Inositol 1,4,5-trisphosphate (InsP3) receptors (InsP3Rs) are channels responsible for calcium release from the endoplasmic reticulum (ER). We show that the anti-apoptotic protein Bcl-2 (either wild type or selectively localized to the ER) significantly inhibited InsP3-mediated calcium release and elevation of cytosolic calcium in WEHI7.2 T cells. This inhibition was due to an effect of Bcl-2 at the level of InsP3Rs because responses to both anti-CD3 antibody and a cell-permeant InsP3 ester were decreased. Bcl-2 inhibited the extent of calcium release from the ER of permeabilized WEHI7.2 cells, even at saturating concentrations of InsP3, without decreasing luminal calcium concentration. Furthermore, Bcl-2 reduced the open probability of purified InsP3Rs reconstituted into lipid bilayers. Bcl-2 and InsP3Rs were detected together in macromolecular complexes by coimmunoprecipitation and blue native gel electrophoresis. We suggest that this functional interaction of Bcl-2 with InsP3Rs inhibits InsP3R activation and thereby regulates InsP3-induced calcium release from the ER.
Bcl-2 functionally interacts with inositol 1,4,5-trisphosphate receptors to regulate calcium release from the ER in response to inositol 1,4,5-trisphosphate
Abbreviations used in this paper: BN-PAGE, blue native–PAGE; ECB, extracellular buffer; D-myo InsP3BM, D-myo InsP3 hexakisbutyryloxymethyl ester; ICB, intracellular buffer; IL-2, interleukin-2; InsP3, inositol 1,4,5-trisphosphate; InsP3R, InsP3 receptor; TCR, T cell receptor; TG, thapsigargin; TMRE, tetramethylrhodamine ethyl ester.
Rui Chen, Ignacio Valencia, Fei Zhong, Karen S. McColl, H. Llewelyn Roderick, Martin D. Bootman, Michael J. Berridge, Stuart J. Conway, Andrew B. Holmes, Gregory A. Mignery, Patricio Velez, Clark W. Distelhorst; Bcl-2 functionally interacts with inositol 1,4,5-trisphosphate receptors to regulate calcium release from the ER in response to inositol 1,4,5-trisphosphate . J Cell Biol 19 July 2004; 166 (2): 193–203. doi: https://doi.org/10.1083/jcb.200309146
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