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AMPK Facilitates Nuclear Accumulation of Nrf2 by Phosphorylating at Serine 550

Min Sung Joo1, Won Dong Kim1, Ki Young Lee2

  • 1College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, South Korea.

Molecular and Cellular Biology
|May 11, 2016
PubMed

Insights

AMP-activated protein kinase (AMPK) activates the antioxidant factor Nrf2 (nuclear factor erythroid 2-related factor 2) by promoting its nuclear accumulation. This occurs through direct phosphorylation and inhibition of nuclear export, enhancing cellular antioxidant responses.

Area of Science:

  • Cellular Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key antioxidant transcription factor.
  • AMP-activated protein kinase (AMPK) regulates cell survival pathways under stress.
  • The mechanistic link between AMPK and Nrf2 regulation was previously undefined.

Purpose of the Study:

  • To investigate the role of AMPK in regulating Nrf2 trafficking and activity.
  • To elucidate the molecular mechanisms connecting AMPK and Nrf2.

Main Methods:

  • Cellular assays to observe Nrf2 localization.
  • In vitro kinase assays to identify phosphorylation sites.
  • Site-directed mutagenesis (S550A) to assess Nrf2 function.
  • Nuclear export inhibition studies using Leptomycin B.
  • Glycogen synthase kinase 3β (GSK3β) activity modulation.

Main Results:

  • AMPK activation led to the nuclear accumulation of Nrf2 in cells.
  • AMPK directly phosphorylated Nrf2 at Ser558 (Ser550 in mouse) within its nuclear export signal.
  • A Ser550Ala Nrf2 mutant showed impaired nuclear accumulation upon AMPK activation.
  • AMPK-mediated inhibition of GSK3β influenced Nrf2 nuclear levels.
  • Data suggest AMPK promotes Nrf2 nuclear entry by inhibiting its nuclear export.

Conclusions:

  • AMPK phosphorylates Nrf2 at Ser550, facilitating its nuclear translocation.
  • AMPK-mediated GSK3β inhibition further contributes to Nrf2 nuclear accumulation.
  • This coordinated action enhances antioxidant response element (ARE)-driven gene transactivation.

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