Subcellular localization of disease-associated prion protein in the human brain

Disease-associated prion protein (PrPTSE) deposits in distinct immunostaining patterns in the brain in Creutzfeldt-jakob disease, including synaptic, extracellular, and cell-associated localizations. After having developed an appropriate pretreatment protocol to enhance immunostaining for PrPTSE without damaging epitopes of other antigens, we systematically evaluated co-localization patterns of distinct PrPTSE immunodeposits by confocal laser microscopy, including optical serial sectioning. As shown by quantification, the most prominent co-localization of PrPTSE is with synaptophysin, but PrPTSE may also co-deposit with connexin-32, a gap junction-related protein. Furthermore, neuronal cell bodies, dendrites, axons, astrocytes, and microglia harbor granular PrPTSE deposits. Highly aggregated deposits are focally ubiquitinated. We conclude that PrPTSE E is not exclusively associated with chemical but also with electric synapses, axonal transport may be a relevant route of PrPTSE spread in the brain, and activated microglia and astrocytes may play a role in PrPTSE processing, degradation, or removal.