Sphingolipid Metabolism Is a Crucial Determinant of Cellular Fate in Nonstimulated Proliferating Madin-Darby Canine Kidney (MDCK) Cells

Sphingolipid Metabolism Is a Crucial Determinant of Cellular Fate in Nonstimulated Proliferating Madin-Darby Canine Kidney (MDCK) Cells

The present report was addressed to study the influence of sphingolipid metabolism in determining cellular fate. In nonstimulated proliferating Madin-Darby canine kidney (MDCK) cells, sphingolipid de novo synthesis is branched mainly to a production of sphingomyelin and ceramide, with a minor produc...

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Bibliographic Details
Published in:The Journal of biological chemistry 2008-09, Vol.283 (37), p.25682-25691
Main Authors: Nieto, Francisco Leocata, Pescio, Lucila G., Favale, Nicolás O., Adamo, Ana M., Sterin-Speziale, Norma B.
Format: Article
Language:eng
Subjects:
Animals
Cell Line
Cell Lineage
Cell Proliferation
Ceramides - metabolism
Dogs
Enzyme Activation
Fumonisins - pharmacology
Models, Biological
Oxidoreductases - metabolism
Phosphotransferases (Alcohol Group Acceptor) - metabolism
Serine C-Palmitoyltransferase - antagonists & inhibitors
Sphingolipids - metabolism
Time Factors
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Summary:The present report was addressed to study the influence of sphingolipid metabolism in determining cellular fate. In nonstimulated proliferating Madin-Darby canine kidney (MDCK) cells, sphingolipid de novo synthesis is branched mainly to a production of sphingomyelin and ceramide, with a minor production of sphingosylphosphocholine, ceramide 1-phosphate, and sphingosine 1-phosphate. Experiments with 32P as a radioactive precursor showed that sphingosine 1-phosphate is produced mainly by a de novo independent pathway. Enzymatic inhibition of the de novo pathway and ceramide synthesis affected cell number and viability only slightly, without changing sphingosine 1-phosphate production. By contrast, inhibition of sphingosine kinase-1 activity provoked a significant reduction in both cell number and viability in a dose-dependent manner. When sphingolipid metabolism was studied, an increase in de novo formed ceramide was found, which correlated with the concentration of enzyme inhibitor and the reduction in cell number and viability. Knockdown of sphingosine kinase-1 expression also induced an accumulation of de novo synthesized ceramide, provoking a slight reduction in cell number and viability similar to that induced by a low concentration of the sphingosine kinase inhibitor. Taken together, our results indicate that the level of de novo formed ceramide is controlled by the synthesis of sphingosine 1-phosphate, which appears to occur through a de novo synthesis-independent pathway, most probably the salvage pathway, that is responsible for the MDCK cell fate, suggesting that under proliferating conditions, a dynamic interplay exists between the de novo synthesis and the salvage pathway.
ISSN:0021-9258
1083-351X