Isolated NIBPL missense mutations that cause Cornelia de Lange syndrome alter MAU2 interaction

Abstract

Cornelia de Lange syndrome (CdLS; or Brachmann-de Lange syndrome) is a dominantly inherited congenital malformation disorder with features that include characteristic facies, cognitive delays, growth retardation and limb anomalies. Mutations in nearly 60% of CdLS patients have been identified in NIPBL, which encodes a regulator of the sister chromatid cohesion complex. NIPBL, also known as delangin, is a homolog of yeast and amphibian Scc2 and C. elegans PQN-85. Although the exact mechanism of NIPBL function in sister chromatid cohesion is unclear, in vivo yeast and C. elegans experiments and in vitro vertebrate cell experiments have demonstrated that NIPBL/Scc2 functionally interacts with the MAU2/Scc4 protein to initiate loading of cohesin onto chromatin. To test the significance of this model in the clinical setting of CdLS, we fine-mapped the NIPBL-MAU2 interaction domain and tested the functional significance of missense mutations and variants in NIPBL and MAU2 identified in these minimal domains in a cohort of patients with CdLS. We demonstrate that specific novel mutations at the N-terminus of the MAU2-interacting domain of NIPBL result in markedly reduced MAU2 binding, although we appreciate no consistent clinical difference in the small group of patients with these mutations. These data suggest that factors in addition to MAU2 are essential in determining the clinical features and severity of CdLS.

Neural crest cell‐specific inactivation of Nipbl or Mau2 during mouse development results in a late onset of craniofacial defects

“…Interestingly, Mau2 1/2 mice were indistinguishable from wild type mice, consistent with the notion that mutations in MAU2 have not been identified in CdLS thus far (Seitan et al, 2006;Braunholz et al, 2012). In contrast, Nipbl 1/2 neonates appeared small ( Fig.…”

AMKL chimeric transcription factors are potent inducers of leukemia

“…Therefore, to evaluate the role of NIPBL in our model we introduced two different SNVs previously shown to disrupt binding of NIPBL to the cohesin component MAU2 (G15R, P29Q)(29). Surprisingly, these single alterations abrogated the ability of cells carrying the fusion to serially replate as well as to induce leukemia (Supplementary Figure S15A–B).…”

Cell cycle-specific cleavage of Scc2 regulates its cohesin deposition activity

“…Vertebrate Scc2 and Scc4 orthologs interact physically through their amino termini (10,13,17,18), but budding yeast Scc2 appears to lack the corresponding amino-terminal region. Nevertheless, we found that Scc2 cleavage prevents its coimmunoprecipitation with Scc4, indicating that the budding yeast Scc2 amino-terminal domain is required for stable interactions with Scc4.…”

“…The amino termini of human and Xenopus Scc2 homologs are required for interactions with their respective Scc4 orthologs (10,13,17,18). Whether this requirement is true in budding yeast is unclear, however, because S. cerevisiae Scc2 lacks the corresponding amino-terminal region present in multicellular eukaryotic homologs.…”

“…Interactions of Scc2 and Scc4 orthologs from Xenopus and humans, and their stable association with chromatin, require the amino termini of both proteins (10,13,17,18). In contrast, the fission yeast Scc2 ortholog alone binds nonchromatinized DNA, but does not exhibit an expected preference for sequences shown to associate with Scc2/Scc4 in vivo (19).…”