Sphingolipid metabolites selectively elicit increases in nuclear calcium concentration in cell suspension cultures and in isolated nuclei of tobacco.
Sphingolipids are known to interfere with calcium-based signalling pathways. Here we report that these compounds modulate nuclear calcium signalling in tobacco BY-2 cells. Nuclear protein kinase activity phosphorylated endogenous sphingoid long-chain bases (LCBs), suggesting that LCBs are actively metabolized in the nucleus of tobacco BY-2 cells. The Delta4-unsaturated LCB D-erythro-sphingosine and the saturated LCB D-ribo-phytosphingosine elicited increases in free calcium in the nucleus in a dose-dependent and structure-related manner. However, neither sphingosine-1-phosphate nor C2-ceramide was able to stimulate nuclear calcium changes. N-,N-Dimethyl-D-erythro-sphingosine, a structural analogue of D-erythro-sphingosine, was the most efficient LCB so far tested in eliciting nuclear calcium changes both in intact tobacco BY-2 cells and in isolated nuclei. TRP channel inhibitors prevent the effect of DMS, suggesting that LCBs may activate TRP-like channels located on the inner nuclear membrane Collectively, the obtained data show that nuclei respond to LCBs on their own independently of the cytosolic compartment.
Xiong
Tou Cheu
TC
UMR CNRS/UPS 5546, Surfaces Cellulaires et Signalisation chez les Végétaux, Pôle de Biotechnologie Végétale, 24 Chemin de Borde Rouge, BP 42617 Auzeville, 31326 Castanet-Tolosan, France.
Coursol
Sylvie
S
Grat
Sabine
S
Ranjeva
Raoul
R
Mazars
Christian
C
D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling; D002458:Cell Fractionation; D002467:Cell Nucleus / Q000201:enzymology / Q000378:metabolism*; D002478:Cells, Cultured; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism; D013107:Sphingolipids / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D013110:Sphingosine / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology; D014026:Nicotiana / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D050051:Transient Receptor Potential Channels / Q000037:antagonists & inhibitors
D013107:Sphingolipids; D050051:Transient Receptor Potential Channels; D017853:Phosphotransferases (Alcohol Group Acceptor); C426837:sphingolipid long-chain base kinase; C061800:N,N-dimethylsphingosine; D013110:Sphingosine; D002118:Calcium