Cross-linking experiments support a physical interaction between the depression-related serotonin transporter and the Alzheimer disease-related β-amyloid peptide

Alzheimer’s disease has been shown to cause an intracellular accumulation of toxic β-amyloids (Aβ) . While it is still unknown how, this accumulation may alter the Serotonin transporter (5-HTT). We hypothesise that Aβ may interact directly with the 5-HTT. In this study, HEK293 cells were treated with antidepressants and cross-linked, using disuccinimidyl suberate (DSS) as a membrane-permeable reagent and bis[sulfosuccinimidyl] suberate (BS3) as a membrane-impermeable reagent, useful for cell-surface protein cross-linking. We then performed a sequential immunoprecipitation (IP) using the 22C11, C-Term, 6E10 and 4G8 antibodies, in that order, to progressively isolate the full length amyloid precursor proteins (APP) and related fragments and specify on which portion of the APP molecule the 5-HTT may be interacting with. Finally, the samples were run on a western blot and then imaged. This study shows that there is physical interaction between the Aβ and the 5-HTT. With this information further studies into the mechanism of this interaction can be justified.