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Updated: May 27, 2026

Oxygen-Independent Assays to Measure Mitochondrial Function in Mammals
Published on: May 19, 2023
Induction of the mitochondrial NDUFA4L2 protein by HIF-1α decreases oxygen consumption by inhibiting Complex I
Daniel Tello1, Eduardo Balsa, Bárbara Acosta-Iborra
1Servicio de Inmunología, Hospital Universitario de La Princesa, Universidad Autónoma de Madrid, Instituto de Investigación Sanitaria Princesa (IIS-IP), Madrid, 28006, Spain.
Abstract:
The fine regulation of mitochondrial function has proved to be an essential metabolic adaptation to fluctuations in oxygen availability. During hypoxia, cells activate an anaerobic switch that favors glycolysis and attenuates the mitochondrial activity. This switch involves the hypoxia-inducible transcription factor-1 (HIF-1). We have identified a HIF-1 target gene, the mitochondrial NDUFA4L2 (NADH dehydrogenase [ubiquinone] 1 alpha subcomplex, 4-like 2). Our results, obtained employing NDUFA4L2-silenced cells and NDUFA4L2 knockout murine embryonic fibroblasts, indicate that hypoxia-induced NDUFA4L2 attenuates mitochondrial oxygen consumption involving inhibition of Complex I activity, which limits the intracellular ROS production under low-oxygen conditions. Thus, reducing mitochondrial Complex I activity via NDUFA4L2 appears to be an essential element in the mitochondrial reprogramming induced by HIF-1.
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