Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.10.1 (ERK)
 95,504 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Vascular endothelial growth factor receptor-2 (VEGFR-2/KDR/Flk-1) is a high-affinity receptor for vascular endothelial growth factor-A (VEGF-A), and mediates most of the endothelial growth and survival signals from VEGF-A. VEGFR-2 has a typical tyrosine kinase receptor structure with seven immunoglobulin (Ig)-like domains in the extracellular region, as well as a long kinase insert in the tyrosine kinase domain. It utilizes a unique signaling system for DNA synthesis in vascular endothelial cells, i.e. a phospholipase C gamma-protein kinase C-Raf-MAP kinase pathway. Although VEGF-A binds two receptors, VEGFR-1 and -2, a newly isolated ligand VEGF-E (Orf-virus-derived VEGF) binds and activates only VEGFR-2. Transgenic mice expressing VEGF-E(NZ-7) showed a dramatic increase in angiogenesis with very few side effects (such as edema and hemorrhagic spots), suggesting strong angiogenic signaling and a potential clinical utility of VEGF-E. VEGF family members bear three loops produced via three intramolecular disulfide bonds, and cooperation between loop-1 and loop-3 is necessary for the specific binding and activation of VEGFR-2 for angiogenesis. As it directly upregulates tumor angiogenesis, VEGFR-2 is an appropriate target for suppression of solid tumor growth using exogenous antibodies, small inhibitory molecules and in vivo stimulation of the immune system.
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PMID:Vascular endothelial growth factor receptor-2: its unique signaling and specific ligand, VEGF-E. 1296 71

Platelet-derived growth factors (PDGFs) play an integral role in normal tissue growth and maintenance as well as many human pathological states including atherosclerosis, fibrosis, and tumorigenesis. The PDGF family of ligands is comprised of A, B, C, and D chains. Here, we provide the first functional characterization of the PDGF-C promoter. We examined 797 bp of the human PDGF-C promoter and identified several putative recognition elements for Sp1, Ets Egr-1, and Smad. The proximal region of the PDGF-C promoter bears a remarkable resemblance to a comparable region of the PDGF-A promoter (1). Binding and transient transfection analysis in primary vascular smooth muscle cells revealed that PDGF-C, like PDGF-A, is under the transcriptional control of the zinc finger nuclear protein Egr-1 (early growth response-1). Electrophoretic mobility shift analysis using both smooth muscle cell nuclear extracts and recombinant protein revealed that Egr-1 and Sp1 bind this region of the PDGF-C promoter (Oligo C, -35 to -1). Egr-1 competes with Sp1 for overlapping binding sites even when the former is at a stoichiometric disadvantage. Reverse transcriptase PCR and supershift analysis demonstrate that fibroblast growth factor-2 (FGF-2) stimulates both Egr-1 and PDGF-C mRNA expression in a time-dependent and transient manner and that FGF-2-inducible Egr-1 binds the proximal PDGF-C promoter. FGF-2-inducible PDGF-C expression was completely abrogated using catalytic DNA (DNAzymes) targeting Egr-1 but not by its scrambled counterpart. Moreover, using pharmacological inhibitors we demonstrate the critical role of ERK but not JNK in FGF-2-inducible PDGF-C expression. These findings thus demonstrate that PDGF-C transcription, activated by FGF-2, is mediated by Egr-1 and its upstream kinase ERK.
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PMID:Fibroblast growth factor-2 induction of platelet-derived growth factor-C chain transcription in vascular smooth muscle cells is ERK-dependent but not JNK-dependent and mediated by Egr-1. 1524 55

