Related Experiment Video
Updated: Jun 13, 2025
Metabolic Mapping: Quantitative Enzyme Cytochemistry and Histochemistry to Determine the Activity of Dehydrogenases in Cells and Tissues
Published on: May 26, 2018
Catalytically distinct metabolic enzyme isocitrate dehydrogenase 1 mutants tune phenotype severity in tumor models
Ashley V Schwartz1, Grace Chao2, Mikella Robinson2
1Computational Science Research Center, San Diego State University, San Diego, California, USA.
Abstract:
Mutations in isocitrate dehydrogenase 1 (IDH1) impart a neomorphic reaction that produces D-2-hydroxyglutarate (D2HG), which can inhibit DNA demethylases to drive tumorigenesis. Mutations affect residue R132 and display distinct catalytic profiles for D2HG production. We show that catalytic efficiency of D2HG production is greater in IDH1 R132Q than R132H mutants, and expression of IDH1 R132Q in cellular and xenograft models leads to higher D2HG concentrations in cells, tumors, and sera compared to R132H. Though expression of IDH1 R132Q leads to hypermethylation in DNA damage pathways, DNA hypomethylation is more notable when compared to IDH1 R132H expression. Transcriptome analysis shows increased expression of many pro-tumor pathways upon expression of IDH1 R132Q versus R132H, including transcripts of EGFR and PI3K signaling pathways. Thus, IDH1 mutants appear to modulate D2HG levels via altered catalysis and are associated with distinct epigenetic and transcriptomic consequences, with higher D2HG levels appearing to be associated with more aggressive tumors.
Insights
Isocitrate dehydrogenase 1 (IDH1) mutations produce D-2-hydroxyglutarate (D2HG), a molecule that drives cancer. IDH1 R132Q mutants produce more D2HG than R132H mutants, leading to more aggressive tumors.
Area of Science:
- Biochemistry
- Oncology
- Molecular Biology
Background:
- Mutations in isocitrate dehydrogenase 1 (IDH1) are common in various cancers.
- These mutations lead to the production of D-2-hydroxyglutarate (D2HG), an oncometabolite that can inhibit DNA demethylases.
- IDH1 mutations at residue R132, particularly R132H and R132Q, are well-studied, but their distinct catalytic profiles and downstream effects require further elucidation.
Purpose of the Study:
- To compare the catalytic efficiency of D2HG production between IDH1 R132Q and R132H mutants.
- To investigate the in vivo consequences of expressing IDH1 R132Q versus R132H in cellular and xenograft models.
- To analyze the distinct epigenetic and transcriptomic alterations associated with different IDH1 mutants.
Main Methods:
- Enzyme kinetics assays to determine D2HG production rates.
- Expression of IDH1 R132Q and R132H in cellular and xenograft models.
- Quantification of D2HG levels in cells, tumors, and sera.
- DNA methylation analysis.
- Transcriptome sequencing (RNA-Seq).
Main Results:
- IDH1 R132Q mutants exhibit greater catalytic efficiency for D2HG production compared to R132H mutants.
- Expression of IDH1 R132Q leads to significantly higher D2HG concentrations in cells, tumors, and sera than R132H.
- While both mutants induce DNA hypermethylation in certain pathways, IDH1 R132Q expression is associated with more pronounced DNA hypomethylation.
- Transcriptome analysis reveals increased expression of pro-tumor pathways, including EGFR and PI3K signaling, in IDH1 R132Q-expressing models compared to R132H.
Conclusions:
- IDH1 mutants differentially modulate D2HG levels through altered catalysis.
- Distinct epigenetic and transcriptomic profiles are associated with different IDH1 mutations.
- Higher D2HG levels driven by IDH1 R132Q mutants correlate with more aggressive tumor phenotypes and altered signaling pathways.
More Related Videos
06:53Visualization of Mitochondrial Respiratory Function using Cytochrome C Oxidase / Succinate Dehydrogenase COX/SDH Double-labeling Histochemistry
Published on: November 23, 2011
11:32Analytical Determination of Mitochondrial Function of Excised Solid Tumor Homogenates
Published on: August 6, 2021
Related Concept Videos
01:46Electron Transport Chain: Complex I and II
ROS generation is regulated and maintained at moderate levels necessary...
02:53Adaptive Mechanisms in Cancer Cells
Some of the advantages that cancer cells have on normal cells include - enhanced ability to divide without terminally differentiating, induce new blood vessel formation,...