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)

Vascular endothelial growth factor is a powerful mitogen for endothelial cells, recently reported to be produced by keratinocytes. In the present work, we examined human keratinocytes in primary culture for the splice variants of vascular endothelial growth factor. In situ hybridization revealed that 100% of cultured human keratinocytes expressed mRNA for this cytokine, and analysis by reverse transcriptase-polymerase chain reaction indicated that three species of mRNA were produced. Southern hybridization and size calculations of PCR products revealed mRNA species corresponding to 121, 165, and 189 amino-acid forms of this cytokine. Using a rabbit anti-vascular endothelial growth factor antiserum, we radioimmunoprecipitated two molecular weight forms (approximately 45 and 58 kDa, non-reducing conditions) from keratinocyte culture supernatants. Under reducing conditions, three bands of approximately 15, 20, and 24 kDa appeared, corresponding with the predominant forms of vascular endothelial growth factor described. We propose that secretion of vascular endothelial growth factor by human keratinocytes in vivo sustains angiogenesis during physiologic tissue repair and in pathologic states accompanied by neovascularization.
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PMID:Human keratinocytes express the three major splice forms of vascular endothelial growth factor. 779 44

The corpus luteum undergoes tremendous growth, development and regression each oestrous or menstrual cycle. These changes are reflected by equally impressive growth and regression of the luteal vasculature. We have previously shown that angiogenic factors from corpora lutea are primarily heparin binding and that one of these factors is similar to vascular endothelial growth factor (VEGF). In an effort to identify this factor, and to define its role in luteal vascular development, the cDNA for the coding region of ovine VEGF was sequenced and a sensitive RNase protection assay was developed to quantitate mRNA encoding VEGF in luteal tissues from ewes in the early (days 2-4), mid- (day 8) and late (days 14-15) stages of the oestrous cycle. In addition, an N-terminal peptide was synthesized from the translated ovine cDNA sequence for VEGF and an antiserum was raised against this peptide for use in western immunoblotting procedures. Nested reverse transcriptase (RT)-PCR of RNA from ovine corpora lutea resulted in three products that correspond in size to the alternatively spliced variants of VEGF (VEGF120, VEGF164, and VEGF188) predicted from other species. The RNase protection assay revealed that the proportion of mRNA encoding VEGF was 2- to 3-fold greater on days 2-4 than on day 8 or days 14-15. Densitometric analysis of gels from the RNase protection assay showed that VEGF120 represented approximately one third of the total mRNA encoding VEGF in the corpus luteum and that this proportion did not vary with stage of the oestrous cycle. SDS-PAGE and western immunoblot analysis of a homogenate from corpora lutea showed a single 18 kDa protein. These data demonstrate that VEGF is expressed in luteal tissue throughout the ovine oestrous cycle and that expression of mRNA encoding VEGF is upregulated during the period of rapid luteal development, when luteal vascular growth is at its maximum.
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PMID:Characterization and expression of vascular endothelial growth factor (VEGF) in the ovine corpus luteum. 895 42

Expression of vascular endothelial growth factor (VEGF), also known as vascular permeability factor (VPF), and its receptors Flt-1 and KDR (Flk-1 in mouse) and their localization in the human testis were analyzed by means of reverse transcriptase-polymerase chain reaction (RT-PCR), Western blotting and immunohistochemistry. VEGF mRNA was detected in the human testicular tissue and in fragments of seminiferous tubules by means of RT-PCR, while fragments of blood vessels isolated from testes were negative. Western blotting procedure using a specific VEGF antibody, revealed two protein bands corresponding to 24 and 49 kDa in the extracts prepared from the whole testis and in the seminiferous tubules while no such bands were found in isolated fragments of human testicular blood vessels. Also immunohistochemically, human testicular blood vessels show no VEGF immunoreactivity, while Leydig cells and Sertoli cells were positive. The mRNA of the VEGF receptor Flt-1 was found to be expressed in human testicular tissue, in isolated fragments of testicular blood vessels and in seminiferous tubules as determined by RT-PCR procedure. In accordance with these results, the Flt-1 protein was immunohistochemically localized in Leydig, Sertoli and perivascular cells. Endothelial cells of certain segments of human testicular microvasculature also stained positive for Flt-1. Expression of VEGF receptor, KDR, could be demonstrated in human testicular tissue, in isolated seminiferous tubules and in isolated fragments of human testicular blood vessels by means of RT-PCR. Immunohistochemically, the KDR protein was localized in endothelial cells and perivascular cells of capillaries within the lamina propria of seminiferous tubules. Leydig cells and Sertoli cells show KDR immunoreactivity, too. Thus we demonstrate the presence of both types of VEGF receptors Flt-1 and KDR on Leydig as well as on Sertoli cells which are normal non-endothelial cells, suggesting hitherto unrecognized and novel functions for such receptors. The results obtained permit us to suggest VEGF as a paracrine mitogenic and angiogenic factor, responsible for modulating the capillarization of the human testicular tissue and maintaining the functions of testicular microvasculature. VEGF may also influence the permeability of capillaries passing through the groups of Leydig cells and those localized within the lamina propria of human seminiferous tubules. The differences in the expression pattern of the VEGF receptors in the human testicular tissue probably reflect different VEGF effects in different compartments of human testis.
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PMID:Vascular endothelial growth factor and its receptors in normal human testicular tissue. 925 59

