1-Deoxysphingolipids Require Very-Long-Chain Ceramide Synthesis to Induce ER Stress and Cytotoxicity

Our top genetic hits highlighted the pathway involved in synthesizing ceramides with very-long-chain fatty acids (C22–C26). Using CRISPR-Cas9–modified SH-SY5Y cells with loss-of-function (LOF) mutations in the TECR or CERS2 genes—both critical for producing very-long-chain ceramides—we validated that this pathway was essential for 1-deoxysphinganine–mediated toxicity. Furthermore, we demonstrated that the ceramide synthesis pathway is required for 1-deoxysphinganine to trigger ER stress, as evidenced by significantly increased expression of the unfolded protein response in WT, but not TECR or CERS2 LOF mutant, SH-SY5Y cells exposed to 1-deoxysphinganine.

Collectively, the data support a model in which ceramide synthase-dependent conversion of 1-deoxysphinganine to very-long-chain 1-deoxyceramide species is required for full ER-stress induction and cytotoxicity. The findings highlight potential therapeutic targets for neuropathological diseases caused by 1-deoxysphingolipid accumulation.