Caveolin and its cellular and subcellular immunolocalisation in lung alveolar epithelium: implications for alveolar epithelial type I cell function
Caveolin and its cellular and subcellular immunolocalisation in lung alveolar epithelium: implications for alveolar epithelial type I cell function
复制标题
DOI：
10.1007/s004410051217
复制
发表时间：
1999-01-01
影响因子：
3.6
通讯作者：
Gumbleton, M
中科院分区：
文献类型：
--
作者：
Newman, GR;Campbell, L;Gumbleton, M
小凹是质膜的烧瓶状内陷，其在细胞质内形成离散的囊泡。从生物化学角度来说，小凹可以通过一种蛋白质（小凹蛋白）的存在来区分，小凹蛋白是构成其条纹状细胞质外壳的细丝的主要成分。 I 型鳞状肺泡上皮 (ATI) 细胞约占肺泡上皮表面积的 95%，具有大量的质膜内陷和细胞质小泡，超微结构表明存在小凹。然而，超微结构外观并不普遍意味着小窝蛋白的生化存在。这项免疫细胞化学研究利用了共焦激光扫描和电子显微镜的新应用，明确地将 Caveolin-1 定位于 ATI 细胞。此外，对ATI细胞中的细胞质囊泡和烧瓶状膜内陷进行了形态学鉴定，其膜上装饰有抗caveolin-1免疫金标记。然而，与此共存的是，在 ATI 和毛细血管内皮细胞中都可以看到具有小凹形态特征的膜内陷，但缺乏相关的小凹蛋白免疫金标记。这可以反映形态相似的质膜内陷群体中真正的生化异质性或标记的抗原阈值要求。立方形肺泡上皮 II 型细胞 (ATII) 也显示出小窝蛋白 1 的特异性标记，但没有形成小窝形成的超微结构证据。 Caveolin 与 ATI 细胞囊泡的生化关联对于 ATI 细胞功能的分配和进一步研究具有广泛的意义。
Caveolae are flask-shaped invaginations of the plasmalemma which pinch off to form discrete vesicles within the cell cytoplasm. Biochemically, caveolae may be distinguished by the presence of a protein, caveolin, that is the principal component of filaments constituting their striated cytoplasmic coat. Squamous alveolar epithelial type I (ATI) cells, comprising approximately 95% of the surface area of lung alveolar epithelium, possess numerous plasma-lemmal invaginations and cytoplasmic vesicles ultrastructurally indicative of caveolae. However, an ultrastructural appearance does not universally imply the biochemical presence of caveolin. This immunocytochemical study has utilised a novel application of confocal laser scanning and electron microscopy unequivocally to localise caveolin-1 to ATI cells. Further, cytoplasmic vesicles and flask-shaped membrane invaginations in the ATI cell were morphologically identified whose membranes were decorated with anti-caveolin-1 immunogold label. Coexistent with this, however, in both ATI and capillary endothelial cells could be seen membrane invaginations morphologically characteristic of caveolae, but which lacked associated caveolin immunogold label. This could reflect a true biochemical heterogeneity in populations of morphologically similar plasmalemmal invaginations or an antigen threshold requirement for labelling. The cuboidal alveolar epithelial type II cell (ATII) also displayed specific label for caveolin-1 but with no ultrastructural evidence for the formation of caveolae. The biochemical association of caveolin with ATI cell vesicles has broad implications for the assignment and further study of ATI cell function.