The role of actin microfilament cytoskeleton on the cell adhesion of chick embryonic arterial endothelium

本项目旨在揭示肌动蛋白微丝特别是应力纤维在发育中的鸡胚胎动脉内皮中的分布规律。本研究采用免疫荧光显微镜和电子显微镜，包括激光扫描共聚焦显微镜。孵育9天以上的鸡胚胎动脉内皮细胞具有发育良好的与细胞长轴平行的应力纤维。15 ~ 16日龄鸡胚绒毛膜-尿囊膜动脉分支注射20 μg/ml细胞松弛素D 0.1 ml，应激纤维分布在1 h内减少。这种变化伴随着在细胞边界出现一束明显的肌动蛋白微丝。这些肌动蛋白束可能支持细胞与细胞之间的黏附，在细胞周围可能存在黏附连接。一些剩余的应力纤维有罗丹明-phalloidin染色的周期性带状图案。在细胞松弛素D处理后的牛主动脉内皮细胞的应力纤维中观察到类似的肌肉瘤样结构。这些研究结果表明：1胚胎发育过程中细胞伸长诱导内皮应激纤维的表达。内皮应力纤维可支持细胞间或细胞与基质的粘附。在发育中的应力纤维中出现的肌动蛋白微丝的肌节状排列可能是其结构基础之一。

This project aimed to reveal the distribution pattern of actin microfilaments especially of the stress fibers in the developing chick embryonic arterial endothelium. The immunofluorescence and electron microscopy, including laser scanning confocal microscopy were used in this study.Arterial endothelial cells of chick embryos aged over 9 days of incubation have well developed stress fibers oriented parallel to the major axis of the cell.When 0.1 ml of 20 μg/ml cytochalasin D was injected into the arterial branch of chorio-allantoic membrane of 15 to 16 day-old chick embryos, the distribution of stress fibers decreased within one hour. This change was accompanied by the appearance of a distinct bundle of actin microfilaments at the cell border. These actin bundles may support the cell to cell adhesion at the cell periphery where the adrehens junction may present. Some of the remaining stress fibers have a periodic banding pattern with rhodamine-phalloidin staining. Similar sarcomere-like pattern was observed in the stress fibers of cultured bovine aortic endothelial cells recovered from cytochalasin D treatment.Results of these studies suggest that : 1 The expression of endothelial stress fibers is induced by a cell elongation during embryonic development. 2 The endothelial stress fibers may support cell adhesion between cells or cell to substrate. 3 The sarcomere-like arrangement of actin microfilaments appeared in the developing stress fibers may represent one of the structural foundations.