Pertussis toxin does not affect the time course of exocytosis in mast cells stimulated by intracellular application of GTP‐γ‐S

Lindau, Manfred; Nüße, Oliver

doi:10.1016/0014-5793(87)80393-9

Cited by 23 publications

(15 citation statements)

References 23 publications

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“…A second G protein (GE) has been proposed to be the target of GTPyS in neutrophils (3) and mast cells (10) and we have presented evidence that the G protein activated by GTPTS is not identical with the pertussis toxin-sensitive G protein in mast ceils (21). Recently, it has been reported that pertussis toxin inhibits exocytosis from mast cells stimulated by compound 48/80 and from human basophils stimulated by fMet-Leu-Phe.…”

Section: Discussionmentioning

confidence: 84%

“…The time course of exocytosis in mast cells is also characterized by a lag phase which is ~1 min at 20 lxM GTPyS if calcium is weakly buffered (13). In the presence of 500 IxM EGTA, however, the degranulation of mast cells is severalfold slower (21,23). The calcium dependence of the time course is thus markedly stronger in mast cells than in neutrophils indicating that the mechanism affecting the rate of granules fusion may be different in both cell types.…”

Section: Discussionmentioning

confidence: 99%

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The dynamics of exocytosis in human neutrophils.

Nüße

Lindau

1988

The Journal of Cell Biology

107

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Abstract. We have investigated the dynamics of exocytosis in single human neutrophils. The increase of membrane area associated with granule fusion was followed by time-resolved patch-clamp capacitance measurements. Intracellular application of 20 ~tM guanosine-5'-O(3-thiotriphosphate) (GTP~,S) in the presence of 2.5 mM ATP stimulated exocytosis and led to an increase of membrane capacitance from 3.0 to ,,~8.4 pF corresponding to a 540 ~tm 2 increase of membrane area. This capacitance change is very close to the value expected from morphological data if all primary and secondary granules fuse with the plasma membrane. High resolution measurements revealed stepwise capacitance changes corresponding to the fusion of individual granules. GTP'tS-stimulated exocytosis did not require pretreatment with cytochalasin B and the amplitude was independent of the intracellular-free calcium concentration between 10 nM and ~2.5 ~tM. In the absence of GTP~S elevation of intracellular-free calcium concentration to the micromolar range led to the fusion of only a limited number of granules. Degranulation stimulated with GTP~S started after a lag phase of 2-7 min and was usually complete within 5-20 min. The time course was affected by the intracellular ATP and calcium concentration. Exocytosis was markedly accelerated by pretreatment with cytochalasin B. Our results demonstrate that the final steps leading to primary and secondary granule fusion are controlled by a guanine nucleotidebinding protein and do not require an elevation of intracellular calcium. Calcium and other factors are, however, involved in the regulation having pronounced effects on the dynamics of exocytosis.

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Section: Discussionmentioning

confidence: 84%

Section: Discussionmentioning

confidence: 99%

The dynamics of exocytosis in human neutrophils.

Nüße

Lindau

1988

The Journal of Cell Biology

107

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“…These results, therefore, reveal that GTP-~,-S is able to relieve inhibition by PtX by dissociating the ADP-ribosylated G protein (16). A lack of sensitivity to PtX of any biochemical process, as determined in the presence of GTP-'y-S, therefore cannot be taken as an indication for the involvement of a PtX-insensitive G protein in this process (21): In agreement, PA formation and histamine secretion induced by an optimal dose of GTP-'y-S (0.1 mM) are both insensitive to PtX treatment (not shown). Figure 10.…”

Section: Effect Of Ptx On 48~80-activated Responses By Control and Gtmentioning

confidence: 90%

Exocytosis in mast cells by basic secretagogues: evidence for direct activation of GTP-binding proteins.

Aridor

Traub

Sagi‐Eisenberg

1990

The Journal of Cell Biology

166

105

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Abstract. Histamine release induced by the introduction of a nonhydrolyzable analogue of GTP, GTP-~/-S, into ATP-permeabilized mast cells, is associated with phosphoinositide breakdown, as evidenced by the production of phosphatidic acid (PA) in a neomycinsensitive process. The dependency of both PA formation and histamine secretion on GTP-3,-S concentrations is bell shaped. Whereas concentrations of up to 0.1 mM GTP-3,-S stimulate both processes, at higher concentrations the cells' responsiveness is inhibited. At a concentration of 1 mM, GTP-'r-S self-inhibits both PA formation and histamine secretion. Inhibition of secretion can, however, be overcome by the basic secretagogues compound 48/80 and mastoparan that in suboptimal doses synergize with 1 mM GTP-3,-S to potentiate secretion. Secretion under these conditions is not accompanied by PA formation and is resistant txoth to depletion of Ca 2+ from internal stores and to pertussis toxin (PtX) treatment. In addition, 48/80, like mastoparan, is capable of directly stimulating the GTPase activity of G-proteins in a cell-free system. Together, our results are consistent with a model in which the continuous activation of a phosphoinositidehydrolyzing phospholipase C (PLC) by a stimulatory G-protein suffices to trigger histamine secretion. Basic secretagogues of mast ceils, such as compound 48/80 and mastoparan, are capable of inducing secretion in a mechanism that bypasses PLC by directly activating a G-protein that is presumably located downstream from PLC (GE). Thereby, these secretagogues induce histamine secretion in a receptor-independent manner.

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“…A recent patch-clamp study (33) (33). This would suggest that the inhibitory effects of pertussis toxin on Ge may be more stringent with 48/80 stimulation and that higher concentrations or longer incubation periods are necessary to antagonize GTP[y-S]-induced secretion.…”

Section: Discussionmentioning

confidence: 99%