteoinduction in eight mouse inbred strains and an outbred strain. Antigen-extracted autolyzed rat bone gelatin was implanted under hind limb muscle fascia of 12-week-old males, and new bone formation was morphologically assessed on serial sections. Four weeks after implantation, less than half of the implants from CBA/J, A/J, BALB/cJ, and C3Hf/Bu mice showed induction of only cartilage. New cartilage was observed in all, and bone and bone marrow in 80% of the implants from AKR/J, C57BL/6J, DBA/2J, and RFM/Rij mice. Volume of the newly formed tissue ranged from 1.3% of the old matrix in A/J strain to 74.6% in DBA/2J strain. Outbred CD1 mice showed only weak cartilage induction. The "good" responders differed among themselves in the volume and type of newly induced tissue: DBA/2J, RFM/Rij, and AKR/J mice had a similar ratio of new bone and cartilage and abundant bone marrow, whereas the predominant newly induced tissue in C57Bl/6J mice was cartilage. The pattern of the expression of BMP-2, -4, and -7, alkaline phosphatase, osteocalcin, interferon-gamma, and granulocyte-macrophage colony-stimulating factor, measured by reverse transcriptase polymerase chain reaction, did not correlate with the type and the quantity of the newly induced tissue. Our results show that adult mice of inbred strains differ not only in the peak bone mass and morphology, but also ability to form new bone after an osteoinductive stimulus. Ectopic osteoinduction may be a useful in vivo model to investigate genetic determinants of endochondral osteogenesis, especially its immunological component.
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PMID:Genetic variability of new bone induction in mice. 1042 18

Multipotential mesenchymal stem cells capable of chondro-osseous induction contribute to the endochondral callus of healing fractured bone. Microvascular pericytes serving the role of multipotential mesenchymal stem cells are considered osteoprogenitors because they express type I collagen, alkaline phosphatase enzyme activity, osteocalcin immunoreactivity, and bone sialoprotein mRNA. Previous electron microscopic studies indicate that this cell type has a contribution to the fracture callus. Limited data suggest that pericytes may also assume a chondrogenic phenotype. We undertook in vitro studies to understand how the chondro-osseous phenotype of the pericyte might be regulated. Using Northern analysis and semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR), we found that cultured pericytes produce aggrecan and type II collagen mRNA indicating their chondrogenic potential. Aggrecan message is elevated by BMP-2 as analyzed by both Northern hybridization and RT-PCR. This finding suggests a regulatory role for this morphogen on this phenotype in pericytes. RT-PCR amplified versican product was also associated with pericyte cultures but was not affected by BMP-2. Our data strongly support a chondrogenic role for the pericyte and that the phenotype is regulated at least in part by BMP.
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PMID:Microvascular pericytes express aggrecan message which is regulated by BMP-2. 1069 96

The expression of hard tissue associated proteins may be used to identify periodontal fibroblasts with the capability to facilitate periodontal regeneration. The aim of this study was to describe, by immunohistochemistry, the distribution of osteocalcin, osteopontin, bone sialoprotein and bone morphogenic proteins-2 and -4 (BMP-2 and BMP-4) within the human periodontium. Furthermore, the expression of mRNA for the above proteins and alkaline phosphatase by gingival and periodontal ligament fibroblasts in vitro was also assessed by reverse transcriptase polymerase chain reaction (RT-PCR). Localization of osteopontin, osteocalcin, BMP-2 and BM P-4 within sections of human periodontal structures was stronger in the periodontal ligament compared to the gingiva. Bone sialoprotein was not detected in either of the soft tissues but, along with osteopontin and osteocalcin, it was localized in the cementum and bone. In vitro, both the gingival and periodontal ligament fibroblasts expressed mRNA for alkaline phosphatase, BMP-2, BMP-4 and osteopontin. Although there were no differences in the expression of alkaline phosphatase and BMP-4 mRNA between the two cell types, we noted significantly higher mRNA levels of osteopontin in the periodontal ligament and BM P-2 in the gingival fibroblasts. Osteocalcin and bone sialoprotein mRNA expression was only noted in the cultured periodontal ligament fibroblasts. From these results, it can be concluded that distinct differences exist between the two fibroblast populations in terms of the localization and mRNA expression of the majority of the hard tissue associated proteins. Furthermore, the elevated in vitro mRNA expression for osteocalcin, osteopontin and bone sialoprotein may be used to identify cells with the potential to facilitate hard tissue formation and hence periodontal regeneration.
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PMID:Expression of bone associated macromolecules by gingival and periodontal ligament fibroblasts. 1145 11

