Prions are self-propagating protein conformations. Recent research brought insight into prion propagation, but how they first appear is unknown. We previously established that the yeast non-Mendelian trait [PIN(+)] is required for the de novo appearance of the [PSI(+)] prion. Here, we show that the presence of prions formed by Rnq1 or Ure2 is sufficient to make cells [PIN(+)]. Thus, [PIN(+)] ca...

In the interspecies transmission of prions, the species barrier influences the susceptibility of the host. Bovine spongiform encephalopathy (BSE) prions affect a wide range of host species but do not affect hamsters. In order to study this species barrier, this study analysed the transmissibility of BSE prions to several lines of transgenic (Tg) mice, including those expressing mouse and hamste...

Three commonly used isolates of murine prions, 79A, 139A, and RML, were derived from the so-called Chandler isolate, which was obtained by propagating prions from scrapie-infected goat brain in mice. RML is widely believed to be identical with 139A; however, using the extended cell panel assay (ECPA), we here show that 139A and RML isolates are distinct, while 79A and RML could not be distingui...

In our previous study, we demonstrated the propagation of mouse-passaged scrapie isolates with long incubation periods (L-type) derived from natural Japanese sheep scrapie cases in murine hypothalamic GT1-7 cells, along with disease-associated prion protein (PrPSc) accumulation. We here analyzed the susceptibility of GT1-7 cells to scrapie prions by exposure to infected mouse brains at differen...

Prions are fascinating but often misunderstood protein aggregation phenomena. The traditional association of the mammalian prion protein with disease has overshadowed a potentially more interesting attribute of prions: their ability to create protein-based molecular memories. In fungi, prions alter the relationship between genotype and phenotype in a heritable way that diversifies clonal popula...

Budding yeast has dozens of prions, which are mutually dependent on each other for the de novo prion formation. In addition to the interactions among prions, transmissions of prions are strictly dependent on two chaperone systems: the Hsp104 and the Hsp70/Hsp40 (J-protein) systems, both of which cooperatively remodel the prion aggregates to ensure the multiplication of prion entities. Since it ...

The concept of a prion as an infectious self-propagating protein isoform was initially proposed to explain certain mammalian diseases. It is now clear that yeast also has heritable elements transmitted via protein. Indeed, the "protein only" model of prion transmission was first proven using a yeast prion. Typically, known prions are ordered cross-β aggregates (amyloids). Recently, there has be...

Prions are self-propagating protein conformers that cause a variety of neurodegenerative disorders in humans and animals. Mouse models have played key roles in deciphering the biology of prions and in assessing candidate therapeutics. The development of transgenic mice that form prions spontaneously in the brain has advanced our understanding of sporadic and genetic prion diseases. Furthermore,...

Diversity of prion strains was attributed to an elusive nucleic acid, yet a search spanning nearly two decades has failed to identify a prion-specific polynucleotide. In our search for a prion-specific nucleic acid, we analyzed nucleic acids in purified fractions from the brains of Syrian hamsters infected with Sc237 prions. Purification of Sc237 prions removed nucleic acids larger than 50 nucl...