Orexin/hypocretin activates mTOR complex 1 (mTORC1) via an Erk/Akt-independent and calcium-stimulated lysosome v-ATPase pathway

Zhiqiang Wang, Shimeng Liu, Miyo Kakizaki, Yuuki Hirose, Yukiko Ishikawa, Hiromasa Funato, Masashi Yanagisawa, Yonghao Yu, Qinghua Liu

Research output: Contribution to journalArticlepeer-review

34 Scopus citations


The lack of the neuropeptide orexin, also known as hypocretin, results in narcolepsy, a chronic sleep disorder characterized by frequent sleep/cataplexy attacks and rapid eye movement sleep abnormalities. However, the downstream pathways of orexin signaling are not clearly understood. Here, we show that orexin activates the mTOR pathway, a central regulator of cell growth and metabolism, in the mouse brain and multiple recombinant cell lines that express the G protein-coupled receptors (GPCRs), orexin 1 receptor (OX1R) or orexin 2 receptor (OX2R). This orexin/GPCR-stimulated mTOR activation is sensitive to rapamycin, an inhibitor of mTOR complex 1 (mTORC1) but is independent of two well known mTORC1 activators, Erk and Akt. Rather, our studies indicate that orexin activates mTORC1 via extracellular calcium influx and the lysosome pathway involving v-ATPase and Rag GTPases. Moreover, a cytoplasmic calcium transient is sufficient to mimic orexin/GPCR signaling to mTORC1 activation in a v-ATPasedependent manner. Together, our studies suggest that the mTORC1 pathway functions downstream of orexin/GPCR signaling, which plays a crucial role in many physiological and metabolic processes.

Original languageEnglish (US)
Pages (from-to)31950-31959
Number of pages10
JournalJournal of Biological Chemistry
Issue number46
StatePublished - Nov 14 2014

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology


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