VIMENTIN MESSENGER-RNA LOCATION CHANGES DURING MUSCLE DEVELOPMENT

The mRNAs for some cytoskeletal proteins are localized, suggesting that mRNA for these proteins may concentrate at sites appropriate for assembly. To test this hypothesis, we observed vimentin mRNA in developing chicken muscle cultures by in situ hybridization with a digoxigenin-labeled DNA probe to vimentin, detected by confocal microscopy using fluorescent anti-digoxigenin antibody. This method has submicrometer resolution. In developing muscle, vimentin mRNA was bipolar in young myoblasts, somewhat perinuclear in elongated myoblasts and spread fibroblasts, and diffuse in young and developing myotubes. In mature myotubes, vimentin mRNA occurred at costameres with vimentin protein. Localization of mRNA may prove important for assembling and maintaining differentiated cytoskeletal structures, as it is for organizing the embryo.