Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P06889 (Mol)
 630,302 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Leptin, the product of ob gene, is an endocrine hormone that regulates adipose tissue mass. Recently, leptin has been found to generate a growth signal involving a tyrosine kinase-dependent intracellular pathway and promote angiogenic processes via activation of leptin receptor (Ob-R) in endothelial cells. However, it is not clear how leptin functions to promote multi-step processes involved in the neovascularization at the atherosclerotic plaque. We have examined the expression of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) and Ob-R in human atherosclerotic lesions, leptin-mediated angiogenesis in vivo and in vitro. Immunohistochemical analysis of human atherosclerotic aorta revealed an increased expression of Ob-R in the intima of neorevascularized regions and of both MMPs and TIMPs predominantly in the endothelial lining of intimal neovessels and macrophages/foam cells. In the rat corneal angiogenesis assay, leptin elicited a comparable sensitivity of angiogenic activity to those of vascular endothelial growth factor (VEGF). The immunohistological analysis of the leptin-treated rat cornea showed definitive rises in Ob-R, MMPs and TIMPs expression as well as those of VEGF receptor (VEGFR-1). Leptin (10-40 ng/ml) induced proliferation of the human umbilical vein endothelial cells (HUVECs) and elevation of MMP-2, MMP-9, TIMP-1, and TIMP-2 expression in a dose-dependent manner. Leptin also induced increases of MMP-2, MMP-9, TIMP-1, and Up-regulated the human coronary artery smooth muscle cells (HCASMCs). These findings suggest that leptin, a hormone with pluralistic properties including a mitogenic activity on vascular endothelial cells, plays a role in matrix remodeling by regulating the expression of MMPs and TIMPs. Taken together, our findings further provide evidences for leptin's role as an angiogenesis inducer in the normal organ (rat cornea) and in aberrant vasculature under duress like atherosclerosis.
Exp Mol Med 2001 Jun 30
PMID:Potential role of leptin in angiogenesis: leptin induces endothelial cell proliferation and expression of matrix metalloproteinases in vivo and in vitro. 1146 Aug 88

Interleukin (IL)-4 and IL-13 are key proinflammatory cytokines in asthma. Studies in transgenic mice show that both cytokines cause inflammation, but only IL-13 causes subepithelial fibrosis, a characteristic feature of asthma. We compared the in vitro profibrogenic effects of IL-4 and IL-13 using bronchial fibroblasts from asthmatic subjects. In the presence of transforming growth factor (TGF)-beta the cells transformed into contractile myofibroblasts and expressed alpha-smooth muscle actin and procollagen I. IL-4 and IL-13 also stimulated proliferation, but were relatively ineffective in promoting myofibroblast transformation. TGF-beta was more potent than the cytokines in stimulating release of endothelin-1 and vascular endothelial growth factor, whereas IL-4 and IL-13 were more potent stimuli for eotaxin release. Although neither IL-4 nor IL-13 induced profibrotic responses, both cytokines caused a corticosteroid-insensitive stimulation of TGF-beta2 release from primary bronchial epithelial cells. These data indicate that epithelial activation by IL-13 or IL-4 plays a critical role in initiating remodeling through release of TGF-beta2. TGF-beta2 then activates the underlying myofibroblasts to secrete matrix proteins and smooth muscle and vascular mitogens to propagate remodeling changes into the submucosa. In contrast, direct activation of submucosal fibroblasts by IL-4 and IL-13 has a proinflammatory effect via eotaxin release and recruitment of eosinophils into the airways.
Am J Respir Cell Mol Biol 2001 Sep
PMID:The contribution of interleukin (IL)-4 and IL-13 to the epithelial-mesenchymal trophic unit in asthma. 1158 18

Cyclooxygenase-2 (COX-2) has been reported to be associated with tumor progression and angiogenesis and we previously reported that an increase in COX-2 expression might be associated with malignant transformation and tumorigenesis of epithelial ovarian neoplasms. In this study, COX-2 expression of ovarian mature cystic teratomas with malignant transformation, a rare entity accounting for just 1.8% of all mature cystic teratomas, was investigated using immunohistochemical techniques. There were 89 cases of mature cystic teratomas treated with surgery as their initial therapy at Osaka City University Medical School Hospital between 1995 and 2001. Ten cases of these were selected for study; five cases of mature cystic teratoma with malignant transformation, and five cases of mature benign teratoma. Expressions of CD34, vascular endothelial growth factor (VEGF), and COX-2 were investigated. Expressions of VEGF and COX-2 were strong in tissues of mature cystic teratomas with squamous cell carcinoma; however, expressions of them were hardly apparent in mature benign teratomas and in mature cystic teratomas with adenocarcinomas. These results tend to suggest that COX-2 is associated with tumor growth and progression in mature cystic teratomas with squamous cell carcinoma, as opposed to mature benign teratomas and mature cystic teratomas with adenocarcinomas.
Int J Mol Med 2001 Nov
PMID:Expression of cyclooxygenase-2 in ovarian mature cystic teratomas with malignant transformation. 1160 16

