Stehbens Samantha J, Paterson Andrew D, Crampton Matthew S, Shewan Annette M, Ferguson Charles, Akhmanova Anna, Parton Robert G, Yap Alpha S
Division of Molecular Cell Biology, Institute for Molecular Bioscience, The University of Queensland, St Lucia, Brisbane, Queensland 4072, Australia.
J Cell Sci. 2006 May 1;119(Pt 9):1801-11. doi: 10.1242/jcs.02903. Epub 2006 Apr 11.
In contrast to the well-established relationship between cadherins and the actin cytoskeleton, the potential link between cadherins and microtubules (MTs) has been less extensively investigated. We now identify a pool of MTs that extend radially into cell-cell contacts and are inhibited by manoeuvres that block the dynamic activity of MT plus-ends (e.g. in the presence of low concentrations of nocodazole and following expression of a CLIP-170 mutant). Blocking dynamic MTs perturbed the ability of cells to concentrate and accumulate E-cadherin at cell-cell contacts, as assessed both by quantitative immunofluorescence microscopy and fluorescence recovery after photobleaching (FRAP) analysis, but did not affect either transport of E-cadherin to the plasma membrane or the amount of E-cadherin expressed at the cell surface. This indicated that dynamic MTs allow cells to concentrate E-cadherin at cell-cell contacts by regulating the regional distribution of E-cadherin once it reaches the cell surface. Importantly, dynamic MTs were necessary for myosin II to accumulate and be activated at cadherin adhesive contacts, a mechanism that supports the focal accumulation of E-cadherin. We propose that this population of MTs represents a novel form of cadherin-MT cooperation, where cadherin adhesions recruit dynamic MTs that, in turn, support the local concentration of cadherin molecules by regulating myosin II activity at cell-cell contacts.
与钙黏着蛋白和肌动蛋白细胞骨架之间已明确的关系形成对比的是,钙黏着蛋白与微管(MTs)之间的潜在联系尚未得到广泛研究。我们现在鉴定出了一类微管,它们径向延伸至细胞间接触部位,并受到阻碍微管正端动态活性的操作的抑制(例如在低浓度诺考达唑存在的情况下以及在CLIP - 170突变体表达后)。通过定量免疫荧光显微镜和光漂白后荧光恢复(FRAP)分析评估发现,阻断动态微管会扰乱细胞在细胞间接触部位浓缩和积累E - 钙黏着蛋白的能力,但不影响E - 钙黏着蛋白向质膜的转运或细胞表面表达的E - 钙黏着蛋白的量。这表明动态微管通过在E - 钙黏着蛋白到达细胞表面后调节其区域分布,使细胞能够在细胞间接触部位浓缩E - 钙黏着蛋白。重要的是,动态微管对于肌球蛋白II在钙黏着蛋白黏附接触部位的积累和激活是必需的,这是一种支持E - 钙黏着蛋白局部积累的机制。我们提出,这类微管代表了一种新型的钙黏着蛋白 - 微管协作形式,其中钙黏着蛋白黏附招募动态微管,而动态微管又通过调节细胞间接触部位的肌球蛋白II活性来支持钙黏着蛋白分子的局部浓缩。