Vacuolin-1-modulated exocytosis and cell resealing in mast cells.
The small chemical vacuolin-1 induces rapid formation of large vacuoles in various cell types. In epithelial cells, vacuolin-1 has been shown to inhibit Ca2+ ionophore-induced exocytosis depending on experimental conditions used but had no effect on repair of damaged membranes. However, it is not known whether vacuolin-1 could inhibit exocytosis induced by immunoreceptor triggering in professional secretory cells and whether there is any correlation between effect of vacuolin-1 on exocytosis and membrane repair in such cells. Here we show that in rat basophilic leukemia (RBL-2H3) cells activated by the high-affinity IgE receptor (FcepsilonRI) triggering vacuolin-1 enhanced exocytosis. Under identical conditions of activation, vacuolin-1 inhibited exocytosis in mouse bone marrow-derived mast cells (BMMCs). This inhibition was not reflected by decreased phosphorylation of the FcepsilonRI alpha and beta subunits, linker for activation of T cells, non-T cell activation linker, Akt and MAP kinase Erk, and uptake of extracellular Ca2+, indicating that early activation events are not affected. In both cell types vacuolin-1 led to formation of numerous vacuoles, a process which was inhibited by bafilomycin A1, an inhibitor of vacuolar H+-ATPase. Thapsigargin- or Ca2+ ionophore A23187-induced exocytosis also showed different sensitivity to the inhibitory effect of vacuolin-1. Pretreatment of the cells with vacuolin-1 followed by permeabilization with bacterial toxin streptolysin O enhanced Ca2+-dependent repair of plasma membrane lesions in RBL-2H3 cells but inhibited it in BMMCs. Our data indicate that lysosomal exocytosis exhibits different sensitivity to vacuolin-1 depending on the cell type analyzed and mode of activation. Furthermore, our results support the concept that lysosomal exocytosis is involved in the repair of injured plasma membranes.
Shaik
Gouse M
GM
Laboratory of Signal Transduction, Institute of Molecular Genetics, Academy of Sciences of the Czech Republic, Prague, Czech Republic.
Dráberová
Lubica
L
Heneberg
Petr
P
Dráber
Petr
P
D000818:Animals; D002118:Calcium / Q000378:metabolism; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000502:physiology; D005089:Exocytosis / Q000187:drug effects*; D006576:Heterocyclic Compounds, 4 or More Rings / Q000494:pharmacology*; D008407:Mast Cells / Q000187:drug effects* / Q000276:immunology / Q000378:metabolism; D051379:Mice; D010766:Phosphorylation; D051381:Rats; D017455:Receptors, IgE / Q000276:immunology / Q000378:metabolism; D014617:Vacuoles / Q000502:physiology
D006576:Heterocyclic Compounds, 4 or More Rings; D017455:Receptors, IgE; C503870:vacuolin-1; D002118:Calcium