Enhancer activation mechanisms in cranial neural crest osteoblast differentiation

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Project Summary Enhancers play a vital role in initiating and maintaining expression of cell specific transcriptional programs. A key feature in enhancer activation and gene regulation is changing the local chromatin state to facilitate binding of transcriptional co-regulators to enhancers. Chromatin-modifying enzymes that are associated with enhancer function are commonly mutated in human craniofacial disorders including histone methylases, demethylases, acetylases, chromatin readers, and chromatin remodeling proteins. Many of these chromatin-modifying factors biochemically associate and may co-regulate enhancer and transcriptional activation events within neural crest, stem cells from which anterior facial bone and cartilage are derived. We have modeled several of these human craniofacial disorders through tissue specific knockout of chromatin-modifying factors in mouse neural crest cells. The experiments outlined in this proposal will characterize de novo enhancer activation by chromatin profiling of primary cranial neural crest cells undergoing osteoblast differentiation. Neural crest cells deficient in chromatin-modifying machinery will be analyzed molecularly for disruption of enhancer chromatin states and to identify cooperative functions between these factors. This proposal will utilize a combination of biochemical, genetic, and low cell number genomic approaches to elucidate the role of chromatin-based enhancer activation in craniofacial disorder pathogenesis.