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Published on: July 29, 2019
mRNA deadenylation by PARN is essential for embryogenesis in higher plants
Sergei V Reverdatto1, James A Dutko, Julia A Chekanova
1Department of Biological Sciences, State University of New York at Albany, 12222, USA.
Abstract:
Deadenylation of mRNA is often the first and rate-limiting step in mRNA decay. PARN, a poly(A)-specific 3' --> 5' ribonuclease which is conserved in many eukaryotes, has been proposed to be primarily responsible for such a reaction, yet the importance of the PARN function at the whole-organism level has not been demonstrated in any species. Here, we show that mRNA deadenylation by PARN is essential for viability in higher plants (Arabidopsis thaliana). Yet, this essential requirement for the PARN function is not universal across the phylogenetic spectrum, because PARN is dispensable in Fungi (Schizosaccharomyces pombe), and can be at least severely downregulated without any obvious consequences in Metazoa (Caenorhabditis elegans). Development of the Arabidopsis embryos lacking PARN (AtPARN), as well as of those expressing an enzymatically inactive protein, was markedly retarded, and ultimately culminated in an arrest at the bent-cotyledon stage. Importantly, only some, rather than all, embryo-specific transcripts were hyperadenylated in the mutant embryos, suggesting that preferential deadenylation of a specific select subset of mRNAs, rather than a general deadenylation of the whole mRNA population, by AtPARN is indispensable for embryogenesis in Arabidopsis. These findings indicate a unique, nonredundant role of AtPARN among the multiple plant deadenylases.
Insights
mRNA deadenylation by Poly(A)-specific Ribonuclease (PARN) is crucial for plant survival. Arabidopsis thaliana lacking PARN shows developmental arrest, highlighting its essential role in embryogenesis and selective mRNA processing.
Area of Science:
- Molecular Biology
- Plant Development
- RNA Metabolism
Background:
- mRNA deadenylation, a key step in mRNA decay, is often initiated by Poly(A)-specific Ribonuclease (PARN).
- The critical role of PARN in whole-organism viability has not been previously demonstrated across diverse species.
Purpose of the Study:
- To investigate the essentiality of PARN-mediated mRNA deadenylation for organismal viability in higher plants.
- To determine the specific role of PARN in Arabidopsis thaliana embryogenesis and mRNA processing.
Main Methods:
- Analysis of Arabidopsis thaliana mutants lacking functional PARN (AtPARN) or expressing enzymatically inactive protein.
- Examination of embryo development, transcript levels, and polyadenylation status in wild-type versus mutant embryos.
Main Results:
- Arabidopsis embryos lacking AtPARN exhibited severe developmental retardation and arrest at the bent-cotyledon stage.
- Mutant embryos showed hyperadenylation of a specific subset of embryo-specific transcripts, not all transcripts.
- PARN function is essential in Arabidopsis but dispensable in Fungi and downregulatable in Metazoa.
Conclusions:
- PARN-mediated mRNA deadenylation is essential for plant viability, specifically during Arabidopsis embryogenesis.
- AtPARN plays a unique, nonredundant role in the preferential deadenylation of select mRNAs critical for development.
- The essentiality of PARN varies significantly across different phylogenetic kingdoms.
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