title: Endoplasmic reticulum to Golgi trafficking in multinucleated skeletal muscle fibers.
abstract: 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.
authors.affiliation: Department of Anatomy, University of Oulu, Finland.
authors.forename: P
authors.initials: P
authors.lastname: Rahkila
authors.forename: K
authors.initials: K
authors.lastname: Väänänen
authors.forename: J
authors.initials: J
authors.lastname: Saraste
authors.forename: K
authors.initials: K
authors.lastname: Metsikkö
mesh_terms: D000818:Animals; D020126:Brefeldin A; D002467:Cell Nucleus / Q000502:physiology*; D003517:Cyclopentanes / Q000494:pharmacology; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism* / Q000648:ultrastructure; D007365:Intercellular Junctions / Q000737:chemistry; D007535:Isomerases / Q000032:analysis; D008562:Membrane Glycoproteins; D008868:Microtubule Proteins / Q000032:analysis; D008870:Microtubules / Q000378:metabolism; D009045:Motor Endplate / Q000378:metabolism; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000166:cytology* / Q000378:metabolism; D009154:Mutation; D019704:Protein Disulfide-Isomerases; D051381:Rats; D013696:Temperature; D014721:Vesicular stomatitis Indiana virus; D014759:Viral Envelope Proteins / Q000378:metabolism
chemical_list: D003517:Cyclopentanes; C028391:G protein, vesicular stomatitis virus; D008562:Membrane Glycoproteins; D008868:Microtubule Proteins; D014759:Viral Envelope Proteins; D020126:Brefeldin A; D007535:Isomerases; D019704:Protein Disulfide-Isomerases