# Recognition and Ubiqutination of neurodevelopmental chromatin regulators

> **NIH NIH R21** · UNIVERSITY OF CALIFORNIA, SAN DIEGO · 2024 · $438,342

## Abstract

PROJECT SUMMARY
 The objective of this proposal is to illuminate the fundamental mechanisms by which ubiquitin ligases
recognize and ubiquitinate substrates within protein complexes. Our interest in this topic arose after our
discovery that the multifunctional ubiquitin ligase Anaphase-Promoting Complex (APC) is mutated in inherited
neurodevelopmental disorders. Studies from the Ferguson and Brown labs in APC mutant in vivo and in vitro
systems demonstrated a previously unknown role for APC-mediated ubiquitin signaling in the regulation of the
composition of neuronal heterochromatin through clearance of specific protein substrates. In post-mitotic
neurons of the developing APC mutant brain, we found that the most significantly dysregulated target of the APC
in neurons was the Chromosome-Passenger Complex (CPC), which includes the kinase Aurora B and the
scaffold INCENP. Imaging analysis showed that Aurora B and its product phosphorylated Histone 3 (p-H3,
H3S10ph) accumulate within heterochromatin in APC mutant neurons during post-mitotic terminal differentiation.
Through the proposed aims, we will examine the interaction between the APC, its target the CPC, and the CPC
product H3S10ph, to generate critical structural insight into the molecular pathogenesis of neurodevelopmental
disorders. In Aim 1, we will build upon past successes in similar experiments by producing the CPC and the APC
as purified recombinant protein complexes and dissect their interaction using in vitro enzyme assays and mass
spectrometry. In Aim 2, we will perform cryo-EM to produce a structural map of the APC interacting with the
CPC. We predict that the completion of these aims will shed light on the molecular interactions required for the
recognition and ubiquitination of the CPC by the APC, providing key mechanistic insight into chromatin regulation
by ubiquitin signaling and the pathogenesis of APC-related neurodevelopmental disorders. Through the
proposed combination of hypothesis-driven and unbiased experiments, we will build upon our discovery of the
neurodevelopmentally essential APC-CPC-H3S10ph axis. Insight gained from these aims will likely serve as the
foundation for us to expand in a multitude of long-term experimental directions in vivo and in vitro. The molecular
understanding gained from these lines of inquiry would provide critical insight that will be necessary for the
development of rational interventions for a class of debilitating diseases that represents a major unmet medical
need.

## Key facts

- **NIH application ID:** 10953301
- **Project number:** 1R21NS139210-01
- **Recipient organization:** UNIVERSITY OF CALIFORNIA, SAN DIEGO
- **Principal Investigator:** Cole John Ferguson
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $438,342
- **Award type:** 1
- **Project period:** 2024-07-05 → 2026-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10953301

## Citation

> US National Institutes of Health, RePORTER application 10953301, Recognition and Ubiqutination of neurodevelopmental chromatin regulators (1R21NS139210-01). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10953301. Licensed CC0.

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