title: SPHK1/sphingosine kinase 1-mediated autophagy differs between neurons and SH-SY5Y neuroblastoma cells.
abstract: Although implicated in neurodegeneration, autophagy has been characterized mostly in yeast and mammalian non-neuronal cells. In a recent study, we sought to determine if SPHK1 (sphingosine kinase 1), implicated previously in macroautophagy/autophagy in cancer cells, regulates autophagy in neurons. SPHK1 synthesizes sphingosine-1-phosphate (S1P), a bioactive lipid involved in cell survival. In our study, we discovered that, when neuronal autophagy is pharmacologically stimulated, SPHK1 relocalizes to the endocytic and autophagic organelles. Interestingly, in non-neuronal cells stimulated with growth factors, SPHK1 translocates to the plasma membrane, where it phosphorylates sphingosine to produce S1P. Whether SPHK1 also binds to the endocytic and autophagic organelles in non-neuronal cells upon induction of autophagy has not been demonstrated. Here, we determined if the effect in neurons is operant in the SH-SY5Y neuroblastoma cell line. In both non-differentiated and differentiated SH-SY5Y cells, a short incubation of cells in amino acid-free medium stimulated the formation of SPHK1-positive puncta, as in neurons. We also found that, unlike neurons in which these puncta represent endosomes, autophagosomes, and amphisomes, in SH-SY5Y cells SPHK1 is bound only to the endosomes. In addition, a dominant negative form of SPHK1 was very toxic to SH-SY5Y cells, but cultured primary cortical neurons tolerated it significantly better. These results suggest that autophagy in neurons is regulated by mechanisms that differ, at least in part, from those in SH-SY5Y cells.
authors.affiliation: a Department of Neurobiology and Anatomy , the University of Texas McGovern Medical School , Houston , TX , USA.
authors.forename: Jose Felix
authors.initials: JF
authors.lastname: Moruno Manchon
authors.affiliation: a Department of Neurobiology and Anatomy , the University of Texas McGovern Medical School , Houston , TX , USA.|b University of Texas Graduate School of Biomedical Sciences , Houston , TX , USA.
authors.forename: Ndidi-Ese
authors.initials: NE
authors.lastname: Uzor
authors.affiliation: c Gladstone Institute of Neurological Disease and the Taube/Koret Center for Neurodegenerative Disease Research , San Francisco , CA , USA.|d Departments of Neurology and Physiology , University of California , San Francisco , CA , USA.
authors.forename: Steven
authors.initials: S
authors.lastname: Finkbeiner
authors.affiliation: a Department of Neurobiology and Anatomy , the University of Texas McGovern Medical School , Houston , TX , USA.|b University of Texas Graduate School of Biomedical Sciences , Houston , TX , USA.
authors.forename: Andrey S
authors.initials: AS
authors.lastname: Tsvetkov
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D000071182:Autophagosomes / Q000378:metabolism; D001343:Autophagy; D002454:Cell Differentiation; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006801:Humans; D008027:Light; D008055:Lipids / Q000737:chemistry; D008246:Lysophospholipids / Q000378:metabolism; D008247:Lysosomes / Q000378:metabolism; D009447:Neuroblastoma / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D010588:Phagosomes / Q000378:metabolism; D010766:Phosphorylation; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D051381:Rats; D015398:Signal Transduction; D013110:Sphingosine / Q000031:analogs & derivatives / Q000378:metabolism; D000099157:Sphingosine Kinase
chemical_list: D049452:Green Fluorescent Proteins; D008055:Lipids; D008246:Lysophospholipids; D017853:Phosphotransferases (Alcohol Group Acceptor); D013110:Sphingosine; D000099157:Sphingosine Kinase; C060506:sphingosine 1-phosphate
keywords: SH-SY5Y cells; autophagy; neurodegeneration; neurons; sphingosine kinase 1