Rescuing Ischemic Brain Injury by Rewiring Mitochondrial Electron Flow.

Area of Science:

• Mitochondrial biochemistry
• Neuroscience
• Cellular metabolism

Background:

• Acute ischemia-reperfusion (IR) brain injury is driven by altered mitochondrial metabolic flux.
• Reverse electron transfer (RET) through mitochondrial complex I generates pathological reactive oxygen species (ROS) under stress.
• RET-supporting substrates accumulate during oxygen deprivation, exacerbating ROS production upon reoxygenation.

Purpose of the Study:

• To investigate the role of RET in IR brain injury.
• To explore the therapeutic potential of modulating mitochondrial electron flux.
• To assess the efficacy of expressing alternative oxidase (AOX) in mitigating IR-induced brain damage.

Main Methods:

• Utilized an in vivo model of brain IR injury.
• Employed transgenic mice xenotopically expressing alternative oxidase (AOX).
• Assessed mitochondrial function, ROS production, complex I integrity, and neuroprotection.

Main Results:

• RET-supporting substrates accumulate during oxygen deprivation, leading to ROS overproduction and complex I dysfunction upon reoxygenation.
• AOX expression effectively diverted electrons from the quinone pool, reducing RET flux and ROS generation during IR.
• AOX preserved complex I function, suppressed oxidative stress, and conferred significant neuroprotection in vivo.

Conclusions:

• Modulating mitochondrial electron flux via AOX is a viable strategy to mitigate acute IR brain injury.
• Targeting the quinone pool offers a novel therapeutic approach for IR-related conditions.
• AOX-mediated rewiring of mitochondrial electron transport provides neuroprotection by limiting initial IR damage.