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.

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Notes/Citation Information

Published in Journal of Lipid Research, v. 59, issue 3, p. 488-506.

This research was originally published in the Journal of Lipid Research. Ji-Na Kong, Zhihui Zhu, Yutaka Itokazu, Guanghu Wang, Michael B. Dinkins, Liansheng Zhong, Hsuan-Pei Lin, Ahmed Elsherbini, Silvia Leanhart, Xue Jiang, Haiyan Qin, Wenbo Zhi, Stefka D. Spassieva, and Erhard Bieberich. Novel Function of Ceramide for Regulation of Mitochondrial ATP Release in Astrocytes. J. Lipid Res. 2018; 59:488-506. © 2018 by the American Society for Biochemistry and Molecular Biology, Inc.

The copyright holder has granted the permission for posting the article here.

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Funding Information

This work was supported by National Institute on Aging Grant R01AG034389, National Institute of Neurological Disorders and Stroke Grant R01NS095215, the National Science Foundation, and Division of Molecular and Cellular Biosciences Grant 1615874.

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Supplemental Material can be found at: http://www.jlr.org/content/suppl/2018/01/10/jlr.M081877.DC1.html

jlr.M081877-1.pdf (1539 kB)
Supplemental Figures

jlr.M081877-2.avi (15060 kB)
Supplemental Movie mitochondria wild type

jlr.M081877-3.avi (15060 kB)
Supplemental Movie mitochondria nSMase2-deficient