Martin Daniel, Galisteo Rebeca, Gutkind J Silvio
Oral and Pharyngeal Cancer Branch, NIDCR, National Institutes of Health, Bethesda, Maryland 20892-4340, USA.
J Biol Chem. 2009 Mar 6;284(10):6038-42. doi: 10.1074/jbc.C800207200. Epub 2008 Dec 26.
Vascular endothelial growth factor (VEGF) is a potent mitogen and permeability factor for endothelial cells that plays a central role in angiogenesis, vascular maintenance, inflammation, and cancer. VEGF also mediates the homeostatic adaptation to hypoxic conditions by promoting an increase in vascular density to compensate for decreased oxygenation. This process is triggered by an oxygen-sensitive transcription factor, hypoxia-inducible factor-1 (HIF1alpha), which becomes active in hypoxic tissues, leading to the synthesis and secretion of VEGF. The role of HIF1alpha in other processes that involve angiogenesis such as in inflammation is less clear. Of interest, endothelial cells not only respond to but also store and secrete VEGF, which is required for the maintenance of the integrity of the vascular system. How this intracellular pool of VEGF is regulated is still not understood. Here, we found that CXCL8/IL8, a potent proangiogenic and inflammatory chemokine, up-regulates VEGF mRNA and protein levels in endothelial cells by acting on its cognate receptor, CXCR2, and that this results in the autocrine activation of VEGFR2. Surprisingly, this process does not involve HIF1alpha but instead requires the activation of the transcription factor NFkappaB. Furthermore, we identified the components of the CBM complex, Carma3, Bcl10, and Malt1, as key mediators of the CXCL8/IL8-induced NFkappaB activation and VEGF up-regulation. Together, these findings support the existence of an NFkappaB-mediated pathway by which the proinflammatory chemokine CXCL8/IL8 controls the expression of VEGF in endothelial cells, thereby promoting the activation of VEGF receptors in an autocrine fashion.
血管内皮生长因子(VEGF)是一种作用于内皮细胞的强效有丝分裂原和通透性因子,在血管生成、血管维持、炎症和癌症中发挥核心作用。VEGF还通过促进血管密度增加以补偿氧合作用降低,介导对缺氧条件的稳态适应。这一过程由氧敏感转录因子缺氧诱导因子-1(HIF1α)触发,HIF1α在缺氧组织中变得活跃,导致VEGF的合成和分泌。HIF1α在其他涉及血管生成的过程(如炎症)中的作用尚不清楚。有趣的是,内皮细胞不仅对VEGF有反应,还储存和分泌VEGF,这是维持血管系统完整性所必需的。VEGF的细胞内池如何被调节仍不清楚。在这里,我们发现CXCL8/IL8,一种强效的促血管生成和炎症趋化因子,通过作用于其同源受体CXCR2上调内皮细胞中VEGF的mRNA和蛋白水平,这导致VEGFR2的自分泌激活。令人惊讶的是,这个过程不涉及HIF1α,而是需要转录因子NFκB的激活。此外,我们确定了CBM复合物的成分Carma3、Bcl10和Malt1,作为CXCL8/IL8诱导的NFκB激活和VEGF上调的关键介质。总之,这些发现支持存在一种由NFκB介导的途径,通过该途径促炎趋化因子CXCL8/IL8控制内皮细胞中VEGF的表达,从而以自分泌方式促进VEGF受体的激活。