ABSTRACT
Amyloid-ß (Aß) deposits are seen in aged individuals of many mammalian species that possess the same aminoacid sequence as humans. This study describes Aß deposition in 102 clinically characterized cattle brains from animals aged 0 to 20 years. Extracellular and intracellular Aß deposition was detected with 4G8 antibody in the cortex, hippocampus, and cerebellum. X-34 staining failed to stain Aß deposits, indicating the non ß-pleated nature of these deposits. Western blot analysis and surface-enhanced laser desorption/ionization time-of-flight (SELDI-TOF) mass spectrometry revealed in Tris, Triton, and formic acid fractions the presence of different Aß peptides, characterized mainly by C-terminally truncated forms. Exploration of the genetic variability of APOE, PSEN1, and PSEN2 genes involved in Alzheimer's disease pathogenesis revealed several previously unreported polymorphisms. This study demonstrates certain similarities between Aß deposition patterns exhibited in cattle brains and those in the human brain in early stages of aging. Furthermore, the identification of the same Aß peptides reported in humans, but unable to form aggregates, supports the hypothesis that cattle may be protected against amyloid plaque formation.
Subject(s)
Amyloid beta-Peptides/metabolism , Brain/metabolism , Aging/metabolism , Aging/pathology , Animals , Apolipoproteins E/genetics , Blotting, Western , Brain/growth & development , Brain/pathology , Cattle , Extracellular Space/metabolism , Gene Frequency , Genotyping Techniques , Glial Fibrillary Acidic Protein/metabolism , Immunohistochemistry , Intracellular Space/metabolism , Neuroglia/metabolism , Neuroglia/pathology , Neurons/metabolism , Neurons/pathology , Polymorphism, Genetic , Presenilin-1/genetics , Presenilin-2/genetics , Spectrometry, Mass, Matrix-Assisted Laser Desorption-IonizationABSTRACT
Prion protein (PrP) is present at extremely low levels in the blood of animals and its detection is complicated by the poor sensitivity of current standard methodologies. Interesting results have been obtained with recent advanced technologies that are able to detect minute amounts of the pathological PrP (PrPSc), but their efficiency is reduced by various factors present in blood. In this study, we were able to extract cellular PrP (PrPC) from plasma-derived exosomes by a simple, fast method without the use of differential ultracentrifugation and to visualize it by Western blotting, reducing the presence of most plasma proteins. This result confirms that blood is capable of releasing PrP in association with exosomes and could be useful to better study its role in the pathogenesis of transmissible spongiform encephalopathies.
