Splice site recognition and regulation

YANOVSKY MARCELO; BECKEL, MAXIMILIANO SEBASTIAN; CHERNOMORETZ ARIEL; RABINOVICH ANDRÉS

CABA

Workshop; Workshop Biologia Celular y Molecular del ARN; 2018

Club de RNA

One of the most important aspects of the alternative splicing regulation is the recognition of splice sites. Even though splicing sites present a consensus sequence, there is a sequence variability that is usually related to site strength, ie. site recognition by Spliceosome.In previous works with Arabidopsis thaliana, it was observed that mutations in PRMT5 (Protein arginin metiltransferases 5) affect weak 5? splice sites (5ss) recognition.In this work we studied the biological role of splice site sequences variability and their connection with PRMT5 mediated regulation.We analysed more than 300,000 5ss sequences annotated in A. thaliana genome and developed a model that takes into account correlations up to two sites. This allowed us to describe the conditional frequencies observed in one and two sites and characterize 5ss strength. In order to understand the relation between site strength, sequence variability and PRTM5 regulatory role, we used RNA-Seq to analyse the effects of PRMT5 mutation on two different A. thaliana accessions, Col-0 and Ler-1. We studied splicing events that were differentially expressed in the interaction between this two factors. On those events with a SNP (single nucleotide polymorphism) on the 5ss, a lower site recognition rate on the accession with a weaker site in PRMT5 mutant compared to the accession with a stronger site was observer. On the other hand, we also analyzed for this events the effects of PRTM5 mutation on Col-0 x Ler-1 hybrids. We found a larger intron retention rate and a lower weak site recognition rate.Using a bioinformatic analysis we were able to create a model that characterizes the strength of 5ss for A. thaliana. The interaction analysis would indicate that PRMT5 could help the splicing machinery to recognize weak splice sites. On the other hand, results obtained with the hybrid analysis rule out the possibility that observed effects can be explained by differences in trans factors between accessions, restricting the effects of PRMT5 to a cis recognition site effect.