Ceramide kinase regulates the production of tumor necrosis factor α (TNFα) via inhibition of TNFα-converting enzyme.
Tumor necrosis factor α (TNFα) is a well known cytokine involved in systemic and acute inflammation. In this study, we demonstrate that ceramide 1-phosphate (C1P) produced by ceramide kinase (CERK) is a negative regulator of LPS-induced TNFα secretion. Specifically, bone marrow-derived macrophages isolated from CERK knock-out mice (CERK(-/-)) generated higher levels of TNFα than the wild-type mice (CERK(+/+)) in response to LPS. An increase in basal TNFα secretion was also observed in CERK(-/-) murine embryonic fibroblasts, which was rescued by re-expression of wild-type CERK. This effect was due to increased secretion and not transcription. The secretion of TNFα is regulated by TNFα-converting enzyme (TACE also known as ADAM17), and importantly, the activity of TACE was higher in cell extracts from CERK(-/-) as compared with wild type. In vitro analysis also demonstrated that C1P is a potent inhibitor of this enzyme, in stark contrast to ceramide and sphingosine 1-phosphate. Furthermore, TACE specifically bound C1P with high affinity. Finally, several putative C1P-binding sites were identified via homology throughout the protein sequence of TACE. These results indicate that C1P produced by CERK has a negative effect on the processing/secretion of TNFα via modulation of TACE activity.
Department of Biochemistry and Molecular Biology, Virginia Commonwealth University, Richmond, Virginia 23298, USA.
Nadia F
NF
Lamour
Dayanjan S
DS
Wijesinghe
Jennifer A
JA
Mietla
Katherine E
KE
Ward
Robert V
RV
Stahelin
Charles E
CE
Chalfant
D051722:ADAM Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000072198:ADAM17 Protein; D000818:Animals; D002478:Cells, Cultured; D002518:Ceramides / Q000494:pharmacology; D005260:Female; D051379:Mice; D018345:Mice, Knockout; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics / Q000378:metabolism*; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism*
D002518:Ceramides; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C065576:ceramide 1-phosphate; D017853:Phosphotransferases (Alcohol Group Acceptor); C066324:ceramide kinase; D051722:ADAM Proteins; D000072198:ADAM17 Protein; C000606463:Adam17 protein, mouse