Developmental changes in cellular prion protein in primate visual cortex

Mapping the prion protein distribution in marsupials: insights from comparing opossum with mouse CNS

The cellular form of the prion protein (PrP^C) is a sialoglycoprotein widely expressed in the central nervous system (CNS) of mammalian species during neurodevelopment and in adulthood. The location of the protein in the CNS may play a role in the susceptibility of a species to fatal prion diseases, which are also known as the transmissible spongiform encephalopathies (TSEs). To date, little is known about PrP^C distribution in marsupial mammals, for which no naturally occurring prion diseases have been reported. To extend our understanding of varying PrP^C expression profiles in different mammals we carried out a detailed expression analysis of PrP^C distribution along the neurodevelopment of the metatherian South American short-tailed opossum (Monodelphis domestica). We detected lower levels of PrP^C in white matter fiber bundles of opossum CNS compared to mouse CNS. This result is consistent with a possible role for PrP^C in the distinct neurodevelopment and neurocircuitry found in marsupials compared to other mammalian species.

The cellular prion protein and its role in Alzheimer disease

The cellular prion protein (PrP(C)) is a membrane-bound glycoprotein especially abundant in the central nervous system (CNS). The scrapie prion protein (PrP(Sc,) also termed prions) is responsible of transmissible spongiform encephalopathies (TSE), a group of neurodegenerative diseases which affect humans and other mammal species, although the presence of PrP(C) is needed for the establishment and further evolution of prions. The present work compares the expression and localization of PrP(C) between healthy human brains and those suffering from Alzheimer disease (AD). In both situations we have observed a rostrocaudal decrease in the amount of PrP(C) within the CNS, both by immunoblotting and immunohistochemistry techniques. PrP(C) is higher expressed in our control brains than in AD cases. There was a neuronal loss and astogliosis in our AD cases. There was a tendency of a lesser expression of PrP(C) in AD cases than in healthy ones. And in AD cases, the intensity of the expression of the unglycosylated band is higher than the di- and monoglycosylated bands. With regards to amyloid plaques, those present in AD cases were positively labeled for PrP(C), a result which is further supported by the presence of PrP(C) in the amyloid plaques of a transgenic line of mice mimicking AD. The work was done according to Helsinki Declaration of 1975, and approved by the Ethics Committee of the Faculty of Medicine of the University of Navarre.