PrP expression, prions and disease.

<p>PrP is expressed by most cells (A) and is rather evenly distributed across the mouse brain (B). Surprisingly, PrDs may develop sporadically or be induced by mutations (C, orange color), but despite widespread expression, different regions are targeted in different familial PrDs (+) and the same is true for sporadic PrDs. Age-related effects likely permit disease-inducing prions to accumulate beyond a threshold that can be reversed in young but not old brains (D), which eventually leads to critical nucleation, followed by rapid replication and pathological changes (E). Data in (B) were obtained from the Allen Brain Atlas website (<a href="http://www.brain-map.org" target="_blank">www.brain-map.org</a>). Abbreviations: CTX, cortex; OLF, olfactory bulb; HPF, hippocampal formation; CTXsp, cortical subplate; STR, striatum; PAL, pallidum; TH, thalamus; HY, hypothalamus; MB, midbrain; P, pons; MY, medulla; CB, cerebellum. HPF is targeted in CJD mice, TH is targeted in FFI mice, and CB is targeted in both models.