title: Ceramide 1-phosphate increases intracellular free calcium concentrations in thyroid FRTL-5 cells: evidence for an effect mediated by inositol 1,4,5-trisphosphate and intracellular sphingosine 1-phosphate.
abstract: Sphingolipid (SP) derivatives have diverse effects on the regulation of intracellular free calcium concentrations ([Ca2+]i) in a multitude of non-excitable cells. In the present investigation, the effect of C2-ceramide 1-phosphate (C1P) on [Ca2+]i was investigated in thyroid FRTL-5 cells. C1P evoked a concentration-dependent increase in [Ca2+]i, both in a calcium-containing and a calcium-free buffer. A substantial part of the C1P-evoked increase in [Ca2+]i was due to calcium entry. The effect of C1P was attenuated by overnight pretreatment of the cells with pertussis toxin. Similar results were obtained with C8-ceramide 1-phosphate, although the magnitude of the responses was smaller than with C1P. The phospholipase C inhibitor U73122 attenuated the effect of C1P. C1P invoked a small, but significant, increase in inositol 1,4,5-trisphosphate (IP3). However, the effect of C1P on [Ca2+]i was inhibited by neither Xestospongin C, 2-aminoethoxydiphenylborate nor neomycin. C1P mobilized calcium from an IP3-sensitive calcium store, as C1P did not increase [Ca2+]i in cells pretreated with thapsigargin. The effect of C1P on [Ca2+]i was potently attenuated by dihydrosphingosine and dimethylsphingosine, two inhibitors of sphingosine kinase, but not by the inactive SP-derivative N -acetyl sphingosine. Stimulating the cells with C1P evoked an increase in the production of intracellular sphingosine 1-phosphate. C1P did not modulate DNA synthesis or the forskolin-evoked production of cAMP. The results indicate that C1P may be an important SP participating in cellular signalling.
authors.affiliation: Department of Biology, Abo Akademi University, BioCity, Artillerigatan 6, 20520 Turku, Finland.
authors.forename: Susanna
authors.initials: S
authors.lastname: Högback
authors.forename: Petra
authors.initials: P
authors.lastname: Leppimäki
authors.forename: Britt
authors.initials: B
authors.lastname: Rudnäs
authors.forename: Sonja
authors.initials: S
authors.lastname: Björklund
authors.forename: J Peter
authors.initials: JP
authors.lastname: Slotte
authors.forename: Kid
authors.initials: K
authors.lastname: Törnquist
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002518:Ceramides / Q000494:pharmacology*; D000242:Cyclic AMP / Q000378:metabolism; D004261:DNA Replication; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism*; D008246:Lysophospholipids; D051381:Rats; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism*; D013961:Thyroid Gland / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
chemical_list: D002518:Ceramides; D008246:Lysophospholipids; C065576:ceramide 1-phosphate; C060506:sphingosine 1-phosphate; D015544:Inositol 1,4,5-Trisphosphate; D000242:Cyclic AMP; D013110:Sphingosine; D002118:Calcium