Prion diseases are fatal, progressive, neurodegenerative diseases caused by prion accumulation in the brain and lymphoreticular system. Here we report that a single subcutaneous injection of cellulose ethers (CEs), which are commonly used as inactive ingredients in foods and pharmaceuticals, markedly prolonged the lives of mice and hamsters intracerebrally or intraperitoneally infected with the 263K hamster prion. CEs provided sustained protection even when a single injection was given as long as one year before infection. These effects were linked with persistent residues of CEs in various tissues. More effective CEs had less macrophage uptake ratios and hydrophobic modification of CEs abolished the effectiveness. CEs were significantly effective in other prion disease animal models; however, the effects were less remarkable than those observed in the 263K prion-infected animals. The genetic background of the animal model was suggested to influence the effects of CEs. CEs did not modify prion protein expression but inhibited abnormal prion protein formation in vitro and in prion-infected cells. Although the mechanism of CEs in vivo remains to be solved, these findings suggest that they aid in elucidating disease susceptibility and preventing prion diseases.

A new type of antiprion compound, Gly-9, was found to inhibit abnormal prion protein formation in prion-infected neuroblastoma cells, in a prion strain-independent manner, when the cells were treated for more than 1 day. It reduced the intracellular prion protein level and significantly modified mRNA expression levels of genes of two types: interferon-stimulated genes were downregulated after more than 2 days of treatment, and the phosphodiesterase 4D-interacting protein gene, a gene involved in microtubule growth, was upregulated after more than 1 day of treatment. A supplement of interferon given to the cells partly restored the abnormal prion protein level but did not alter the normal prion protein level. This interferon action was independent of the Janus activated kinase-signal transducer and activator of transcription signaling pathway. Therefore, the changes in interferon-stimulated genes might be a secondary effect of Gly-9 treatment. However, gene knockdown of phosphodiesterase 4D-interacting protein restored or increased both the abnormal prion protein level and the normal prion protein level, without transcriptional alteration of the prion protein gene. It also altered the localization of abnormal prion protein accumulation in the cells, indicating that phosphodiesterase 4D-interacting protein might affect prion protein levels by altering the trafficking of prion protein-containing structures. Interferon and phosphodiesterase 4D-interacting protein had no direct mutual link, demonstrating that they regulate abnormal prion protein levels independently. Although the in vivo efficacy of Gly-9 was limited, the findings for Gly-9 provide insights into the regulation of abnormal prion protein in cells and suggest new targets for antiprion compounds. IMPORTANCEThis report describes our study of the efficacy and potential mechanism underlying the antiprion action of a new antiprion compound with a glycoside structure in prion-infected cells, as well as the efficacy of the compound in prion-infected animals. The study revealed involvements of two factors in the compound's mechanism of action: interferon and a microtubule nucleation activator, phosphodiesterase 4D-interacting protein. In particular, phosphodiesterase 4D-interacting protein was suggested to be important in regulating the trafficking or fusion of prion protein-containing vesicles or structures in cells. The findings of the study are expected to be useful not only for the elucidation of cellular regulatory mechanisms of prion protein but also for the implication of new targets for therapeutic development.

