UTX-guided neural crest function underlies craniofacial features of Kabuki syndrome

Abstract

Kabuki syndrome, a congenital craniofacial disorder, manifests from mutations in an X-linked histone H3 lysine 27 demethylase (UTX/KDM6A) or a H3 lysine 4 methylase (KMT2D). However, the cellular and molecular etiology of histone-modifying enzymes in craniofacial disorders is unknown. We now establish Kabuki syndrome as a neurocristopathy, whereby the majority of clinical features are modeled in mice carrying neural crest (NC) deletion of UTX, including craniofacial dysmorphism, cardiac defects, and postnatal growth retardation. Female UTX NC knockout (FKO) demonstrates enhanced phenotypic severity over males (MKOs), due to partial redundancy with UTY, a Y-chromosome demethylase-dead homolog. Thus, NC cells may require demethylase-independent UTX activity. Consistently, Kabuki causative point mutations upstream of the JmjC domain do not disrupt UTX demethylation. We have isolated primary NC cells at a phenocritical postmigratory timepoint in both FKO and MKO mice, and genome-wide expression and histone profiling have revealed UTX molecular function in establishing appropriate chromatin structure to regulate crucial NC stem-cell signaling pathways. However, the majority of UTX regulated genes do not experience aberrations in H3K27me3 or H3K4me3, implicating alternative roles for UTX in transcriptional control. These findings are substantiated through demethylase-dead knockin mutation of UTX, which supports appropriate facial development.