Vaughan Erin E, Dean David A
Division of Pulmonary and Critical Care Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
Mol Ther. 2006 Feb;13(2):422-8. doi: 10.1016/j.ymthe.2005.10.004. Epub 2005 Nov 21.
Little is known about how plasmids move through the cytoplasm to the nucleus. It has been suggested that the dense latticework of the cytoskeleton impedes free diffusion of large macromolecules, including DNA. However, since transfections do work, there must be mechanisms by which DNA circumvents cytoplasmic obstacles. One possibility is that plasmids become cargo on cytoskeletal motors, much like viruses do, and move to the nucleus in a directed fashion. Using microinjection and electroporation approaches in the presence of drugs that alter the dynamics and organization of the cytoskeleton, we show that microtubules are involved in plasmid trafficking to the nucleus. Further, by co-injecting inhibitory antibodies, we find that dynein likely facilitates this movement. These results were confirmed using an in vitro spin-down assay that demonstrated that plasmids bind to microtubules through adaptor proteins provided by cytoplasmic extracts. Taken together, these results suggest that plasmids, like most viruses, utilize the microtubule network and its associated motor proteins to traffic through the cytoplasm to the nucleus.
关于质粒如何穿过细胞质进入细胞核，我们知之甚少。有人提出，细胞骨架的致密网络结构会阻碍包括DNA在内的大分子自由扩散。然而，由于转染确实有效，所以必然存在DNA绕过细胞质障碍的机制。一种可能性是，质粒像病毒一样成为细胞骨架马达上的货物，并以定向方式移动到细胞核。在存在改变细胞骨架动力学和组织的药物的情况下，我们使用显微注射和电穿孔方法表明，微管参与了质粒向细胞核的运输。此外，通过共注射抑制性抗体，我们发现动力蛋白可能促进了这种移动。使用体外沉降试验证实了这些结果，该试验表明质粒通过细胞质提取物提供的衔接蛋白与微管结合。综上所述，这些结果表明，质粒与大多数病毒一样，利用微管网络及其相关的马达蛋白穿过细胞质进入细胞核。
