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)

This study characterizes the distribution of the two tyrosine kinase receptors for vascular endothelial growth factor (VEGF), Flt-1 and Flk-1, in the rat hippocampus following transient forebrain ischemia. The semi-quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis of Flt-1 and Flk-1 in hippocampal CA1 showed upregulation of these receptors following ischemic injury. Expression of Flt-1 and Flk-1 mRNA was restricted to neurons in the pyramidal cell and granule cell layers in control animals; however, upregulation was detected in activated glial cells and in the vascular endothelial cells rather than in neurons, in ischemic hippocampi. Most of the activated glial cells expressing Flt-1 and Flk-1 were reactive astrocytes, although some were microglial cells. The spatiotemporal expression of Flt-1 in the ischemic hippocampus mirrored that of Flk-1 expression. Expression of mRNA for both receptors was induced after 12 h, appeared to be increased progressively until 3 days when the highest expression was reached, and was sustained for more than 2 weeks. Flt-1 and Flk-1 immunoreactivity in the ischemic hippocampus matched the mRNA induction patterns except for a somewhat delayed onset. These data suggest that VEGF may be involved in the glial response via specific VEGF receptors in the rat hippocampus following transient forebrain ischemia.
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PMID:Upregulation of vascular endothelial growth factor receptors Flt-1 and Flk-1 in rat hippocampus after transient forebrain ischemia. 1740 57

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

1. The aim of the present study was to examine if and how rat hypoxia-induced astrocytes affect the migration of neural progenitor cells (NPC) and to investigate the expression patterns of some chemokines, such as vascular endothelial growth factor (VEGF), stem cell factor (SCF), stromal-derived factor-1alpha (SDF-1alpha), fractalkine and monocyte chemoattractant protein-1 (MCP-1) in hypoxia-induced astrocytes and their contribution to NPC migration in vitro. 2. Costar Transwell inserts were used for the chemotaxis assay and quantified changes in the chemokines mRNA for between 0 h and 24 h posthypoxia were tested using real-time quantitative reverse transcriptase-polymerase chain reaction (RT-PCR) analysis. The results showed that the chemotaxis of astrocyte cells exposed to hypoxia for 18 h reached a peak value, whereas the chemotaxis of astrocytes exposed to hypoxia for 24 h began to decrease compared with those exposed to hypoxia for 18 h. Hypoxia upregulated chemokine VEGF, SCF, SDF-1alpha and MCP-1 expression in a time-dependent manner but downregulated fractalkine expression in astrocytes. In addition, the time points of the peak expressions for VEGF, SCF, SDF-1alpha and MCP-1 were similar to the time point of maximum NPC migration. 3. Specific inhibitors that block the binding of specific chemokines to its receptors were used for analysing the contribution of the chemokine to NPC migration. When VEGF, SCF, SDF-1alpha and MCP-1 were each inhibited independently, NPC migration was reduced. When they were inhibited together, NPC migration was obviously inhibited compared with both the control and single-block cultures, which implies that the migratory effect of hypoxia-induced astrocytes was synergetic by several chemokines. 4. In conclusion, we demonstrated the time-dependent manner of NPC migration promotion by hypoxia-induced astrocytes. We also provide evidence that soluble factors, such as VEGF, SCF, SDF-1alpha and MCP-1, released from astrocytes, direct the migration of NPC under hypoxic circumstances. Given that astrocytes were activated to all hypoxia-ischaemia diseases, these results indicate an important role for astrocytes in directing NPC replacement therapy in the central nervous system.
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PMID:Hypoxia-induced astrocytes promote the migration of neural progenitor cells via vascular endothelial factor, stem cell factor, stromal-derived factor-1alpha and monocyte chemoattractant protein-1 upregulation in vitro. 1758 Dec 19

