文章基本信息

标题：Ryanodine receptors are targeted by anti-apoptotic Bcl-X_L involving its BH4 domain and Lys87 from its BH3 domain
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作者：Tim Vervliet ; Irma Lemmens ; Elien Vandermarliere 等
期刊名称：Scientific Reports
电子版ISSN：2045-2322
出版年度：2015
卷号：5
DOI：10.1038/srep09641
出版社：Springer Nature
摘要：Anti-apoptotic B-cell lymphoma 2 (Bcl-2) family members target several intracellular Ca²⁺-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-X_L, likely independently of its BH4 domain, sensitizes IP₃Rs. It remains elusive whether Bcl-X_L can also target and modulate RyRs. Here, Bcl-X_L co-immunoprecipitated with RyR3 expressed in HEK293 cells. Mammalian protein-protein interaction trap (MAPPIT) and surface plasmon resonance (SPR) showed that Bcl-X_L 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-X_L to bind to RyRs, loading the BH4-Bcl-X_L peptide into RyR3-overexpressing HEK293 cells or in rat hippocampal neurons suppressed RyR-mediated Ca²⁺ release. In silico superposition of the 3D-structures of Bcl-2 and Bcl-X_L indicated that Lys87 of the BH3 domain of Bcl-X_L could be important for interacting with RyRs. In contrast to Bcl-X_L, the Bcl-X_L^K87D mutant displayed lower binding affinity for RyR3 and a reduced inhibition of RyR-mediated Ca²⁺ release. These data suggest that Bcl-X_L binds to RyR channels via its BH4 domain, but also its BH3 domain, more specific Lys87, contributes to the interaction.