Rahkila P, Väänänen K, Saraste J, Metsikkö K
Department of Anatomy, University of Oulu, Finland.
Exp Cell Res. 1997 Aug 1;234(2):452-64. doi: 10.1006/excr.1997.3633.
The organization of membrane trafficking between endoplasmic reticulum and Golgi within multinucleated muscle fibers was analyzed. We found that markers for the compartment involved in endoplasmic reticulum to Golgi trafficking exhibited perinuclear as well as interfibrillar localization. Furthermore, these markers showed prominent colocalization with microtubules. To analyze membrane trafficking, we followed the temperature-controlled transport of the G protein of the mutant vesicular stomatitis virus, tsO45, in isolated myofibers. Perinuclear and cross-striated staining were seen at 39 degrees C, while at 15 degrees C a diffuse staining component appeared along a subset of interfibrillar microtubules. At 20 degrees C, bright Golgi spots were seen to be associated with microtubules that appeared as circumnuclear rings and longitudinal bundles. Beneath the motor end plate, however, the organization of the Golgi elements and microtubules was found to be distinctive. Retrograde trafficking induced by brefeldin A resulted in the disappearance of the Golgi spots throughout the myofibers and the appearance of staining along microtubules. Thus, interfibrillar membranes seem to be active in protein export, and trafficking between endoplasmic reticulum and Golgi elements occurred throughout the myofibers. The results suggest that microtubules served as tracks for the two-way trafficking between the endoplasmic reticulum and the Golgi compartment.
分析了多核肌纤维内质网和高尔基体之间膜运输的组织情况。我们发现，参与内质网到高尔基体运输的区室标记物表现出核周以及纤维间定位。此外，这些标记物与微管显示出明显的共定位。为了分析膜运输，我们追踪了突变水泡性口炎病毒tsO45的G蛋白在分离的肌纤维中的温控运输。在39℃时可见核周和横纹染色，而在15℃时，沿一部分纤维间微管出现弥漫性染色成分。在20℃时，可见明亮的高尔基体斑点与呈核周环和纵向束状的微管相关。然而，在运动终板下方，发现高尔基体元件和微管的组织是独特的。布雷菲德菌素A诱导的逆向运输导致整个肌纤维中高尔基体斑点消失，并沿微管出现染色。因此，纤维间膜似乎在蛋白质输出中起作用，内质网和高尔基体元件之间的运输发生在整个肌纤维中。结果表明，微管作为内质网和高尔基体区室之间双向运输的轨道。
