title: Regulation of the ryanodine receptor by anti-apoptotic Bcl-2 is independent of its BH3-domain-binding properties.
abstract: The regulation of intracellular Ca(2+) signaling is an important aspect of how anti-apoptotic B-cell lymphoma 2 (Bcl-2) proteins regulate cell death and cell survival. At the endoplasmic reticulum (ER) the Bcl-2 homology (BH) 4 domain of Bcl-2 is known to bind to and inhibit both inositol 1,4,5-trisphosphate receptors (IP3Rs) and ryanodine receptors (RyRs). Besides this, drugs that target the hydrophobic cleft of Bcl-2 have been reported to deplete ER Ca(2+) stores in an IP3R- and RyR-dependent way. This suggests that the hydrophobic cleft of Bcl-2 may also be involved in regulating these ER-located Ca(2+)-release channels. However, the contribution of the hydrophobic cleft on the binding and regulatory properties of Bcl-2 to either IP3Rs or RyRs has until now not been studied. Here, the importance of the hydrophobic cleft of Bcl-2 in binding to and inhibiting the RyR was assessed by using a genetic approach based on site-directed mutagenesis of Bcl-2's hydrophobic cleft and a pharmacological approach based on the selective Bcl-2 hydrophobic cleft inhibitor, ABT-199. Both binding assays and single-cell Ca(2+) measurements indicated that RyR binding and the inhibition of RyR-mediated Ca(2+) release by Bcl-2 is independent of its hydrophobic cleft.
authors.affiliation: KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, B-3000 Leuven, Belgium.
authors.forename: Tim
authors.initials: T
authors.lastname: Vervliet
authors.affiliation: University of Gent, Cytokine Receptor Lab, VIB Department of Medical Protein Research, B-9000 Gent, Belgium.
authors.forename: Irma
authors.initials: I
authors.lastname: Lemmens
authors.affiliation: KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, B-3000 Leuven, Belgium.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Welkenhuyzen
authors.affiliation: University of Gent, Cytokine Receptor Lab, VIB Department of Medical Protein Research, B-9000 Gent, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Tavernier
authors.affiliation: KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, B-3000 Leuven, Belgium.
authors.forename: Jan B
authors.initials: JB
authors.lastname: Parys
authors.affiliation: KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, B-3000 Leuven, Belgium. Electronic address: geert.bultynck@med.kuleuven.be.
authors.forename: Geert
authors.initials: G
authors.lastname: Bultynck
mesh_terms: D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology; D020013:Calcium Signaling; D004721:Endoplasmic Reticulum / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D011485:Protein Binding; D060066:Protein Interaction Maps; D017434:Protein Structure, Tertiary; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000378:metabolism*; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism*; D013449:Sulfonamides / Q000494:pharmacology
chemical_list: D019086:Bridged Bicyclo Compounds, Heterocyclic; D019253:Proto-Oncogene Proteins c-bcl-2; D019837:Ryanodine Receptor Calcium Release Channel; D013449:Sulfonamides; C579720:venetoclax
keywords: ABT-199; B-cell lymphoma 2; BH3 mimetic; Hydrophobic cleft; P2A; Ryanodine receptors