Poster abstracts
Poster number 27 submitted by Laura de Lorenzo
The interplay between alternative polyadenylation and RNA quality control in Arabidopsis
Laura de Lorenzo (Department of Plant and Soil Sciences. University of Kentucky, Lexington, KY ), Julia Bailey-Serres (Center for Plant Cell Biology, University of California Riverside, Riverside CA), Arthur G. Hunt (Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY )
Abstract:
In plants, alternative polyadenylation (APA) is a widespread process, affecting a large majority of genes. APA may occur at any position during the transcription of a gene and determine protein length or influence mRNA stability, translation, and/or transport (1). The selection of polyadenylation signals (PAS) from distal to proximal in the 3’-UTR of premRNAs can quantitatively affect protein synthesis, and the PAS selection in upstream regions (5’-UTRs, introns, or protein coding regions; called noncanonical isoforms) is expected to yield RNAs that may be subject to any of RNA quality-control (RQC) processes. The roles of noncanonical isoforms have not been explored and possible connections with negative regulatory mechanisms have been suggested. In this context, the stabilities and translatabilities of Arabidopsis RNA isoforms derived from proximal PAS usage were studied. A genome-wide approach using libraries of 3’-end-directed cDNA tags were generated from RNA isolated from plants treated with a transcriptional inhibitor, or from polysomes purified, and sequenced. The results suggest that each isoform has different properties (2). RNAs with 3’-ends within protein-coding regions and introns were less stable than 3’-UTR PAS and were under-represented in polysomes, suggesting that these RNA isoforms may be subject to quality-control processes. In contrast, 5’-UTR mRNA isoforms were over-represented in polysomes, and as stable as canonical isoforms. Likewise, different RQC mutants were evaluated using 3’-end tags libraries to elucidate an interplay between APA and RQC. Thus, coding-region isoforms are accumulated in decapping mutants, and intronic and 5’-UTR isoforms are accumulated in upf3 mutant. These results show that APA may re-direct transcriptional output into products that are subject to surveillance processes, and thus may constitute a form of negative regulation.
References:
(1) Lutz, C.S., and Moreira, A. (2011). Alternative mRNA polyadenylation in eukaryotes: an effective regulator of gene expression. Wiley Interdiscip. Rev. RNA 2: 22–31.
(2) de Lorenzo, L., Sorenson, R., Bailey-Serres, J., and Hunt A.G. (2017). Noncanonical alternative polyadenylation contributes to gene regulation in response to hypoxia. The Plant Cell 29: 1262–1277.
Keywords: stability-translatability, RNA quality-control, Arabidopsis