Vascular endothelial growth factor (VEGF) has been indicated to play a role during endochondral ossification by stimulation of blood vessel invasion into hypertrophic cartilage resulting in its replacement by trabecular bone. We could demonstrate a dose-dependent chemoattractive effect of VEGF-A and PlGF-1, but not VEGF-E or VEGF-C, on human mesenchymal progenitor cells. Quantitative realtime PCR revealed the expression of VEGFR-1 (Flt-1), VEGFR-2 (KDR/Flk-1), and VEGFR-3 (Flt-4), which markedly declined during osteogenic differentiation. In addition, expression of neuropilin-1 and -2 was detected by RT-PCR. In an in vitro kinase assay, we could demonstrate activation of VEGFR-1 and VEGFR-2 upon stimulation with specific ligands. These findings are consistent with the idea that the chemotactic effect of VEGF-A on MPC is mediated via VEGFR-1, and that VEGF-A and PlGF-1, have a functional role for recruitment of osteoprogenitor cells in the course of endochondral bone formation or remodeling.
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PMID:VEGF-A and PlGF-1 stimulate chemotactic migration of human mesenchymal progenitor cells. 1600 48

The platelet-derived growth factor (PDGF) family, which regulates many physiological and pathophysiological processes has recently been enlarged by two new members, the isoforms PDGF-C and -D. Little is known about the expression levels of these new members in hepatic fibrosis. We therefore investigated by quantitative real time PCR (Taqman) the mRNA expression profiles of all four PDGF isoforms in transdifferentiating primary cultured hepatic stellate cells (HSC), an in vitro model system of hepatic fibrogenesis, either with or without stimulation of the cells with PDGF-BB or TGF-beta1. All four isoforms were expressed in HSC transdifferentiating to myofibroblast-like cells (MFB) albeit with different profiles: while PDGF-A mRNA exhibited minor fluctuations only, PDGF-B was rapidly down-regulated. In contrast, both PDGF-C and -D mRNA were strongly induced: PDGF-C up to 5 fold from day 2 to day 8 and PDGF-D up to 8 fold from day 2 to day 5 of culture. Presence of PDGF-DD in activated HSC was confirmed at the protein level by immunocytochemistry. Stimulation of HSC and MFB with PDGF-BB led to down-regulation of the new isoforms, whereas TGF-beta1 upregulated PDGF-A only. We further show that PDGF receptor-beta (PDGFR-beta) mRNA was rapidly upregulated within the first day of culture and was constantly expressed from day 2 on while the expression profile of PDGFR-alpha mRNA was very similar to that of PDGF-A during transdifferentiation. Given the dramatic changes in PDGF-C and -D expression, which may compensate for down-regulation of PDGF-B, we hypothesize that the new PDGF isoforms may fulfil specific functions in hepatic fibrogenesis.
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PMID:Expression patterns of PDGF-A, -B, -C and -D and the PDGF-receptors alpha and beta in activated rat hepatic stellate cells (HSC). 1603 37

Platelet-derived growth factor (PDGF)-D is a member of the PDGF/vascular endothelial growth factor family that activates PDGF receptor beta (PDGFR-beta). We show that PDGF-D is highly expressed in the myocardium throughout development and adulthood, as well as by arterial vascular smooth muscle cells (vSMCs). To obtain further knowledge regarding the in vivo response to PDGF-D, we generated transgenic mice overexpressing the active core domain of PDGF-D in the heart. Transgenic PDGF-D stimulates proliferation of cardiac interstitial fibroblasts and arterial vSMCs. This results in cardiac fibrosis followed by dilated cardiomyopathy and subsequent cardiac failure. Transgenic mice also display vascular remodeling, including dilation of vessels, increased density of SMC-coated vessels, and proliferation of vSMCs, leading to a thickening of tunica media. The thickening of arterial walls is a unique feature of PDGF-D, because this is not seen when PDGF-C is overexpressed in the heart. These results show that PDGF-D, via PDGFR-beta signaling, is a potent modulator of both vascular and connective tissue growth and may provide both paracrine and autocrine stimulation of PDGFR-beta. Our data raise the possibility that this growth factor may be involved in cardiac fibrosis and atherosclerosis.
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PMID:Platelet-derived growth factor D induces cardiac fibrosis and proliferation of vascular smooth muscle cells in heart-specific transgenic mice. 1622 65

