FcepsilonRI cross-linking-induced actin assembly mediates calcium signalling in RBL-2H3 mast cells.
1. To determine the role of actin assembly in the Ca(2+) signalling of mast cells activated by cross-linking of FcepsilonRI, we examined the effects of cytochalasin D, an inhibitor of actin polymerization. 2. In the RBL-2H3 cells, F-actin content was increased by sensitization with anti-dinitrophenol (DNP) IgE. In these cells, cytochalasin D induced oscillatory increases in cytosolic Ca(2+) ([Ca(2+)](i)); these increase were inhibited by jasplakinolide, a stabilizer of actin filaments. 3. In the IgE-sensitized RBL-2H3 cells, DNP-human serum albumin (DNP-HSA) augmented actin assembly. DNP-HSA also increased the production of IP(3), [Ca(2+)](i) and degranulation. Cytochalasin D enhanced all of these DNP-HSA-induced effects. 4. In a Ca(2+)-free solution, DNP-HSA induced a transient increase in [Ca(2+)](i), and this increase was accelerated by cytochalasin D. After cessation of the DNP-HSA-induced Ca(2+) release, the re-addition of Ca(2+) induced a sustained increase in [Ca(2+)](i) through capacitative Ca(2+) entry (CCE), and this increase was enhanced by cytochalasin D. 5 The effect of cytochalasin D in enhancing the CCE activity was prevented by xestospongin C. 6. In contrast, neither the Ca(2+) release nor the CCE activation that was induced by thapsigargin was affected by cytochalasin D. 7. These results suggest that actin de-polymerization stimulates the FcepsilonRI-mediated signalling to augment the release of Ca(2+) from the endoplasmic reticulum in RBL-2H3 cells.
Department of Veterinary Pharmacology, The University of Tokyo, Bunkyo-Ku, Tokyo 113-8657, Japan.
Tatsuya
T
Oka
Koichi
K
Sato
Masatoshi
M
Hori
Hiroshi
H
Ozaki
Hideaki
H
Karaki
D000199:Actins / Q000378:metabolism / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D020013:Calcium Signaling; D002413:Cations, Divalent; D015550:Cell Degranulation; D003432:Cross-Linking Reagents / Q000494:pharmacology; D015638:Cytochalasin D / Q000494:pharmacology; D047630:Depsipeptides; D004140:Dinitrophenols / Q000276:immunology / Q000494:pharmacology; D006801:Humans; D007073:Immunoglobulin E / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000096:biosynthesis; D047028:Macrocyclic Compounds; D008407:Mast Cells / Q000166:cytology / Q000378:metabolism*; D010080:Oxazoles / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D051381:Rats; D017455:Receptors, IgE / Q000737:chemistry / Q000502:physiology*; D012709:Serum Albumin / Q000276:immunology / Q000494:pharmacology; D019284:Thapsigargin / Q000494:pharmacology; D014407:Tumor Cells, Cultured
D000199:Actins; D002413:Cations, Divalent; D003432:Cross-Linking Reagents; D047630:Depsipeptides; D004140:Dinitrophenols; D047028:Macrocyclic Compounds; D010080:Oxazoles; D010456:Peptides, Cyclic; D017455:Receptors, IgE; D012709:Serum Albumin; C058064:dinitrophenyl-human serum albumin conjugate; C108644:xestospongin A; C057531:jasplakinolide; D015638:Cytochalasin D; D007073:Immunoglobulin E; D019284:Thapsigargin; D015544:Inositol 1,4,5-Trisphosphate