Histone H3 variants and their chaperones during development and disease: contributing to epigenetic control.

Within the nucleus, the interplay between lineage-specific transcription factors and chromatin dynamics defines cellular identity. Control of this interplay is necessary to properly balance stability and plasticity during the development and entire life span of multicellular organisms. Here, we present our current knowledge of the contribution of histone H3 variants to chromatin dynamics during development. We review the network of histone chaperones that governs their deposition timing and sites of incorporation and highlight how their distinct distribution impacts genome organization and function. We integrate the importance of H3 variants in the context of nuclear reprogramming and cell differentiation, and, using the centromere as a paradigm, we describe a case in which the identity of a given genomic locus is propagated across different cell types. Finally, we compare development to changes in stress and disease. Both physiological and pathological settings underline the importance of H3 dynamics for genome and chromatin integrity.