Abstracts
Résumé
Les histones sont les pièces maîtresses de la compaction de l’ADN en chromatine et jouent un rôle majeur dans la régulation des fonctions du génome. Elles sont les cibles de multiples modifications post-traductionnelles qui apportent une information épigénétique. L’ensemble de ces modifications constituerait un « code histone », permettant d’associer à chaque combinaison de modifications un état particulier de la chromatine. De surcroît, les histones se déclinent sous forme de variants dont on sait qu’ils diffèrent par leur séquence, leur fonction et leur mécanisme d’incorporation dans la chromatine. Ce répertoire élargi d’informations permet d’envisager de nouvelles possibilités de régulation épigénétique.
Summary
Histones are the fundamental structural proteins intimately associated with eukaryotic DNA to form a highly ordered and condensed nucleoproteic complex termed chromatin. They are the targets of various posttranslational modifications including acetylation, methylation, phosphorylation and ubiquitination that modulate the structure/function of chromatin. The combinatorial nature of histone modifications is hypothesized to define a « histone code » that considerably extends the information potential of the genetic code, giving rise to epigenetic information. Moreover, most core histones consist of several nonallelic variants that can mark specific loci and could play an important role in establishment and maintenance of epigenetic memory. Here we will briefly present our current knowledge about histone posttranslational modifications and their implications in the regulation of epigenetic information. We will next describe core histone variants, insisting on their mode of incorporation into chromatin to discuss their epigenetic function and inheritance.
Appendices
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