The mechanisms of excessive body weight gain after diet-restriction are still unclear. In this study, we investigated expression of angiogenic factors in adipose tissue and skeletal muscle of rabbits which had rebound weight gains; trying to make inquiries into the mechanisms of this rebound weight gain. Ten rabbits were divided into two groups. One group had free food intake (group C), and the other group had restricted food intake until day 40 of the experiments and then had free food intake (group DR). Specimens of adipose tissue and skeletal muscle were collected from each rabbit on days 20, 40, and 60 after the initial examination, and expressions of CD34, vascular endothelial growth factor (VEGF), and platelet-derived endothelial cell growth factor (PD-ECGF) were investigated. Expression of VEGF was significantly strong in the adipose tissue of group DR at the recovery period of body weight. In conclusion, rebound weight gain after a restricted-diet may be associated with angiogenesis in adipose tissue, and the angiogenesis may be induced by VEGF.
Int J Mol Med 2001 Nov
PMID:Angiogenesis in adipose tissues and skeletal muscles with rebound weight-gain after diet-restriction in rabbits. 1160 17

The body's weight loss mechanism while in a tumor-bearing state is still unclear. In this study, we investigated expressions of angiogenic factors in the adipose tissue of tumor-bearing and diet-restricted rabbits evaluating the differences between the two groups. We postulated that low nutrition induced vasculogenesis to transport nutrition in the adipose tissues of diet-restricted rabbits, unlike in tumor-bearing rabbits, and that vascular endothelial growth factor (VEGF) and platelet-derived endothelial cell growth factor (PD-ECGF) were related to angiogenesis of the adipose tissues. Although we investigated the expressions of VEGF and PD-ECGF immunohistochemically in tumor-bearing and diet-restricted rabbits, there was no significant difference between the two groups. Whether angiogenesis of the adipose tissue in the diet-restricted animals may be observed during the nutritional recovery period should be investigated.
Int J Mol Med 2001 Nov
PMID:Involvement of angiogenesis in weight-loss in tumor-bearing and diet-restricted animals. 1160 23

Altered placental and circulating levels of vascular endothelial growth factor (VEGF) and its receptor (flt-1) may be associated with pre-eclampsia and intrauterine growth restriction (IUGR). The aim of this study was to determine whether chorionic villous VEGF or flt-1 mRNA are altered at early gestation in pregnancies subsequently found to be complicated by abnormal fetal growth. Quantitative reverse transcription-polymerase chain reaction was performed on chorionic villous samples for VEGF and flt-1 using an internal RNA standard. Using the individualized birthweight ratio (IBR), the subjects (n = 51) were divided into three groups; IUGR (IBR <10th centile, n = 6), normal (IBR 10th-90th centiles, n = 41) and macrosomic (IBR >90th centile, n = 4). There was no correlation between the mRNA expression of VEGF(121) or VEGF(165) and gestational age of the normal controls. There was also no difference in the expression of either of the VEGF isoforms between the IUGR or macrosomic groups and the normal controls. Expression of flt-1 was below the detection limit of the assay. In conclusion, we have found that altered chorionic villous expression of VEGF is not associated with the initial stages of development of IUGR or macrosomia.
Mol Hum Reprod 2001 Nov
PMID:Abnormal fetal growth is not associated with altered chorionic villous expression of vascular endothelial growth factor mRNA. 1167 77

Endothelial cell proliferation and migration is initiated by growth factors including FGF and VEGF that bind to specific transmembrane receptor tyrosine kinases. Mechanisms that regulate in vivo expression of fibroblast growth factor receptors (FGFR) and vascular endothelial growth factor receptors (VEGFR) are not well understood. Since it is well known that different matrices influence the proliferation and migration of endothelial cells in culture, we hypothesized that changes in the extracellular matrix environment can regulate growth factor receptors on endothelial cells. We cultured human microvascular endothelial cells on different matrices (vitronectin, laminin, fibronectin, fibrin, and collagen IV) and examined for the presence of growth factor receptors (FGFR-1, FGFR-2, VEGFR-1, and VEGFR-2). We show that vitronectin increased the presence of all four growth factor receptors and most notably, VEGFR-1. In contrast, fibrin decreased all four receptors, especially FGFR-1 and FGFR-2. Inhibiting phosphotyrosine signaling abolished immunostaining for all four receptors, regardless of the matrix, but was not dependent on activating the Fyn-Shc pathway. Cells plated on vitronectin in the presence of blocking antibodies to integrins alphavbeta3 and alphavbeta5 similarly decreased presence of these growth factor receptors. Our data suggests a possible mechanism of how matrix-integrin interactions regulate endothelial cell responsiveness to growth factors and anchorage-dependent cell growth.
Mol Cell Biochem 2001 Aug
PMID:Integrin activation is required for VEGF and FGF receptor protein presence on human microvascular endothelial cells. 1169 2

