Understanding Factors Influencing The Propagation of Prions

Prions are altered conformations of a protein that have gained the ability to convert the normal form of the protein into the prion form. They are an infectious, misfolded and aggregated form of a protein. In mammals, prions are associated with neurodegenerative diseases that can be passed from one organism to another. Recent evidence has shown that the prion phenomenon is not limited to mammals but extends to yeast. We have investigated if any genes affect the propagation of the yeast prion [PIN+] and found that only two previously known deletions (rnq1 and hsp104) abolish [PIN+] maintenance. However, a deletion of CUE2, a gene implicated in the ubiquitin pathway, shows an altered [PIN+] phenotype. We are investigating the basis of this difference, which will provide clues to what genes are involved in the morphology of prion aggregates. We have also investigated various factors that might affect prion transmission across species. We have found that QN rich prions, but not non-QN rich prions and polyglutamine aggregates, enhance the appearance of a foreign prion. Furthermore, we have found that a cellular factor, UBC4, involved in prion appearance might play a role in the prevention of transmission of a prion across species.