Although PDGF family members play a vital role in cell proliferation, motility and chemotaxis via activation of structurally similar alpha- and beta-receptors, little is known of their function in ovarian regulation and induction of tumorigenesis. Microarray analyses of ovaries from young follitropin receptor knockout (FORKO) mice that are prone to late ovarian tumors upon aging have revealed significant imbalances in PDGF ligands and receptors. We hypothesized that FSH/FSH-R signaling may exert effects partly by regulation of PDGF the family. To further understand their implications for ovarian tumorigenesis, we studied FORKO ovaries and hormonal regulation of the PDGF family members in normal mice, by using RT-PCR, Q-PCR, immunohistochemistry and western blotting. While PDGF-C and PDGFR-alpha increased, PDGFR-beta mRNA and protein decreased significantly in absence of FSH-R signaling. In the normal ovary, PDGFR-alpha was not affected by gonadotropin (eCG) stimulation but PDGF-C and PDGFR-beta decreased. Administration of estradiol decreased PDGF and their receptors. To further probe the differential regulation of PDGF family members by eCG and estradiol, we co-administered eCG with estrogen antagonist, ICI 182780. Increase in PDGFR-alpha in the absence of estradiol suggests direct effects of FSH signaling. During the estrous cycle in mice PDGF-C, PDGF-D and PDGFR-alpha mRNA levels were higher at the proestrous. By IHC, we report for the first time the localization of PDGF-C, PDGFR-alpha and PDGFR-beta protein in mouse ovarian compartments including the surface epithelium that is also altered in mutants. Immunostaining of PDGFRs increased as the follicle developed to preantral stage and declined thereafter. Thus, FSH modulates PDGF family members, partly via E2, suggesting that loss of FSH-R signaling causes an imbalance of PDGF family members predisposing the abnormal ovarian follicular environment for inducing tumorigenesis in aging FORKO mice.
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PMID:Aberrant expression of PDGF ligands and receptors in the tumor prone ovary of follitropin receptor knockout (FORKO) mouse. 1634 72

Vascular endothelial growth factor-A (VEGF), which binds to both VEGF receptor-1 (Flt1) and VEGFR-2 (KDR/Flk-1), requires nitric oxide (NO) to induce angiogenesis in a cGMP-dependent manner. Here we show that VEGF-E, a VEGFR-2-selective ligand stimulates NO release and tube formation in human umbilical vein endothelial cells (HUVEC). Inhibition of phospholipase Cgamma (PLCgamma) with U73122 abrogated VEGF-E induced endothelial cell migration, tube formation and NO release. Inhibition of endothelial nitric oxide synthase (eNOS) using l-NNA blocked VEGF-E-induced NO release and angiogenesis. Pre-incubation of HUVEC with the soluble guanylate cyclase inhibitor, ODQ, or the protein kinase G (PKG) inhibitor, KT-5823, had no effect on angiogenesis suggesting that the action of VEGF-E is cGMP-independent. Our data provide the first demonstration that VEGFR-2-mediated NO signaling and subsequent angiogenesis is through a mechanism that is dependent on PLCgamma but independent of cGMP and PKG.
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PMID:VEGF-E activates endothelial nitric oxide synthase to induce angiogenesis via cGMP and PKG-independent pathways. 1672 9

