CHD3 regulates BMP signalling response during cranial neural crest cell specification

CHD3 is a component of the NuRD chromatin remodeling complex. Pathogenic CHD3 variants cause Snijders Blok-Campeau Syndrome, a neurodevelopmental disorder with variable features including developmental delays, intellectual disability, speech/language difficulties, and craniofacial anomalies. To unveil the role of CHD3 in craniofacial development, we differentiated CHD3 -KO induced pluripotent stem cells into cranial neural crest cells (CNCCs). CHD3 expression is low in wild-type iPSCs and neuroectoderm, but upregulated during CNCC specification, where it opens the chromatin at BMP-responsive enhancers, to allow binding of DLX5 and other factors. CHD3 loss leads to repression of BMP target genes and an imbalance between BMP and Wnt signalling, ultimately resulting in aberrant mesodermal fate. Consequently, CNCC specification fails, replaced by early-mesoderm identity, which can be partially rescued by titrating Wnt levels. Our findings highlight a novel role for CHD3 as a pivotal regulator of BMP signalling, essential for proper neural crest specification and craniofacial development.