Warrington Kelly, Hillarby M Chantal, Li Chenggang, Letarte Michelle, Kumar Shant
Division of Laboratory and Regenerative Medicine, Medical School, The University of Manchester M13 9PT, UK.
Anticancer Res. 2005 May-Jun;25(3B):1851-64.
Angiogenesis is important in health and several disease states. CD105 is a proliferation-associated and hypoxia-inducible transmembrane protein abundantly expressed in angiogenic endothelial cells. CD105 is a receptor for transforming growth factors (TGF)-beta1 and -beta3. The exact mechanisms for CD105 regulation of vascular development have not been fully elucidated.
In this study, an antisense approach to create a murine and a human stably transfected endothelial cell line expressing a reduction in CD105 protein was used.
We showed that inhibition of CD105 in cultured murine and human endothelial cells enhanced the ability of TGF-beta1 to suppress growth and migration, and influenced TGF-beta1 promoter activity. TGF-beta1 not only reduced the length of the capillary-like structures, but also caused mortality in CD105-deficient murine antisense cells compared to control cultures. To determine whether CD105 affected TGF-beta1-induced gene expression, a luciferase assay in transiently transfected cells with p3TP-Lux promoter constructs was performed. Both murine and human antisense transfectants showed a significant increase in p3TP-Lux promoter activity. Further studies on the functional importance of CD105 was undertaken in irradiated normoxic and hypoxic cells. The levels of pro- and anti-apoptotic markers were also evaluated. There was an increase in pro-apoptotic marker (p53), but a reduction in anti-apoptotic marker (Bcl-2) in CD105-deficient cells.
These results provide direct evidence that CD105 antagonises the inhibitory effects of TGF-beta1 on human and murine vascular endothelial cells and that normal cellular levels of CD105 are required for the formation of new blood vessels.
血管生成在健康及多种疾病状态中都很重要。CD105是一种与增殖相关且受缺氧诱导的跨膜蛋白，在血管生成的内皮细胞中大量表达。CD105是转化生长因子（TGF）-β1和-β3的受体。CD105调节血管发育的确切机制尚未完全阐明。
在本研究中，采用反义方法构建了表达CD105蛋白水平降低的小鼠和人稳定转染内皮细胞系。
我们发现，在培养的小鼠和人内皮细胞中抑制CD105可增强TGF-β1抑制生长和迁移的能力，并影响TGF-β1启动子活性。与对照培养物相比，TGF-β1不仅缩短了毛细血管样结构的长度，还导致CD105缺陷型小鼠反义细胞死亡。为了确定CD105是否影响TGF-β1诱导的基因表达，对用p3TP-Lux启动子构建体瞬时转染的细胞进行了荧光素酶测定。小鼠和人反义转染子均显示p3TP-Lux启动子活性显著增加。对受辐照的常氧和缺氧细胞中CD105的功能重要性进行了进一步研究。还评估了促凋亡和抗凋亡标志物的水平。在CD105缺陷细胞中，促凋亡标志物（p53）增加，但抗凋亡标志物（Bcl-2）减少。
这些结果提供了直接证据，表明CD105拮抗TGF-β1对人和小鼠血管内皮细胞的抑制作用，且新血管形成需要正常细胞水平的CD105。
