Induction of apoptosis using sphingolipids activates a chloride current in Xenopus laevis oocytes.
The purpose of this study was to investigate whether the cell shrinkage that occurs during apoptosis could be explained by a change of the activity in ion transport pathways. We tested whether sphingolipids, which are potent pro-apoptotic compounds, can activate ionic currents in Xenopus laevis oocytes. Apoptosis was characterized in our model by a decrease in cell volume, a loss of cell viability, and DNA cleavage. Oocytes were studied using voltage-clamp after injection with N,N-dimethyl-D-erythrosphingosine (DMS) or D-sphingosine (DS). DMS and DS activated a fast-activating, slowly inactivating, outwardly rectifying current, similar to I(Cl-swell), a swelling-induced chloride current. Lowering the extracellular chloride dramatically reduced the current, and the channel was more selective for thiocyanate and iodide (thiocyanate > iodide) than for chloride. The current was blocked by 5-nitro-2-(3-phenylpropylamino)-benzoic acid (NPPB) and lanthanum but not by niflumic acid. Oocytes injected with a pseudosubstrate inhibitor of protein kinase C (PKC), PKC-(19-31), exhibited the same current. DMS-activated current was abolished by preexposure with phorbol myristate acetate. Our results suggest that induction of apoptosis in X. laevis oocytes, using sphingolipids or PKC inhibitors, activates a current similar to swelling-induced chloride current previously described in oocytes.
Souktani
R
R
Laboratoire de Pharmacologie, Faculté de Médecine Paris Sud 94275, France.
Berdeaux
A
A
Ghaleh
B
B
Giudicelli
J F
JF
Guize
L
L
Le Heuzey
J Y
JY
Henry
P
P
D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D016923:Cell Death / Q000502:physiology; D002478:Cells, Cultured; D018118:Chloride Channels / Q000502:physiology*; D053938:DNA Fragmentation; D004553:Electric Conductivity; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D009865:Oocytes / Q000166:cytology / Q000187:drug effects* / Q000502:physiology*; D011493:Protein Kinase C / Q000502:physiology; D013107:Sphingolipids / Q000494:pharmacology*; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology; D014982:Xenopus laevis
D018118:Chloride Channels; D004791:Enzyme Inhibitors; D013107:Sphingolipids; D011493:Protein Kinase C; C061800:N,N-dimethylsphingosine; D013110:Sphingosine