Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.4.21.7 (plasmin)
 9,023 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Monoamine-activated alpha 2-macroglobulin (alpha 2M) has been shown to inhibit beta-nerve growth factor (NGF)-promoted neurite outgrowth and the survival of embryonic sensory and forebrain neurons, whereas normal alpha 2M has little or no such activity. The objective of this study is to elucidate the mechanism of inhibition by monoamine-activated alpha 2M. Methylamine-activated alpha 2M (MA-alpha 2M) and serotonin-activated alpha 2M (5HT-alpha 2M) dose dependently inhibit NGF-promoted neurite outgrowth of the pheochromocytoma PC12 cell and its subline PC12(6-24) which overexpresses human trk protooncogene product, but have no effect on their viability, and this inhibition can be blocked by high concentrations of NGF. The binding of MA-alpha 2M to trk, which is a part of high-affinity NGF receptor, was studied with PC12(6-24) cells and NIH-3T3 fibroblasts expressing trk (trk-3T3). In each case MA-alpha 2M readily forms stable complexes with trk in vivo, whereas normal alpha 2M does not. Both 5HT-alpha 2M and MA-alpha 2M also dose dependently block NGF-promoted autophosphorylation of trk in vivo, whereas normal alpha 2M and plasmin-reacted alpha 2M are inactive or much less active. MA-alpha 2M also blocks NGF-promoted incorporation of 32P from [32P]ATP into trk receptors in vitro. Neither MA-alpha 2M, 5HT-alpha 2M, nor normal alpha 2M, however, blocks either platelet-derived growth factor-stimulated or epidermal growth factor-stimulated tyrosine phosphorylation of the respective receptors. Tyrosine phosphorylation of two of the intracellular substrates, phospholipase C-gamma 1 and extracellular signal-regulated kinase-2, in the NGF-promoted pathways is also dose dependently blocked by MA-alpha 2M. However, by comparison MA-alpha 2M is more effective in inhibiting the activation of phospholipase C-gamma 1 than trk. We conclude that monoamine-activated alpha 2M may block neurite outgrowth and neuronal survival by its specific binding to NGF receptors, thus inhibiting the NGF-promoted activation of intracellular second messenger pathways.
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PMID:Monoamine-activated alpha 2-macroglobulin binds trk receptor and inhibits nerve growth factor-stimulated trk phosphorylation and signal transduction. 750 36

The mouse is the most commonly used species for in vivo studies on angiogenesis related to tumor development. Yet, to the best of our knowledge, very few reports on the in vitro interaction of the angiogenic basic fibroblast growth factor (bFGF) with mouse endothelial cells are available. Three mouse endothelial cell lines originated from aorta (MAECs), brain capillaries (MBECs), and heart capillaries (MHECs) were characterized for endothelial phenotypic markers, in vivo tumorigenic activity, and the capacity to respond in vitro to bFGF. These cells express angiotensin-converting enzyme, acetylated LDL receptor, constitutive endothelial nitric oxide synthase, and vascular cell adhesion molecule-1 and bind Griffonia simplicifolia-I lectin. When injected subcutaneously in nude mice, MAECs induced the appearance of slow-growing vascular lesions reminiscent of epithelioid hemangioendothelioma, whereas MBEC xenografts grew rapidly, showing Kaposi's sarcoma-like morphological features. No lesions were induced by injection of MHECs. MAECs, MBECs, and MHECs expressed both low-affinity heparan sulfate bFGF-binding sites and high-affinity tyrosine kinase receptors (FGFRs) on their surfaces. In particular, MAECs expressed FGFR-2/bek mRNA, whereas microvascular MBECs and MHECs expressed FGFR-1/flg mRNA. Accordingly, bFGF induced a mitogenic response and the phosphorylation of extracellular signal-regulated kinase-2 in all the cell lines. In contrast, upregulation of urokinase-type plasminogen activator expression was observed in bFGF-treated microvascular MBECs and MHECs but not in MAECs. Also, bFGF-treated MBECs and MHECs but not MAECs invaded a three-dimensional fibrin gel and formed hollow, capillary-like structures. The relevance of the modifications of the fibrinolytic balance of mouse microvascular endothelium in bFGF-induced angiogenesis was validated in vivo by a gelatin-sponge assay in which the plasmin inhibitors tranexamic acid and epsilon-aminocaproic acid given to mice in the drinking water inhibited neovascularization induced by the growth factor. In conclusion, differences in response to bFGF exist between large-vessel MAECs and microvascular MBECs and MHECs. Both in vitro and in vivo data point to a role of the profibrinolytic phenotype induced by bFGF in microvascular endothelial cells during mouse angiogenesis. Our observations make these endothelial cell lines suitable for further studies on mouse endothelium during angiogenesis and in angioproliferative diseases.
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PMID:Basic fibroblast growth factor-induced angiogenic phenotype in mouse endothelium. A study of aortic and microvascular endothelial cell lines. 910 63