Cellular prion protein status in sheep: tissue-specific biochemical signatures

Expression of the cellular prion protein PrPC is sine qua none for the deve lopment of transmissible spongiform encephalopathy and thus for the accumul ation of the illness-associated conformer PrPSSc. Therefore, the tissue dis tribution of PrPC at the protein level in both quantitative and qualitative terms was investigated, PrPC was quantified using a two-site enzyme immuno metric assay which was calibrated with purified ovine recombinant prion pro tein (rPrP), The most PrPC-rich tissue was the brain, followed by the lungs , skeletal muscle, heart, uterus, thymus and tongue, which contained betwee n 20- and 50-fold less PrPC than the brain. The PrPC content of these tissu es seems to be comparable between sheep, Other organs, however, showed diff erent, but low, levels of the protein depending on the animal examined. Thi s was also the case for tissues from the gastrointestinal tract. The tissue containing the lowest concentration of PrPC was shown to be the liver, whe re PrPC was found to be between 564- and 16000-fold less abundant than in t he brain. PrPC was concentrated from crude cellular extracts by immunopreci pitation using several monoclonal and polyclonal anti-ovine PrP antibodies, Interestingly, it was observed that the isoform profile of PrPC was tissue -specific, The most atypical electrophoretic profile of PrPC was found in t he skeletal muscle, where two polypeptides of 32 and 35 kDa were detected.