# Regulation of oxidative stress signaling by tyrosine phosphorylation of antioxidant enzymes

> **NIH NIH K99** · MASSACHUSETTS INSTITUTE OF TECHNOLOGY · 2024 · $50,069

## Abstract

Project Summary
Oxidative stress is a byproduct of energy production necessary for all living organisms and caused by
unregulated reactive oxygen/nitrogen/carbonyl species (ROS/RNS/RCS) among others. Nature has evolved the
oxidative stress response (OSR) as a key component of metabolism that maintains cellular homeostasis by
detoxifying and neutralizing aberrant reactive molecules. Spatiotemporally control of OSR is achieved through
compartmentalization and redundancies that are coupled to create a redox balance to promote survival.
Unbalanced OSR due to a defective or overactive capacity to resolve oxidative damage is associated with
various human diseases. For example, chronic OSR is a hallmark of obesity, a global epidemic as well as a
major risk factor for developing cardiovascular diseases, metabolic syndrome, and cancer. To better understand
obesity, it is paramount that we elucidate the coordination of the OSR metabolon, defined here as the sequential
antioxidant enzymes, biochemical reactions, and cellular compartments that maintain redox homeostasis.
The proper regulation of and adaptive changes by OSR require rapid signaling taking place in the seconds-to-
minute timeframe. Such dynamics must therefore require fast regulatory networks such as protein post-
translational modifications (PTMs). Phosphorylation of serine (S) (~90%), threonine (T) (~9%), and tyrosine (Y)
(~0.1-1%) residues are one of the many ways cells regulate pathways that maximize survival. Initial evaluation
of the published phosphoproteome stratified by enzyme classification and pathway enrichment analysis indicates
that, despite low intracellular stoichiometry, pY are enriched on antioxidant enzymes. However, the majority of
pY sites on antioxidant enzymes are not functionally characterized. My overarching goal in this proposal is to
gain network level insight into the pY directed regulation of antioxidant enzymes and the resulting dynamics of
dysregulated OSR. I hypothesize that obesity-driven pY on multiple antioxidant enzymes modulates their
catalytic activity to produce systemic changes in OSR. I will test this hypothesis by employing proteomics,
metabolomics, structural analysis, and computational modeling. During the mentored phase of this application,
I will predict the functional role of previously uncharacterized pY, validate predictions using in vivo as well as in
vitro enzyme kinetic assays, and demonstrate pY-driven OSR dysregulation in an in vivo high-fat diet (HFD)-
induced obesity mouse model. Through these interdisciplinary approaches, I aim to define systems of pY-
modified enzymes that “tune” metabolic response to HFD, and evaluate differential regulation of OSR in a sex
specific manner. Additionally, I will determine how altered dietary serine, glycine, or addition of small molecule
antioxidants ameliorate HFD phenotypes, and the sex specific responses in the OSR metabolon that may be
therapeutically relevant. This proposal and the outlined training...

## Key facts

- **NIH application ID:** 10909314
- **Project number:** 5K99GM152834-02
- **Recipient organization:** MASSACHUSETTS INSTITUTE OF TECHNOLOGY
- **Principal Investigator:** Tigist Y Tamir
- **Activity code:** K99 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $50,069
- **Award type:** 5
- **Project period:** 2023-09-01 → 2024-12-15

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10909314

## Citation

> US National Institutes of Health, RePORTER application 10909314, Regulation of oxidative stress signaling by tyrosine phosphorylation of antioxidant enzymes (5K99GM152834-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10909314. Licensed CC0.

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