Pleiotropy of autism-associated chromatin regulators

University Of California, San Francisco, San Francisco CA

Investigators

Abstract

ABSTRACT Despite tremendous success in the reliable identification of more than 100 genes carrying large risk for autism, an actionable understanding of the underlying biology has been elusive. Gene ontology analyses have repeatedly emphasized an enrichment of genes encoding proteins involved in gene expression regulation and neurotransmission. These areas have thus become a central focus for the field. However, ontology-based analyses rely on incomplete knowledge of gene function and pleiotropy, and therefore, have the potential to miss key aspects of the underlying biology. Indeed, our recent functional in vivo work has begun to elucidate additional roles for proteins annotated as chromatin regulators in directly remodeling microtubules and the cytoskeleton. In fact, there exists a “tubulin code” of post-translational modifications analogous to the “histone code” and ample examples of canonical chromatin modifiers that directly modify tubulin to regulate microtubule dynamics. We have generated preliminary data for five such autism-associated chromatin regulators suggesting that they have dual functions, localizing to and functioning at microtubule-rich structures such as mitotic spindles, neuronal growth cones, and cilia in a wide variety of cell types, including human neurons. Thus, we have developed the bold hypothesis that autism-associated chromatin regulators have dual functions regulating both histones and tubulins. To test this hypothesis, we will deploy innovative experiments leveraging unique advantages of the Xenopus experimental toolkit, complemented by state-of-the-art proteomic profiling of tubulin post-translational modifications in human cells. In doing so, this work will illuminate how high-confidence ASD-associated chromatin regulators function at microtubules and the underlying post-translational modifications of tubulin that mediate these effects. This will set the stage for future work exploring how these fundamental effects on tubulin cascade to influence other neuronal processes like neuronal migration, axon outgrowth, dendrite formation, synaptogenesis, and synaptic transmission. This work has the potential to completely reframe the potentially relevant functions of these genes to autism biology, potentially bringing together the seemingly disparate enriched annotations since microtubule dysfunction impacts neurotransmission. I am uniquely positioned to lead this project, leveraging my experience in ASD genetics, proteomics, and innovative use of Xenopus to model ASD gene variants and identify core underlying biology.