Phosphorylation of phase-separated p62 bodies by ULK1 activates a redox-independent stress response

  • EMBO J. 2023 Jul 17;42(14):e113349. doi: 10.15252/embj.2022113349.
Ryo Ikeda  1  2 ,  Daisuke Noshiro  3 ,  Hideaki Morishita  1 ,  Shuhei Takada  1 ,  Shun Kageyama  1 ,  Yuko Fujioka  3 ,  Tomoko Funakoshi  1 ,  Satoko Komatsu-Hirota  1 ,  Ritsuko Arai  4 ,  Elena Ryzhii  4 ,  Manabu Abe  5 ,  Tomoaki Koga  6 ,  Hozumi Motohashi  7 ,  Mitsuyoshi Nakao  6 ,  Kenji Sakimura  5 ,  Arata Horii  2 ,  Satoshi Waguri  4 ,  Yoshinobu Ichimura  1 ,  Nobuo N Noda  3 ,  Masaaki Komatsu  1
Affiliations
  • 1. Department of Physiology, Juntendo University Graduate School of Medicine, Tokyo, Japan.
  • 2. Department of Otolaryngology Head and Neck Surgery, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan.
  • 3. Institute for Genetic Medicine, Hokkaido University, Sapporo, Japan.
  • 4. Department of Anatomy and Histology, Fukushima Medical University School of Medicine, Fukushima, Japan.
  • 5. Department of Animal Model Development, Brain Research Institute, Niigata University, Niigata, Japan.
  • 6. Department of Medical Cell Biology, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto, Japan.
  • 7. Department of Gene Expression Regulation, Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
PMID: 37306101 DOI: 10.15252/embj.2022113349
Abstract

NRF2 is a transcription factor responsible for antioxidant stress responses that is usually regulated in a redox-dependent manner. p62 bodies formed by liquid-liquid phase separation contain Ser349-phosphorylated p62, which participates in the redox-independent activation of NRF2. However, the regulatory mechanism and physiological significance of p62 phosphorylation remain unclear. Here, we identify ULK1 as a kinase responsible for the phosphorylation of p62. ULK1 colocalizes with p62 bodies, directly interacting with p62. ULK1-dependent phosphorylation of p62 allows KEAP1 to be retained within p62 bodies, thus activating NRF2. p62S351E/+ mice are phosphomimetic knock-in mice in which Ser351, corresponding to human Ser349, is replaced by Glu. These mice, but not their phosphodefective p62S351A/S351A counterparts, exhibit NRF2 hyperactivation and growth retardation. This retardation is caused by malnutrition and dehydration due to obstruction of the esophagus and forestomach secondary to hyperkeratosis, a phenotype also observed in systemic Keap1-knockout mice. Our results expand our understanding of the physiological importance of the redox-independent NRF2 activation pathway and provide new insights into the role of phase separation in this process.

Keywords
KEAP1; NRF2/NFE2L2; ULK1; liquid-liquid phase separation; p62/SQSTM1.