The Epigenetics of Early Lymphocyte Development

The mammalian genome is highly structured, both spatially and functionally. Chromosomes are organized into specific territories, which are further folded into euchromatic or heterochromatic compartments. The euchromatic compartment often contains domains decorated with activating epigenetic marks, whereas heterochromatic regions lack activating marks or bear repressive ones. During lymphocyte development, gene segments move between these compartments. Additionally, some genes undergoing changes in transcriptional activity also display elaborate alterations in chromatin folding. Lineage-specific transcription factors help mediate these reconfigurations. Herein, I describe how genetic loci encoding for key regulators switch nuclear neighborhoods and reorganize their 3D structures to drive cell fate.