A Cornelia de Lange syndrome NIPBL 5'‑UTR mutation reduces cell proliferation in an <i>in vitro</i> model by downregulating RAD21 and β‑catenin

Cornelia de Lange Syndrome (CdLS) is a prevalent chromatinopathy, frequently caused by mutations in genes encoding cohesin complex components, with <i>NIPBL</i> being the most commonly affected. The present study aimed to investigate the effects of a 5'-untranslated region (UTR) mutation (c.-467C>T) in the <i>NIPBL</i> gene on gene expression and cohesin complex integrity. Using CRISPR/Cas9 technology, a heterozygous cell line harboring the <i>NIPBL</i> 5'-UTR mutation was generated. A combination of molecular biology techniques, including RNA secondary structure prediction and luciferase reporter assays, was employed to evaluate the effect of the mutation. These findings indicated that the 5'-UTR mutation introduces an additional upstream open reading frame, leading to diminished expression levels of NIPBL protein. This decrease was associated with downregulation of RAD21, a pivotal component of the cohesin complex, and reduced β-catenin levels, thereby affecting cell proliferation. The present study elucidates the significance of 5'-UTR elements in regulating gene expression and the potential consequences of sequence variations within this region, demonstrating that a 5'-UTR mutation in <i>NIPBL</i> contributes to CdLS by disrupting gene expression and cellular processes. These results advance the understanding of the molecular mechanisms underlying CdLS.