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Induction of ferritin expression by oxalomalate
Rita Santamaria1, Carlo Irace, Michela Festa
1Dipartimento di Farmacologia Sperimentale, Università di Napoli Federico II, Via D. Montesano 49, 80131 Naples, Italy.
Biochimica Et Biophysica Acta
|April 28, 2004
Summary
Oxalomalate (OMA), an aconitase inhibitor, reduces iron-regulatory protein 1 (IRP1) binding activity, increasing ferritin expression. This ferritin upregulation protects cells from oxidative stress and lipid peroxidation during iron challenges.
Area of Science:
- Biochemistry
- Cell Biology
- Molecular Biology
Background:
- Ferritin is crucial for intracellular iron storage, with biosynthesis regulated post-transcriptionally by iron-regulatory proteins (IRP1 and IRP2) to prevent iron-induced oxidative stress.
- IRP1 activity is modulated by intracellular iron, oxidants (H2O2, NO), and recently identified, oxalomalate (OMA).
- OMA is a competitive inhibitor of aconitase, an enzyme in the citric acid cycle.
Purpose of the Study:
- To investigate the effect of oxalomalate (OMA) on ferritin expression.
- To determine if OMA influences the RNA-binding activity of IRP1.
- To assess the consequences of OMA-induced ferritin changes on cellular oxidative stress.
Main Methods:
- Gel retardation assay to evaluate IRP1 RNA-binding activity after OMA treatment.
- Western blot analysis to quantify intracellular ferritin levels.
- Measurement of ferritin mRNA levels and cellular reactive oxygen species (ROS) and lipid peroxidation.
Main Results:
- OMA treatment (5 mM) significantly decreased IRP1 RNA-binding activity in various cell lines by up to 3-fold within 6 hours, with effects sustained up to 48 hours.
- Intracellular ferritin levels and ferritin mRNA levels increased in correlation with the decrease in IRP1 binding activity.
- OMA-induced ferritin overexpression in iron-challenged cells effectively prevented ROS formation and lipid peroxidation.
Conclusions:
- Oxalomalate (OMA), an aconitase inhibitor, modulates ferritin expression through mechanisms potentially involving post-transcriptional regulation or transcriptional modulation of IRP1.
- OMA's ability to control ferritin expression offers cellular protection against oxidative damage, particularly under iron overload conditions.
- This study highlights a novel role for OMA beyond energy metabolism, impacting iron homeostasis and cellular defense against oxidative stress.