Intra- and interspecies interactions between prion proteins and effects of mutations and polymorphisms

Recently, crystallization of the prion protein in a dimeric form was reported. Here we show that native soluble homogenous FLAG-tagged prion proteins from hamster, man and cattle expressed in the baculovirus system are predominantly dimeric. The PrP/PrP interaction was confirmed in Semliki Forest virus-RNA transfected BHK cells co-expressing FLAG- and oligohistidine-tagged human PrP. The yeast two-hybrid system identified the octarepeat region and the C-terminal structured domain (aa90-aa230) of PrP as PrP/PrP interaction domains. Additional octarepeats identified in patients suffering from fCJD reduced (wtPrP versus PrP+90R) and completely abolished (PrP+90R versus PrP+90R) the PrP/PrP interaction in the yeast two-hybrid system. In contrast, the Met/Val polymorphism (aa129), the GSS mutation Pro102Leu and the FFI mutation Asp178Asn did not affect PrP/PrP interactions. Proof of interactions between human or sheep and bovine PrP, and sheep and human PrP, as well as lack of interactions between human or bovine PrP and hamster PrP suggest that interspecies PrP interaction studies in the yeast two-hybrid system may serve as a rapid pre-assay to investigate species barriers in prion diseases

Microscopie Pathology of the Gray Collie Syndrome; Cyclic Neutropenia, Amyloidosis, Enteritis, and Bone Necrosis

Microscopie changes in tissues of 8 dogs with the gray collie syndrome (GCS) and in 5 related non-gray dogs were described. Three of the GCS dogs died as neonates, 2 as puppies, and 3 (treated clinically) as adults. Clinical signs of disease were abnormal hair pigmentation, cyclic neutropenia, diarrhea, lameness, and chronic ulceration of oral and genital mucosa. Lesions included lymphoid atrophy, amyloidosis, enteritis, aseptic bone necrosis, and acute and chronic purulent inflammation of several organs. Abnormalities in serum included decreased albumin and increased γ- and α-globulin. Electron microscopy of the spleen revealed amyloid fibers deposited chiefly at the periphery of the splenic follicles and within the central artery. Tissues from non-gray related dogs were normal except for laminar malacia of the motor areas of the cerebral cortex in 3 of these dogs which probably resulted from ischemia due to epileptiform seizures. </jats:p