The dynamics of mammalian P body transport, assembly, and disassembly in vivo

The degradation of mRNA in eukaryotes begins with deadenylation, followed by degradation through one of two pathways: 3' → 5' cleavage by the exosome complex or 5' → 3' cleavage which begins with the removal of the 5'-7meG cap. The second mechanism occurs in cytoplasmic foci known as P bodies and involves multiple factors, such as decapping proteins and nucleases. This study examines the movement and interactions of P bodies (PBs) in the cytoplasm. PB movement was tracked by fluorescence microscopy and live cell imaging, using fluorescent proteins fused to conserved PB components such as decapping proteins. PBs were mostly found in the inner cytoplasmic region or near the nuclear envelope (Fig. 1), and, although dynamic, exhibited a tendency to remain in the same spatial neighborhood throughout the cell cycle. These confined movements suggest association with filamentous networks. PBs were shown to travel on microtubule networks and were also found to be associated with actin and centrosomes. When microtubules were disrupted by addition of inhibitors such as nocoda-zole and vinblastine, PB mobility was significantly impaired. This suggests that the microtubule network is used by PB bodies for anchoring and moving within the cytoplasm.