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)

Vascular endothellal growth factor (VEGF) increases vascular permeability and acts as a mitogen for endothelial cells in vivo and in vitro. We and others recently demonstrated that cultured human keratinocytes constitutively secrete VEGF. In the present study, we examined the expression of this growth factor in various epithelial skin tumors and in normal skin. Using in situ hybridization, we detected strong VEGF mRNA expression in all of 10 squamous cell carcinomas, 13 common warts, 11 seborrheic keratoses, and in 7 of 8 keratoacanthomas studied. By contrast, we found no VEGF mRNA in 9 of 14 basal cell carcinomas. VEGF mRNA was readily detectable within the epidermis adjacent to the tumors as well as in tumor cells and in the epidermis of normal human skin. Northern hybridization of RNA derived from normal human epidermis identified VEGF transcripts of 3.7 and 1.8 kb, and reverse transcriptase polymerase chain reaction confirmed that epidermal cells, like keratinocytes in vitro, express the three major splice forms of VEGF. Immunohistochemical staining with monoclonal antibodies confirmed that expression of VEGF mRNA was accompanied by the presence of VEGF protein. Our data demonstrate that VEGF production by tumor cells in situ does not distinguish malignant from benign epithelial tumors of the skin because it is present in both. The constitutive expression of VEGF by normal keratinocytes in situ suggests that this angiotropic cytokine is important for the regulation of vessel function under physiologic conditions.
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PMID:Vascular endothelial growth factor production in normal epidermis and in benign and malignant epithelial skin tumors. 894 Dec 11

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

Vascular endothelial growth factor (VEGF)/vascular permeability factor is a likely angiogenic mediator in proliferative diabetic retinopathy, and its role is under scrutiny in the pathogenesis of the capillary leakage characteristic of background diabetic retinopathy. To examine whether the diabetic milieu induces or increases retinal VEGF expression in humans, we examined retinas from nondiabetic eye donors and donors with 9 +/- 5 years of diabetes and documented microangiopathy. To identify possible confounding effects of the postmortem period, we also studied the postmortem stability of the VEGF transcript and the expression of the VEGF protein in rat retinas. In both human and rat retina we detected by Northern analysis a 4.2-kb VEGF mRNA species and by reverse transcriptase polymerase chain reaction the transcripts encoding VEGF165 (the most abundant), VEGF121, and VEGF189. By in situ hybridization and immunohistochemistry VEGF mRNA and protein co-localized at the ganglion cell, inner nuclear, and outer plexiform layers and in the walls of the blood vessels (where mRNA was scarce). The protein was additionally detected in photoreceptors. The abundance and distribution of VEGF mRNA and protein were not altered in the diabetic retinas, indicating that the diabetic environment is not sufficient to increase retinal VEGF expression. The demonstration that VEGF is constitutively expressed in the adult retina and is localized to discrete neural cells and their processes proposes a role for the cytokine in retinal homeostasis and/or function.
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PMID:Expression of vascular endothelial growth factor in the human retina and in nonproliferative diabetic retinopathy. 962 50

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

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

In the present study, we examined the effect of glucose concentration on the expression of vascular endothelial growth factor (VEGF), basic fibroblast growth factor (bFGF), and transforming growth factor-beta (TGF-beta) mRNA using reverse transcriptase-polymerase chain reaction (RT-betaCR) in normal healthy leukocytes in vitro and in leukocytes from patients with type 1 diabetes mellitus. In vitro, the level of TGF-beta mRNA was altered in response to the glucose concentration (maximum at 10 mmol/L), while bFGF mRNA remained relatively constant and VEGF mRNA varied with no clear correlation with the glucose concentration. Leukocytes from type 1 patients showed no difference in bFGF or TGF-beta mRNA levels compared with age-matched healthy controls. However, VEGF mRNA was significantly lower in type 1 patients compared with controls (P < .05). When the patients were subtyped according to the severity of retinopathy, the level of TGF-beta mRNA was elevated selectively in patients with evidence of active new retinal vessels (P < .01) and VEGF121 mRNA was reduced in patients with mild to moderate retinopathy. Thus, leukocyte growth factor mRNAs respond to acute changes in the glucose concentration in vitro, and are differentially expressed in type 1 diabetic patients during the course of the disease.
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PMID:Regulation of transforming growth factor-beta, basic fibroblast growth factor, and vascular endothelial cell growth factor mRNA in peripheral blood leukocytes in patients with diabetic retinopathy. 1048 60

We hypothesized that the regulation of microvascular functions and angiogenesis in breast tissue, a well known target of ovarian steroid action, is dependent on the hormonal exposure of the breast. Relative expression levels of VEGF-A (vascular endothelial growth factor A), a putative key regulator of angiogenesis in breast cancer, were analysed in the tumour and the adjacent non-neoplastic breast tissue of 19 breast cancer patients by quantitative reverse transcriptase polymerase chain reaction. In non-neoplastic breast specimens the expression levels of all detected VEGF-A-isoforms (189, 165, 121) were significantly higher in premenopausal compared to post-menopausal women (P = 0.02) and were inversely correlated with the patient's age (P = 0.006). In contrast, in cancerous tissues menopausal status had no influence on VEGF-A-expression levels. Benign and malignant tissues exhibited a similar expression pattern of VEGF-A-isoforms relative to each other. Thus, the regulation of the vasculature in normal breast tissue, as opposed to breast cancer tissue, appears to be hormonally dependent. Endogenous and therapeutically used hormonal steroids might, therefore, cause clinically relevant changes of the angiogenic phenotype of the human breast.
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PMID:Vascular endothelial growth factor A (VEGF-A) mRNA expression levels decrease after menopause in normal breast tissue but not in breast cancer lesions. 1049 46


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