Biology subjects

Villa, T.

Publications and source records attributed to Villa, T..

3 recordsLinked to original sources

bioRxiv2025

Chemical inhibition of Exon Junction Complex assembly impairs mRNA localization and neural stem cells ciliogenesis

The Exon Junction Complex (EJC) is formed by the essential eIF4A3, MAGOH and Y14 core proteins. It is universally deposited during splicing at exon-exon junctions. The EJC is known to impact almost every post-transcriptional regulatory step throughout the life of mRNAs including their modifications, splicing, decay and trafficking. Its dysregulation leads to neurodevelopmental pathologies. Here we show that EJC-i, a compound known to block the ATPase activity of eIF4A3, inhibits de novo EJC assembly. EJC-i and targeted knockdown of either eIF4A3 or Y14 core EJC subunits lead to very similar phenotypes by impacting the destiny of mRNAs due to alterations in alternative splicing, nonsense-mediated mRNA decay, genome-wide m6A methylation and proper intracellular addressing of specific transcripts, in particular to the centrosome. Both EJC impairment methods disrupt the centrosome function that might be responsible for mitotic arrest at prometaphase. As a small molecule that readily diffuses into cells, EJC-i is a particularly attractive easy to use and versatile tool to investigate EJC functions in live cells or whole organism that are not prone to genetic manipulation. Indeed, this property was used to disrupt ciliogenesis in primary neural stem cells.

molecular biology↗

bioRxiv2022

The S. cerevisiae m6A-reader Pho92 impacts meiotic recombination by controlling key methylated transcripts

N6-methyladenosine (m6A), the most abundant internal modification of eukaryotic mRNAs, participates in the post-transcriptional control of gene expression. In Saccharomyces cerevisiae, m6A is only found during meiosis. Although the deletion of the m6A- methyltransferase Ime4 impairs this process, the molecular impact of m6A on gene expression remains ill defined. Here we investigated the function of the budding yeast m6A reader Pho92. We found that Pho92 is specifically expressed during meiosis and impacts meiotic progression. We used high-throughput RNA sequencing and mapping of Pho92-binding sites following UV-crosslinking to show that Pho92 is recruited to specific mRNAs in an m6A-dependent manner during the meiotic prophase, preceding their down-regulation. Strikingly, point mutations altering m6A sites in mRNAs targeted by Pho92 are sufficient to delay their down-regulation and, in one case, to impact meiotic progression. Altogether, our results indicate that Pho92 facilitate the meiotic progression by accelerating the down-regulation of timely-regulated mRNAs during meiotic recombination.

molecular biology↗

bioRxiv2019

Degradation of non-coding RNAs promotes recycling of termination factors at sites of transcription

A large share of the non-coding transcriptome in yeast is controlled by the Nrd1-Nab3-Sen1 (NNS) complex, which promotes transcription termination of non-coding RNA (ncRNA) genes, and by the nuclear exosome, which limits the steady state levels of the transcripts produced. How unconstrained ncRNA levels impact RNA metabolism and gene expression are longstanding and important question. Here we show that degradation of ncRNAs by the exosome is required for freeing Nrd1 and Nab3 from the released transcript after termination. In exosome mutants, these factors are sequestered by ncRNAs and cannot be efficiently recycled to sites of transcription, inducing termination defects at NNS targets. ncRNA-dependent, genome-wide termination defects can be recapitulated by the expression of a degradation-resistant, circular RNA containing a natural NNS target in exosome proficient cells. Our results have important implications for the mechanism of termination, the general impact of ncRNAs abundance and the importance of nuclear ncRNA degradation.

molecular biology↗