# Isocitrate dehydrogenase (IDH) mutations as drivers of organelle stress and dysfunction"

> **NIH NIH R35** · SAN DIEGO STATE UNIVERSITY · 2022 · $376,250

## Abstract

ABSTRACT/SUMMARY
The consequences of mutations in isocitrate dehydrogenase 1 (IDH1) and IDH2 in cancer are unusual. Though
these mutations confer a loss of function of the normal activity of the NADP+-dependent conversion of isocitrate
to α-ketoglutarate (αKG), mutant IDH is more of an oncogene than tumor suppressor, as a neomorphic activity
is also conferred: the NADPH-dependent production of oncometabolite D-2-hydroxyglutarate (D2HG) from αKG.
D2HG inhibits αKG-dependent enzymes like DNA and histone demethylases, and NADPH depletion results in
oxidative stress. A variety of point mutations affecting residue R132 in IDH1 can grant these catalytic properties,
causing prominent structural modifications that allow mutant IDH1 to be a bona fide drug target. Indeed, a se-
lective allosteric mutant IDH1 inhibitor is now in the clinic. Both mutant and WT IDH1 localize to the cytosol and
peroxisomes, while IDH2 is found in the mitochondria, raising the possibility of organelle-specific consequences
of IDH mutations, though this has not yet been explored. Interestingly, there is a communication pipeline between
the peroxisomes and mitochondria in that they share an interconnected role in lipid processing and mitigation of
oxidative stress, though the role of IDH in this communication is not yet known. To date, several limitations have
restricted the rigor of mutant IDH studies. First, the catalytic and inhibition profile for R132H IDH1 is extrapolated
to other disease-relevant IDH1 mutants, though we show several mutants have very unique profiles. Second,
the role of NADPH depletion, and thus oxidative stress, is often overlooked in favor of studying consequences
of D2HG. Third, studies focus on the global/cytosolic contributions of mutant IDH1, ignoring its role of sole
NADPH and αKG producer in this organelle. However, we report evidence of dysfunctional lipid biosynthetic
pathways in the peroxisomes upon introduction of cellular IDH1 mutations. The overall goal of our research
program is to determine the mechanisms of metabolic enzyme catalysis, regulation, inhibition, and cellular/orga-
nellular function in health and disease, from the chemical to the cellular levels. By leveraging kinetic, structural,
cellular, and -omics technologies, we can establish the unique consequences of disease-relevant mutational
variants in metabolic enzymes. Here, we have identified critical questions to illuminate the role of mutant IDH1
in disease: 1) How do protein dynamics affect IDH1 catalysis and inhibition? 2) What are the effects of oxidative
stress on IDH1 and IDH2? 3) What are the organelle-specific consequences of IDH1 mutations? 4) What are the
roles of IDH1 mutations in organelle crosstalk? Through this work, we will uncover fundamental catalytic and
regulatory strategies affecting WT and mutant IDH activity, determine the role of IDH1 in the peroxisomes and
identify the unique consequences of mutation at this location, and establish the role of mutant IDH1 ...

## Key facts

- **NIH application ID:** 10434769
- **Project number:** 5R35GM137773-03
- **Recipient organization:** SAN DIEGO STATE UNIVERSITY
- **Principal Investigator:** Christal Dyane Sohl
- **Activity code:** R35 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $376,250
- **Award type:** 5
- **Project period:** 2020-08-01 → 2025-06-30

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10434769

## Citation

> US National Institutes of Health, RePORTER application 10434769, Isocitrate dehydrogenase (IDH) mutations as drivers of organelle stress and dysfunction" (5R35GM137773-03). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10434769. Licensed CC0.

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