In vivo monitoring of mRNA movement in Drosophila body wall muscle cells reveals the presence of myofiber domains.

Alice M C Van Gemert,Jasprina N Noordermeer,Annelies M A Van Der Laan,Gonneke S K Pilgram,Carolina R Jost,Lee G Fradkin,Hans J Tanke,Jörg Langowski

doi:10.1371/journal.pone.0006663

Alice M C Van Gemert, Jasprina N Noordermeer + Show 6 more

Open Access

https://doi.org/10.1371/journal.pone.0006663

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Journal: PloS one	Publication Date: Aug 17, 2009
Citations: 58	License type: CC BY 4.0

Affiliation: Leiden University

Abstract

BackgroundIn 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 FindingsIn 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/SignificanceThese 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.

Highlights

The movement of mRNAs within the cytoplasm is central to the regulation of translation
The differential distribution of the mRNAs between the above mentioned structures determines the rate at which mRNAs are degraded or translated and determines the level of protein production. This view on mRNAs is in agreement with the finding that single mRNA molecules diffuse through the cell but can be transiently anchored or actively transported [4].This holds true for all cytoplasmic mRNAs, both the targeted mRNAs that are directed to a specific location within the cell and the mRNAs that move as part of the normal process of metabolic regulation [4,5]
To study the movement of mRNAs in Drosophila embryonic muscle fibers we generated transgenic flies directing the synthesis of the reporter mRNA and a Green Fluorescent Protein (GFP)fusion protein which are the two components of the MS2 tagging system (Fig. 1A)

Summary

Introduction

The movement of mRNAs within the cytoplasm is central to the regulation of translation. The differential distribution of the mRNAs between the above mentioned structures determines the rate at which mRNAs are degraded or translated and determines the level of protein production. This view on mRNAs is in agreement with the finding that single mRNA molecules diffuse through the cell but can be transiently anchored or actively transported [4].This holds true for all cytoplasmic mRNAs, both the targeted mRNAs that are directed to a specific location within the cell and the mRNAs that move as part of the normal process of metabolic regulation [4,5]. Experiments in fixed myofibers show that mRNAs remain localized around the nuclei in which they are produced

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