Phagophore Ceramide Promotes LC3 Lipidation and Autophagy in T-Lymphoid Cell Death.

The bioactive sphingolipid ceramide induces various types of cell death, including autophagy-dependent cell death (ADCD). However, its role in autophagy and ADCD is not fully understood. Here, we demonstrated that amino acid deprivation (AA[-]) in murine lymphoid WR19L cells promoted the accumulation of ceramide at phagophores and autophagy, resulting in ADCD. Control of ceramide production by sphingomyelin synthase 1 and neutral sphingomyelinase 2 altered cell fate by regulating AA(-)-induced autophagy and ADCD. In vitro reconstruction analysis of phosphatidylethanolamine (PE) binding to microtubule-associated protein-1 light chain-3 (LC3), a key step in phagophore formation leading to autophagic flux, revealed that ceramide promoted the PE lipidation of LC3. These results suggest that ceramide promotes autophagosome formation by enhancing PE lipidation of LC3, leading to excess autophagy and ADCD. This study highlights novel insights into the ceramide/sphingomyelin balance at autophagy-related membranes, which controls the switch on autophagy and ADCD through enhanced lipidation of LC3.