title: Ryanodine receptors are targeted by anti-apoptotic Bcl-XL involving its BH4 domain and Lys87 from its BH3 domain.
abstract: Anti-apoptotic B-cell lymphoma 2 (Bcl-2) family members target several intracellular Ca(2+)-transport systems. Bcl-2, via its N-terminal Bcl-2 homology (BH) 4 domain, inhibits both inositol 1,4,5-trisphosphate receptors (IP3Rs) and ryanodine receptors (RyRs), while Bcl-XL, likely independently of its BH4 domain, sensitizes IP3Rs. It remains elusive whether Bcl-XL can also target and modulate RyRs. Here, Bcl-XL co-immunoprecipitated with RyR3 expressed in HEK293 cells. Mammalian protein-protein interaction trap (MAPPIT) and surface plasmon resonance (SPR) showed that Bcl-XL bound to the central domain of RyR3 via its BH4 domain, although to a lesser extent compared to the BH4 domain of Bcl-2. Consistent with the ability of the BH4 domain of Bcl-XL to bind to RyRs, loading the BH4-Bcl-XL peptide into RyR3-overexpressing HEK293 cells or in rat hippocampal neurons suppressed RyR-mediated Ca(2+) release. In silico superposition of the 3D-structures of Bcl-2 and Bcl-XL indicated that Lys87 of the BH3 domain of Bcl-XL could be important for interacting with RyRs. In contrast to Bcl-XL, the Bcl-XL(K87D) mutant displayed lower binding affinity for RyR3 and a reduced inhibition of RyR-mediated Ca(2+) release. These data suggest that Bcl-XL binds to RyR channels via its BH4 domain, but also its BH3 domain, more specific Lys87, contributes to the interaction.
authors: KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, B-3000 Leuven, Belgium.
authors: Tim
authors: T
authors: Vervliet
authors: University of Gent, Cytokine Receptor Lab, VIB Department of Medical Protein Research, B-9000 Gent, Belgium.
authors: Irma
authors: I
authors: Lemmens
authors: University of Gent, Computational Omics and Systems Biology Group, VIB Department of Medical Protein Research, B-9000 Gent, Belgium.
authors: Elien
authors: E
authors: Vandermarliere
authors: University of Gent, Physiology Group, Department of Basic Medical Sciences, B-9000 Gent, Belgium.
authors: Elke
authors: E
authors: Decrock
authors: KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, B-3000 Leuven, Belgium.
authors: Hristina
authors: H
authors: Ivanova
authors: KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, B-3000 Leuven, Belgium.
authors: Giovanni
authors: G
authors: Monaco
authors: University of Siena, Molecular Medicine Section, Department of Molecular and Developmental Medicine, and Interuniversitary Institute of Myology, 53100 Siena, Italy.
authors: Vincenzo
authors: V
authors: Sorrentino
authors: Radboud University Medical Center, Donders Institute for Brain, Cognition and Behaviour, Department of Cognitive Neuroscience, Department of Human Genetics, 6500HB Nijmegen, The Netherlands.
authors: Nael
authors: N
authors: Nadif Kasri
authors: KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, B-3000 Leuven, Belgium.
authors: Ludwig
authors: L
authors: Missiaen
authors: University of Gent, Computational Omics and Systems Biology Group, VIB Department of Medical Protein Research, B-9000 Gent, Belgium.
authors: Lennart
authors: L
authors: Martens
authors: KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, B-3000 Leuven, Belgium.
authors: Humbert
authors: H
authors: De Smedt
authors: University of Gent, Physiology Group, Department of Basic Medical Sciences, B-9000 Gent, Belgium.
authors: Luc
authors: L
authors: Leybaert
authors: KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, B-3000 Leuven, Belgium.
authors: Jan B
authors: JB
authors: Parys
authors: University of Gent, Cytokine Receptor Lab, VIB Department of Medical Protein Research, B-9000 Gent, Belgium.
authors: Jan
authors: J
authors: Tavernier
authors: KU Leuven, Laboratory of Molecular and Cellular Signaling, Department of Cellular and Molecular Medicine, B-3000 Leuven, Belgium.
authors: Geert
authors: G
authors: Bultynck
mesh_terms: D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D009154:Mutation; D011485:Protein Binding; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs / Q000235:genetics; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry / Q000378:metabolism*; D051020:bcl-X Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: D019837:Ryanodine Receptor Calcium Release Channel; D051020:bcl-X Protein; D002118:Calcium