Next-generation Cu(II) selective peptide shuttles prevent Cu(Aβ)-induced toxicity and microglial activation in organotypic hippocampal slices

Alzheimers disease (AD) remains the most prevalent neurodegenerative disease characterized by intracellular neurofibrillary tangles of Tau protein and extracellular senile plaques build on Amyloid-{beta} (A{beta}) peptides. The latter result from an abnormal processing of Amyloid Precursor Protein (APP) leading to its accumulation in plaques. Ex vivo analyses of AD patients brains show an abnormally elevated concentration of metals including Cu, Zn and Fe within these plaques. Altered Cu levels have also been reported in brain regions most affected in AD. These modifications are often accompanied by reduced neuronal Cu levels and by an increased pool of extracellular labile Cu, which in turn promotes reactive oxygen species (ROS) formation. To counteract this Cu dyshomeostasis and limit Cu-A{beta}-induced extracellular ROS generation, we designed and synthesized two Cu(II)-selective peptide shuttles based on kinetically optimized ATCUN sequences for fast Cu(II) extraction out of A{beta}: DapHH-R5W4NBD and HDapH-R5W4NBD. They were also equipped with a fluorophore that showed a very strong response to Cu(II)-binding and release. Interestingly, these two Cu(II) shuttles displayed a dual mode of action. They promptly retrieve Cu from extracellular A{beta}, stop the associated ROS formation, and hence protect both cell culture models and organotypic hippocampal slices (OHSCs) from Cu(A{beta})-induced neurotoxicity. Moreover, these shuttles import and redistribute bioavailable Cu inside cells with a sequence-dependent kinetics.