Ldb1 mediates trans enhancement in mammals

The monoallelic expression of olfactory receptor (OR) genes is governed by a large number of intergenic enhancer elements that are located in intergenic regions of OR gene clusters. In mature olfactory sensory neurons (OSNs), multiple OR enhancers colocalize in an interchromosomal enhancer hub together with the active OR allele. Here we show that in OSNs OR enhancers are bound by Ldb1, but not general purpose mediators of nuclear architecture (CTCF or the cohesin complex subunit Rad21). Conditional deletion of Ldb1 in OSNs results in the dissolution of long range and interchromosomal contacts between OR Enhancers and in pervasive reductions in OR gene expression. Overall design: Two types of data are included: Crosslinked ChIP-Seq data identifies sites bound by CTCF, Rad21, or Ldb1 and RNA-Seq data profiles changes in gene expression in Ldb1 deleted mOSNs, Lhx2 deleted cells, or Enhancer Knockout mOSNs. The number of replicates varies between experiments.