Tan L, Meyer T, Pfau B, Hofmann T, Tan T W, Jones D
Institut für Experimentelle Orthopädie und Biomechanik, Universität Marburg, Germany.
J Musculoskelet Neuronal Interact. 2010 Mar;10(1):92-9.
The adaptor protein vinculin plays a key position in the formation of focal adhesions and regulates cell attachment. To study the turnover of vinculin in bone-derived cells, we expressed green fluorescent protein-tagged vinculin in primary bovine osteoblasts and examined the appearance of focal adhesions in cells exposed to laminar shear flow. Already 20 sec after application of shear stress fluorescently labelled focal adhesions became visible as small flashing dots at the periphery of cells. The number of newly formed focal adhesions per individual cell increased continuously over approximately 300 sec and then remained relatively stable. The assembly of focal adhesions in shear stress-stimulated osteoblasts was accompanied by a transient rise in intracellular calcium levels. The mean assembly time of an individual focal adhesion plaque was 32.2+/-2.2 sec and the mean disassembly time was 60.5+/-6.0 sec. The recruitment of vinculin to nascent focal adhesions was in the same range as the recovery half-life of GFP-vinculin at stable focal adhesions (13.0+/-2.0 sec). These data show that accumulation of GFP-vinculin in newly formed focal adhesions and its exchange from pre-existing, mature plaques are both rapid processes that occur in mechanically stimulated osteoblasts within less than one minute.
衔接蛋白纽蛋白在粘着斑的形成中起关键作用，并调节细胞附着。为了研究骨源细胞中纽蛋白的周转，我们在原代牛成骨细胞中表达了绿色荧光蛋白标记的纽蛋白，并检测了暴露于层流剪切力的细胞中粘着斑的出现情况。在施加剪切应力后仅20秒，荧光标记的粘着斑就作为小的闪烁点出现在细胞周边。单个细胞中新形成的粘着斑数量在大约300秒内持续增加，然后保持相对稳定。剪切应力刺激的成骨细胞中粘着斑的组装伴随着细胞内钙水平的短暂升高。单个粘着斑斑块的平均组装时间为32.2±2.2秒，平均拆卸时间为60.5±6.0秒。纽蛋白募集到新生粘着斑的时间与稳定粘着斑处绿色荧光蛋白-纽蛋白的恢复半衰期（13.0±2.0秒）在同一范围内。这些数据表明，绿色荧光蛋白-纽蛋白在新形成的粘着斑中的积累及其从先前存在的成熟斑块中的交换都是快速过程，在机械刺激的成骨细胞中不到一分钟内就会发生。