The Xenopus tropicalis BMP-2 and BMP-4 genes have been cloned and sequenced. A comparison with the corresponding genes from X. laevis reveals that the BMP-4 genes are conserved at a higher extent than the BMP-2 genes. This is especially evident for the intron sequences, but is also reflected by the exon sequences. While the amino acids of X. tropicalis and X. laevis BMP-4 proteins diverge at about 4%, those of BMP-2 proteins diverge at about 7%. By reverse transcriptase polymerase chain reaction analyses and whole mount in situ hybridizations, we demonstrate the temporal and spatial expression patterns of X. tropicalis BMP-2 and BMP-4 genes. BMP-2 is found to be expressed maternally, and later in development, in migrating heart progenitor cells as well as in the final heart, within the pineal gland and the olfactory placodes. BMP-4 is zygotically activated within the ventral marginal zone and later found in the eye, the otic vesicle, the heart and within blood islands. Although the overall patterns are very similar to those found in X. laevis, there is some distinct difference which might result from the accelerated development in X. tropicalis.
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PMID:Structure and expression of Xenopus tropicalis BMP-2 and BMP-4 genes. 1167 55

MEPE, 56.6 kDa protein isolated from tumors associated with hypophosphatemic osteomalacia, increases renal phosphate excretion and is expressed in normal human bone cells. AC-100, a central 23-amino acid fragment of MEPE, contains motifs that are important in regulating cellular activities in the bone microenvironment. Thus, we assessed in vitro effects of AC-100 on multipotential normal human marrow stromal (hMS) cells that have the capacity to differentiate into mature osteoblasts. Proliferation was quantified by [H3]thymidine uptake and cell counting and differentiation by the levels of mRNA for the alpha2-chain of type I procollagen (COL1A2), alkaline phosphatase (AP), and osteocalcin (OC) measured using real time reverse transcriptase PCR (RT-PCR) and by the formation of mineralized nodules. AC-100 increased proliferation by 257 +/- 89% (P < 0.005), increased gene expression of COL1A2 by 339 +/- 85% (P < 0.005), AP by 1,437 +/- 40% (P < 0.001), and OC by 1,962 +/- 337% (P < 0.001). In addition, it increased mineralized nodule formation by 81 +/- 14% (P < 0.001) in a dose- and time-dependent fashion. In equimolar dosages, the parent compound, MEPE, had the full activity of the AC-100 fragment. AC-100 elicited a comparable response to both IGF-I and BMP-2 with respect to proliferation and differentiation of hMS cells. Using gene expression microarray analysis, we demonstrated that AC-100 increased (by approximately 3-fold) the mRNA for cyclooxgenase-2 (COX-2), an inducible enzyme required for prostaglandin synthesis. Moreover, NS-398, a specific inhibitor of COX-2 action completely blocked AC-100-induced increases in proliferation and differentiation. Thus, AC-100 has potent anabolic activity on osteoblast precursor cells in vitro and these effects require the induction of COX-2.
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PMID:A fragment of the hypophosphatemic factor, MEPE, requires inducible cyclooxygenase-2 to exert potent anabolic effects on normal human marrow osteoblast precursors. 1544 21

In the context of bone development and regeneration, the intimate association of the vascular endothelium with osteogenic cells suggests that endothelial cells (ECs) may directly regulate the differentiation of osteoprogenitor cells. To investigate this question, bone marrow stromal cells (BMSCs) were cultured: in the presence of EC-conditioned medium, on EC extracellular matrix, and in EC cocultures with and without cell contact. RNA and protein were isolated from ECs and analyzed by reverse transcriptase-polymerase chain reaction and Western blotting, respectively, for expression of bone morphogenetic protein 2 (BMP-2). In animal studies, BMSCs and ECs were cotransplanted into severe combined immunodeficient mice on biodegradable polymer matrices, and histomorphometric analysis was performed to determine the extent of new bone and blood vessel formation. ECs significantly increased BMSC osteogenic differentiation in vitro only when cultured in direct contact. ECs expressed BMP-2, and experiments employing interfering RNA inhibition confirmed its production as contributing to the increased BMSC osteogenic differentiation. In vivo, cotransplantation of ECs with BMSCs resulted in greater bone formation than did transplantation of BMSCs alone. These data suggest that ECs function not only to form the microvasculature that delivers nutrients to developing bone but also to modulate the differentiation of osteoprogenitor cells in vitro and in vivo.
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PMID:Endothelial cell modulation of bone marrow stromal cell osteogenic potential. 1567 93

