Oxygen-dependent constraint of glycolysis through the mitochondrial electron transport chain.

In clear cell renal cell carcinoma (ccRCC) cells, hypoxia triggers NADH reductive stress that attenuates lactate release when extracellular pyruvate is limited, and this is restored by Lb NOX expression.

• Why it matters: Canonical HIF activation is constitutively active in ccRCC, leaving open how these cells adapt to low oxygen when glycolysis depends on limited pyruvate supply.
• What they did: The study tested glycolytic output under hypoxia with extracellular pyruvate limitation, then used ectopic Lb NOX and inhibition of the mitochondrial electron transport chain, including mitochondrial complex IV blockade, plus mitochondrial-targeted AOX rescue.
• The result: Suppressing mtETC—especially via complex IV inhibition—reduces glycolytic flux under pyruvate limitation, and mitochondrial-targeted AOX restores it, implying oxygen tension can regulate glycolysis through mitochondrial NADH/NAD+ elevation.

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