Identifying the substrates of the PHF21A-containing neuron-specific demethylase complex

This project aims to unravel the unique chromatin regulation mechanisms in neurons and their role in neurodevelopmental disorders. Mutations in chromatin regulators, including the histone-binding protein PHF21A, are frequent causes of neurodevelopmental disorders such as intellectual disabilities, autism, and schizophrenia. The abundance of chromatin regulator mutations poses a question: why is the brain so vulnerable to chromatin dysregulation? The molecular basis of this vulnerability remains elusive, which prevents the understanding of the etiology of neurodevelopmental disorders. Our previous work identified 14 chromatin regulator genes undergoing neuron-specific mRNA splicing, including the histone demethylase LSD1 and PHF21A, which form a complex within neurons. Loss-of-function mutations in both cause rare neurodevelopmental disorders characterized by intellectual disability and craniofacial features. We discovered that neuronal splicing events in LSD1 and PHF21A impair nucleosome binding and reduce H3K4 demethylation activity. Contrary to previously reported LSD1 histone substrates, we found the neuronal complex does not demethylate these sites. Building on these findings, we propose to determine the bona fide histone and non-histone substrates of the neuronal LSD1-PHF21A complex. Our research will employ chromatin biochemistry and proteome-wide methylation analysis. This study is expected to improve our understanding of neuron-specific chromatin regulation, involving PHF21A and LSD1, and its implications in neurodevelopmental disorders, potentially leading to new therapeutic strategies for conditions associated with chromatin dysregulation in the brain. Project Number: 1R03NS148802-01 | Fiscal Year: 2026 | NIH Institute/Center: National Institute of Neurological Disorders and Stroke (NINDS) | Principal Investigator: Shigeki Iwase | Institution: UNIVERSITY OF MICHIGAN AT ANN ARBOR, ANN ARBOR, MI | Award Amount: $146,630 | Activity Code: R03 | Study Section: Special Emphasis Panel[ZRG1 BN-F (92)] View on NIH RePORTER: https://reporter.nih.gov/project-details/11353152