Microdeletions within the hydrophobic core region of cellular prion protein alter its topology and metabolism

Diverse functions of the prion protein - Does proteolytic processing hold the key?

Proteolytic processing of the cellular and disease-associated form of the prion protein leads to generation of bioactive soluble prion protein fragments and modifies the structure and function of its cell-bound form. The nature of proteases responsible for shedding, α-, β-, and γ-cleavage of the prion protein are only partially identified and their regulation is largely unknown. Here, we provide an overview of the increasingly multifaceted picture of prion protein proteolysis and shed light on physiological and pathological roles associated with these cleavages. This article is part of a Special Issue entitled: Proteolysis as a Regulatory Event in Pathophysiology edited by Stefan Rose-John.

(Ctm)PrP and ER stress: a neurotoxic mechanism of some special PrP mutants

The pathogenic agent is hypothesized to be PrP(Sc) in prion diseases. However, little accumulation of PrPSc is repeatedly observed in some kinds of natural and experimental prion diseases, including some special genetic human prion diseases. One of the specific topology forms of PrP, (Ctm)PrP, representing a key neurotoxic intermediate in prion disorders, has been testified in cell-free translation systems and transgenic mice models. Recently, some studies have showed that point-mutations within the hydrophobic transmembrane region increase the amount of (Ctm)PrP in cells, such as human homologue A117V which is associated with GSS and G114V associated with gCJD, while the mutations outsides transmembrane region do not. The retention of the CtmPrP in ER subsequently is able to induce ER stress and apoptosis, which is supported by up-regulation of ER chaperone synthesis, such as Grp78, Grp58, Grp94, Bip and the transcription factor CHOP/GADD153. In conclusion, some kinds of intermediate forms of PrP(Sc) , including (Ctm)PrP, may work as the ultimate cause of neurodegeneration.