Photic regulation of the mTOR signaling pathway in the suprachiasmatic circadian clock

Ruifeng Cao, Boyoung Lee, Hee yeon Cho, Sanjida Saklayen, Karl Obrietan

Research output: Contribution to journalArticlepeer-review

78 Scopus citations


Here we analyzed the light-responsiveness of the mammalian target of rapamycin (mTOR) cascade, a key regulator of inducible translation, in the suprachiasmatic nuclei (SCN), the locus of the master circadian clock. Brief light exposure during the subjective night, but not during the subjective day, triggered rapid phosphorylation (a marker of catalytic activity) of the mTOR translation effectors p70 S6K, ribosomal S6 protein (S6) and 4E-BP1. In the absence of photic stimulation, marked S6 and 4E-BP1 phosphorylation was detected, indicating tonic mTOR activity in the SCN. Light stimulated the colocalized activation of p70 S6K and extracellular signal-regulated protein kinase (ERK), and pharmacological disruption of ERK signaling abolished light-induced mTOR activity, revealing that the MAPK cascade is an essential intermediate that couples light to mTOR. Together these data identify a light-responsive mTOR cascade in the SCN, and thus, raise the possibility that inducible translation contributes to the clock entrainment process.

Original languageEnglish (US)
Pages (from-to)312-324
Number of pages13
JournalMolecular and Cellular Neuroscience
Issue number3
StatePublished - Jul 2008

Bibliographical note

Funding Information:
We are grateful to Yunsik Choi and Mary Cheng for technical assistance and helpful discussion. This work was supported by an NSF grant (IBN-0090974) a grant from the NIMH (MH62335) and by the Ohio State Neuroscience Center Core grant (5P30NS045758).


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