title: Mediation of the antiapoptotic activity of Bcl-xL protein upon interaction with VDAC1 protein.
abstract: The mitochondrial protein, the voltage-dependent anion channel (VDAC), is implicated in the control of apoptosis, including via its interaction with the pro- and antiapoptotic proteins. We previously demonstrated the direct interaction of Bcl2 with VDAC, leading to reduced channel conductance. VDAC1-based peptides interacted with Bcl2 to prevent its antiapoptotic activity. Here, using a variety of approaches, we show the interaction of the antiapoptotic protein, Bcl-xL, with VDAC1 and reveal that this interaction mediates Bcl-xL protection against apoptosis. C-terminally truncated Bcl-xL(Δ21) interacts with purified VDAC1, as revealed by microscale thermophoresis and as reflected in the reduced channel conductivity of bilayer-reconstituted VDAC1. Overexpression of Bcl-xL prevented staurosporine-induced apoptosis in cells expressing native VDAC1 but not certain VDAC1 mutants. Having identified mutations in VDAC1 that interfere with the Bcl-xL interaction, certain peptides representing VDAC1 sequences, including the N-terminal domain, were designed and generated as recombinant and synthetic peptides. The VDAC1 N-terminal region and two internal sequences were found to bind specifically, and in a concentration- and time-dependent manner, to immobilized Bcl-xL(Δ21), as revealed by surface plasmon resonance. Moreover, expression of the recombinant peptides in cells overexpressing Bcl-xL prevented protection offered by the protein against staurosporine-induced apoptosis. These results point to Bcl-xL acting as antiapoptotic protein, promoting tumor cell survival via binding to VDAC1. These findings suggest that interfering with Bcl-xL binding to the mitochondria by VDAC1-based peptides may serve to induce apoptosis in cancer cells and to potentiate the efficacy of conventional chemotherapeutic agents.
authors.affiliation: Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
authors.forename: Nir
authors.initials: N
authors.lastname: Arbel
authors.forename: Danya
authors.initials: D
authors.lastname: Ben-Hail
authors.forename: Varda
authors.initials: V
authors.lastname: Shoshan-Barmatz
mesh_terms: D017209:Apoptosis / Q000502:physiology*; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D057809:HEK293 Cells; D006801:Humans; D008928:Mitochondria / Q000502:physiology; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000503:physiopathology*; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000235:genetics / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D034741:RNA, Small Interfering / Q000235:genetics; D020349:Surface Plasmon Resonance; D050995:Voltage-Dependent Anion Channel 1 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051020:bcl-X Protein / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
chemical_list: C494811:BCL2L1 protein, human; D010446:Peptide Fragments; D034741:RNA, Small Interfering; C494762:VDAC1 protein, human; D051020:bcl-X Protein; D050995:Voltage-Dependent Anion Channel 1