What if the ability of neurons to communicate, adapt, and maintain normal brain function depends partly on how efficiently they repair DNA breaks?

A fascinating new study by Crewe and colleagues, published in Cell Reports (2026), provides compelling evidence that tyrosyl-DNA phosphodiesterase 2 (TDP2) is essential for repairing DNA double-strand breaks generated by topoisomerase IIβ (TOP2β) during neuronal gene activation. These findings extend the biological significance of DNA topoisomerases beyond their classical functions in DNA topology and genome maintenance, revealing an important connection between DNA repair, transcriptional regulation, and neuronal circuitry.

The investigators demonstrated that neuronal stimulation induces TOP2β-dependent DNA breaks associated with the activation of early response genes, including Fos and Npas4. TDP2 facilitates the repair of these breaks by processing the covalent TOP2β–DNA intermediates, enabling subsequent DNA repair through the nonhomologous end-joining (NHEJ) pathway. Remarkably, loss of TDP2 prolongs early response gene expression, promotes the accumulation of DNA damage, and results in abnormal excitatory signaling and cortical circuit hyperexcitability in mice.

The implications are particularly intriguing for neurobiology, DNA repair research, and drug discovery. These findings raise important questions about how TDP2 functions in concert with TOP2β, proteasomal processing, DNA-PK, and other components of the DNA damage response. Could protein interactions regulate TDP2 activity or its access to covalent TOP2β–DNA intermediates? Might small molecules enhance or suppress TDP2 catalytic function? Could modulation of this pathway influence neuronal transcription, genome stability, or cellular responses to TOP2-targeting drugs? These are important opportunities for future investigation, although therapeutic applications remain to be established.

At TopoGEN, we provide specialized research tools to investigate precisely these molecular events. Our portfolio includes purified human TDP2, a dedicated TDP2 activity assay kit, and a defined TOP2–DNA covalent-complex substrate suitable for investigating TDP2 catalytic function and identifying potential pharmacological modulators.

Importantly, our ICE–TOP2β (In Vivo Complex of Enzyme) assay provides a complementary approach for detecting covalently trapped TOP2β–DNA complexes directly in cells. By integrating ICE–TOP2β measurements with biochemical TDP2 activity assays, researchers can investigate both the formation and persistence of TOP2β cleavage complexes and the downstream enzymatic mechanisms responsible for processing these lesions.

This combined experimental strategy offers a promising foundation for screening compounds that influence TOP2β trapping, investigating functional relationships between TDP2 and associated DNA repair pathways, and studying how drug-induced DNA damage may affect neuronal gene regulation.

The emerging story is that DNA breakage and DNA repair are not simply responses to genomic injury; they can also participate in the regulation of normal gene expression and cellular function. Understanding the molecular partnership between TOP2β and TDP2 may therefore reveal new biological mechanisms and opportunities for therapeutic discovery.

TopoGEN welcomes inquiries from academic investigators, biotechnology companies, and pharmaceutical research groups interested in TDP2 biology, TOP2β-mediated DNA damage, and collaborative drug discovery programs.

Explore our research tools:

TDP2 enzymes and assay systems: https://topogen.com/tdp2-products/

ICE assay technology: https://topogen.com/product/human-topoisomerase-ice-assay-kit/

Reference: Crewe et al. (2026), Cell Reports, “TDP2-mediated DNA repair regulates the dynamics of neuronal early response gene transcription and cortical neuron connectivity.”

https://doi.org/10.1016/j.celrep.2026.118152

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