The RNA-binding protein MSS8 regulates the plant miRNA biogenesis tissuespecifically

PABLO A. MANAVELLA

Foz do Iguaçu

Congreso; 11th International Congress of Plant Molecular Biology; 2015

The biogenesis of microRNAs (miRNAs), which regulate mRNA abundance throughpost-transcriptional silencing, comprises multiple well-orchestrated processing steps.We have used a large-scale luciferase-based screen followed by whole-genomesequencing to identify MSS8 as a new cofactor in Arabidopsis thaliana miRNAbiogenesis with specific functions in the shoot apex. MiRNA and miRNA-targetlevels were significantly reduced in apices and apex-enriched samples of mss8mutants, but not in other tissues, thus pointing to MSS8 as a tissue-specific regulatorof miRNA biogenesis in plants. Mechanistically, MSS8 affects miRNA biogenesisthrough nuclear interactions with the phosphatases CPL1 and CPL2. Theseinteractions are essential to regulate the phosphorylation status, and thus the activity,of the double-stranded RNA binding protein and DCL1 cofactor HYL1