Ceramide 1-(2-cyanoethyl) phosphate enhances store-operated Ca2+ entry in thyroid FRTL-5 cells
作者:Kid Törnquist、Cia Ramström、Britt Rudnäs、Karel D Klika、Benoit Dugué、Jeffrey Adams、Robert Zipkin、Kalevi Pihlaja、Michael Pasternack
DOI:10.1016/s0014-2999(02)02362-2
日期:2002.10
Sphingolipid derivatives cause diverse effects towards the regulation of intracellular free Ca2+ concentrations ([Ca2+](i)) in a multitude of nonexcitable cells. In the present investigation, the effect of C-8 ceramide-1-(2-cyanoethyl) phosphate (C1CP) on store-operated Ca2+ (SOC) entry was investigated. C1CP evoked a modest increase in [Ca2+](i) The increase was inhibited by the SOC channel antagonist 1-(beta-[3-(4methoxyphenyl)propoxy]-4-methoxyphenethyl)-1H-imidazole (SKF96365) but not by overnight pretreatment of the cells with pertussis toxin. C1CP did not invoke the production of inositol phosphates. When cells were stimulated with both C1CP and thapsigargin, the thapsigargin-invoked increase in [Ca2+](i) was enhanced in comparison to control cells. When Ca2+ was added to cells treated with both C1CP and thapsigargin in a Ca2+-free buffer, the increase in [Ca2+](i) was enhanced in comparison to control cells. In patch-clamp experiments, C1CP hyperpolarized the membrane potential (E-m) of the cells and attenuated the thapsigargin-invoked depolarization of the E-m. The effects of C1CP came, in part, as a result of a decreased conductance of the cell membrane towards Cl- ions, as C1CP in a Cl--free solution also enhanced Ca2+ entry. Barium 2-cyanoethylphosphate (Ba2Cy), which also contains the 2-cyanoethyl group, did not modulate thapsigargin-invoked changes in [Ca2+](i) nor did it modulate the E-m. In conclusion, C1CP enhances SOC entry, in part, via hyperpolarization of the E-m and attenuation of the thapsigargin-invoked membrane depolarization, thus increasing the electrochemical gradient for Ca2+ ions. Hence, C1CP may be a useful reagent for investigating the cellular effects of ceramide derivatives. (C) 2002 Elsevier Science B.V. All rights reserved.