부산대학교 도서관

Background: Ceramide, important for both neuronal differentiation and dedifferentiation, resides in several membranes, is synthesized in the endoplasmic reticulum, mitochondrial, and nuclear membranes, and can be further processed into glycosphingolipids or sphingomyelin. Ceramide may also be generated by hydrolysis of sphingomyelin by neutral or acidic sphingomyelinases in lysosomes and other membranes. Here we asked whether the differing functions of ceramide derived from different origins. Methods: We added NGF to PC12 cells and to TrkA cells. These latter overexpress NGF receptors and are partially activated to differentiate, whereas NGF is required for PC12 cells to differentiate. We differentiated synthesis from hydrolysis by the use of appropriate inhibitors. Ceramide and sphingomyelin were measured by radiolabeling. Results: When NGF is added, the kinetics and amounts of ceramide and sphingomyelin indicate that the ceramide comes primarily from hydrolysis but, when hydrolysis is inhibited, can also come from neosynthesis. When NGF is removed, the ceramide comes from both neosynthesis and hydrolysis. Conclusion: We conclude that the function of ceramide depends heavily on its intracellular location, and that further understanding of its function will depend on resolving its location during changes of cell status. 9jaz4dWkruTZSXMGGTBHtm Video Abstract Plain English summary: Ceramide and sphingomyelin reportedly are important both for differentiation of nerve cells and for their death. We studied PC12 cells, which can differentiate into neuron-like cells in the presence of nerve growth factor and cells that overexpress receptors for nerve growth factor. By combining various inhibitors, we conclude that in the presence of nerve growth factor ceramide comes from hydrolysis of sphingomyelin, but when nerve growth factor is removed and the cells atrophy and die, sphingomyelin comes from both neosynthesis and hydrolysis. [ABSTRACT FROM AUTHOR]