Fingolimod suppresses neuronal autophagy through the mTOR/p70S6K pathway and alleviates ischemic brain damage in mice

PLoS One. 2017 Nov 29;12(11):e0188748. doi: 10.1371/journal.pone.0188748. eCollection 2017.

Abstract

The bioactive, signaling lipid, sphingosine-1-phosphate (S1P), and its analog, fingolimod (FTY720), have previously shown neuroprotective effects against ischemic brain injury. However, the underlying mechanisms have not yet been fully clarified. The roles of autophagy in ischemic stroke are being increasingly recognized. In the present study, we sought to determine whether the S1P pathway is involved in neuronal autophagy and investigate its possible mechanisms following stroke. Interestingly, we found that FTY720 significantly attenuates infarct volumes and reduces neuronal apoptosis on days 1 and 3 post stroke, accompanied by amelioration of functional deficits. Additionally, FTY720 was found to decrease the induction of autophagosome proteins, microtubule-associated protein 1 light chain 3(LC3-II) and Beclin1, following ischemic stroke in a dose-dependent manner. Meanwhile, protein levels of the mammalian target of rapamycin (mTOR) and the 70-kDa ribosomal protein, S6 kinase1 (p70S6K), were also up-regulated in FTY720-treated animals, and the nonspecific SphK inhibitor, N,N-dimethylsphingosine (DMS), was found to cause a reverse effect. Our results indicate that modulation of the S1P signaling pathway by FTY720 could effectively decrease neuronal autophagy through the mTOR/p70S6K pathway and attenuate ischemic brain injury in mice.

MeSH terms

  • Animals
  • Apoptosis / drug effects
  • Autophagy / drug effects*
  • Behavior, Animal
  • Brain Ischemia / enzymology
  • Brain Ischemia / etiology
  • Brain Ischemia / metabolism
  • Brain Ischemia / pathology*
  • Dose-Response Relationship, Drug
  • Fingolimod Hydrochloride / pharmacology*
  • Magnetic Resonance Imaging
  • Male
  • Mice
  • Mice, Inbred C57BL
  • Neurons / drug effects*
  • Neuroprotective Agents / pharmacology*
  • Ribosomal Protein S6 Kinases, 70-kDa / metabolism*
  • Signal Transduction / drug effects
  • TOR Serine-Threonine Kinases / metabolism*
  • Thrombosis / complications

Substances

  • Neuroprotective Agents
  • mTOR protein, mouse
  • Ribosomal Protein S6 Kinases, 70-kDa
  • TOR Serine-Threonine Kinases
  • Fingolimod Hydrochloride

Grants and funding

This work was supported by National Natural Science Foundation of China (81571132, 81171157 and 81301000) and the Fundamental Research Funds for the Central Universities (2017KFYXJJ107). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.