The 5'-to-3' 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 P-bodies during amino acid starvation. The 5' and 3' 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.

• PMID: 25128566
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Journal Article | Research Support, Non-U.S. Gov't

Authors

Aizer A, Kalo A, Kafri P, Shraga A, Ben-Yishay R, Jacob A, Kinor N, Shav-Tal Y

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