PrP(ST), a soluble, protease resistant and truncated PrP form features in the pathogenesis of a genetic prion disease.

While the conversion of PrP(C) into PrP(Sc) in the transmissible form of prion disease requires a preexisting PrP(Sc) seed, in genetic prion disease accumulation of disease related PrP could be associated with biochemical and metabolic modifications resulting from the designated PrP mutation. To investigate this possibility, we looked into the time related changes of PrP proteins in the brains of TgMHu2ME199K/wt mice, a line modeling for heterozygous genetic prion disease linked to the E200K PrP mutation. We found that while oligomeric entities of mutant E199KPrP exist at all ages, aggregates of wt PrP in the same brains presented only in advanced disease, indicating a late onset conversion process. We also show that most PK resistant PrP in TgMHu2ME199K mice is soluble and truncated (PrP(ST)), a pathogenic form never before associated with prion disease. We next looked into brain samples from E200K patients and found that both PK resistant PrPs, PrP(ST) as in TgMHu2ME199K mice, and "classical" PrP(Sc) as in infectious prion diseases, coincide in the patient's post mortem brains. We hypothesize that aberrant metabolism of mutant PrPs may result in the formation of previously unknown forms of the prion protein and that these may be central for the fatal outcome of the genetic prion condition

Correction: PrP^ST, a Soluble, Protease Resistant and Truncated PrP Form Features in the Pathogenesis of a Genetic Prion Disease

<p>Correction: PrP^ST, a Soluble, Protease Resistant and Truncated PrP Form Features in the Pathogenesis of a Genetic Prion Disease</p

PK-resistant PrP in light fractions of TgMHu2ME199K brain gradients.

<p>Sarkosyl extracted brain homogenates of sick TgMHu2ME199K/wt mice (in the figure: 9 month old score = 4) were subjected to ultracentrifugation in 10–60% sucrose gradients. Individual fractions were digested in the presence or absence of PK and immunoblotted with: (<b>a</b>) α-PrP mAb 6H4 and (<b>b</b>) α-PrP pAb RTC directed against the C-terminal end of PrP.</p

PrP forms in soluble and membranal brain fractions.

<p>(<b>a</b>) Fractionation protocol of brain homogenates. (<b>b</b>) Soluble and membranal brain fractions were digested in the presence and absence of PK and immunoblotted with two α-PrP c-terminal Ab; pAb RTC and mAb EP1802Y (EP) (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069583#pone-0069583-g002" target="_blank">figure 2a</a> for epitope mapping).</p

Similar disease kinetics and PrP accumulation in heterozygous and homozygous TgMH2ME199K mice.

<p>(<b>a</b>) The percentage of mice presenting a score <2 in both E199K/ko and E199K/wt lines as related to age. Median was 5.2±0.8 for TgMHu2ME199K/ko mice and 6.0±1.2 for TgMHu2ME199K/wt mice. (<b>b</b>) PK-resistant PrP levels are similar in both lines as related to age. Brain homogenates from both TgMHu2ME199K/KO and TgMHu2ME199K/wt lines in different ages and clinical stages (1 month, 3 months and 7 months, score = 0, score = 0 score = 3 respectively) as well as wt and scrapie RML controls were digested with PK and immunoblotted with α-PrP pAb RTC.</p

Aggregation of wt and mutant PrP in TgMHu2ME199K/wt mice.

<p>(<b>a</b>) <b>Epitope mapping of α-PrP antibodies:</b> epitopes of antibodies used in this manuscript are depicted on a schematic representation of the chimeric mouse-human E199K PrP. In the next panels (b &c) αPrP mAbs IPC1 and 3F4 were used to differentiate between wt PrP and chimeric-mutant PrP respectively. (<b>b</b>) <b>Oligomeric E199K PrP in asymptomatic TgMHu2ME199K/ko mice:</b> Sarkosyl extracted brain homogenates of wt and 3 months old (score = 0) TgMHu2ME199K/ko mouse were subjected to ultracentrifugation in 10–60% sucrose gradients <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0069583#pone.0069583-Tzaban1" target="_blank">[34]</a>. Individual fractions were immunoblotted with αPrP mAb IPC1 to detect wt PrP and αPrP mAb 3F4 to detect chimeric-mutant PrP. (<b>c</b>) <b>Oligomeric wt PrP in sick TgMHu2ME199K/wt mice.</b> Sarkosyl extracted brain homogenates from TgMHu2ME199K/wt mice at different ages (1 month, 3 months and 7 months, score = 0, score = 0 score = 3 respectively) were subjected to ultracentrifugation in 10–60% sucrose gradients. Individual fractions of each gradient were immunoblotted with mAb IPC1 to detect wt PrP and mAb 3F4 to detect chimeric-mutant PrP.</p