Ceramide-mediated Macroautophagy Involves Inhibition of Protein Kinase B and Up-regulation of Beclin 1

Francesca Scarlatti, Chantal Bauvy, Annamaria Ventruti, Giusy Sala, Françoise Cluzeaud, Alain Vandewalle, Riccardo Ghidoni, Patrice Codogno
2004 Journal of Biological Chemistry  
The sphingolipid ceramide is involved in the cellular stress response. Here we demonstrate that ceramide controls macroautophagy, a major lysosomal catabolic pathway. Exogenous C 2 -ceramide stimulates macroautophagy (proteolysis and accumulation of autophagic vacuoles) in the human colon cancer HT-29 cells by increasing the endogenous pool of long chain ceramides as demonstrated by the use of the ceramide synthase inhibitor fumonisin B 1 . Ceramide reverted the interleukin 13-dependent
more » ... on of macroautophagy by interfering with the activation of protein kinase B. In addition, C 2 -ceramide stimulated the expression of the autophagy gene product beclin 1. Ceramide is also the mediator of the tamoxifen-dependent accumulation of autophagic vacuoles in the human breast cancer MCF-7 cells. Monodansylcadaverine staining and electron microscopy showed that this accumulation was abrogated by myriocin, an inhibitor of de novo synthesis ceramide. The tamoxifen-dependent accumulation of vacuoles was mimicked by 1-phenyl-2-decanoylamino-3-morpholino-1-propanol, an inhibitor of glucosylceramide synthase. 1-Phenyl-2-decanoylamino-3-morpholino-1-propanol, tamoxifen, and C 2 -ceramide stimulated the expression of beclin 1, whereas myriocin antagonized the tamoxifendependent up-regulation. Tamoxifen and C 2 -ceramide interfere with the activation of protein kinase B, whereas myriocin relieved the inhibitory effect of tamoxifen. In conclusion, the control of macroautophagy by ceramide provides a novel function for this lipid mediator in a cell process with major biological outcomes.
doi:10.1074/jbc.m313561200 pmid:14970205 fatcat:6ymmxfeupzhh5md4him73pm75a