# Control of Chromosome Segregation by DNA Topoisomerase II

> **NIH NIH R01** · UNIVERSITY OF MINNESOTA · 2024 · $317,795

## Abstract

Title: Control of Chromosome Segregation by DNA Topoisomerase II.
Abstract
Chromosome segregation errors result in aneuploidy, which causes birth defects and cancer. We have
defined a new mitotic Topo II-responsive control (TRC) that delays the cell cycle when Topo II activity is
insufficient for accurate chromosome segregation. This TRC mechanism is conserved from yeast to human
cells but has not been extensively studied. Activation of the TRC is triggered by stalling of the strand
passage reaction of Topo II, when the enzyme becomes trapped on DNA in the Closed Clamp structural
conformation. TRC activation requires two distinct modules within the catalytically inert C-terminal domain of
TopoII: (i) A cluster of SUMOylation sites, and (ii) The Chromatin Tether domain of Topo II, which interacts
with methylated nucleosomes. The central molecular model is that stalled strand passage leads to C-terminal
domain SUMOylation that functions as a signal-generating scaffold to halt the cell cycle. The conservation
between the human and yeast TRC responses provided unique opportunities to identify TRC components,
but gaps remain in our understanding of the mechanism of TRC activation. We aim to determine how the
TRC activates Mad2 to inhibit anaphase initiation, which will require determining the identity of the E3 ligase
that SUMOylates TopoII as well as the relevant substrates of Aurora B kinase. We will determine how
trapped Closed Clamps trigger TopoII SUMOylation and how they are repaired. The role of the ChT domain
will be determined and whether interaction with nucleosomes is required for TRC activation. The results of
these studies will impact opportunities for translational research because we will identify new potential
therapeutic targets. Our findings will also impact the use of widely prescribed therapeutic drugs that target
Topo II because we will gain mechanistic insight into cellular responses to Topo II inhibition. The preliminary
data and newly developed experimental tools place us in a unique position to determine the conserved
mechanism of this scarcely studied mitotic control.

## Key facts

- **NIH application ID:** 10880062
- **Project number:** 2R01GM130858-05A1
- **Recipient organization:** UNIVERSITY OF MINNESOTA
- **Principal Investigator:** DUNCAN J. CLARKE
- **Activity code:** R01 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $317,795
- **Award type:** 2
- **Project period:** 2019-03-01 → 2028-02-29

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10880062

## Citation

> US National Institutes of Health, RePORTER application 10880062, Control of Chromosome Segregation by DNA Topoisomerase II (2R01GM130858-05A1). Retrieved via AI Analytics 2026-05-25 from https://api.ai-analytics.org/grant/nih/10880062. Licensed CC0.

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