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

本课题旨在揭示鸡胚胎动脉内皮细胞发育过程中肌动蛋白微丝的分布规律，尤其是应力纤维的分布规律。用免疫荧光和电子显微镜包括激光扫描共聚焦显微镜观察发现，9日龄以上鸡胚的动脉内皮细胞内可见平行于细胞主轴方向的应力纤维，15~16日龄鸡胚绒毛膜-尿囊膜动脉支注射0.1ml 20μg/ml细胞松弛素D后，1h内应力纤维分布减少。这一变化伴随着细胞边缘一束明显的肌动蛋白微丝的出现。这些肌动蛋白束可以支持细胞与细胞之间的黏附，在细胞周围可能存在阿德海斯连接。一些残留的应力纤维具有罗丹明-鬼臼糖苷染色的周期性条带图案。细胞松弛素D处理后培养的牛主动脉内皮细胞的应力纤维中也观察到了类似的肌节样图案。这些研究结果表明：1在胚胎发育过程中，内皮应力纤维的表达是由细胞的伸长诱导的。2内皮应力纤维可能支持细胞间或细胞与基质的黏附。3肌动蛋白微丝的肌节样排列可能是应力纤维发育的结构基础之一。

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.