Abstract
Ceramide, a product of sphingomyelin hydrolysis, is now recognized as an intracellular lipid messenger, which mediates the effects of extracellular agents on cellular growth, differentiation and apoptosis. Recently, ceramide has been implicated in the regulation of phospholipase D (PLD). In this study, we examined the effects of ceramide on the activity and mRNA level of PLD during apoptotic process in FRTL-5 thyroid cells. C2-ceramide (N-acetyl sphingosine) induced apoptosis in FRTL-5 thyroid cells. Fluorescent staining showed that ceramide induced the typical features of apoptosis including condensed or fragmented nuclei. DNA fragmentation was also observed by agarose gel electrophoresis. Flow cytometric cell cycle analysis showed more clearly that ceramide induced apoptotic cell death in FRTL-5 thyroid cells. The treatment of FRTL-5 thyroid cells with thyroid-stimulating hormone (TSH) resulted in an increased PLD activity in a dose- and time-dependent manner. However, the TSH-induced increase in PLD activity was down-regulated within 2 h after ceramide treatment. Furthermore, the levels of PLD mRNA were found to be decreased throughout apoptotic process as inferred by reverse transcription-polymerase chain reaction. However, the decreases in PLD mRNA levels were not correlated with those in PLD activities after ceramide treatment. Taken together, these data suggest that ceramide inhibits the PLD activity in an early apoptotic phase and down-regulation of the levels of PLD mRNA may be implicated in apoptotic process in FRTL-5 thyroid cells.
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This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Park, BJ., Kim, JH., Han, JS. et al. Effect of ceramide on apoptosis and phospholipase D activity in FRTL-5 thyroid cells. Exp Mol Med 31, 142–150 (1999). https://doi.org/10.1038/emm.1999.24
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DOI: https://doi.org/10.1038/emm.1999.24