Cholesterol Depletion Inhibits Store-Operated Calcium Currents and Exocytotic Membrane Fusion in RBL-2H3 Cells
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- 作者：Naoto Kato ; Mamoru Nakanishi ; and Naohide Hirashima
- 刊名：Biochemistry
- 出版年：2003
- 出版时间：October 14, 2003
- 年：2003
- 卷：42
- 期：40
- 页码：11808 - 11814
- 全文大小：127K
- 年卷期：v.42,no.40(October 14, 2003)
- ISSN：1520-4995
文摘
The effects of cholesterol depletion from the plasma membrane with methyl-
-cyclodextrin(MCD) on exocytotic processes were investigated in rat basophil leukemia cells (RBL-2H3 cells).Pretreatment of the cells with MCD inhibited antigen-evoked exocytotic release dose-dependently. Toelucidate the mechanism of this inhibition, we performed experiments on the effects of MCD on exocytoticmembrane fusion and mobilization of Ca2+ and on the localization of the tyrosine kinase Lyn. Inhibitionof degranulation by MCD was observed even under stimulation with the phorbol ester and calciumionophore. Therefore, MCD affected a process downstream of Ca2+ influx, or membrane fusion betweenthe granule and the plasma membrane. Intracellular calcium measurements revealed that MCD inhibitedthe Ca2+ increase induced by antigen. Furthermore, we found that MCD significantly inhibited Ca2+influx from the extracellular medium through the store-operated calcium channel (SOC) but did not affectCa2+ release from the intracellular Ca2+ store. Fluorescent image analysis of cells expressing Lyn-YFPshowed that treatment with MCD scarcely affected the localization and lateral mobility of Lyn in theplasma membrane. These results suggest that cholesterol depletion by MCD decreases degranulationmainly by inhibiting the SOC and membrane fusion between the secretory granules and the plasmamembrane in mast cells.
-cyclodextrin(MCD) on exocytotic processes were investigated in rat basophil leukemia cells (RBL-2H3 cells).Pretreatment of the cells with MCD inhibited antigen-evoked exocytotic release dose-dependently. Toelucidate the mechanism of this inhibition, we performed experiments on the effects of MCD on exocytoticmembrane fusion and mobilization of Ca2+ and on the localization of the tyrosine kinase Lyn. Inhibitionof degranulation by MCD was observed even under stimulation with the phorbol ester and calciumionophore. Therefore, MCD affected a process downstream of Ca2+ influx, or membrane fusion betweenthe granule and the plasma membrane. Intracellular calcium measurements revealed that MCD inhibitedthe Ca2+ increase induced by antigen. Furthermore, we found that MCD significantly inhibited Ca2+influx from the extracellular medium through the store-operated calcium channel (SOC) but did not affectCa2+ release from the intracellular Ca2+ store. Fluorescent image analysis of cells expressing Lyn-YFPshowed that treatment with MCD scarcely affected the localization and lateral mobility of Lyn in theplasma membrane. These results suggest that cholesterol depletion by MCD decreases degranulationmainly by inhibiting the SOC and membrane fusion between the secretory granules and the plasmamembrane in mast cells.