Hypoxia triggers AMPK activation through reactive oxygen species-mediated activation of calcium release-activated calcium channels

Paul T. Mungai, Gregory B. Waypa, Amit Jairaman, Murali Prakriya, Danijela Dokic, Molly K. Ball, Paul T. Schumacker*

*Corresponding author for this work

Research output: Contribution to journalArticle

217 Scopus citations

Abstract

AMP-activated protein kinase (AMPK) is an energy sensor activated by increases in [AMP] or by oxidant stress (reactive oxygen species [ROS]). Hypoxia increases cellular ROS signaling, but the pathways underlying subsequent AMPK activation are not known. We tested the hypothesis that hypoxia activates AMPK by ROS-mediated opening of calcium release-activated calcium (CRAC) channels. Hypoxia (1.5% O 2) augments cellular ROS as detected by the redox-sensitive green fluorescent protein (roGFP) but does not increase the [AMP]/[ATP] ratio. Increases in intracellular calcium during hypoxia were detected with Fura2 and the calcium-calmodulin fluorescence resonance energy transfer (FRET) sensor YC2.3. Antioxidant treatment or removal of extracellular calcium abrogates hypoxia-induced calcium signaling and subsequent AMPK phosphorylation during hypoxia. Oxidant stress triggers relocation of stromal interaction molecule 1 (STIM1), the endoplasmic reticulum (ER) Ca 2+ sensor, to the plasma membrane. Knockdown of STIM1 by short interferingRNA (siRNA) attenuates the calcium responses to hypoxia and subsequent AMPK phosphorylation, while inhibition of L-type calcium channels has no effect. Knockdown of the AMPK upstream kinase LKB1 by siRNA does not prevent AMPK activation during hypoxia, but knockdown of CaMKKβ abolishes the AMPK response. These findings reveal that hypoxia can trigger AMPK activation in the apparent absence of increased [AMP] through ROS-dependent CRAC channel activation, leading to increases in cytosolic calcium that activate the AMPK upstream kinase CaMKKβ.

Original languageEnglish (US)
Pages (from-to)3531-3545
Number of pages15
JournalMolecular and cellular biology
Volume31
Issue number17
DOIs
StatePublished - Sep 1 2011

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology

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