Precocious sister chromatid separation (PSCS) in Cornelia de Lange syndrome

Abstract

The Cornelia de Lange syndrome (CdLS) (OMIM# 122470) is a dominantly inherited multisystem developmental disorder. The phenotype consists of characteristic facial features, hirsutism, abnormalities of the upper extremities ranging from subtle changes in the phalanges and metacarpal bones to oligodactyly and phocomelia, gastroesophageal dysfunction, growth retardation, and neurodevelopmental delay. Prevalence is estimated to be as high as 1 in 10,000. Recently, mutations in NIPBL were identified in sporadic and familial CdLS cases. To date, mutations in this gene have been identified in over 45% of individuals with CdLS. NIPBL is the human homolog of the Drosophila Nipped-B gene. Although its function in mammalian systems has not yet been elucidated, sequence homologs of Nipped-B in yeast (Scc2 and Mis4) are required for sister chromatid cohesion during mitosis, and a similar role was recently demonstrated for Nipped-B in Drosophila. In order to evaluate NIPBL role in sister chromatid cohesion in humans, metaphase spreads on 90 probands (40 NIPBL mutation positive and 50 NIPBL mutation negative) with CdLS were evaluated for evidence of precocious sister chromatid separation (PSCS). We screened 50 metaphases from each proband and found evidence of PSCS in 41% (compared to 9% in control samples). These studies indicate that NIPBL may play a role in sister chromatid cohesion in humans as has been reported for its homologs in Drosophila and yeast.

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

“…42 Briefly, cells were arrested at metaphase with 0.8 mg/ml Colchicine (Sigma-Aldrich, St Louis, MO, USA) for 20 min at 37 1C, treated with hypotonic 0.075 M KCl at room temperature and fixed with three parts of methanol and one part of acetic acid. The slides were stained with Wright's Stain (Fisher Scientific, Pittsburgh, PA, USA).…”

Roles of the sister chromatid cohesion apparatus in gene expression, development, and human syndromes

“…The Scc2 factor of S. cerevisiae and its orthologs (Mis4, Nipped-B, delangin, Xscc2) in other organisms, known collectively as adherins, are required for sister chromatid cohesion (Furuya et al 1998;Gillespie and Hirano 2004;Kaur et al 2005;Michaelis et al 1997;Rollins et al 2004;Seitan et al 2006). Scc2 and its orthologs are required for cohesin to bind to chromosomes (Arumugam et al 2003;Ciosk et al 2000;Gillespie and Hirano 2004;Seitan et al 2006;Takahashi et al 2004;Tomonaga et al 2000).…”

“…Using immortalized cell lines, a recent study revealed mild cohesion defects in 40% of CdLS patients (Kaur et al 2005). The procedures used to prepare metaphase spreads enhance chromatid separation, so it is unclear if such cohesion defects occur in vivo, or if the analysis reveals a subtle defect that has little role in the etiology of CdLS.…”

Association of cohesin and Nipped-B with transcriptionally active regions of the Drosophila melanogaster genome

“…CdLS patients display slow growth, mental retardation, and defects in limbs and organs (Dorsett 2007;Jackson et al 1993;Strachan 2005). Most do not show cohesion defects (Kaur et al 2005;Vrouwe et al 2007), suggesting that the diverse developmental deficits are caused by gene expression changes similar to those in Drosophila. The similar effects of reduced NIPBL activity and cohesin subunit missense mutations on human development in the absence of obvious effects on sister chromatid cohesion further suggest that Nipped-B/NIPBL are likely to dynamically regulate cohesin.…”