A lamina-associated domain border governs nuclear lamina interactions, transcription and recombination of the Tcrb locus [ChIP-seq]

Tcrb locus V(D)J recombination is regulated by positioning at the nuclear periphery. Here we used DamID to profile Tcrb locus interactions with the nuclear lamina at high-resolution. We identified a lamina-associated domain (LAD) border composed of several CTCF binding elements that segregates active non-LAD from inactive LAD regions of the locus. Deletion of the LAD border caused an enhancer-dependent spread of H3K27ac from the active recombination center into recombination center-proximal LAD chromatin. This was associated with a disruption to LAD organization, increased chromatin looping to the recombination center, and increased transcription and recombination of recombination center-proximal gene segments. Our results show that a Tcrb locus LAD and LAD border are critical components of Tcrb locus gene regulation and suggest that LAD borders may generally function to constrain the activity of nearby enhancers. H3K9me2 and H3K27ac ChIP-seq in primary Rag2-/- DN and DP thymocytes and VL3-3M2-cell lines (one wild-type and two modified)