Comprendre le rôle du transporteur d'ADP/ATP dans la mort cellulaire – URAAPO

The mitochondrial ADP/ATP translocator (ANT) plays a central role in aerobic eukaryotic cells and can be involved in human pathologies. Four isoforms with tissue-specific expressions have been identified in humans. Based on cellular pharmacology, biochemistry and isoform-specific over-expression experiments, it has been hypothesized that ANT may participate in the formation of the mitochondrial permeability transition pore (PTP) and thereby may act as checkpoint in apoptosis, a programmed cell death process. However, this view has been strongly challenged by recent genetic evidence in mice conditionally inactivated for ANT1 and 2 in the liver. Consequently, the complete demonstration of ANTs central role in cell death remains a crucial basic question, which could be re-evaluated by original tools and a combination of multidisciplinary approaches. Thus, the partners of this project have carefully established original tools (siRNA, stable ANT-over expressing cell lines, new library of small cell permeant ANT-ligands) and assays (ADP/ATP translocation screening assay on isolated mitochondria, screening assays on genetically modified yeasts). Moreover, they are developing physico-chemical methods (biomimetic double membrane to reconstitute ANT-VDAC interaction, molecular docking in silico, medicinal chemistry and SAR, surface plasmon resonance). The combined use of these approaches constitutes a novel opportunity to determine: (1) the role of ADP/ATP translocator function of ANT in cell death mechanisms (apoptosis, autophagy, necrosis), (2) which ANT isoform (ANT-1, 2, -3, -4) participates in cell death, (3) the requirement of ANT-VDAC interactions for mitochondrial membrane permeabilization and cell death. The informations provided by these approaches will allow the identification of ANT isoform(s) as a potent therapeutic target. As a tool to answer to these basic questions, the partners will select and optimize the chemical structure of small ANT-ligands by medicinal chemistry and will improve their affinity for a given ANT isoform, to enhance translocase inhibition, and to modulate cell death. Moreover, in a pharmacological perspective, the best ANT-ligands will be evaluated for druggability (solubility, stability, formulation, and preliminary pharmacokinetics) to open the possibility of future efficacy studies in ad hoc animal models. We anticipate that the results will allow a better knowledge of the ANT isoforms role in apoptosis and contribute to the conception of novel compounds capable to modulate the ADP/ATP translocase function of ANT to modulate apoptosis in a therapeutic perspective.