The aim of this study is to investigate the plasticity of human epithelial ovarian cancer cell SKOV3ip and formation of vasculogenic mimicry (VM) in vivo. SKOV3ip was transfected with lentiviral vector carrying green fluorescence protein (GFP). Female nude mice were implanted intraperitoneally with GFP-labled SKOV3ip. When the transplanted tumor reached a volume of approximately 1 cm(3), paraffin-embedded, formaldehyde-fixed tissue was prepared and stained with hematoxylin and eosin (H & E). Tumor tissues were also studied by electron microscopy and fluorescence microscopy. The results of H & E staining, electron microscopy, and fluorescence microscopy indicated SKOV3ip formed patterned networks with erythrocytes in them, in the absence of vascular epithelial cells, which was a sign that SKOV3ip engaged in VM in vivo. Expression of vascular epithelium marker CD31 was investigated by immunohistochemical staining, immunofluorescence assay, semiquantitative reverse transcriptase-polymerase chain reaction (RT-PCR), and flow cytometric analysis (FACS). Factor VIII and vascular endothelial growth factor (VEGF) were also analyzed by FACS. Weak and focal CD31 immunohistochemical staining was found along the channels of tumor cells. Immunofluorescence assay and RT-PCR demonstrated that CD31 was expressed in primary-cultured SKOV3ip. CD31 and Factor VIII, but not VEGF were detected in primary-cultured SKOV3ip by FACS. The present study has shown that human ovarian cancer cell line SKOV3ip may be able to express some specific markers of vascular epithelial cells and has plasticity to form VM in vivo. In the following study, we indicated that hypoxia-inducible factor (HIF)-1alpha inhibitor, rapamycin, could possibly prevent VM and phenotype transformation of SKOV3ip, reflected by down-regulating expression of CD31 and Factor VIII. HIF-1alpha protein expression correlated with CD31 and Factor VIII protein expression in SKOV3ip. These results indicated that VM might be associated with HIF-1alpha.
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PMID:Plasticity of ovarian cancer cell SKOV3ip and vasculogenic mimicry in vivo. 1764 4

Deficient angiogenesis after ischemia may contribute to worse outcomes of peripheral arterial disease in patients with diabetes mellitus (DM). Vascular endothelial growth factor (VEGF) and its receptors promote angiogenesis. We hypothesized that in peripheral arterial disease, maladaptive changes in VEGF ligand/receptor expression could account for impaired angiogenesis in DM. Skeletal muscle from diet-induced, type 2 diabetic (DM) and age-matched normal chow (NC)-fed mice was collected at baseline and 3 and 10 days after hindlimb ischemia and analyzed for expression of VEGF (n=10 per group), full-length VEGF receptor (VEGFR)-1, soluble VEGFR-1, and markers of downstream VEGF signaling (n=20 per group) using ELISA, reverse transcriptase-polymerase chain reaction, and Western blots. In the absence of ischemia, DM mice had increased VEGF (NC versus DM: 26.6+/-2.6 versus 53.5+/-8.8 pg/mg protein; P<0.05), decreased soluble and membrane-bound VEGFR-1 (NC versus DM: 1.44+/-0.30 versus 0.85+/-0.08 and 1.03+/-0.10 versus 0.72+/-0.10, respectively; P<0.05), decreased phospho-AKT/AKT and phospho-endothelial NO synthase/endothelial NO synthase (NC versus DM: 0.76+/-0.2 versus 0.38+/-0.1 and 0.36+/-0.06 versus 0.25+/-0.04, respectively; P<0.05), and no change in VEGFR-2. After ischemia, both DM and NC had comparable increases in VEGF-A. VEGFR-1 and soluble VEGFR-1 expression increased in both groups, but the fold increase was significantly greater in DM. These data demonstrate that soluble VEGFR-1, an angiogenesis inhibitor, is regulated in skeletal muscle by type 2 DM and ischemia. In the absence of ischemia, despite reductions in both soluble VEGFR-1 and VEGFR-1, VEGF ligand signaling is lower in DM compared with controls. After ischemia, maladaptive upregulation of these receptors further reduces the capacity of VEGF to induce an angiogenic response, which may provide a novel target for therapy.
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PMID:Impaired angiogenesis after hindlimb ischemia in type 2 diabetes mellitus: differential regulation of vascular endothelial growth factor receptor 1 and soluble vascular endothelial growth factor receptor 1. 1782 71

