Activation of S1P₁ receptor regulates PI3K/Akt/FoxO3a pathway in response to oxidative stress in PC12 cells

Area of Science:

• Neuroscience
• Cell Biology
• Pharmacology

Background:

• Fingolimod (FTY720) is a sphingosine analogue modulating sphingosine-1-phosphate (S1P) receptors.
• FTY720 demonstrates neuroprotective and regenerative effects in the central nervous system (CNS).
• Oxidative stress is implicated in neuronal cell death.

Purpose of the Study:

• To investigate if the PI3K-Akt-FoxO3a pathway is activated by S1P1 receptor modulation.
• To determine the role of this pathway in FTY720's cytoprotective effects against hydrogen peroxide (H2O2)-induced oxidative stress in PC12 cells.

Main Methods:

• PC12 cells were exposed to H2O2 to induce oxidative stress.
• Cell survival, phosphorylation of PI3K, Akt, and FoxO3a were assessed.
• Effects of FTY720, S1P receptor agonists (p-FTY720, SEW2871), an S1P1 antagonist (W123), and a sphingosine kinase inhibitor (DMS) were evaluated.

Main Results:

• Oxidative stress reduced cell survival and phosphorylation of PI3K, Akt, and FoxO3a.
• FTY720 pretreatment enhanced cell survival by increasing inactive phosphorylated FoxO3a.
• S1P1 receptor activation by FTY720, p-FTY720, and SEW2871 conferred protection, which was blocked by W123.
• DMS abolished FTY720's protective effects, indicating the involvement of sphingosine kinase.

Conclusions:

• S1P1 receptor activation by FTY720 protects PC12 cells from oxidative stress.
• This protection is mediated by the PI3K/Akt pathway, which maintains Akt signaling.
• Inhibition of FoxO3a activation by FTY720 promotes cell survival under oxidative stress conditions.