The ciliary proteins Meckelin and Jouberin are required for retinoic acid-dependent neural differentiation of mouse embryonic stem cells

摘要

The dysfunction of the primary cilium, a complex, evolutionarilyconserved, organelle playing an important role insensing and transducing cell signals, is the unifying pathogeneticmechanism of a growing number of diseasescollectively termed “ciliopathies”, typically characterized bymultiorgan involvement. Developmental defects of thecentral nervous system (CNS) characterize a subset ofciliopathies showing clinical and genetic overlap, such asJoubert syndrome (JS) and Meckel Syndrome (MS).Although several knock-out mice lacking a variety of ciliaryproteins have shown the importance of primary cilia inthe development of the brain and CNS-derived structures,developmental in vitro studies, extremely useful to unravelthe role of primary cilia along the course of neural differentiation,are still missing. Mouse embryonic stem cells(mESCs) have been recently proven to mimic brain development,giving the unique opportunity to dissect the CNSdifferentiation process along its sequential steps. In thepresent study we show that mESCs express the ciliary proteinsMeckelin and Jouberin in a developmentally-regulatedmanner, and that these proteins co-localize withacetylated tubulinlabeled cilia located at the outer embryoniclayer. Further, mESCs differentiating along the neuronallineage activate the cilia-dependent sonic hedgehogsignaling machinery, which seems to be impaired in Meckelinknock-down cells but results unaffected in JouberindeficientmESCs. However, both seems to lose the abilityto acquire a neuronal phenotype. Altogether these findingssuggest a pivotal role of Meckelin and Jouberin duringembryonic neural specification and indicate mESCs as asuitable tool to investigate the developmental impact ofciliary proteins dysfunction.