Protein kinase Cdelta functions downstream of Ca2+ mobilization in FcepsilonRI signaling to degranulation in mast cells.
BACKGROUND
Mobilization of Ca 2+ plays an important role in the degranulation of mast cells. Although events upstream of Ca 2+ mobilization in the regulation of degranulation are relatively well characterized, the downstream mediators of Ca 2+ remain largely unknown.


OBJECTIVE
We sought to characterize the downstream signaling mechanism by which Ca 2+ mobilization mediates degranulation in antigen-stimulated mast cells.


METHODS
The effect of various inhibitors was examined in the antigen-induced or Ca 2+ ionophore A23187-induced degranulation process, and the effect of inhibitors on histamine release was tested in the mouse model of asthma.


RESULTS
The delta isoform of protein kinase C (PKC) functions downstream of Ca 2+ in the signaling pathway from FcepsilonRI to degranulation in RBL-2H3 mast cells. Stimulation of cells with either antigen or the Ca 2+ ionophore A23187 induced a rapid translocation of PKC-delta from the cytosol to the cellular membranes, and either treatment with the PKC-delta-specific inhibitor rottlerin or infection with an adenovirus encoding a dominant negative mutant of PKC-delta markedly inhibited degranulation induced with antigen or A23187. Furthermore, both the translocation of PKC-delta and degranulation induced by A23187 were inhibited by prevention of the accumulation of reactive oxygen species normally elicited by the ionophore. Finally, intraperitoneal injection of rottlerin prevented the increase in the concentration of histamine in bronchoalveolar lavage fluid induced by means of antigen challenge in a mouse model of allergic asthma. conclusion: PKC-delta plays an essential downstream mediatory role in the degranulation elicited by Ca 2+ mobilization, and reactive oxygen species mediate the activation of PKC-delta by Ca 2+ in the regulation of degranulation.
Cho
Sung-Hoon
SH
School of Life Sciences and Biotechnology, Korea University, 5-1 Anam-dong, Sungbuk-gu, Seoul 136-701, Korea.
Woo
Chang-Hoon
CH
Yoon
Seog-Beom
SB
Kim
Jae-Hong
JH
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D015550:Cell Degranulation; D002478:Cells, Cultured; D008407:Mast Cells / Q000502:physiology*; D051966:Phospholipase C gamma; D011493:Protein Kinase C / Q000502:physiology*; D051745:Protein Kinase C-delta; D051381:Rats; D017382:Reactive Oxygen Species; D017455:Receptors, IgE / Q000502:physiology*; D015398:Signal Transduction; D010738:Type C Phospholipases / Q000502:physiology; D020744:rac GTP-Binding Proteins / Q000502:physiology
D017382:Reactive Oxygen Species; D017455:Receptors, IgE; D000001:Calcimycin; C497260:Prkcd protein, rat; D011493:Protein Kinase C; D051745:Protein Kinase C-delta; D010738:Type C Phospholipases; D051966:Phospholipase C gamma; D020744:rac GTP-Binding Proteins; D002118:Calcium