Ceramide increase cytoplasmic Ca2+ concentration in Jurkat T cells by liberation of calcium from intracellular stores and activation of a store-operated calcium channel.
The effect of ceramide on the cytoplasmic Ca2+ concentration ([Ca2+]i) varies depending on the cell type. We have found that in Jurkat human T cells ceramide increases the [Ca2+]i from a thapsigargin-sensitive calcium pool and the subsequent activation of a capacitative Ca2+ entry. This effect occurs both in the presence and in the absence of extracellular calcium. Addition of ceramine, a non-hydrolysable analogue of ceramide, reproduced its effect on the [Ca2+]i ruling out that this is due to the conversion of ceramide to sphingosine. The effect of ceramide was additive to that obtained by sphingosine, but not to the Jurkat T cells specific antibody OKT3. However, different to the latter, ceramide do not induced an elevation of InsP3. The opening of a store operated Ca2+ channel by ceramide was corroborated by experiments of Fura-2 quenching, using Mn2+ as a surrogate for Ca2+ and confirmed by whole-cell recording patch clamp techniques.
Colina
Claudia
C
Centro de Biociencias y Medicina Molecular, Instituto de Estudios Avanzados (IDEA), Caracas, Venezuela.
Flores
Adriana
A
Rojas
Héctor
H
Acosta
Angie
A
Castillo
Cecilia
C
Garrido
María del Rosario
Mdel R
Israel
Anita
A
DiPolo
Reinaldo
R
Benaim
Gustavo
G
D002118:Calcium / Q000737:chemistry* / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002518:Ceramides / Q000737:chemistry / Q000378:metabolism*; D003593:Cytoplasm / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D015544:Inositol 1,4,5-Trisphosphate / Q000737:chemistry; D019169:Jurkat Cells; D008214:Lymphocytes / Q000378:metabolism; D008274:Magnesium / Q000737:chemistry; D008345:Manganese / Q000737:chemistry; D018613:Microscopy, Confocal; D018408:Patch-Clamp Techniques; D015398:Signal Transduction; D013107:Sphingolipids / Q000737:chemistry; D013110:Sphingosine / Q000737:chemistry; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors
D015220:Calcium Channels; D002518:Ceramides; D013107:Sphingolipids; D008345:Manganese; D019284:Thapsigargin; D015544:Inositol 1,4,5-Trisphosphate; D008274:Magnesium; D013110:Sphingosine; D002118:Calcium