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bioRxiv · 10.1101/366690

mRNP architecture in translating and stress conditions reveals an ordered pathway of mRNP compaction

Khong, A.·Parker, R.
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Abstract

Stress granules (SGs) are non-translating mRNP assemblies that form during stress. Herein, we use multiple smFISH probes for specific mRNAs to examine their SG recruitment and spatial organization. We observed that ribosome run-off is required for SG entry with long ORF mRNAs being delayed in SG accumulation, revealing SG transcriptome changes over time. Moreover, mRNAs are ~20X compacted from an expected linear length when translating and compact ~2 fold further in a stepwise manner beginning at the 5 end during ribosome run-off. Surprisingly, the 5 and 3 ends of the examined mRNAs were separated in non-stress conditions, but in non-translating conditions, the ends of AHNAK and DYNC1H1 mRNAs become close, suggesting the closed-loop model of mRNPs preferentially forms on non-translating mRNAs. These results suggest translation inhibition triggers a mRNP reorganization that brings ends closer, which has implications for the regulation of mRNA stability and translation by 3 UTR elements and the poly(A) tail.

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Khong, A., Parker, R.. 2018-07-10. mRNP architecture in translating and stress conditions reveals an ordered pathway of mRNP compaction. https://doi.org/10.1101/366690

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