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

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. DamID in VL3-3M2-cell lines (one wild-type and one modified) Please note that the 'WT_DamID_LAD.bed' contains LAD calls based on DamID tracks in .bed (Bioinformatic calling based on DamID).

T细胞受体β链（Tcrb）位点的V(D)J重组受核周缘定位调控。本研究采用DamID技术，以高分辨率绘制Tcrb位点与核纤层的染色质互作图谱。我们鉴定到一个由多个CTCF结合元件构成的核纤层关联结构域（lamina-associated domain, LAD）边界，该边界可将位点内的活性非LAD区域与失活LAD区域分隔开。删除该LAD边界后，会导致增强子依赖的H3K27ac修饰从活性重组中心向重组中心近端的LAD染色质扩散。该现象伴随LAD组织结构的破坏、与重组中心的染色质环互作增强，以及重组中心近端基因片段的转录与重组水平上调。本研究结果表明，Tcrb位点的LAD及其边界是Tcrb位点基因调控的关键组分，并提示LAD边界通常可发挥限制邻近增强子活性的功能。本数据集包含VL3-3M2细胞系的DamID实验数据，其中1株为野生型，1株为基因修饰型。请注意，"WT_DamID_LAD.bed"文件包含基于.bed格式DamID轨道的LAD调用结果，即通过DamID数据进行生物信息学分析所得的LAD预测结果。