Mechanisms of de novo Germline Histone Mutations Underlying Developmental Disorders

Project Summary Chromatin integrates environmental and intrinsic cellular cues to orchestrate nucleosome modifications, therefore regulating basic cellular functions that are essential for cell fate and identity in normal development. Mutations in enzymes that deposit or remove nucleosome modifications often dysregulate chromatin structure and result in pathological gene expression programs in many human developmental disorders. As the basic unit of the nucleosome, alterations in histone genes themselves have only been recently identified in children with developmental disorders and their mechanistic and functional roles remain largely unknown. Given the increasing number of histone germline mutations and lack of understanding of their impact, it is imperative to establish animal models to elucidate their physiological functions and delineate underlying mechanisms. My goal is to uncover the function of histone mutations during development by integrating biochemical and genomic assays, along with employing animal models through the followings aims: (1) Investigate the mechanism of how histone H4 mutants are recruited to heterochromatin, (2) Determine how histone H4 mutations regulate chromatin accessibility and neural differentiation, and (3) Identify the function of histone mutations during development. The central hypothesis guiding this proposal is that histone mutations alter heterochromatin silencing, impact gene expression, and promote neural differentiation, which altogether contribute to brain defects. This research will provide new insights into molecular mechanisms underlying histone germline mutations and the epigenetic causes of developmental disorders. During the mentored period, I will gain training in the following key skillsets: acquiring expertise in mouse models, expanding my knowledge of mouse brain development and in vivo brain models of developmental disorders, deepening training in grant writing and mentoring, as well as scientific career development. With acquisition of these valuable skills, the well-established biochemical and genomics approaches in the Allis laboratory, the great training in neurogenesis and mammalian brain development from my co-mentor Dr. Hatten, and strong support and expertise from my outstanding collaborators, I will be in a unique position to apply diverse approaches to study histone germline mutations in developmental disorders. Importantly, I will receive additional mentoring from my Scientific Advisory Committee, along with fantastic mentorship from Dr. Allis and Dr. Hatten to facilitate my transition to independence. Together, this training and support from the K99/R00 award will fulfill my career goal of becoming an independent investigator in the field of chromatin and developmental biology.