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Antioxid Redox Signal. 2019 Sep 20;31(9):608-622. doi: 10.1089/ars.2018.7693. Epub 2019 Jul 1.

Redox-Dependent Loss of Flavin by Mitochondrial Complex I in Brain Ischemia/Reperfusion Injury.

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1Division of Neonatology, Department of Pediatrics, Columbia University, New York, New York.
2Feil Family Brain and Mind Research Institute, Weill Cornell Medicine, New York, New York.
3Functional Proteomics, SFB815 Core Unit, Medical School, Goethe University, Frankfurt, Germany.
4German Center for Cardiovascular Research (DZHK), Partner Site RheinMain, Frankfurt, Germany.


Aims: Brain ischemia/reperfusion (I/R) is associated with impairment of mitochondrial function. However, the mechanisms of mitochondrial failure are not fully understood. This work was undertaken to determine the mechanisms and time course of mitochondrial energy dysfunction after reperfusion following neonatal brain hypoxia-ischemia (HI) in mice. Results: HI/reperfusion decreased the activity of mitochondrial complex I, which was recovered after 30 min of reperfusion and then declined again after 1 h. Decreased complex I activity occurred in parallel with a loss in the content of noncovalently bound membrane flavin mononucleotide (FMN). FMN dissociation from the enzyme is caused by succinate-supported reverse electron transfer. Administration of FMN precursor riboflavin before HI/reperfusion was associated with decreased infarct volume, attenuation of neurological deficit, and preserved complex I activity compared with vehicle-treated mice. In vitro, the rate of FMN release during oxidation of succinate was not affected by the oxygen level and amount of endogenously produced reactive oxygen species. Innovation: Our data suggest that dissociation of FMN from mitochondrial complex I may represent a novel mechanism of enzyme inhibition defining respiratory chain failure in I/R. Strategies preventing FMN release during HI and reperfusion may limit the extent of energy failure and cerebral HI injury. The proposed mechanism of acute I/R-induced complex I impairment is distinct from the generally accepted mechanism of oxidative stress-mediated I/R injury. Conclusion: Our study is the first to highlight a critical role of mitochondrial complex I-FMN dissociation in the development of HI-reperfusion injury of the neonatal brain. Antioxid. Redox Signal. 31, 608-622.


flavin mononucleotide; ischemia/reperfusion injury; mitochondrial complex I; reverse electron transfer; secondary energy failure


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