SP23 S1P

SP23 The role of sphingosine 1-phosphate (S1P) signalling in genotoxic stress-induced protection from septic shock

Project leader: Markus Gräler

Background and previous work
Sphingolipids are actively involved in cell fate decisions particularly in the presence of genotoxic stimuli. Ceramide predominantly induces cell death while S1P mainly protects cells from apoptosis. Pathways involved are DDR, ER-stress, mTOR, p53, ERK, and p38 MAPK-activated protein kinases. The finding that low-dose genotoxic stress was protective in an experimental sepsis model mainly by induction of autophagy suggests that the sphingolipid rheostat between ceramide and S1P is involved in this regulation.

Specific aims and working programme
On the basis of these recent data we postulate that low-dose genotoxic stress predominantly activates anti-apoptotic S1P-mediated autophagy while high concentrations of genotoxic agents switch to increased ceramide production and apoptosis. This project aims to identify the molecular checkpoints of this proposed hormetic regulation.
The dose-dependent effect of epirubicin-induced genotoxic stress will be investigated in experimental sepsis in mice and in cell culture experiments upon lipopolysaccharide (LPS) stimulation. Enzymes and metabolites establishing the sphingolipid rheostat will be analysed by quantitative PCR, Western-blot and mass spectrometry, respectively. Apoptosis will be analysed according to DNA fragmentation, annexin V-staining, and TdT dUTP nick-end labelling (TUNEL), autophagy and underlying signalling pathways by Western-blot, EM, FACS, microscopy, and ELISA.
These analyses will establish the potential role of sphingolipid signalling in low-dose genotoxic stress-induced adaptations that result in protection from septic shock.