Instituto de Investigaciones Bioquímicas de Bahía Blanca, Bahía Blanca, Argentina.
J Membr Biol. 2010 Jun;235(3):163-75. doi: 10.1007/s00232-010-9261-6. Epub 2010 Jun 8.
Extensive evidence supports the notion that the cytoskeleton participates in the immobilization and membrane clustering of the nicotinic acetylcholine receptor (AChR) at the neuromuscular junction. Stimulated emission depletion fluorescence microscopy has revealed the supramolecular organization of AChR nanoclusters at the surface of CHO-K1/A5 cells with subdiffraction resolution (Kellner et al., Neuroscience 144:135-143 2007). We studied the effect of two cytoskeletal-disrupting drugs (cytochalasin D and jasplakinolide) on the nanoscale distribution of muscle-type AChR expressed in these cells by means of mathematical and statistical analysis of images obtained with the same high-resolution microscopy. AChR nanoclusters were found to be randomly distributed in both controls and cells treated with either drug for distances larger than 500 nm. Treatments altered the distribution of AChR nanoclusters according to their brightness/size. Cytochalasin D and jasplakinolide produced a statistically significant increase in the proportion of medium-size nanoclusters and a diminution of small nanoclusters, indicating higher disrupting activity on the latter. This was further corroborated by the diminution of the brightness/diameter ratio of nanoclusters (a measure of the intracluster density of AChR molecules) and by Ripley's analysis applied to simulated patterns with intracluster aggregation of AChR molecules. The combined analytical tools bring out subtle changes in the two-dimensional organization of the AChR nanoaggregates on disruption of the cytoskeletal network and throw light on the possible link between the cytoskeleton and the distribution of the AChR at the cell surface.
大量证据表明细胞骨架参与了神经肌肉接头处烟碱型乙酰胆碱受体 (AChR) 的固定和膜聚集。受激发射损耗荧光显微镜已经揭示了 CHO-K1/A5 细胞表面 AChR 纳米簇的超分子结构,具有亚衍射分辨率 (Kellner 等人,《神经科学》144:135-143, 2007)。我们通过对使用相同高分辨率显微镜获得的图像进行数学和统计分析,研究了两种细胞骨架破坏药物(细胞松弛素 D 和 Jasplakinolide)对这些细胞中表达的肌肉型 AChR 的纳米级分布的影响。发现在距离大于 500nm 的情况下,AChR 纳米簇在对照和用药物处理的细胞中均随机分布。处理方式根据其亮度/大小改变了 AChR 纳米簇的分布。细胞松弛素 D 和 Jasplakinolide 导致中等大小纳米簇的比例和小纳米簇的数量明显增加,表明对后者的破坏活性更高。这进一步得到了纳米簇的亮度/直径比减小(衡量 AChR 分子簇内密度的指标)和 Ripley 分析的证实,该分析应用于具有 AChR 分子簇内聚集的模拟模式。这些综合分析工具揭示了细胞骨架网络破坏后 AChR 纳米聚集体的二维组织的细微变化,并阐明了细胞骨架与细胞表面 AChR 分布之间的可能联系。