Inhibition of glucosylceramide synthase stimulates autophagy flux in neurons.

Abstract

Aggregate-prone mutant proteins, such as α-synuclein and huntingtin, play a prominent role in the pathogenesis of various neurodegenerative disorders; thus, it has been hypothesized that reducing the aggregate-prone proteins may be a beneficial therapeutic strategy for these neurodegenerative disorders. Here, we identified two previously described glucosylceramide (GlcCer) synthase inhibitors, DL-threo-1-Phenyl-2-palmitoylamino-3-morpholino-1-propanol and Genz-123346(Genz), as enhancers of autophagy flux. We also demonstrate that GlcCer synthase inhibitors exert their effects on autophagy by inhibiting AKT-mammalian target of rapamycin (mTOR) signaling. More importantly, siRNA knock down of GlcCer synthase had the similar effect as pharmacological inhibition, confirming the on-target effect. In addition, we discovered that inhibition of GlcCer synthase increased the number and size of lysosomal/late endosomal structures. Although inhibition of GlcCer synthase decreases levels of mutant α-synuclein in neurons, it does so, according to our data, through autophagy-independent mechanisms. Our findings demonstrate a direct link between glycosphingolipid biosynthesis and autophagy in primary neurons, which may represent a novel pathway with potential therapeutic value for the treatment of Parkinson's disease. Inhibition of GlcCer synthase enhances autophagy by inhibiting AKT-mTOR signaling, and increases the number and size of lysosomal/late endosomal structures. Furthermore, inhibition of GlcCer synthase decreased levels of mutant α-synuclein in neurons, which may represent a potential therapeutic target for Parkinson's disease.

• Authors: Wei Shen, Anastasia G Henry, Katrina L Paumier, Li Li, Kewa Mou, John Dunlop, Zdenek Berger, Warren D Hirst
• Journal: Journal of neurochemistry (J Neurochem) Vol. 129 Issue 5 Pg. 884-94 (Jun 2014) ISSN: 1471-4159 [Electronic] England
• PMID: 24494600 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: © 2014 International Society for Neurochemistry.

Chemical References

• (2-(2',3'-dihydrobenzo(1,4)dioxin-6'-yl)-2-hydroxy-1-pyrrolidin-1-ylmethylethyl)nonanoic acid amide
• Dioxanes
• Enzyme Inhibitors
• Glycosphingolipids
• Pyrrolidines
• RNA, Small Interfering
• 4-propionyloxy-4-phenyl-N-methylpiperidine
• Meperidine
• Glucosyltransferases
• ceramide glucosyltransferase
• Oncogene Protein v-akt

Topics

• Animals
• Autophagy (physiology)
• Blotting, Western
• Cells, Cultured
• Dioxanes (pharmacology)
• Enzyme Inhibitors (pharmacology)
• Female
• Glucosyltransferases (antagonists & inhibitors)
• Glycosphingolipids (biosynthesis)
• HEK293 Cells
• Humans
• Male
• Meperidine (analogs & derivatives, pharmacology)
• Mice
• Mice, Knockout
• Mice, Transgenic
• Neurons (physiology)
• Oncogene Protein v-akt (metabolism)
• Parkinson Disease (genetics)
• Phosphorylation
• Primary Cell Culture
• Pyrrolidines (pharmacology)
• RNA, Small Interfering (genetics)
• Real-Time Polymerase Chain Reaction