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bioRxiv · 10.1101/2022.12.21.521356

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

Komatsu, M.·Ikeda, R.·Noshiro, D.·Morishita, H.·Takada, S.·Kageyama, S.·Fujioka, Y.·Funakoshi, T.·Komatsu-Hirota, S.·Arai, R.·Ryzhii, E.·Abe, M.·Koga, T.·Nakao, M.·Sakimura, K.·Horii, A.·Waguri, S.·Ichimura, Y.·Noda, N. N.
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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 phosphorylation remain unclear. Herein, we identify ULK1 as a kinase responsible for phosphorylation of p62. ULK1 co-localizes with p62 bodies, and directly interacts with p62. This phosphorylation allows KEAP1 to be retained within p62 bodies, activating NRF2. p62S351E/+ mice are phosphomimetic knock-in mice in which Ser351 corresponding to human Ser349 is replaced by Glu. These mice, but not phosphodefective p62S351A/S351A mice, exhibit NRF2 hyperactivation and growth retardation, the latter caused by malnutrition and dehydration due to obstruction of the esophagus and forestomach secondary to hyperkeratosis. p62S351E/+ mice are a phenocopy of systemic Keap1-knockout mice. Our results expand our understanding of the physiological importance of the redox-independent NRF2 activation pathway and provide new insight into the role of phase separation in this process.

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Komatsu, M., Ikeda, R., Noshiro, D., Morishita, H., Takada, S., Kageyama, S., Fujioka, Y., Funakoshi, T., Komatsu-Hirota, S., Arai, R., Ryzhii, E., Abe, M., Koga, T., Nakao, M., Sakimura, K., Horii, A., Waguri, S., Ichimura, Y., Noda, N. N.. 2022-12-21. Phosphorylation of phase-separated p62 bodies by ULK1 activates a redox-independent stress response. https://doi.org/10.1101/2022.12.21.521356

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