Structural organization of the polysomes adjacent to mammalian processing bodies (P-bodies).

Abstract : A finely tuned balance of translation, storage and decay of mRNAs (mRNAs) is important for the regulation of gene expression. In eukaryotic cells, this takes place in dynamic cytoplasmic RNA-protein granules termed Processing bodies (P-bodies). In this study, by using immunoelectron tomography, 3D modeling and template matching, we analyze the size and the organization of the polysomes in the vicinity of human P-bodies. Our results show the presence of several polysomes that are compatible with a translational activity around P-bodies. Therefore, movement of mRNAs between polysomes and P-bodies can take place when the two compartments are in close contact. The presence of initiation factors in the proximity of P-bodies also suggests that translation of mRNAs can resume at the periphery of these granules.