# Redox Regulation of Cysteine-Dependent Peroxidases and Signal Transduction Pathways

> **NIH NIH R35** · WAKE FOREST UNIVERSITY HEALTH SCIENCES · 2020 · $320,554

## Abstract

SUMMARY
While hydrogen peroxide has long been understood as a toxin used by the human immune system to kill
infectious organisms, only recently has it become well accepted that it serves as a second messenger in
eukaryotes, produced in response to growth factors, cytokines and immune system effectors and promoting or
modulating downstream signal transduction pathways. Through insights contributed in part by the work of the
PI, a family of cysteine-dependent, peroxide-reducing enzymes known as the peroxiredoxins (Prxs) have also
emerged from relative obscurity to become widely recognized not just as one of the primary oxidant removal
systems in almost all organisms, but also as key modulators of cell signaling pathways. PI Poole's work on the
enzymology, biophysical attributes and structures of Prxs from a variety of organisms has contributed greatly to
understanding the mechanism and regulation of this highly abundant family of enzymes. In 2003, PI Poole and
collaborator Andy Karplus published a Science paper in which structural determinants of the sensitivity of Prxs
toward peroxide-mediated hyperoxidation of the active site cysteine were identified. This led to our proposal of
the “floodgate hypothesis” explaining the potential benefits of such a peroxide-mediated “off switch”; under
conditions where peroxide levels begin to rise (e.g. NADPH oxidase activation), Prx inactivation would promote
the local accumulation of peroxide near the source, allowing for the oxidation of alternative protein targets. Dr.
Poole has also been at the forefront of developing chemical tools to evaluate protein oxidation in cells through
targeting sulfenic acid (R-SOH), the direct product of peroxide-mediated oxidation. These probes are now
commercially available and have been used widely by researchers studying redox regulation and signaling to
evaluate protein oxidation with high spatiotemporal precision. PI Poole's lab used these tools to show that
cancer-associated growth factors elicit “hot spots” of protein oxidation proximal to the internalized receptors,
providing support for the floodgate hypothesis. Future studies proposed here will build upon our existing
strengths and collaborations. Specifically, we propose to investigate the effects of additional posttranslational
modifications, including nitration, acetylation and phosphorylation, on Prx structure and activity. We will also
investigate the mechanism by which thioredoxin can regulate and be regulated by human Prxs. The interface
of Prx function with the regulation of signal transduction pathways involving protein oxidation is another area
with significant gaps; we plan to follow up on our data suggesting that Prx inactivation and rising peroxide
levels are key to cell cycle regulation. Finally, a new area that we are currently investigating in collaboration
with Sharon Campbell is the oxidation sensitivity of the cancer-causing G12C mutant of KRAS, which has the
potential to severely limit the effectiv...

## Key facts

- **NIH application ID:** 9858554
- **Project number:** 1R35GM135179-01
- **Recipient organization:** WAKE FOREST UNIVERSITY HEALTH SCIENCES
- **Principal Investigator:** LESLIE B POOLE
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2020
- **Award amount:** $320,554
- **Award type:** 1
- **Project period:** 2020-02-01 → 2025-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/9858554

## Citation

> US National Institutes of Health, RePORTER application 9858554, Redox Regulation of Cysteine-Dependent Peroxidases and Signal Transduction Pathways (1R35GM135179-01). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/9858554. Licensed CC0.

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