Biology subjects

Mereau, A.

Publications and source records attributed to Mereau, A..

4 recordsLinked to original sources

bioRxiv2026

Mapping of CELF1-RNA interactions reveals post-transcriptional control of lens development

Precise post-transcriptional regulation of gene expression is essential for vertebrate lens development. Disruption of the gene encoding the RNA-binding protein CELF1 leads to early-onset cataract in mice. Here, using iCLIP-seq in lenses, we mapped transcriptome-wide CELF1 binding sites, revealing interactions with the 3'UTRs of key transcripts involved in lens development and pathology like Gja8, Jag1, Maf, Pax6, or Prox1. Integrated analysis with transcriptomic data and luciferase reporter assays demonstrated that binding of CELF1 protein represses its target mRNAs by destabilizing transcripts and/or inhibiting their translation. Indeed, the cataract-linked genes Maf and Gja8 are upregulated in Celf1cKO lenses. In Xenopus laevis, overexpression of maf resulted in abnormal lens structure and eye morphology, confirming the developmental relevance of CELF1-mediated repression. Our findings uncover a post-transcriptional network in which CELF1 controls lens morphogenesis by limiting the expression of critical genes at the mRNA level to achive their proper dosage.

developmental biology↗

bioRxiv2022

EXONIZATION BY THE EMERGENCE OF A CLEAVAGE-POLYADENYLATION SITE

Exonization is the evolutionary process of recruitment of new exonic regions from previously intronic regions. It is a major contributor to the increased complexity of alternative splicing. Here, we explore exonization mediated by the emergence of a novel cleavage-polyadenylation site in an intron. In Xenopus laevis, the tpm1 gene, which encodes muscular tropomyosin, contains alternative terminal exons. In adult muscles and embryonic hearts, exon 9A is joined to the terminal exon 9B. In embryonic somites, it is joined to the exonic region 9, which is transcribed from the intron immediately downstream of exon 9A. Consequently, exon 9A is either an internal exon when ligated to exon 9B, or a part of a terminal exon along with region 9. We show here that region 9 is present only in amphibians and coelacanths. This suggests that it emerged in sarcopterygians and was lost in amniotes. We used antisense morpholino oligonucleotides to mask the regions of tpm1 pre-mRNA that potentially regulate the inclusion of exon 9A9. This revealed that the definition of exon 9A9 relies on a weak cleavage-polyadenylation site and an intronic enhancer, but is independent of the 3 splice site. We demonstrate that RNAs containing exon 9B are toxic in somites. This may have contributed to the evolutionary pressure that led to the exonization of region 9 in sarcopterygians. These findings reveal the emergence of a novel cleavage-polyadenylation site that avoids the accumulation of a toxic RNA as a novel mechanism for exonization-mediated diversification of terminal exons.

evolutionary biology↗

bioRxiv2021

THE SPLICING FACTOR PTBP1 REPRESSES TP63 γ ISOFORM PRODUCTION IN SQUAMOUS CELL CARCINOMA

The TP63 gene encodes the transcription factor p63. It is frequently amplified or overexpressed in squamous cell carcinomas. Owing to alternative splicing, p63 has multiple isoforms called , {beta}, {gamma} and {delta}. The regulatory functions of p63 may be isoform-specific. The isoform inhibits the epithelial to mesenchymal transition (EMT) and controls apoptosis, while the {gamma} isoform promotes EMT. Here, we observed in TCGA data that a high ratio of the TP63{gamma} isoform to the other isoforms is a pejorative factor for the survival of patients with head and neck squamous cell carcinoma (HNSCC). We therefore addressed the regulation of the {gamma} isoform. In several tissues (GTEX data), the expression of the RNA-binding protein PTBP1 (polypyrimidine tract binding protein 1) is negatively correlated with the abundance of TP63{gamma}. Accordingly, we demonstrated that PTBP1 depletion in HNSCC cell lines leads to an increase in abundance of the {gamma} isoform. By RNA immunoprecipitation and in vitro interaction assays, we showed that PTBP1 directly binds to TP63 pre-mRNA in close proximity to the TP63{gamma}-specific exon. The region around the TP63{gamma}-specific exon was sufficient to elicit a PTBP1-dependent regulation of alternative splicing in a splice reporter minigene assay. Finally, we demonstrated that the regulation of TP63{gamma} production by PTBP1 is conserved in amphibians, revealing that it encounters a strong evolutionary pressure. Together, these results identify TP63{gamma} as a prognostic marker in HNSCC, and identify PTBP1 as a direct negative regulator of its production.

cancer biology↗

bioRxiv2020

Aurora-A phosphorylates splicing factors and regulates alternative splicing

Aurora-A kinase is well known to regulate progression through mitosis. However, the kinase also performs additional functions that could explain the failure of its inhibitors to be effective in cancer treatments. To identify these functions, we applied a proteomics approach to search for interactors of Aurora-A. We found a large number of proteins involved in pre-mRNA splicing, strongly suggesting an important role for Aurora-A in this biological process. Consistently, we first report the subcellular localization of Aurora-A in nuclear speckles, the storehouse of splicing proteins. We also demonstrate direct interaction of Aurora-A with RRM domain-containing splicing factors such as hnRNP and SR proteins and their phosphorylation in vitro. Further, RNA-sequencing analysis following pharmacological inhibition of Aurora-A resulted in alternative splicing changes corresponding to 505 genes, including genes with functions regulated by Aurora-A kinase. Finally, we report enrichment of RNA motifs within the alternatively spliced regions affected by Aurora-A kinase inhibition which are bound by Aurora-A interacting splicing factors, suggesting that Aurora-A regulates alternative splicing by modulating the activity of these interacting splicing factors. Overall our work identified Aurora-A as a novel splicing kinase and for the first time, describes a broad role of Aurora-A in regulating alternative splicing.

molecular biology↗