Agnès Méreau

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An equilibrium between spliced and unspliced primary transcripts is essential for retrovirus multiplication. This equilibrium is maintained by the presence of inefficient splice sites. The A3 3'-splice site of human immunodeficiency virus type I (HIV-1) is required for Tat mRNA production. The infrequent utilization of this splice site has been attributed(More)
Retroviral protein production depends upon alternative splicing of the viral transcript. The HIV-1 acceptor site A7 is required for tat and rev mRNA production. Production of the Tat transcriptional activator is highly controlled because of its apoptotic properties. Two silencer elements (ESS3 and ISS) and two enhancer elements (ESE2 and ESE3/(GAA)3) were(More)
The structure and accessibility of the S. cerevisiae U3A snoRNA was studied in semi-purified U3A snoRNPs using both chemical and enzymatic probes and in vivo using DMS as the probe. The results obtained show that S. cerevisiae U3A snoRNA is composed of a short 5' domain with two stem-loop structures containing the phylogenetically conserved boxes A' and A(More)
Post-transcriptional regulation in eukaryotes can be operated through microRNA (miRNAs) mediated gene silencing. MiRNAs are small (18-25 nucleotides) non-coding RNAs that play crucial role in regulation of gene expression in eukaryotes. In insects, miRNAs have been shown to be involved in multiple mechanisms such as embryonic development, tissue(More)
In mammals, the CELF/Bruno-like family of RNA-binding proteins contains six members. The founder members of the family are the CUG-BP1 (CELF1) and ETR-3 (CELF2) proteins. Four other members have been identified mainly by sequence similarity. The founder members were cloned or identified in a number of laboratories which has lead to a profusion of names and(More)
The master regulator of the melanocyte lineage Mitf is intimately involved in development as well as melanoma, controlling cell survival, differentiation, proliferation and metastasis/migration. Consistent with its central role, Mitf expression and Mitf post-translational modifications are tightly regulated. An additional potential level of regulation is(More)
The polypyrimidine tract binding protein (PTB) has been described as a global repressor of regulated exons. To investigate PTB functions in a physiological context, we used a combination of morpholino-mediated knockdown and transgenic overexpression strategies in Xenopus laevis embryos. We show that embryonic endoderm and skin deficient in PTB displayed a(More)
MicroRNAs are small non-coding RNAs that are now recognised as key regulators of gene expression in eukaryotes. Over the past few years, hundreds of miRNAs have been identified from various organisms including vertebrates, nematodes, insects and plants. A high level of conservation of some miRNAs from animals to plants underlines their crucial role in(More)
The Xenopus alpha(fast)-tropomyosin gene contains, at its 3' -end, a composite internal/3' -terminal exon (exon 9A9'), which is subjected to three different patterns of splicing according to the cell type. Exon 9A9' is included as a terminal exon in the myotome and as an internal exon in adult striated muscles, whereas it is skipped in nonmuscle cells. We(More)
The output of alternative splicing depends on the cooperative or antagonistic activities of several RNA-binding proteins (RBPs), like Ptbp1 and Esrp1 in Xenopus. Fine-tuning of the RBP abundance is therefore of prime importance to achieve tissue- or cell-specific splicing patterns. Here, we addressed the mechanisms leading to the high expression of the(More)