Pasqualini R, Bodorova J, Ye S, Hemler M E
Division of Tumor Virology, Dana Farber Cancer Institute, Harvard Medical School, Boston, MA 02115.
J Cell Sci. 1993 May;105 ( Pt 1):101-11. doi: 10.1242/jcs.105.1.101.
Here, we have utilized six new anti-human beta 5 monoclonal antibodies to perform a detailed investigation of the structure, function and distribution of beta 5 integrins. Monoclonal anti-beta 5 specificity was confirmed by reactivity with beta 5-transfected CHO cells, by direct binding to the beta 5 subunit (immunoblotting), and by immunodepletion experiments using polyclonal anti-beta 5 serum. The beta 5 subunit was predominantly associated with the alpha v subunit, although on some cell lines, the level of beta 5 exceeded that of alpha v for unknown reasons. Cell adhesion studies showed that the adhesive function of beta 5 could be stimulated, inhibited or unaltered by different anti-beta 5 monoclonal antibodies. The beta 5 subunit was involved in adhesion to both vitronectin and fibronectin and, at least for K562 cells, fibronectin appeared to be the preferred ligand. Flow-cytometry studies showed that the beta 5 subunit was expressed at moderate to high levels on all adherent cell lines examined, was absent from all lymphoid cell lines, and was only weakly expressed on myeloid cell lines. Staining of thymic sections showed the distribution of beta 5 on blood vessels, Hassal's corpuscles, cortical and medullary stromal cells, and basement membranes. Skin sections showed beta 5 on the basal layer of the epidermis and on some dermal blood vessel walls, and kidney sections showed staining of glomerular regions, juxta glomerular apparatus, proximal convoluted tubules and collecting tubules, and at least one anti-beta 5 antibody also stained epithelial cells of proximal tubules.
在此，我们利用六种新的抗人β5单克隆抗体对β5整合素的结构、功能及分布进行了详细研究。通过与β5转染的CHO细胞反应、直接结合β5亚基（免疫印迹法）以及使用多克隆抗β5血清进行免疫耗竭实验，证实了单克隆抗β5的特异性。β5亚基主要与αv亚基相关联，不过在某些细胞系中，β5的水平出于未知原因超过了αv。细胞黏附研究表明，不同的抗β5单克隆抗体可刺激、抑制或不改变β5的黏附功能。β5亚基参与了对玻连蛋白和纤连蛋白的黏附，并且至少对于K562细胞而言，纤连蛋白似乎是更受青睐的配体。流式细胞术研究显示，在所检测的所有贴壁细胞系中，β5亚基以中度至高表达水平存在，在所有淋巴细胞系中均不存在，而在髓样细胞系中仅微弱表达。胸腺切片染色显示β5在血管、哈氏小体、皮质和髓质基质细胞以及基底膜上的分布。皮肤切片显示β5存在于表皮基底层和一些真皮血管壁上，肾脏切片显示肾小球区域、近球小体、近端曲管和集合管有染色，并且至少一种抗β5抗体也对近端小管的上皮细胞进行了染色。