Two high-affinity receptors for vascular endothelial growth factor (VEGF)-A, VEGFR1 and VEGFR2, cooperate for physiological vasculogenesis and angiogenesis in embryogenesis. VEGFR2 transduces the major signals for angiogenesis via its strong tyrosine kinase activity. However, unlike other representative tyrosine kinase receptors, VEGFR2 does not use the Ras pathway as a major downstream signaling but rather uses the phospholipase C-protein kinase C pathway to signal mitogen-activated protein (MAP)-kinase activation and DNA synthesis. Cell migration signals from VEGFR2 were recently shown to use, at least partly, a pathway dependent on the adaptor molecule TSAd from the kinase-insert region of VEGFR2. VEGFR2 is a direct and major signal transducer for pathological angiogenesis, including cancer and diabetic retinopathy, in cooperation with many other signaling partners; thus, VEGFR2 and its downstream signaling appear to be critical targets for the suppression of these diseases. More than 10 antagonists of VEGFR2, including kinase inhibitors and neutralizing antibodies, are now under clinical trials. Recently, the VEGFR2-specific ligand VEGF-E (also known as Orf-VEGF) family was extensively characterized. Interestingly, activation of VEGFR2 via VEGF-E in vivo results in a strong angiogenic response in mice, with minor effects on inflammation and hypervascular permeability compared with VEGF-A, suggesting that VEGF-E is a useful tool for proangiogenic therapy in ischemic diseases.
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PMID:Vascular endothelial growth factor (VEGF)-Receptor2: its biological functions, major signaling pathway, and specific ligand VEGF-E. 1672 25

Retinoic acid (RA) is a teratogen that induces a variety of craniofacial abnormalities, including branchial arch deformities and cleft palate. Platelet-derived growth factor C (PDGF-C) is a recently identified member of the PDGF family. PDGF-C contributes to normal development of the heart, central nervous system, kidney and palatogenesis. But the roles of PDGF-C in branchial arches development and the relationship between PDGF-C and RA-induced branchial arches abnormalities are poorly understood. We examined the effects of RA on PDGF-C and its receptor PDGFR-alpha expressions. We demonstrated that administration of RA to mouse embryos resulted in dramatic losses of PDGF-C and its receptor PDGFR-alpha. Furthermore, we confirmed that blocking PDGF-C signaling by anti-PDGF-C neutralization antibody led to branchial arch malformations similar to that of RA induced, both hypoplastic branchial arches and FBA. These findings suggest the down-regulation of PDGF-C may be one of mechanisms of branchial arch abnormalities induced by RA and PDGF-C signaling is required for branchial arch morphogenesis.
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PMID:PDGF-C participates in branchial arch morphogenesis and is down-regulated by retinoic acid. 1695 36

Vascular endothelial growth factor (VEGF)-A, a major regulator for angiogenesis, binds and activates two tyrosine kinase receptors, VEGFR1 (Flt-1) and VEGFR2 (KDR/Flk-1). These receptors regulate physiological as well as pathological angiogenesis. VEGFR2 has strong tyrosine kinase activity, and transduces the major signals for angiogenesis. However, unlike other representative tyrosine kinase receptors which use the Ras pathway, VEGFR2 mostly uses the Phospholipase-Cgamma-Protein kinase-C pathway to activate MAP-kinase and DNA synthesis. VEGFR2 is a direct signal transducer for pathological angiogenesis including cancer and diabetic retinopathy, thus, VEGFR2 itself and the signaling appear to be critical targets for the suppression of these diseases. VEGFR1 plays dual role, a negative role in angiogenesis in the embryo most likely by trapping VEGF-A, and a positive role in adulthood in a tyrosine kinase-dependent manner. VEGFR1 is expressed not only in endothelial cells but also in macrophage-lineage cells, and promotes tumor growth, metastasis, and inflammation. Furthermore, a soluble form of VEGFR1 was found to be present at abnormally high levels in the serum of preeclampsia patients, and induces proteinurea and renal dysfunction. Therefore, VEGFR1 is also an important target in the treatment of human diseases. Recently, the VEGFR2-specific ligand VEGF-E (Orf-VEGF) was extensively characterized. Interestingly, the activation of VEGFR2 via VEGF-E in vivo results in a strong angiogenic response in mice with minor side effects such as inflammation compared with VEGF-A, suggesting VEGF-E to be a novel material for pro-angiogenic therapy.
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PMID:Differential roles of vascular endothelial growth factor receptor-1 and receptor-2 in angiogenesis. 1700 66


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