Ylänne J, Cheresh D A, Virtanen I
Department of Anatomy, University of Helsinki, Finland.
Blood. 1990 Aug 1;76(3):570-7.
The localization of five integrin subunit proteins was studied in human erythroleukemia (HEL) cells spreading on various culture substrata in the presence of 12-O-tetradecanoylphorbol-13-acetate (TPA) and the absence of serum. The cells readily adhered on fibronectin, but TPA was needed for adherence on vitronectin and for the spreading of the cells on both substrata. Indirect immunofluorescence microscopy showed that in the spread cells cultured on vitronectin or fibronectin for 2 hours, beta 1, beta 3, alpha 5, and alpha IIb integrin subunits were localized at focal adhesions as identified by talin-immunoreactivity. The alpha v integrin immunoreactivity was initially found at the focal adhesions when the cells were cultured on vitronectin, but was also found later in cells cultured on fibronectin. The alpha IIb integrin immunoreactivity disappeared from focal adhesions within 24 hours. The alpha 5 and beta 1 integrin immunoreactivities disappeared from the focal adhesions in cells cultured on vitronectin, but not in cells cultured on fibronectin. When the cells were plated on glass substratum in the presence of TPA, they spread much slower than on vitronectin or fibronectin, but some cells showed focal adhesions after only 8 hours in culture. In this case, the alpha v and beta 3 integrin subunits were found at focal adhesions. After TPA treatment, HEL cells deposited thrombospondin-immunoreactive material onto their culture substratum, but synthesis of fibronectin, vitronectin, fibrinogen, or von Willebrand factor was not detected. Thus, the results suggest that TPA would activate several integrin receptors in HEL cells and also stimulate the secretion of thrombospondin, which might be used as an adhesion ligand for the integrin vitronectin receptor alpha v/beta 3 complex.
在无血清且存在12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯（TPA）的条件下，研究了5种整合素亚基蛋白在铺展于不同培养底物上的人红白血病（HEL）细胞中的定位情况。细胞很容易黏附在纤连蛋白上，但黏附在玻连蛋白上以及在两种底物上的铺展都需要TPA。间接免疫荧光显微镜检查显示，在铺展于玻连蛋白或纤连蛋白上培养2小时的细胞中，β1、β3、α5和αIIb整合素亚基定位于由踝蛋白免疫反应性所确定的黏着斑处。当细胞在玻连蛋白上培养时，αv整合素免疫反应性最初在黏着斑处被发现，但在纤连蛋白上培养的细胞中后来也能发现。αIIb整合素免疫反应性在24小时内从黏着斑处消失。α5和β1整合素免疫反应性在玻连蛋白上培养的细胞的黏着斑处消失，但在纤连蛋白上培养的细胞中未消失。当细胞在TPA存在的情况下接种于玻璃底物上时，它们的铺展比在玻连蛋白或纤连蛋白上慢得多，但一些细胞在培养仅8小时后就显示出黏着斑。在这种情况下，αv和β3整合素亚基在黏着斑处被发现。TPA处理后，HEL细胞将血小板反应蛋白免疫反应性物质沉积到其培养底物上，但未检测到纤连蛋白、玻连蛋白、纤维蛋白原或血管性血友病因子的合成。因此，结果表明TPA会激活HEL细胞中的几种整合素受体，还会刺激血小板反应蛋白的分泌，血小板反应蛋白可能用作整合素玻连蛋白受体αv/β3复合物的黏附配体。