Dietary seaweed fucoidan delays the onset of disease of enterally infected mice with scrapie when given orally for 6 days after infection, but not when given before the infection. This effect was not modified at a tested fucoidan dose range and appeared to reach the maximum level at a concentration of 2.5% or less in feed. Daily uptake of fucoidan might be prophylactic against prion diseases caused by ingestion of prion-contaminated materials, although further evaluation of its pharmacology remains to be done.Transmissible spongiform encephalopathies, or prion diseases, are fatal neurodegenerative disorders that include Creutzfeldt-Jakob disease (CJD) and Gerstmann-Sträussler-Scheinker syndrome in humans and scrapie, bovine spongiform encephalopathy (BSE), and chronic wasting disease in animals. Recent outbreaks of BSE and variant CJD (vCJD), both of which are considered to occur through ingestion of BSE-contaminated materials (reviewed in reference 21), have necessitated the development of preventive measures against these diseases.Sulfated polysaccharides, such as heparin, dextran sulfate, and pentosan polysulfate (PPS), are known either to prolong incubation periods in animals with prion diseases or to inhibit formation of pathogen-related abnormal prion protein (PrP) in prion-infected cells (reviewed in reference 3). Their therapeutic effects are attributed to inhibition of the conversion of normal PrP to abnormal PrP by either competitively binding to the normal PrP (4) or reducing normal PrP on the cell surface through stimulation of endocytosis (20). These large-molecule compounds are not taken up well from the gut to blood or from blood to the brain (a target organ of prion diseases). Therefore, these compounds are effective in cases of peripheral infection when given intraperitoneally, intravenously, or subcutaneously (8) and even in cases of intracranial infection when given intracerebroventricularly (5). Recently, PPS intracerebroventricular injection has been utilized for clinical trials of patients; the clinical outcome remains to be determined (17).Fucoidans, complex sulfated fucosylated polysaccharides, are known to have various biological activities: anticoagulant, antiviral, antiparasital, anti-inflammatory, contraceptive, and so on, because of their ability to imitate patterns of sulfate substitution on glycosaminoglycans and other sulfated glycans (2). Some fucoidans are present in large quantities in dietary brown seaweed food products, which are eaten frequently in Asian countries (9). Here, we report that fucoidan from popularly eaten brown algae has antiprion activity and delays disease onset when it is ingested after the enteral prion infection.Fucoidan was prepared from the brown seaweed Cladosiphon okamuranus Tokida (Fig. 1A) and subsequently tested as described previously (15). Briefly, the brown seaweed was suspended in distilled water adjusted to pH 3.0 with 30% HCl and heated at 100°C for 30 or 60 min. The suspension was centrifuged (10,000 ϫ g) at room temperature, and the supernat...

Various proteins are modified post-translationally to localize them at the cell membrane. Among them, hedgehog-family proteins are modified by cholesterol at the C-terminal. In this study, green fluorescent protein (GFP) modified with cholesterol (GFP-Chol) at the C-terminal was prepared semisynthetically and investigated. This semi-synthesis was performed using the following native chemical ligation: GFP-Cα-thioester was prepared using the intein-mediated thioester exchange reaction and was ligated to Cys-NH-diethylene glycol-NHCO-cholesterol in the presence of a detergent. After removal of the detergent, the GFP-Chol was applied to mouse live cells. Confocal laser fluorescent microscopy confirmed localization of GFP-Chol at the cell membrane. The findings suggest that modifying proteins with cholesterol at the C-terminal is useful for targeting the proteins to the cell membrane of live cells.

Our previous study on prion-infected rodents revealed that hydroxypropyl methylcellulose compounds (HPMCs) with different molecular weights but similar composition and degree of substitution have different levels of long-lasting anti-prion activity. In this study, we searched these HPMCs for a parameter specifically associated with in vivo anti-prion activity by analyzing in vitro chemical properties and in vivo tissue distributions. Infrared spectroscopic and thermal analyses revealed no differences among HPMCs, whereas pyrene conjugation and spectroscopic analysis revealed that the fluorescence intensity ratio of peak III/peak I correlated with anti-prion activity. This correlation was more clearly demonstrated in the anti-prion activity of the 1-year pre-infection treatment than that of the immediate post-infection treatment. In addition, the intensity ratio of peak III/peak I negatively correlated with the macrophage uptake level of HPMCs in our previous study. However, the in vivo distribution pattern was apparently not associated with anti-prion activity and was different in the representative tissues. These findings suggest that pyrene conjugation and spectroscopic analysis are powerful methods to successfully demonstrate local dielectric differences in HPMCs and provide a feasible parameter denoting the long-lasting anti-prion activity of HPMCs in vivo.