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Passive calcium leak via translocon is a first step for iPLA2-pathway regulated store operated channels activation.

Abstract : Calcium concentration within the endoplasmic reticulum (ER) plays an essential role in cell physiopathology. One of the most enigmatic mechanisms responsible for Ca2+ concentration in the ER is passive calcium leak. Previous studies have shown that the translocon complex is permeable to calcium. However, the involvement of the translocon in the passive calcium leak has not been directly demonstrated. Furthermore, the question whether the passive store depletion via the translocon could activate SOC (store operated channels) replenishing the ER, remains still unresolved. In this study, for the first time, we show that thapsigargin and calcium chelators deplete ER via translocon. Indeed, using confocal imaging, we demonstrate that when the number of opened translocons was lowered neither thapsigargin nor calcium chelators could induce ER store depletion. We also demonstrate that calcium leakage occurring via the translocon activates store-operated current, which is, by its kinetic and pharmacology, similar to that evoked by thapsigargin and EGTA (but not IP3), thus highlighting our hypothesis that calcium leakage via the translocon is a first step for activation of the specific iPLA2-regulated SOC. As the translocon is present in yeast and mammalian cells, our findings suggest that translocon-related calcium signaling is a common phenomenon.
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https://www.hal.inserm.fr/inserm-00137702
Contributor : Matthieu Flourakis <>
Submitted on : Wednesday, March 21, 2007 - 1:31:14 PM
Last modification on : Thursday, February 21, 2019 - 10:34:03 AM
Long-term archiving on: : Friday, November 25, 2016 - 2:21:13 PM

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Matthieu Flourakis, Fabien van Coppenolle, V'Yacheslav Lehen'Kyi, Benjamin Beck, Roman Skryma, et al.. Passive calcium leak via translocon is a first step for iPLA2-pathway regulated store operated channels activation.. FASEB Journal, Federation of American Society of Experimental Biology, 2006, 20 (8), pp.1215-7. ⟨10.1096/fj.05-5254fje⟩. ⟨inserm-00137702⟩

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