To define better the putative targets of vascular endothelial growth factor (VEGF) in the developing brain we have examined the ontogeny of the two VEGF tyrosine kinase receptors, Flt-1 and Flk-1, in embryonic rat forebrain. Semiquantitative reverse transcriptase-polymerase chain reaction and immunoblot analysis showed expression of both receptors in the forebrain at all embryonic ages studied. Messenger RNAs for Flt-1 and Flk-1 appeared along most of the ventricular zone of the lateral ventricle as early as embryonic day (E) 13. Messages gradually became restricted to a limited ventricular zone at E20. Expression of VEGF receptors was also observed in the cerebral cortex, hippocampus and thalamic nuclei. In the cortex, expression of mRNA for both receptors was detected in the cortical plate around E15, and became relatively weak and restricted to the deeper layers of the cortical plate at E20. These data suggest that VEGF may contribute to early developmental processes including the proliferation, differentiation and maturation of specific neuronal populations via specific VEGF receptors in the developing rat forebrain.
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PMID:Expression of vascular endothelial growth factor receptors Flt-1 and Flk-1 in embryonic rat forebrain. 1785 94

This study investigated the expression of core-binding factor alpha-1 (cbfa-1), osteocalcin, and vascular endothelial growth factor (VEGF) relative to new bone formation during guided bone regeneration; cbfa-1 is a prerequisite transcription factor for osteoblastic differentiation. Osteocalcin, a bone-specific extracellular matrix protein, is a marker of mature osteoblasts, whereas VEGF, a mitogen for endothelial cells, is a polypeptide thought to stimulate new blood vessel formation. Membranes (expanded polytetrafluoroethylene) were applied to defects created in the left tibiae of rats, while right tibial defects remained uncovered as a control group. Animals were killed 6, 8, or 10 days later. The cbfa-1 was detected by immunohistochemistry, and reverse transcriptase-polymerase chain reaction was used to detect osteocalcin and VEGF. The ratio of cbfa-1 positive cells in experimental bone defects was higher than in the control group. Osteocalcin mRNA expression increased gradually in the control group but significantly in the experimental group over time. The VEGF mRNA expression in the experimental group at 10 days was significantly lower than in the control group. These findings suggested that osteogenic cells differentiated into osteoblasts in the membrane-covered defects and that the bone healing process would be completed at an early stage.
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PMID:Characteristics of newly formed bone during guided bone regeneration: analysis of cbfa-1, osteocalcin, and VEGF expression. 1824 Jul 90

Expansion of the thyroid microvasculature is the earliest event during goiter formation, always occurring before thyrocyte proliferation; however, the precise mechanisms governing this physiological angiogenesis are not well understood. Using reverse transcriptase-polymerase chain reaction and immunohistochemistry to measure gene expression and laser Doppler to measure blood flow in an animal model of goitrogenesis, we show that thyroid angiogenesis occurred into two successive phases. The first phase lasted a week and involved vascular activation; this process was thyroid-stimulating hormone (TSH)-independent and was directly triggered by expression of vascular endothelial growth factor (VEGF) by thyrocytes as soon as the intracellular iodine content decreased. This early reaction was followed by an increase in thyroid blood flow and endothelial cell proliferation, both of which were mediated by VEGF and inhibited by VEGF-blocking antibodies. The second, angiogenic, phase was TSH-dependent and was activated as TSH levels increased. This phase involved substantial up-regulation of the major proangiogenic factors VEGF-A, fibroblast growth factor-2, angiopoietin 1, and NG2 as well as their receptors Flk-1/VEGFR2, Flt-1/VEGFR1, and Tie-2. In conclusion, goiter-associated angiogenesis promotes thyroid adaptation to iodine deficiency. Specifically, as soon as the iodine supply is limited, thyrocytes produce proangiogenic signals that elicit early TSH-independent microvascular activation; if iodine deficiency persists, TSH plasma levels increase, triggering the second angiogenic phase that supports thyrocyte proliferation.
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PMID:Iodine deficiency induces a thyroid stimulating hormone-independent early phase of microvascular reshaping in the thyroid. 1827 86