The mechanisms responsible for the divergent physiological responses of endothelial cells to vascular endothelial growth factor (VEGF) are incompletely understood. We hypothesized that VEGF elicits increased endothelial permeability and cell migration via differential activation of intracellular signal transduction pathways. To test this hypothesis, we established a model of VEGF-induced endothelial barrier dysfunction and chemotaxis with bovine pulmonary endothelial cells. We compared the effects of VEGF on transendothelial electrical resistance (TER), actin cytoskeletal remodeling, and chemotaxis of lung endothelial cells and then evaluated the role of the mitogen-activated protein kinases (MAPKs) p38 and extracellular signal-regulated kinase (ERK)1/2 in VEGF-mediated endothelial responses. The dose response of pulmonary arterial and lung microvascular endothelial cells to VEGF differed when barrier regulation and chemotaxis were evaluated. Inhibition of tyrosine kinase, phosphoinositol 3-kinase, or p38 MAPK significantly attenuated VEGF-mediated TER, F-actin remodeling, and chemotaxis. VEGF-mediated decreased TER was also significantly attenuated by inhibition of ERK1/2 MAPK but not by inhibition of fetal liver kinase-1 (flk-1) or Src kinase. In contrast, VEGF-mediated endothelial migration was not attenuated by ERK1/2 inhibition but was abolished by inhibition of either flk-1 or Src kinase. These data suggest potential mechanisms by which VEGF may differentially mediate physiological responses in vivo.
Am J Physiol Lung Cell Mol Physiol 2001 Dec
PMID:Differential regulation of diverse physiological responses to VEGF in pulmonary endothelial cells. 1170 47

We recently demonstrated that the very long 5'-untranslated region (5'-UTR) of the vascular endothelial growth factor (VEGF) mRNA contains two independent internal ribosome entry sites (IRES A and B). In the human sequence, four potential CUG translation initiation codons are located in between these IRES and are in frame with the classical AUG start codon. By in vitro translation and COS-7 cell transfections, we demonstrate that a high mol wt VEGF isoform [called large VEGF (L-VEGF)] is generated by an alternative translation initiation process, which occurs at the first of these CUG codons. Using a bicistronic strategy, we show that the upstream IRES B controls the translation initiation of L-VEGF. This isoform is 206 amino acids longer than the classical AUG-initiated form. With a specific antibody raised against this NH2 extension, we show that the L-VEGF is present in different mouse tissues or in transfected COS-7 cells. We also demonstrate that L-VEGF is cleaved into two fragments: a 23-kDa NH2-specific fragment and a fragment with an apparent size similar to that of the classical AUG-initiated form. This cleavage requires the integrity of a hydrophobic sequence located in the central part of the L-VEGF molecule. This sequence actually plays the role of signal peptide in the classical AUG-initiated form. The AUG-initiated form and the COOH cleavage product of the L-VEGF are both secreted. In contrast, the large isoform and its NH2 fragment present an intracellular localization. These data unravel a further level of complexity in the regulation of VEGF expression.
Mol Endocrinol 2001 Dec
PMID:New vascular endothelial growth factor isoform generated by internal ribosome entry site-driven CUG translation initiation. 1173 20

Hypoxia is a potent inducer of tumor angiogenesis, the process of which is mostly mediated by induction of vascular endothelial growth factor (VEGF). In this study, we investigated the effect of hypoxia on the expression of hypoxia-inducible factor-1alpha (HIF-1alpha) and endothelial PAS domain protein-1 (EPAS1). These two similar but distinct basic helix-loop-helix-PAS proteins have been postulated to activate VEGF expression in response to hypoxia. We showed that EPAS1, but not HIF-1alpha, is abundantly expressed in human lung adenocarcinoma A549 cells. Exposure of cultured A549 cells to hypoxia increased EPAS1 mRNA and protein levels. A specific inhibitor for Src family kinases, PP1, abolished the hypoxia-induced expression of EPAS1. Transient transfection assays revealed that forced expression of EPAS1 increased the reporter gene activity driven by EPAS1 promoter as well as by VEGF promoter. Finally, overexpression of EPAS1 by infection of adenoviral vector expressing EPAS1 cDNA evidently induced the endogenous EPAS1 gene expression. Together, these data demonstrate Src family kinases mediate the hypoxia-mediated EPAS1 gene expression, which in turn positively autoregulates its own expression. Given an EPAS1 as a potent activator of the VEGF gene, these findings will provide a novel insight into the mechanisms underlying the enhancement of growth property of EPAS1-expressing tumor cells under the hypoxic environment.
Am J Respir Cell Mol Biol 2002 Jan
PMID:Inducible expression of endothelial PAS domain protein-1 by hypoxia in human lung adenocarcinoma A549 cells. Role of Src family kinases-dependent pathway. 1175 Dec 12


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