TGFb induced embryonic cell senescence at the origin of the Cornelia de Lange syndrome

Cornelia de Lange Syndrome (CdLS) largely caused by mutation of the cohesin loader NIPBL is a rare developmental disorder affecting the formation of many organs. Besides a short body size and neurological defects, more than half of CdLS children feature various cardiac malformations. To mimic the disease and test a therapeutic strategy, we generated a C57/Bl6 Nipbl+/- mouse model of the disease. These mice featured a severe delay in both embryonic and postnatal growth. The Nipbl-deficient embryonic and neonatal hearts developed ventricular hypertrophy, aortic and valve defects associated with a persistent truncus arteriosus and a ventricular septal defect. Muscles derived from the second heart field were deficient in the Nipbl haplo-insufficient mouse embryos. The adult hearts then featured a severe aortic senescence phenotype and a stenosis resulting in an increase in aortic flux velocity and persistent left ventricular hypertrophy. Using proteomics and RNA-sequencing in embryos, we identified a dysregulated TGF{beta} pathway in the outflow tract of embryonic hearts as well as the presence of senescent cells as early as in E13.5 Nipbl+/- embryonic hearts, limb primordium cartilage as well as in different post-natal tissues including muscle and brain cortex. Treatment of pregnant Nipbl+/- mice with a TGF{beta}R (ALK5) inhibitor from E9.5 to E13.5 prevented cell -senescence and rescued the cardiac phenotype as well as the body size of mice at birth. Altogether our data revealed that an exacerbated TGF{beta} pathway associated with cell senescence is at the origin of many defects in a CdL mouse model. This druggable pathway opens the path toward a potential preventive and/or therapeutic strategy for post-natal CdLS patients.