Journal of Biochemistry Advance Access originally published online on October 25, 2008
Journal of Biochemistry 2009 145(1):31-36; doi:10.1093/jb/mvn138
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Regulation by Sphingolipids of the Fate of FRTL-5 Cells
1Department of Clinical Laboratory, The University of Tokyo Hospital, Tokyo; 2Department of Pathology, Faculty of Medicine, University of Yamanashi, Yamanashi; 3Department of Clinical and Laboratory Medicine, Faculty of Medicine, University of Yamanashi, Yamanashi; and 4Department of Clinical Laboratory Medicine, Graduate School of Medicine, The University of Tokyo, Tokyo, Japan
To whom correspondence should be addressed. Tel: +81-3-5800-8721, Fax: +81-3-5689-0495, E-mail: yatoyuta-tky{at}umin.ac.jp
Received August 4, 2008; Accepted October 6, 2008
 |
Abstract |
|---|
Sphingolipids, including ceramide (Cer), sphingosine (Sph), and sphingosine 1-phosphate (Sph-1-P) have recently emerged as signal-transducing molecules. Functionally, a distinguishing characteristic of these lipids is their apparent participation in pro- or anti-proliferative cell regulation pathways. In this study, we examined the involvement of sphingolipids in the fate of FRTL-5 thyroid follicular cells. We first examined the effects of sphingolipids on FRTL-5 cell viability. Sph and Cer induced apoptosis, as revealed by fluorescence microscopy of TUNEL-positive fragmented nuclei and 180–300 bp DNA fragmentation on agarose gel electrophoresis while Sph-1-P was confirmed to prevent FRTL-5 cell apoptosis induced by deprivation of serum and TSH, possibly via cell surface receptors. We then analysed the metabolism of radiolabelled Sph and C6-Cer (a synthetic cell-permeable Cer) in FRTL-5 cells by thin layer chromatography, followed by autoradiography. Sph was mainly metabolized to Cer, and then to sphingomyelin, while Sph conversion into Sph-1-P was hardly detected. These changes were not affected by stimulation of the cells with TSH. Our results indicate the involvement of sphingolipid mediators in the fate of FRTL-5 thyroid cells.
Key Words: ceramide, FRTL-5, sphingosine, sphingosine 1-phosphate, thyrocyte
Abbreviations: Sph, sphingosine; Sph-1-P, sphingosine-1-phosphate; Cer, ceramide; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrasodium bromide; DAPI, diamido-2-phenylindole hydrochloride; PCR, polymerase chain reaction; TLC, thin layer chromatography; PLSD, Protected Least Significance Difference; TUNEL, terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling; S1Ps, Sph-1-P receptors
*These two authors contributed equally to this work.