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Dual RNA Processing Roles of Pat1b via Cytoplasmic Lsm1-7 and Nuclear Lsm2-8 Complexes
Caroline Vindry1, Aline Marnef2, Helen Broomhead1
1Department of Biochemistry, University of Cambridge, Tennis Court Road, Cambridge CB2 1QW, UK.
Cell Reports
|August 3, 2017
Summary
Pat1 proteins enhance mRNA decay in the cytoplasm and participate in pre-mRNA processing in the nucleus. This dual role involves distinct Lsm complexes, impacting both mRNA stability and splicing.
Area of Science:
- Molecular Biology
- Cell Biology
- RNA Biology
Background:
- Pat1 proteins are known cytoplasmic factors crucial for mRNA decay.
- They function with the Lsm1-7 heptamer to promote mRNA decapping.
- Their nuclear functions and interactions with other RNA processing machinery remain less understood.
Purpose of the Study:
- To investigate the nuclear roles of Pat1 proteins, specifically Pat1b.
- To identify nuclear interaction partners and functions of Pat1b.
- To elucidate the dual role of Pat1 proteins in both mRNA decay and pre-mRNA processing.
Main Methods:
- Co-immunoprecipitation assays to identify protein complexes.
- Immunofluorescence microscopy to determine subcellular localization.
- RNA interference (RNAi) to deplete Pat1b.
- RNA sequencing to analyze global gene expression changes.
- Analysis of alternative splicing events.
Main Results:
- Evidence for a nuclear Pat1b complex with the Lsm2-8 heptamer binding to U6 snRNA.
- Identification of Pat1b/Lsm2-8/U6 snRNA/SART3 interactions within Cajal bodies.
- Pat1b depletion leads to upregulation of P body-associated mRNAs with 3' UTR AU-rich elements.
- Over 180 alternative splicing events are altered, with preferential skipping of exons with weak donor sites.
Conclusions:
- Pat1 proteins possess a dual function, acting as decapping enhancers in both cytoplasmic mRNA decay and nuclear pre-mRNA processing.
- These distinct functions are mediated by separate nuclear and cytoplasmic Lsm complexes.
- Pat1b plays a significant role in regulating mRNA processing and decay pathways.
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