HSF1 critically attunes proteotoxic stress sensing by mTORC1 to combat stress and promote growth

KH Su, J Cao, Z Tang, S Dai, Y He, SB Sampson… - Nature cell …, 2016 - nature.com
KH Su, J Cao, Z Tang, S Dai, Y He, SB Sampson, IJ Benjamin, C Dai
Nature cell biology, 2016nature.com
To cope with proteotoxic stress, cells attenuate protein synthesis. However, the precise
mechanisms underlying this fundamental adaptation remain poorly defined. Here we report
that mTORC1 acts as an immediate cellular sensor of proteotoxic stress. Surprisingly, the
multifaceted stress-responsive kinase JNK constitutively associates with mTORC1 under
normal growth conditions. On activation by proteotoxic stress, JNK phosphorylates both
RAPTOR at S863 and mTOR at S567, causing partial disintegration of mTORC1 and …
Abstract
To cope with proteotoxic stress, cells attenuate protein synthesis. However, the precise mechanisms underlying this fundamental adaptation remain poorly defined. Here we report that mTORC1 acts as an immediate cellular sensor of proteotoxic stress. Surprisingly, the multifaceted stress-responsive kinase JNK constitutively associates with mTORC1 under normal growth conditions. On activation by proteotoxic stress, JNK phosphorylates both RAPTOR at S863 and mTOR at S567, causing partial disintegration of mTORC1 and subsequent translation inhibition. Importantly, HSF1, the central player in the proteotoxic stress response (PSR), preserves mTORC1 integrity and function by inactivating JNK, independently of its canonical transcriptional action. Thereby, HSF1 translationally augments the PSR. Beyond promoting stress resistance, this intricate HSF1–JNK–mTORC1 interplay, strikingly, regulates cell, organ and body sizes. Thus, these results illuminate a unifying mechanism that controls stress adaptation and growth.
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