Quantifying mRNA targeting to P bodies in living human cells reveals a dual role in mRNA decay and storage

Abstract

BSTRACTThe 59-to-39 mRNA degradation machinery localizes to cytoplasmic processing bodies (P-bodies), which are non-membranous structures found in all eukaryotes. Although P-body function has been intensively studied in yeast, less is known about their role in mammalian cells, such as whether P-body enzymes are actively engaged in mRNA degradation or whether P-bodies serve as mRNA storage depots, particularly during cellular stress. We examined the fate of mammalian mRNAs in P-bodies during translational stress, and show that mRNAs accumulate within Pbodies during amino acid starvation. The 59 and 39 ends of the transcripts residing in P-bodies could be identified, but poly(A) tails were not detected. Using the MS2 mRNA-tagging system for mRNA visualization in living cells, we found that a stationary mRNA population formed in P-bodies during translational stress, which cleared gradually after the stress was relieved. Dcp2-knockdown experiments showed that there is constant degradation of part of the P-body-associated mRNA population. This analysis demonstrates the dual role of P-bodies as decay sites and storage areas under regular and stress conditions.

Nuclease escape elements protect messenger RNA against cleavage by multiple viral endonucleases

“…Signals from the MS2 probes (red) and DAPI stained nuclei (blue) were detected by confocal microscopy. the MS2 sequences [42]. We verified that the presence of the stem-loops did not prevent the escape of the SRE-containing reporter or degradation of the ΔSRE reporter in SOX-expressing cells (S1 Fig). There was no distinguishable difference in the localization of the SRE and ΔSRE containing mRNAs, both of which were present relatively diffusely throughout the cell (Fig 1C).…”

Somatic insulin signaling regulates a germline starvation response in Drosophila egg chambers

“…We saw no significant decrease in the population of P body-enriched mRNAs in the previtellogenic ovary of starved females, suggesting that these P bodies are similar to germline P bodies of C. elegans , which serve as storage sites for CGH-1 (Me31B) associated mRNA, such as nos-2 (Boag et al, 2008), or P bodies in mammalian cells that appear to store mRNAs during amino acid deprivation (Aizer et al, 2014). …”

Principles and Properties of Stress Granules

“…P-bodies contain mRNAs associated with translational repressors, and the mRNA decay machinery. mRNAs within P-bodies can be targeted for decapping and degradation but mRNAs can also be degraded outside of P-bodies [8]. P-bodies and stress granules can dock and/or overlap in both yeast and mammalian cells suggesting a dynamic mRNA cycle wherein mRNPs can be remodeled within these assemblies and exchange between stress granules and P-bodies ([9,10]; Figure 1).…”