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J Lipid Res. 2018 Mar;59(3):488-506. doi: 10.1194/jlr.M081877. Epub 2018 Jan 10.

Novel function of ceramide for regulation of mitochondrial ATP release in astrocytes.

Author information

1
Department of Neuroscience and Regenerative Medicine Augusta University, Augusta, GA.
2
Department of Biology, Massachusetts Institute of Technology, Cambridge, MA.
3
Department of Physiology, University of Kentucky, Lexington, KY.
4
College of Basic Medicine, China Medical University, Shenyang, People's Republic of China.
5
Rehabilitation Center, ShengJing Hospital of China Medical University, Shenyang, People's Republic of China.
6
Center of Biotechnology and Genomic Medicine, Medical College of Georgia, Augusta University, Augusta, GA.
7
Department of Physiology, University of Kentucky, Lexington, KY erhard.bieberich@uky.edu stefanka.spassieva@uky.edu.
8
Department of Neuroscience and Regenerative Medicine Augusta University, Augusta, GA erhard.bieberich@uky.edu stefanka.spassieva@uky.edu.

Abstract

We reported that amyloid β peptide (Aβ42) activated neutral SMase 2 (nSMase2), thereby increasing the concentration of the sphingolipid ceramide in astrocytes. Here, we show that Aβ42 induced mitochondrial fragmentation in wild-type astrocytes, but not in nSMase2-deficient cells or astrocytes treated with fumonisin B1 (FB1), an inhibitor of ceramide synthases. Unexpectedly, ceramide depletion was concurrent with rapid movements of mitochondria, indicating an unknown function of ceramide for mitochondria. Using immunocytochemistry and super-resolution microscopy, we detected ceramide-enriched and mitochondria-associated membranes (CEMAMs) that were codistributed with microtubules. Interaction of ceramide with tubulin was confirmed by cross-linking to N-[9-(3-pent-4-ynyl-3-H-diazirine-3-yl)-nonanoyl]-D-erythro-sphingosine (pacFACer), a bifunctional ceramide analog, and binding of tubulin to ceramide-linked agarose beads. Ceramide-associated tubulin (CAT) translocated from the perinuclear region to peripheral CEMAMs and mitochondria, which was prevented in nSMase2-deficient or FB1-treated astrocytes. Proximity ligation and coimmunoprecipitation assays showed that ceramide depletion reduced association of tubulin with voltage-dependent anion channel 1 (VDAC1), an interaction known to block mitochondrial ADP/ATP transport. Ceramide-depleted astrocytes contained higher levels of ATP, suggesting that ceramide-induced CAT formation leads to VDAC1 closure, thereby reducing mitochondrial ATP release, and potentially motility and resistance to Aβ42 Our data also indicate that inhibiting ceramide generation may protect mitochondria in Alzheimer's disease.

KEYWORDS:

adenosine 5′-triphosphate; sphingolipids • mitochondria-associated membranes

PMID:
29321137
PMCID:
PMC5832933
[Available on 2019-03-01]
DOI:
10.1194/jlr.M081877

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