Coupling between endocytosis and sphingosine kinase 1 recruitment

H Shen, F Giordano, Y Wu, J Chan, C Zhu… - Nature cell …, 2014 - nature.com
H Shen, F Giordano, Y Wu, J Chan, C Zhu, I Milosevic, X Wu, K Yao, B Chen, T Baumgart
Nature cell biology, 2014nature.com
Genetic studies have suggested a functional link between cholesterol/sphingolipid
metabolism and endocytic membrane traffic. Here we show that perturbing the cholesterol/
sphingomyelin balance in the plasma membrane results in the massive formation of clusters
of narrow endocytic tubular invaginations positive for N-BAR proteins. These tubules are
intensely positive for sphingosine kinase 1 (SPHK1). SPHK1 is also targeted to
physiologically occurring early endocytic intermediates, and is highly enriched in nerve …
Abstract
Genetic studies have suggested a functional link between cholesterol/sphingolipid metabolism and endocytic membrane traffic. Here we show that perturbing the cholesterol/sphingomyelin balance in the plasma membrane results in the massive formation of clusters of narrow endocytic tubular invaginations positive for N-BAR proteins. These tubules are intensely positive for sphingosine kinase 1 (SPHK1). SPHK1 is also targeted to physiologically occurring early endocytic intermediates, and is highly enriched in nerve terminals, which are cellular compartments specialized for exo/endocytosis. Membrane recruitment of SPHK1 involves a direct, curvature-sensitive interaction with the lipid bilayer mediated by a hydrophobic patch on the enzyme’s surface. The knockdown of SPHKs results in endocytic recycling defects, and a mutation that disrupts the hydrophobic patch of Caenorhabditis elegans SPHK fails to rescue the neurotransmission defects in loss-of-function mutants of this enzyme. Our studies support a role for sphingosine phosphorylation in endocytic membrane trafficking beyond the established function of sphingosine-1-phosphate in intercellular signalling.
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