Voltage-dependent anion channel 1-based peptides interact with hexokinase to prevent its anti-apoptotic activity.
In brain and tumor cells, the hexokinase isoforms, HK-I and HK-II, bind to the voltage-dependent anion channel (VDAC) in the outer mitochondrial membrane. The VDAC domains interacting with these anti-apoptotic proteins were recently defined using site-directed mutagenesis. Now, we demonstrate that synthetic peptides corresponding to the VDAC1 N-terminal region and selected sequences bound specifically, in a concentration- and time-dependent manner, to immobilized HK-I, as revealed by real time surface plasmon resonance technology. The same VDAC1-based peptides also detached HK bound to brain or tumor-derived mitochondria. Moreover, expression of the VDAC1-based peptides in cells overexpressing HK-I or HK-II prevented HK-mediated protection against staurosporine-induced release of cytochrome c and subsequent cell death. One loop-shaped VDAC1-based peptide corresponding to a selected sequence and fused to a cell-penetrating peptide entered the cell and prevented the anti-apoptotic effects of HK-I and HK-II. This peptide detached mitochondrial-bound HK better than did the same peptide in its linear form. Both cell-expressed and exogenously added cell-penetrating peptide detached mitochondrial-bound HK-I-GFP. These results point to HK-I and HK-II as promoting tumor cell survival through binding to VDAC1, thereby inhibiting cytochrome c release and apoptotic cell death. Moreover, VDAC1-based peptides interfering with HK-mediated anti-apoptotic activity may potentiate the efficacy of conventional chemotherapeutic agents.
Arzoine
Laetitia
L
Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel 84105.
Zilberberg
Noam
N
Ben-Romano
Ronit
R
Shoshan-Barmatz
Varda
V
D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006593:Hexokinase / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D009928:Organ Specificity; D010455:Peptides / Q000737:chemistry / Q000494:pharmacology*; D019311:Staurosporine / Q000494:pharmacology; D050995:Voltage-Dependent Anion Channel 1 / Q000737:chemistry / Q000378:metabolism*
D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D010455:Peptides; C494762:VDAC1 protein, human; C494763:Vdac1 protein, mouse; D045304:Cytochromes c; D050995:Voltage-Dependent Anion Channel 1; C472074:HK1 protein, human; C515658:HK1 protein, mouse; D006593:Hexokinase; D019311:Staurosporine