Prion protein with an E200K mutation displays properties similar to those of the cellular isoform PrP^C

Abstract

Creutzfeldt±Jakob disease (CJD) in Libyan Jews, linked to the E200K mutation in PRNP (E200KCJD), is the most prevalent of the inherited prion diseases. As other prion diseases, E200KCJD is characterized by the brain accumulation of PrP Sc , a pathologic conformational isoform of a normal glycoprotein denominated PrP C . To investigate whether the E200K mutation is enough to de novo confer PrP Sc properties to mutant PrP, as suggested by experiments in Chinese hamster ovary cells, we examined the biochemical behavior of E200KPrP in brains and ®broblasts from sporadic as well as homozygous and heterozygous E200KCJD patients, asymptomatic transgenic mice carrying the E200K mutation, as well as in normal and scrapie-infected mouse neuroblastoma cells expressing E200KPrP. E200KPrP was examined for protease sensitivity, solubility in detergents, releasibility by phosphoinositol phospholypase-C and localization in cholesterol enriched membrane microdomains (rafts). In all tissues except in brains of CJD patients and ScN2a cells, E200KPrP displayed properties similar to those of PrP C . Our results indicate that the E200K mutation does not automatically convey the properties of PrP Sc to new PrP molecules. A conversion process occurs mainly in the prion disease affected brain, suggesting the presence of a tissue-speci®c or age-dependent factor, in accord with the late onset nature of inherited CJD.

PrPST, a Soluble, Protease Resistant and Truncated PrP Form Features in the Pathogenesis of a Genetic Prion Disease

“…It was found to be either readily digested by PK or otherwise resistant to marginal PK concentrations [22], [23]. Interestingly, E200K PrP in recombinant form is spontaneously oxidized in its helix 3 methionine residues, a covalent modification which precedes the conversion of PrP C into PrP Sc [24].…”

Prion protein with an octapeptide insertion has impaired neuroprotective activity in transgenic mice

“…These results would seem to indicate that E200K, in contrast to PG14, does not impair the physiological activity of PrP. However, it is noteworthy that E200K transgenic mice do not become ill like Tg(PG14) mice, and the mutant PrP found in their brains is not aggregated or protease‐resistant like PG14 PrP (Telling et al , 1996; Rosenmann et al , 2001). Thus, the functional activity of E200K PrP in transgenic mice may result from the large proportion of the protein that remains soluble and protease sensitive in the brains of these animals.…”

Selective Processing and Metabolism of Disease-Causing Mutant Prion Proteins

“…In other cases, different studies examining the same or related mutants come to diametrically opposite conclusions about what is aberrant [16],[24]. Thus, the conclusions from these mutant studies are rather diverse and range from no identifiable effects [25],[26] to nearly quantitative and dramatically abnormal processing [13],[27], sometimes for the same mutant. Which, if any, of these alterations might actually contribute to disease progression versus representing innocuous or even adaptive changes, remains difficult to discern.…”