Microtubule-based Transport is Essential to Distribute RNA and Nascent Protein in Skeletal Muscle

SUMMARY While the importance of RNA localization in highly differentiated cells is well appreciated, basic principles of RNA localization in skeletal muscle remain poorly characterized. Here, we develop a method to detect single RNA molecules and quantify localization patterns in skeletal myofibers, and we uncover a critical and general role for directed transport of RNPs in muscle. We find that RNAs are localized and translated along cytoskeletal filaments, and we identify the Z-disk as a biological hub for RNA localization and protein synthesis. We show that muscle development triggers complete reliance on the lattice-like microtubule network to transport RNAs and that disruption of microtubules leads to striking accumulation of RNPs and nascent protein around myonuclei. Our observations suggest that active transport may be globally required to distribute RNAs in highly differentiated cells and reveal fundamental mechanisms relevant to myopathies caused by perturbations to RNPs, microtubules, and the nuclear envelope. Abstract Figure