Department of Pathology, University of California, San Francisco, San Francisco, CA 94143, USA.
J Cell Biol. 2012 Jan 9;196(1):103-14. doi: 10.1083/jcb.201105127.
Increasing evidence supports a critical role for the septin cytoskeleton at the plasma membrane during physiological processes including motility, formation of dendritic spines or cilia, and phagocytosis. We sought to determine how septins regulate the plasma membrane, focusing on this cytoskeletal element's role during effective amoeboid motility. Surprisingly, septins play a reactive rather than proactive role, as demonstrated during the response to increasing hydrostatic pressure and subsequent regulatory volume decrease. In these settings, septins were required for rapid cortical contraction, and SEPT6-GFP was recruited into filaments and circular patches during global cortical contraction and also specifically during actin filament depletion. Recruitment of septins was also evident during excessive blebbing initiated by blocking membrane trafficking with a dynamin inhibitor, providing further evidence that septins are recruited to facilitate retraction of membranes during dynamic shape change. This function of septins in assembling on an unstable cortex and retracting aberrantly protruding membranes explains the excessive blebbing and protrusion observed in septin-deficient T cells.
越来越多的证据表明，在生理过程中，包括运动、树突棘或纤毛的形成以及吞噬作用，隔膜细胞骨架在质膜中起着关键作用。我们试图确定隔膜如何调节质膜，重点研究该细胞骨架元件在有效阿米巴样运动中的作用。令人惊讶的是，正如在响应不断增加的静水压力和随后的调节性体积减少时所证明的那样，隔膜起着反应性而不是主动性的作用。在这些情况下，隔膜对于快速皮质收缩是必需的，并且 SEPT6-GFP 在全局皮质收缩期间以及在肌动蛋白丝耗竭期间被募集到丝和圆形斑块中。在使用 dynamin 抑制剂阻断膜运输引发的过度起泡时，也可以明显看到隔膜的募集，这进一步证明了隔膜被募集以促进在动态形状变化期间膜的回缩。隔膜在不稳定的皮质上组装并缩回异常突出的膜的这种功能解释了在隔膜缺陷 T 细胞中观察到的过度起泡和突出。
