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Blood ; 111(10): 4997-5007, 2008 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-18337563

RESUMO

Pathological angiogenesis associated with wound healing often occurs subsequent to an inflammatory response that includes the secretion of cytokines such as tumor necrosis factor (TNF). Controversy exists on the angiogenic actions of TNF, with it being generally proangiogenic in vivo, but antiangiogenic in vitro. We find that whereas continuous administration of TNF in vitro or in vivo inhibits angiogenic sprouting, a 2- to 3-day pulse stimulates angiogenesis by inducing an endothelial "tip cell" phenotype. TNF induces the known tip cell genes platelet-derived growth factor B (PDGFB) and vascular endothelial cell growth factor receptor-2 (VEGFR2), while at the same time blocking signaling through VEGFR2, thus delaying the VEGF-driven angiogenic response. Notch signaling regulates tip cell function, and we find that TNF also induces the notch ligand jagged-1, through an NFkappaB-dependent mechanism. Enrichment of jagged-1 in tip cells was confirmed by immunofluorescent staining as well as by laser capture microdissection/quantitative reverse-transcription-polymerase chain reaction (qRT-PCR) of tip cells sprouting in vitro. Thus, in angiogenesis, the temporal expression of TNF is critical: it delays angiogenesis initially by blocking signaling through VEGFR2, but in addition by inducing a tip cell phenotype through an NFkappaB-dependent pathway, it concomitantly primes endothelial cells (ECs) for sprouting once the initial inflammatory wave has passed.


Assuntos
Células Endoteliais/efeitos dos fármacos , Neovascularização Fisiológica/efeitos dos fármacos , Fator de Necrose Tumoral alfa/farmacologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/fisiologia , Humanos , Inflamação , NF-kappa B/metabolismo , Fenótipo , Proteínas Proto-Oncogênicas c-sis , Fatores de Tempo , Veias Umbilicais/citologia , Receptor 2 de Fatores de Crescimento do Endotélio Vascular/metabolismo
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