The fail-safe mechanism of post-transcriptional silencing of unspliced HAC1 mRNA

Abstract
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Abstract

HAC1 encodes a transcription factor that is the central effector of the unfolded protein response (UPR) in budding yeast. When the UPR is inactive, HAC1 mRNA is stored as an unspliced isoform in the cytoplasm and no Hac1 protein is detectable. Intron removal is both necessary and sufficient to relieve the post-transcriptional silencing of HAC1 mRNA, yet the precise mechanism by which the intron prevents Hac1 protein accumulation has remained elusive. Here, we show that a combination of inhibited translation initiation and accelerated protein degradation-both dependent on the intron-prevents the accumulation of Hac1 protein when the UPR is inactive. Functionally, both components of this fail-safe silencing mechanism are required to prevent ectopic production of Hac1 protein and concomitant activation of the UPR. Our results provide a mechanistic understanding of HAC1 regulation and reveal a novel strategy for complete post-transcriptional silencing of a cytoplasmic mRNA.

Data availability

The following data sets were generated

1. Di Santo R
2. Weinberg DE
(2016) Whole-genome sequencing of spontaneous mutants
Publicly available at the NCBI Sequence Read Archive (accession no: SRP081128).

http://trace.ncbi.nlm.nih.gov/Traces/sra/?study=SRP081128

The following previously published data sets were used

(2016) Data from: Improved Ribosome-Footprint and mRNA Measurements Provide Insights into Dynamics and Regulation of Yeast Translation
Publicly available at the NCBI Gene Expression Omnibus (accession no: GSE75897).

http://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GSE75897

Article and author information

Author details

Rachael Di Santo

Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States

Competing interests
The authors declare that no competing interests exist.
Soufiane Aboulhouda

Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States

Competing interests
The authors declare that no competing interests exist.
David E Weinberg

Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, United States

For correspondence
david.weinberg@ucsf.edu

Competing interests
The authors declare that no competing interests exist.

"This ORCID iD identifies the author of this article:" 0000-0002-9348-1709

Funding

NIH Office of the Director (DP5OD017895)

Rachael Di Santo
Soufiane Aboulhouda
David E Weinberg

UCSF Program for Breakthrough Biomedical Research

Rachael Di Santo
Soufiane Aboulhouda
David E Weinberg

The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.

Copyright

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.