Compartimentation et dynamique des fonctions nucléaires

Publications de l’équipe

Année de publication : 2017

Amandine Batté, Clémentine Brocas, Hélène Bordelet, Antoine Hocher, Myriam Ruault, Adouda Adjiri, Angela Taddei, Karine Dubrana (2017 Jul 30)

Recombination at subtelomeres is regulated by physical distance, double-strand break resection and chromatin status.

The EMBO journal : 2609-2625 : DOI : 10.15252/embj.201796631 En savoir plus
Résumé

Homologous recombination (HR) is a conserved mechanism that repairs broken chromosomes via intact homologous sequences. How different genomic, chromatin and subnuclear contexts influence HR efficiency and outcome is poorly understood. We developed an assay to assess HR outcome by gene conversion (GC) and break-induced replication (BIR), and discovered that subtelomeric double-stranded breaks (DSBs) are preferentially repaired by BIR despite the presence of flanking homologous sequences. Overexpression of a silencing-deficient SIR3 mutant led to active grouping of telomeres and specifically increased the GC efficiency between subtelomeres. Thus, physical distance limits GC at subtelomeres. However, the repair efficiency between reciprocal intrachromosomal and subtelomeric sequences varies up to 15-fold, depending on the location of the DSB, indicating that spatial proximity is not the only limiting factor for HR EXO1 deletion limited the resection at subtelomeric DSBs and improved GC efficiency. The presence of repressive chromatin at subtelomeric DSBs also favoured recombination, by counteracting EXO1-mediated resection. Thus, repressive chromatin promotes HR at subtelomeric DSBs by limiting DSB resection and protecting against genetic information loss.

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Eldad Kepten, Judith Miné-Hattab (2017 Feb 28)

[Lamin A: a key protein in chromatin motion].

Medecine sciences : M/S : 126-130 : DOI : 10.1051/medsci/20173302004 En savoir plus
Résumé

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Année de publication : 2016

Elodie Gazquez, Yuli Watanabe, Florence Broders-Bondon, Perrine Paul-Gilloteaux, Julie Heysch, Viviane Baral, Nadège Bondurand, Sylvie Dufour (2016 Dec 2)

Endothelin-3 stimulates cell adhesion and cooperates with β1-integrins during enteric nervous system ontogenesis.

Scientific reports : 37877 : DOI : 10.1038/srep37877 En savoir plus
Résumé

Endothelin-3 (EDN3) and β1-integrins are required for the colonization of the embryonic gut by enteric neural crest cells (ENCCs) to form the enteric nervous system (ENS). β1-integrin-null ENCCs exhibit migratory defects in a region of the gut enriched in EDN3 and in specific extracellular matrix (ECM) proteins. We investigated the putative role of EDN3 on ENCC adhesion properties and its functional interaction with β1-integrins during ENS development. We show that EDN3 stimulates ENCC adhesion to various ECM components in vitro. It induces rapid changes in ENCC shape and protrusion dynamics favouring sustained growth and stabilization of lamellipodia, a process coincident with the increase in the number of focal adhesions and activated β1-integrins. In vivo studies and ex-vivo live imaging revealed that double mutants for Itgb1 and Edn3 displayed a more severe enteric phenotype than either of the single mutants demonstrated by alteration of the ENS network due to severe migratory defects of mutant ENCCs taking place early during the ENS development. Altogether, our results highlight the interplay between the EDN3 and β1-integrin signalling pathways during ENS ontogenesis and the role of EDN3 in ENCC adhesion.

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N R Chevalier, E Gazguez, L Bidault, T Guilbert, C Vias, E Vian, Y Watanabe, L Muller, S Germain, N Bondurand, S Dufour, V Fleury (2016 Feb 19)

How Tissue Mechanical Properties Affect Enteric Neural Crest Cell Migration.

Scientific reports : 20927 : DOI : 10.1038/srep20927 En savoir plus
Résumé

Neural crest cells (NCCs) are a population of multipotent cells that migrate extensively during vertebrate development. Alterations to neural crest ontogenesis cause several diseases, including cancers and congenital defects, such as Hirschprung disease, which results from incomplete colonization of the colon by enteric NCCs (ENCCs). We investigated the influence of the stiffness and structure of the environment on ENCC migration in vitro and during colonization of the gastrointestinal tract in chicken and mouse embryos. We showed using tensile stretching and atomic force microscopy (AFM) that the mesenchyme of the gut was initially soft but gradually stiffened during the period of ENCC colonization. Second-harmonic generation (SHG) microscopy revealed that this stiffening was associated with a gradual organization and enrichment of collagen fibers in the developing gut. Ex-vivo 2D cell migration assays showed that ENCCs migrated on substrates with very low levels of stiffness. In 3D collagen gels, the speed of the ENCC migratory front decreased with increasing gel stiffness, whereas no correlation was found between porosity and ENCC migration behavior. Metalloprotease inhibition experiments showed that ENCCs actively degraded collagen in order to progress. These results shed light on the role of the mechanical properties of tissues in ENCC migration during development.

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