Title: Neutropenia with impaired immune response to Streptococcus pneumoniae in ceramide kinase-deficient mice
Authors: Graf, Christine
Zemann, Barbara
Rovina, Philipp
Urtz, Nicole
Schanzer, Andrea
Reuschel, Roland
Mechtcheriakova, Diana
Mueller, Matthias
Fischer, Evelin
Reichel, Claudia
Huber, Susanna
Dawson, Janet
Meingassner, Josef G
Billich, Andreas
Niwa, Satoru
Badegruber, Rudolf
Van Veldhoven, Paul P
Kinzel, Bernd
Baumruker, Thomas
Bornancin, Frederic # ×
Issue Date: Mar-2008
Publisher: Amer assoc immunologists
Series Title: Journal of Immunology vol:180 issue:5 pages:3457-3466
Abstract: In mammals, ceramide kinase (CerK)-mediated phosphorylation of ceramide is the only known pathway to ceramide-I-phosphate (C1P), a recently identified signaling sphingolipid metabolite. To help delineate the roles of CerK and C1P, we knocked out the gene of CerK in BALB/c mice by homologous recombination. All in vitro as well as cell-based assays indicated that CerK activity is completely abolished in Cerk(-/-) mice. Labeling with radioactive orthophosphate showed a profound reduction in the levels of de novo C1P formed in Cerk(-/-) macrophages. Consistently, mass spectrometry analysis revealed a major contribution of CerK to the formation of C16-C1P. However, the significant residual C1P levels in Cerk(-/-) animals indicate that alternative routes to C1P exist. Furthermore, serum levels of proapoptotic ceramide in these animals were significantly increased while levels of dihydroceramide as the biosynthetic precursor were reduced. Previous literature pointed to a role of CerK or C1P in innate immune cell function. Using a variety of mechanistic and disease models, as well as primary cells, we found that macrophage- and mast cell-dependent readouts are barely affected in the absence of CerK. However, the number of neutrophils was strikingly reduced in blood and spleen of Cerk(-/-) animals. When tested in a model of fulminant pneumonia, Cerk(-/-) animals developed a more severe disease, lending support to a defect in neutrophil homeostasis following CerK ablation. These results identify ceramide kinase as a key regulator of C1P, dihydroceramide and ceramide levels, with important implications for neutrophil homeostasis and innate immunity regulation.
ISSN: 0022-1767
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Laboratory of Lipid Biochemistry and Protein Interactions
× corresponding author
# (joint) last author

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