SH001 - Hierarchical DNA repair in human neurons shapes genomic stability and identity
SH001
Hierarchical DNA repair in human neurons shapes genomic stability and identity
D. Gallagher1,*, I. Sala1, K. Balzaretti1, M. Muhar2,3, J. Corn3
1D-Biol, ETH Zürich, Zürich, Switzerland, 2Max Planck Institute of Molecular Cell Biology and Genetics, Dresden, Germany, 3ETH Zürich, Zürich, Switzerland
Rationale: Neurons are exceptionally long-lived, post-mitotic cells with high transcriptional activity, placing unique demands on genome maintenance. Exactly how the neuronal genome is protected over decades remains poorly understood. We therefore examined whether the DNA damage response (DDR) is governed by distinct regulatory mechanisms in mature human neurons.
Methods: Using human ESC-derived neurons, we combined CRISPR perturbation with enrichment-based screening and a multi-omics approach to characterize DDR.
Results: Remarkably, mature neurons activate a DDR resembling that of cycling cells, including induction of canonical double strand break repair pathways and p53-dependent signaling. p21, a cyclin-dependent kinase inhibitor most known for its role in cell cycle regulation, emerged as a major regulator. Under extensive DNA damage, p21 is initially robustly upregulated. However, as DNA damage persists, p21 levels decline and neuronal populations diverge toward distinct outcomes, including repair with a return to quiescence, apoptotic cell death, or survival with persistent 𝛾H2Ax-marked lesions. Despite repairing damage, a significant number of neurons exhibit transcriptional dysregulation, with impaired expression of neuronal identity genes and induction of glial signatures. Meanwhile, neurons with persistent DNA damage reveal prioritized repair. While some loci are repaired efficiently, key neuronal identity genes exhibit delayed or incomplete repair, with lesions persisting at the termini of long genes.
Conclusions: Together, these findings indicate that although neurons engage in conserved DDR mechanisms, hierarchical constraints on repair permits the persistence of lesions with long-term consequences for neuronal identity and function, and these mechanisms are modulated by p21. These dynamics resemble molecular features of neurodegeneration, including sustained DNA damage and disruption of neuronal identity programs, and may represent the early events that predispose neurons to degeneration.
Disclosure of Interest: None declared