Defective Cohesin in CdLS Mediates Gene Expression with Characteristics of Transcription Factor and Insulator Activity

The Cohesin apparatus has a canonical role in sister chromatid cohesion. Heterozygous mutations in Nipped B-like (NIPBL), SMC1A, and SMC3 have been found in 60% of probands with Cornelia de Lange Syndrome (CdLS), a dominant multi-system genetic disorder with variable expression. We have performed a genome-wide transcription assessment as well as cohesin binding analysis using human lymphoblastoid cell lines (LCLs) from probands with CdLS and controls. Here, we report a unique profile of genes dysregulated in CdLS that correlates with different clinical presentations. Genome-wide analysis of cohesin binding demonstrates a preference for intergenic regions suggesting a cis-regulatory function mimicking that of an insulator. However, the binding sites are enriched within the promoter regions of the dysregulated genes and are significantly decreased in CdLS probands, indicating an alternative role of cohesin as a classic transcription factor. Cohesin also co-localizes with CTCF at the boundary elements affecting neighboring gene expression in CdLS probands. We propose that the CdLS phenotype is the result of dysregulated gene expression rather than defective sister chromatid cohesion. Phenotype specific expression profiles are also described.

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Liu J, Zhang Z, Bando M, Itoh T, Deardorff MA, Clark D, Kaur M, Tandy S, Kondoh T, Rappaport E, Spinner NB, Vega H, Jackson LG, Shirahige K, Krantz ID