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J Lipid Res. 2015 Aug;56(8):1501-10. doi: 10.1194/jlr.M058750. Epub 2015 Jun 9.

Regulation of mitochondrial ceramide distribution by members of the BCL-2 family.

Author information

1
Clayton Foundation Laboratories for Peptide Biology, Helmsley Center for Genomic Medicine, Salk Institute for Biological Studies, San Diego, CA 92037.
2
Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215.
3
Department of Pediatric Oncology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215 Dana-Farber Cancer Institute and Children's Hospital Boston, and Linde Program in Cancer Chemical Biology, Dana-Farber Cancer Institute, Harvard Medical School, Boston, MA 02215.

Abstract

Apoptosis is an intricately regulated cellular process that proceeds through different cell type- and signal-dependent pathways. In the mitochondrial apoptotic program, mitochondrial outer membrane permeabilization by BCL-2 proteins leads to the release of apoptogenic factors, caspase activation, and cell death. In addition to protein components of the mitochondrial apoptotic machinery, an interesting role for lipids and lipid metabolism in BCL-2 family-regulated apoptosis is also emerging. We used a comparative lipidomics approach to uncover alterations in lipid profile in the absence of the proapoptotic proteins BAX and BAK in mouse embryonic fibroblasts (MEFs). We detected over 1,000 ions in these experiments and found changes in an ion with an m/z of 534.49. Structural elucidation of this ion through tandem mass spectrometry revealed that this molecule is a ceramide with a 16-carbon N-acyl chain and sphingadiene backbone (d18:2/16:0 ceramide). Targeted LC/MS analysis revealed elevated levels of additional sphingadiene-containing ceramides (d18:2-Cers) in BAX, BAK-double knockout MEFs. Elevated d18:2-Cers are also found in immortalized baby mouse kidney epithelial cells lacking BAX and BAK. These results support the existence of a distinct biochemical pathway for regulating ceramides with different backbone structures and suggest that sphingadiene-containing ceramides may have functions that are distinct from the more common sphingosine-containing species.

KEYWORDS:

apoptosis; ceramides; lipidomics; mass spectrometry; sphingolipids

PMID:
26059977
PMCID:
PMC4513991
DOI:
10.1194/jlr.M058750
[Indexed for MEDLINE]
Free PMC Article

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