Exp Mol Med.  1999 Sep;31(3):142-150.

Effect of ceramide on apoptosis and phospholipase D activity in FRTL-5 thyroid cells

Affiliations
  • 1Department of General Surgery, College of Medicine, Sung Kyun Kwan University, Seoul, Korea.

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.

Keyword

ceramide; apoptosis; thyroid-stimulating hormone; phospholipase D; FRTL-5 thyroid cells

MeSH Terms

Animal
Apoptosis/drug effects*
Cells, Cultured
DNA Fragmentation
Enzyme Activation/drug effects
Flow Cytometry
Gene Expression Regulation, Enzymologic/drug effects
Phospholipase D/metabolism*
Phospholipase D/genetics
RNA, Messenger/genetics
Rats
Rats, Inbred Strains
Sphingosine/pharmacology
Sphingosine/analogs & derivatives*
Thyroid Gland/enzymology
Thyroid Gland/drug effects*
Thyrotropin/pharmacology
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