Unveiling hidden regulators: exploring non-coding transcripts arising from alternative splicing and their impact on protein function

FLORENCIA S. RODRÍGUEZ; ROCÍO S. TOGNACCA; LUCAS SERVI; MARÍA FLORENCIA LEGASCUE; FEDERICO ARIEL; EZEQUIEL PETRILLO

Rosario

Congreso; XXXIV Argentinian Meeting of Plant Physiology RAFV Conference 2023; 2023

Sociedad Argentina de Fisiología Vegetal

Alternative splicing (AS) produces multiple transcripts from a single gene through a variable and regulated selection of splice sites. Different isoforms can be translated into different proteins. In addition, AS can also give rise to non-coding variants, which tend to degrade, allowing delicate regulation of the levels of coding isoforms and of the amount of protein generated. However, non-coding transcripts can also control chromatin status, modulate the abundance of other RNAs and even translation. Light is an important environmental cue that influences gene expression and AS. The serine-arginine rich protein At-RS31, undergoes AS in a light-regulated fashion. As a result, the coding isoform mRNA1 is accumulated in light whereas the non-coding isoform mRNA3 accumulates in darkness. We demonstrated that Arabidopsis seedlings overexpressing mRNA1 (mRNA1ox) have a deleterious phenotype, while the overexpression of the genomic construct generates seedlings with a normal phenotype. We hypothesize that mRNA3 is the cause of this phenotype reversion. Since we showed that the mRNA3 remains in the nucleus and accumulates as time in darkness increases, we generated transgenic mRNA3ox and mRNA1ox/mRNA3ox plants to test for phenotype reversion under different physiological conditions. We found that mRNA1ox/mRNA3ox plants behave as wild-type under our experimental conditions. By using bioinformatic and molecular approaches we found other stable, nuclear-retained, non-coding isoforms that could have a potential regulatory function/s as the mRNA3. We are currently evaluating the interaction between the non-coding isoform and the protein generated by the coding isoform of the same gene to check an autoregulatory loop is underlying the mechanism of action. This will help us testing our central hypothesis, that the mRNA3 modulates the activity of the RS31 protein.