The loss of cell cycle control in malignant melanomas is thought to be due to a lack of retinoblastoma protein (pRb) activity. We have recently reported a progressive deficiency of the retinoblastoma-binding protein 2-homolog 1 (RBP2-H1) in advanced and metastatic melanomas in vivo, suggesting a role of RBP2-H1 in loss of pRb-mediated control. Therefore, in this study, we re-established the pRb-modulating function of RBP2-H1 in highly metastatic A375-SM melanoma cells by re-expressing its C-term (cRBP2-H1). As previously shown, the corresponding domains comprise the pRb-binding region of the RBP2-H1 protein (non-T/E1A-pRb-binding domain (NTE1A)). As a result, we detected pRb-hypophosphorylation selectively at Ser795, but not at Ser780 and Ser807/811 throughout the G1 phase of the cell cycle. As a further consequence, a block in G1/S transition was observed accompanied by a significant decrease of DNA replication and cellular proliferation. As demonstrated by cDNA microarrays of cRBP2-H1-transduced cells and confirmed by quantitative TaqMan reverse transcriptase-PCR, differential expression of melanoma-progression-related genes was observed, among them bone morphogenetic protein 2, follistatin, transforming growth factor alpha, hepatocyte growth factor, transcription factor 4 and microphthalmia-associated transcription factor. Conclusively, these data suggest that RBP2-H1 exerts a broad tumor-suppressive function partially mediated by pRb modulation. Therefore, re-establishing of RBP2-H1 could evolve as an interesting novel approach in developing experimental treatments for metastatic melanomas.
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PMID:Re-expression of the retinoblastoma-binding protein 2-homolog 1 reveals tumor-suppressive functions in highly metastatic melanoma cells. 1664 88

In this study, we delineate the sequential expression of selected growth factors associated with bone formation in vitro. Mineralization, osteocalcin, and alkaline phosphatase (ALP-2) were measured to monitor the differentiation and maturation of osteoprogenitor cells collected from C57BL mice. Bone-related growth factors, including transforming growth factor beta (TGF-beta), fibroblast growth factor 2 (FGF-2), platelet-derived growth factor (PDGF), insulinlike growth factor (IGF)-1, vascular endothelial growth factor (VEGF), bone morphogenetic protein (BMP)-2, and BMP-7, were selected. Enzyme-linked immunosorbent assay (ELISA) and reverse transcriptase polymerase chain reaction (RT-PCR) were used to measure growth factors at the protein and messenger ribonucleic acid (mRNA) level, respectively. The results found that ALP-2 expression increased progressively over time, whereas mineralization and osteocalcin did not become evident until culture day 14. VEGF and IGF-1 were upregulated early during proliferation. PDGF and TGF-beta mRNA expression was bimodal. FGF-2 and BMP-2 mRNAs were expressed only later in differentiation. FGF-2 mRNA signal levels were highest at day 14 and remained prominent through day 28 of culture. BMP-2 showed a similar profile as FGF-2. BMP-7 was not detectable using RT-PCR or ELISA. Strong correlations existed for the expression patterns between several early-response growth factors (VEGF, TGF-beta, and IGF-1) and were also evident for several late-response growth factors (BMP-2, PDGF, and FGF-2). Differential expression for grouped sets of growth factors occurs during the temporal acquisition of bone-specific markers as osteoprogenitor cell maturation proceeds in vitro.
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PMID:The sequential expression profiles of growth factors from osteoprogenitors [correction of osteroprogenitors] to osteoblasts in vitro. 1752 79

The aim of the present study was to test the osteogenic effects of BMP-2 (bone morphogenetic protein-2) gene transfer in BMSCs (bone-marrow stromal cells) and rabbit calvarial bone defects. The pBMP-2-cDNA3.1 plasmid was constructed by subcloning hBMP-2 (human BMP-2) cDNA into the plasmid pcDNA3.1. BMSCs were transfected with a pBMP-2-cDNA3.1-Lipofect-amine complex. Transfected cells were observed for localization of the BMP-2 coding plasmid. Also, the level of BMP-2 in the culture medium of transfected cells was measured. The culture medium was collected and we tested whether this medium could induce non-transfected BMSCs to express ALP (alkaline phosphatase) and osteocalcin. The pBMP-2-cDNA3.1 complexes were incorporated into the collagen scaffold and the plasmid-loaded collagen scaffolds were then grafted into rabbit calvarial defects. After 2 weeks, granulation tissue at the grafted site was obtained and mRNA of BMP-2 was examined via RT (reverse transcriptase)--PCR. After 4 and 8 weeks, the animals were killed and the calvarial tissue was excised. After specimen preparation, optical microscopical examination was performed to evaluate bone formation. The results show that transfected cells were able to incorporate the BMP-2 gene into their nuclei. Also, the level of expressed and secreted BMP-2 was significantly higher in transfected cells than in untransfected cells (P<0.01). The retrieved culture medium could induce the expression of ALP and osteocalcin in non-transfected BMSCs. hBMP-2 mRNA was detected at the granulation tissue of experimental animals, but not in control animals after 2 weeks. At both 4 and 8 weeks, experimental groups showed significantly more newly formed bone area than the control group (P<0.01). Therefore pBMP-2-cDNA3.1 gene delivery could induce BMSCs into osteoblastic phenotype cells and enhance bone regeneration in rabbit calvarial bone defects.
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PMID:Osteogenic effects of bone-morphogenetic-protein-2 plasmid gene transfer. 1760 24


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