Sphingosine Kinase 1 Cooperates with Autophagy to Maintain Endocytic Membrane Trafficking.
Sphingosine kinase 1 (Sphk1) associates with early endocytic membranes during endocytosis; however, the role of sphingosine or sphingosine-1-phosphate as the critical metabolite in endocytic trafficking has not been established. Here, we demonstrate that the recruitment of Sphk1 to sphingosine-enriched endocytic vesicles and the generation of sphingosine-1-phosphate facilitate membrane trafficking along the endosomal pathway. Exogenous sphingosine and sphingosine-based Sphk1 inhibitors induce the Sphk1-dependent fusion of endosomal membranes to accumulate enlarged late endosomes and amphisomes enriched in sphingolipids. Interestingly, Sphk1 also appears to facilitate endosomal fusion independent of its catalytic activity, given that catalytically inactive Sphk1G82Dis recruited to endocytic membranes by sphingosine or sphingosine-based Sphk1 inhibitor and promotes membrane fusion. Furthermore, we reveal that the clearance of enlarged endosomes is dependent on the activity of ceramide synthase, lysosomal biogenesis, and the restoration of autophagic flux. Collectively, these studies uncover intersecting roles for Sphk1, sphingosine, and autophagic machinery in endocytic membrane trafficking.
Department of Pharmacology, Penn State University College of Medicine, Hershey, PA 17033, USA; Department of Pediatrics, Penn State University College of Medicine, Hershey, PA 17033, USA.
Megan M
MM
Young
Department of Pediatrics, Penn State University College of Medicine, Hershey, PA 17033, USA.
Yoshinori
Y
Takahashi
Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA.
Todd E
TE
Fox
Department of Pharmacology, Penn State University College of Medicine, Hershey, PA 17033, USA.
Jong K
JK
Yun
Department of Pharmacology, University of Virginia, Charlottesville, VA 22908, USA.
Mark
M
Kester
Department of Pharmacology, Penn State University College of Medicine, Hershey, PA 17033, USA; Department of Pediatrics, Penn State University College of Medicine, Hershey, PA 17033, USA. Electronic address: hwang3@hmc.psu.edu.
Hong-Gang
HG
Wang
D000605:Amino Alcohols / Q000494:pharmacology; D000818:Animals; D001343:Autophagy / Q000187:drug effects; D000071187:Autophagy-Related Protein 5 / Q000378:metabolism; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / Q000378:metabolism; D004705:Endocytosis / Q000187:drug effects; D011992:Endosomes / Q000187:drug effects / Q000378:metabolism*; D007425:Intracellular Membranes / Q000378:metabolism*; D008247:Lysosomes / Q000187:drug effects / Q000378:metabolism; D051379:Mice; D010766:Phosphorylation / Q000187:drug effects; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D021381:Protein Transport / Q000187:drug effects; D013107:Sphingolipids / Q000378:metabolism; D014617:Vacuoles / Q000187:drug effects / Q000378:metabolism; D000099157:Sphingosine Kinase
D000605:Amino Alcohols; D000071187:Autophagy-Related Protein 5; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D017853:Phosphotransferases (Alcohol Group Acceptor); D047428:Protein Kinase Inhibitors; D013107:Sphingolipids; D000099157:Sphingosine Kinase; C495773:Atg5 protein, mouse; C544832:N-methyl-5-(4'-pentylphenyl)-2-aminopent-4-ene-1,3-diol; C484068:Tcfeb protein, mouse
autophagy; endocytic trafficking; late endosome; sphingosine; sphingosine kinase 1; sphingosine-1-phosphate