title: Sphingolipid metabolites selectively elicit increases in nuclear calcium concentration in cell suspension cultures and in isolated nuclei of tobacco.
abstract: 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.
authors.affiliation: 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.
authors.forename: Tou Cheu
authors.initials: TC
authors.lastname: Xiong
authors.forename: Sylvie
authors.initials: S
authors.lastname: Coursol
authors.forename: Sabine
authors.initials: S
authors.lastname: Grat
authors.forename: Raoul
authors.initials: R
authors.lastname: Ranjeva
authors.forename: Christian
authors.initials: C
authors.lastname: Mazars
mesh_terms: 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
chemical_list: 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