Laboratory of Gene Expression and Imaging, Department of Molecular Cell Biology, Leiden University Medical C, Leiden, The Netherlands.
PLoS One. 2009 Aug 17;4(8):e6663. doi: 10.1371/journal.pone.0006663.
In skeletal muscle each muscle cell, commonly called myofiber, is actually a large syncytium containing numerous nuclei. Experiments in fixed myofibers show that mRNAs remain localized around the nuclei in which they are produced.
METHODOLOGY/PRINCIPAL FINDINGS: In this study we generated transgenic flies that allowed us to investigate the movement of mRNAs in body wall myofibers of living Drosophila embryos. We determined the dynamic properties of GFP-tagged mRNAs using in vivo confocal imaging and photobleaching techniques and found that the GFP-tagged mRNAs are not free to move throughout myofibers. The restricted movement indicated that body wall myofibers consist of three domains. The exchange of mRNAs between the domains is relatively slow, but the GFP-tagged mRNAs move rapidly within these domains. One domain is located at the centre of the cell and is surrounded by nuclei while the other two domains are located at either end of the fiber. To move between these domains mRNAs have to travel past centrally located nuclei.
CONCLUSIONS/SIGNIFICANCE: These data suggest that the domains made visible in our experiments result from prolonged interactions with as yet undefined structures close to the nuclei that prevent GFP-tagged mRNAs from rapidly moving between the domains. This could be of significant importance for the treatment of myopathies using regenerative cell-based therapies.
在骨骼肌中，每个肌细胞，通常称为肌纤维，实际上是一个包含许多核的巨大合胞体。固定肌纤维的实验表明，mRNA 仍然定位于其产生的核周围。
方法/主要发现：在这项研究中，我们生成了转基因苍蝇，使我们能够研究活果蝇胚胎体壁肌纤维中 mRNA 的运动。我们使用体内共聚焦成像和光漂白技术确定了 GFP 标记的 mRNAs 的动态特性，发现 GFP 标记的 mRNAs 不能在肌纤维中自由移动。受限的运动表明体壁肌纤维由三个域组成。域之间的 mRNA 交换相对较慢，但 GFP 标记的 mRNAs 在这些域内快速移动。一个域位于细胞的中心，被核包围，而另外两个域位于纤维的两端。为了在这些域之间移动，mRNA 必须经过位于中心的核。
结论/意义：这些数据表明，我们实验中可见的域是由于与靠近核的尚未定义的结构长时间相互作用而产生的，这阻止了 GFP 标记的 mRNAs 在域之间快速移动。这对于使用基于再生细胞的治疗方法治疗肌病可能具有重要意义。