To investigate temporal changes in capillarization and increases in mitochondrial enzyme activity, rabbit tibialis anterior muscles underwent chronic low-frequency stimulation for up to 50 days. Capillary density (CD), capillary-to-fiber ratio (C/F), intercapillary distance (ICD), and mean capillary area (MCA), as well as several other parameters of capillarization, were examined. In addition, tissue levels of mRNA specific to vascular endothelial growth factor (VEGF) were assessed by reverse transcriptase-polymerase chain reaction. Citrate synthase (CS) activity, a marker of aerobic-oxidative metabolic potential, was measured in the same muscles. Significant increases in CD and C/F, respectively, and decreases in ICD and MCA were observed after 2 days. These changes reached stable maxima by 14 days. The increases in capillarization occurred in a fiber-type-specific manner, affecting type IId fibers before types IIda and IIa. VEGF mRNA levels increased in a bimodal time pattern with a first elevation (2.5-fold) after 1 day and a second (9-fold) after 6-8 days. Increases in CS were first noted after 8 days. Obviously, increases in capillarization as induced by enhanced contractile activity precede increases in the aerobic-oxidative potential of energy metabolism.
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PMID:Sequential increases in capillarization and mitochondrial enzymes in low-frequency-stimulated rabbit muscle. 953 Jan 13

We examined the role of vascular endothelial growth factor (VEGF) in preventing apoptosis in primary human umbilical vein endothelial (HUVE) cells. VEGF was capable of preventing serum starvation-induced apoptosis at concentrations between 10 and 100 ng/ml. The addition of VEGF to serum-starved HUVE cells led to a 5. 2-fold induction of Bcl-2 after 36 h and to a transient, 2.4-fold induction of A1 after a 7-h incubation, as quantitated by real time reverse transcriptase-polymerase chain reaction analysis. Western blot analysis demonstrated a 2-3-fold induction of Bcl-2 protein after 18-36 h of exposure to VEGF and a transient induction of A1 after 7 h of VEGF stimulation. Moreover, overexpression of Bcl-2 by means of transient biolistic transfection experiments of HUVE cells was sufficient to prevent endothelial cells from apoptotic cell death in the absence of VEGF. These findings indicate that Bcl-2 plays an important role in mediating the survival activity of VEGF on endothelial cells.
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PMID:Vascular endothelial growth factor induces expression of the antiapoptotic proteins Bcl-2 and A1 in vascular endothelial cells. 958 77

Saliva is an enriched milieu containing biologically active proteins, including several different growth factors and cytokines. This study documents that vascular endothelial growth factor (VEGF), a potent, multifunctional, angiogenic cytokine, is a component of normal human saliva. VEGF was measured by ELISA in whole saliva (median concentration, 460 pg/ml) and in ductal secretions obtained from the parotid (277 pg/ml) and the submandibular-sublingual (80 pg/ml) salivary glands. VEGF seems to be synthesized endogenously by the salivary glands because both VEGF mRNA and protein (as revealed by in situ reverse transcriptase-PCR and by immunohistochemistry, respectively) colocalized to serous acinar cells and ductal epithelial cells within the parotid, submandibular, and minor salivary glands. These findings point to the existence of a "salivary VEGF system." It is possible that salivary VEGF plays a role in regulating physiologic and pathologic angiogenic and other vascular responses in salivary and mucosal tissues. And in particular, the presence of VEGF in saliva may contribute to the remarkable healing capacity of the oral mucosa as well as other regions of the digestive tract.
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PMID:Vascular endothelial growth factor in normal human salivary glands and saliva: a possible role in the maintenance of mucosal homeostasis. 969 May 64

Glomerular podocytes are major determinants of filtration permselectivity in the glomerulus. Although the molecular mechanisms determining the characteristics of the glomerular filtration unit are incompletely understood, vascular endothelial growth factor (VEGF) has been implicated. To analyze this process in situ, we established a method that allows exploration of in vivo mRNA expression of podocytes using single-cell reverse transcriptase-polymerase chain reaction (RT-PCR). Microdissected mouse glomeruli were held in a patch-clamp apparatus, and single podocytes were harvested by aspiration. After lysis, the cells were reverse transcribed, and PCR was performed (45 cycles). The podocyte nature of the material was confirmed by detection of podocyte-specific mRNA (glomerular epithelial protein 1 and Wilms' tumor protein 1). Using specific oligonucleotide primers, VEGF was detected in mRNA obtained from renal cortex, single microdissected glomeruli, cultured murine podocytes, and single podocytes in situ. All cells examined expressed three VEGF isoforms (121, 165, and 189). These differ in their capacity for binding to extracellular matrix and could have different potencies regulating glomerular endothelial permeability. Our approach should allow a semiquantitative, isoform-specific evaluation of VEGF mRNA expression in podocytes during nephrogenesis and in glomerular disease.
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PMID:Detection of multiple vascular endothelial growth factor splice isoforms in single glomerular podocytes. 973 76

