The role of nitric oxide in the vascular endothelial growth factorsignaling cascade /
Vascular endothelial growth factor (VEGF) is an endothelium-specific, secreted protein that potently stimulates vasodilation, microvascular hyperpermeability, and angiogenesis. Nitric oxide (NO) is also reported to modulate vascular tone, permeability, and capillary growth. The ability of VEGF to...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1998.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=737708611&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Vascular endothelial growth factor (VEGF) is an endothelium-specific, secreted protein that potently stimulates vasodilation, microvascular hyperpermeability, and angiogenesis. Nitric oxide (NO) is also reported to modulate vascular tone, permeability, and capillary growth. The ability of VEGF to alter endothelial production of nitric oxide and interventions in nitric oxide signaling to alter VEGF-induced proliferation were studied using human umbilical vein endothelial cells (HUVECS) as a model. The production of nitrogen oxides (NOx) by HUVECs was measured over time after incubation with VEGF. VEGF treatment resulted in both an acute and chronic stimulation of NO production. Western and northern blotting revealed a VEGF-elicited, dose-dependent increase in the cellular content of nitric oxide synthase (ecNOS) message and protein that may account for the chronic upregulation of NO production elicited by VEGF. This study also examined the mechanisms by which the VEGF-mediated release of NO transduced the VEGF mitogenic signal in HUVECS. Nitric oxide synthase blockade by Nco-Nitro-L-arginine-methyl ester (L-NAME) after VEGF treatment inhibited HUVEC proliferation in response to VEGF. Furthermore, pretreatment of HUVECs with L-NAME blocked the VEGF-induced activation of Raf-1, a vital initiator of the MAP kinase cascade. VEGF-induced proliferation and Raf-1 kinase activity were also inhibited by inhibitors of cGMP-dependent protein kinase (PKG). The ability of PKG to stimulate proliferation was verified by the observation that the PKG activator, 8-pCPT-cGMPs, stimulated both Raf1 kinase activity and endothelial proliferation in a dose-dependent manner. Furthermore, catalytically active synthetic PKG was capable of phosphorylating and activating Raf-1 immunoprecipitated from HUVECS. Finally, Raf-1 immunoprecipitated from VEGF-stimulated endothelial cells coprecipitated with PKG, indicating a complex in activated cells. We conclude that VEGF induces increased NO production that is necessary for VEGF-stimulated proliferation and that these effects are mediated by NO activation of PKG and subsequent phosphorylation of Raf-1 kinase by PKG. |
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| Item Description: | Vita. "Major Subject: Medical Sciences". |
| Physical Description: | x, 127 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilms Inc. |
| Bibliography: | Includes bibliographical references: pages 106-125. |