The function and development of cells rely heavily on the signaling interactions with the surrounding extracellular matrix (ECM). Therefore, a tissue engineering scaffold should mimic native ECM to recreate the in vivo environment. Previously, we have shown that an in vitro generated ECM secreted by cultured cells enhances the mineralized matrix deposition of marrow stromal cells (MSCs). In this study, MSC expression of 45 bone-related genes using real-time reverse transcriptase polymerase chain reaction (RT-PCR) was determined. Upregulation of osteoblastic markers such as collagen type I, matrix extracellular phosphoglycoprotein with ASARM motif, parathyroid hormone receptor, and osteocalcin, indicated that the MSCs on plain titanium scaffolds differentiated down the osteoblastic lineage and deposited a mineralized matrix on day 12. Significant mineralized matrix deposition was observed as early as day 4 on ECM-containing scaffolds and was associated with the enhancement in expression of a subset of osteoblast-specific genes that included a 2-fold increase in osteopontin expression at day 1 and a 6.5-fold increase in osteocalcin expression at day 4 as well as downregulation of chondrogenic gene markers. These results were attributed to the cellular interactions with growth factors and matrix molecules that are likely present in the in vitro generated ECM since the genes for insulin-like growth factor 1, insulin-like growth factor 2, vascular endothelial growth factor, dentin matrix protein, collagen type IV, cartilage oligomeric protein, and matrix metalloproteinase 13 were significantly upregulated during ECM construct generation. Overall, the data demonstrate that modulation of MSC differentiation occurs at the transcriptional level and gene expression of bone-related proteins is differentially regulated by the ECM. This study presents enormous implications for tissue engineering strategies, as it demonstrates that modification of a biomaterial with an in vitro generated ECM containing cell-generated bioactive signaling molecules can effectively direct gene expression and differentiation of seeded progenitor cell populations.
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PMID:The influence of an in vitro generated bone-like extracellular matrix on osteoblastic gene expression of marrow stromal cells. 1836 45

During pancreatic islet transplantation, delayed and insufficient revascularization can deprive islets of oxygen and nutrients, resulting in cell death and early graft failure. Deferoxamine (DFO), an iron chelator, increases vascular endothelial growth factor (VEGF) expression in cells. The aim of this work was to study the effect of DFO on beta-cell and pancreatic islet viability as well as VEGF expression. beta-cell lines from rat insulinoma (Rin m5f) and primary cultures of pancreatic islets from Wistar rats were incubated with DFO (10, 100, and 1000 micromol/L). The viability was evaluated using fluorescein diacetate/propidium iodide for dying pancreatic islets and using cell titers for Rin m5f. Expression of VEGF messenger RNA (mRNA) was quantified using reverse transcriptase polymerase chain reaction (RT-PCR). Finally, VEGF secretion was determined using enzyme-linked immunosorbent assays at 1 to 3 days after treatment. The addition of 10 micromol/L of DFO preserved Rin m5F viability at 24 hours after treatment (10 micromol/L; 101.33% +/- 5.66%; n = 7). However, 100 and 1000 micromol/L of DFO induced cell death (68.92% +/- 5.83% and 65.89% +/- 5.83%, respectively; n = 4). In the same way, viability of pancreatic islets in the presence of DFO was preserved. RT-PCR analysis showed stimulation of VEGF mRNA in the presence of 10 micromol/L of DFO in islets at 3 days after culture. Finally, 10 micromol/L of DFO stimulated secretion of VEGF 7.95 +/- 0.84 versus 1.80 +/- 1.10 pg/microg total protein with 10 micromol/L of DFO in rat islets at 3 days after culture, n = 3; P < .001). The use of DFO to stimulate VEGF expression and increase islet vascularization may be a realistic approach to improve islet viability during transplantation.
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PMID:Overexpression of vascular endothelial growth factor in vitro using deferoxamine: a new drug to increase islet vascularization during transplantation. 1837 6


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