SMC1 ELISA Kit

Cornelia de Lange syndrome (CdLS) is a complex multisystem developmental disorder caused by mutations in cohesin subunits and regulators. While its precise molecular mechanisms are not well defined, they point toward a global deregulation of the transcriptional gene expression program. Cohesin is associated with the boundaries of chromosome domains and with enhancer and promoter regions connecting the three-dimensional genome organization with transcriptional regulation. Here, we show that connected gene communities, structures emerging from the interactions of noncoding regulatory elements and genes in the three-dimensional chromosomal space, provide a molecular explanation for the pathoetiology of CdLS associated with mutations in the cohesin-loading factor NIPBL and the cohesin subunit SMC1A. NIPBL and cohesin are important constituents of connected gene communities that are centrally positioned at noncoding regulatory elements. Accordingly, genes deregulated in CdLS are positioned within reach of NIPBL- and cohesin-occupied regions through promoter-promoter interactions. Our findings suggest a dynamic model where NIPBL loads cohesin to connect genes in communities, offering an explanation for the gene expression deregulation in the CdLS.

Cornelia de Lange Syndrome (CdLS) is a multiple congenital anomaly disorder resulting from mutations in genes that encode the core components of the cohesin complex, SMC1A, SMC3, and RAD21, or two of its regulatory proteins, NIPBL and HDAC8. HDAC8 is the human SMC3 lysine deacetylase required for cohesin recycling in the cell cycle. To date, 16 different missense mutations in HDAC8 have recently been identified in children diagnosed with CdLS. To understand the molecular effects of these mutations in causing CdLS and overlapping phenotypes, we have fully characterized the structure and function of five HDAC8 mutants: C153F, A188T, I243N, T311M, and H334R. X-ray crystal structures reveal that each mutation causes local structural changes that compromise catalysis and/or thermostability. For example, the C153F mutation triggers conformational changes that block acetate product release channels, resulting in only 2% residual catalytic activity. In contrast, the H334R mutation causes structural changes in a polypeptide loop distant from the active site and results in 91% residual activity, but the thermostability of this mutant is significantly compromised. Strikingly, the catalytic activity of these mutants can be partially or fully rescued in vitro by the HDAC8 activator N-(phenylcarbamothioyl)benzamide. These results suggest that HDAC8 activators might be useful leads in the search for new therapeutic strategies in managing CdLS.