title: AMPK Facilitates Nuclear Accumulation of Nrf2 by Phosphorylating at Serine 550.
abstract: Nrf2 (nuclear factor erythroid 2-related factor 2) is an antioxidant transcription factor. AMP-activated protein kinase (AMPK) functions as a central regulator of cell survival in response to stressful stimuli. Nrf2 should be coordinated with the cell survival pathway controlled by AMPK, but so far the mechanistic connections remain undefined. This study investigated the role of AMPK in Nrf2 trafficking and its activity regulation. A subnetwork integrating neighbor molecules suggested direct interaction between AMPK and Nrf2. In cells, AMPK activation caused nuclear accumulation of Nrf2. In the in vitro kinase and peptide competition assays, AMPK phosphorylated Nrf2 at the Ser558 residue (Ser550 in mouse) located in the canonical nuclear export signal. Nrf2 with an S550A mutation failed to be accumulated in the nucleus after AMPK activation. Leptomycin B, a nuclear export inhibitor, did not enhance nuclear accumulation of wild-type Nrf2 (WT-Nrf2) activated by AMPK or a phospho-Ser550-mimetic Nrf2 mutant, corroborating the finding that AMPK facilitated nuclear accumulation of Nrf2, probably by inhibiting nuclear export. Activated glycogen synthase kinase 3β (GSK3β) diminished the basal nuclear level of Myc-S550A-Nrf2. Taking the data collectively, AMPK phosphorylates Nrf2 at the Ser550 residue, which, in conjunction with AMPK-mediated GSK3β inhibition, promotes nuclear accumulation of Nrf2 for antioxidant response element (ARE)-driven gene transactivation.
authors.affiliation: College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, South Korea.
authors.forename: Min Sung
authors.initials: MS
authors.lastname: Joo
authors.affiliation: College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, South Korea.
authors.forename: Won Dong
authors.initials: WD
authors.lastname: Kim
authors.affiliation: Department of Biomedical Informatics, Ajou University School of Medicine, Suwon, South Korea.
authors.forename: Ki Young
authors.initials: KY
authors.lastname: Lee
authors.affiliation: Department of Biomedical Informatics, Ajou University School of Medicine, Suwon, South Korea.
authors.forename: Ji Hyun
authors.initials: JH
authors.lastname: Kim
authors.affiliation: College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, South Korea.
authors.forename: Ja Hyun
authors.initials: JH
authors.lastname: Koo
authors.affiliation: College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, South Korea sgk@snu.ac.kr.
authors.forename: Sang Geon
authors.initials: SG
authors.lastname: Kim
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000378:metabolism*; D021581:Active Transport, Cell Nucleus; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism*; D053263:Gene Regulatory Networks; D000071679:Glycogen Synthase Kinase 3 beta / Q000378:metabolism; D057809:HEK293 Cells; D056945:Hep G2 Cells; D006801:Humans; D051379:Mice; D009154:Mutation; D051267:NF-E2-Related Factor 2 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D012694:Serine / Q000235:genetics / Q000378:metabolism*
chemical_list: D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; C495636:Nfe2l2 protein, mouse; D012694:Serine; D000071679:Glycogen Synthase Kinase 3 beta; D055372:AMP-Activated Protein Kinases