Vascular endothelial growth factor is a potent direct-acting angiogenic factor. Early in hepatocarcinogenesis, hepatocellular carcinomas do not show hypervascularity; at later stages, they require abundant arterial blood flow. We investigated the role of vascular endothelial growth factor in hepatocellular carcinoma arterialization. We studied 51 patients with hepatocellular carcinoma. All patients had undergone hepatic arteriography. Vascular endothelial growth factor expression was investigated by immunohistochemistry (n = 51) and in situ hybridization (n = 13), and the changes in vascular endothelial growth factor expression were evaluated in relation to tumor differentiation and changes in tumor vascularity. The expression of vascular endothelial growth factor isoforms in hepatocellular carcinomas was also analyzed by reverse transcriptase-polymerase chain reaction (n = 10). Vascular endothelial growth factor expression was detected in hepatoma cells and hepatic stellate cells, and increased vascular endothelial growth factor expression was associated with tumor dedifferentiation. Vascular endothelial growth factor expression in hypervascular hepatocellular carcinomas was greater than in those not showing hypervascularity. The major vascular endothelial growth factor isoforms expressed in hepatocellular carcinoma were 121 and 165. These findings indicate that vascular endothelial growth factors 121 and 165 play a critical role in the process of angiogenesis in hepatocellular carcinomas.
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PMID:Increased expression of vascular endothelial growth factor is associated with tumor progression in hepatocellular carcinoma. 974 16

Angiopoietin-2 (Ang2) is a ligand for the endothelial cell tyrosine kinase receptor Tie2 and counteracts blood vessel maturation/stability mediated by angiopoietin-1 (Ang1), the other known ligand of Tie2. Using degenerate oligonucleotides and reverse transcriptase-polymerase chain reaction, we have screened bovine microvascular endothelial (BME), aortic, lymphatic, pulmonary artery, and transformed fetal aortic endothelial cells, as well as rat smooth muscle cells for Ang1 and Ang2 expression. Except for high Ang2 mRNA levels found in BME cells, none of the endothelial cell types studied expressed appreciable levels of Ang1 or Ang2 mRNAs, whereas smooth muscle cells expressed both Ang1 and Ang2. BME cell Ang2 mRNA levels were increased by vascular endothelial growth factor (1.9- to 2.9-fold), basic fibroblast growth factor (1.6- to 2-fold), both cytokines in combination (2.9- to 4-fold), and hypoxia (3.1- to 5.6-fold) and were decreased by Ang1 (31% to 70%) or transforming growth factor-ss1 (64% to 81%). Ang2 also decreased (60% to 82%) BME cell Ang2 mRNA. mRNA levels for the Tie1 or Tie2 receptors were only slightly modulated under the conditions described above. These findings suggest that the angiogenic effect of a number of regulators may be achieved in part through the regulation of an autocrine loop of Ang2 activity in microvascular endothelial cells.
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PMID:Regulation of angiopoietin-2 mRNA levels in bovine microvascular endothelial cells by cytokines and hypoxia. 977 32

Tumour angiogenesis, as assayed by microvessel density (MVD), and the expression of vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) have become established as important prognostic indicators for many tumour types. In this study, MVD and the expression of VEGF and PD-ECGF were examined by immunohistochemical staining of 50 pancreatic cancer tissues, and the relationships between either MVD or the expression of these two angiogenic factors and the clinicopathological features, including survival, were analysed. The expression of VEGF and PD-ECGF proteins were confirmed by Western blot analysis and VEGF mRNA isoforms were determined by reverse transcriptase-polymerase chain reaction (RT-PCR) in five pancreatic cancer cell lines. Twenty-eight (56%) of 50 pancreatic cancers were positive for VEGF protein in cancer cells, and 16 (32%) showed strong PD-ECGF staining in cancer and infiltrating cells. VEGF121 and VEGF165 were identified as the predominant species produced in pancreatic cancer cells. The overexpression of VEGF and PD-ECGF protein significantly correlated with high MVD (P = 0.002, 0.044, respectively). Advanced stage of disease was significantly more frequent in patients with high MVD (P = 0.025). No significant association was found between the expression of VEGF or PD-ECGF and clinicopathological features, except for tumour histology. The expression of PD-ECGF correlated with poor survival (P = 0.011), but MVD and VEGF expression were not found to be useful for the prediction of overall survival. This study suggests that VEGF and PD-ECGF may play an important role in tumour angiogenesis, and that PD-ECGF expression seems to be useful for establishing prognoses for pancreatic cancer.
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PMID:Expression of two angiogenic factors, vascular endothelial growth factor and platelet-derived endothelial cell growth factor in human pancreatic cancer, and its relationship to angiogenesis. 984 29


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