ACTIVATION OF DEFECTIVE WNT PATHWAY IN CORNELIA DE LANGE SYNDROME IN IN VITRO MODELS

Background: Cornelia de Lange Syndrome (CdLS) is a rare genetic disease caused by de novo mutations in cohesin genes. CdLS phenotypic features vary from mild to severe and is characterized by an array of congenital malformations, neurodevelopmental delay, and autism-spectrum disorder. Current hypothesis is that CdLS clinical signs arise from deregulation of developmental molecular pathways, and we have previously shown that canonical WNT pathway is perturbed. In this study, our goal was assessing possible ameliorative effects of canonical WNT pathway chemical activation in Lymphoblastoid cell lines (LCLs) from CdLS patients and ex vivo FUCCI2 murine neurons. Methods: LCLs from CdLS patients (6) and from healthy donors (4) were exposed to different concentrations of WNT pathway activators: lithium chloride (LiCl), BIO, IQ-1, DCA, CHIRR99021 or vehicle for 24h. Proliferation/death rate were measured using Tripan blue staining, TUNEL and Ki67 assays. CyclinD1 gene expression was analysed by qPCR. Primary cultures of murine neurons from day2 pups (FUCCI2) harvested from cerebellum were cultured and treated with PCI34051(HDAC8 inhibitor) and LiCl for 13 days. Immunostaining for Tuj1 was performed. Results: Upon WNT activation, proliferation rate is restored and CyclinD1 gene expression increased, rescuing physiological levels. Immunostaining for Tuj1 on FUCCI2 primary cultures, markers of neurons, demonstrated that LiCl treatment increases the rate of neuronal differentiation. Conclusions and Perspectives: I confirmed the impairment of WNT canonical pathway in CdLS models and described that WNT activators such as lithium are capable of rescuing adverse phenotype. Due to SARS-CoV-2 pandemic, clinical trial for lithium in CdLS patients is still under development. During this period, I was part of the team that worked for optimization of a new device for saliva collection and molecular testing to detect SARS-CoV-2 RNA – an exceptional tool for fragile patients such as CdLS. When enrolment begins, I plan to use the new device for COVID-19 surveillance in CdLS patients enrolled in the trial.