Prion diseases belong to a class of fatal, infectious neurodegenerative diseases known as transmissible spongiform encephalopathies (TSEs), including the bovine spongiform encephalopathies (BSE or mad cow disease) in cattle and Creutzfeldt-Jakob disease (CJD) in human. It is generally accepted that the infectious agent of prion disease is a normal host protein (PrPC) adopted a pathogenic conformation that is infectious (PrPSc). Remarkably, there are several atypical yeast proteins capable of existing in multiple stable conformations, each of which is associated with distinct phenotypes. Intriguingly, some of the conformations are able to self-propagate and are “infectious.” They are thus referred to as yeast prions. Our laboratory is interested in study this fascinating prion phenomenon using yeast as a model organism. Yeast offers a powerful system that is amenable to biochemical, cell biological and genetic manipulations. We want to obtain information on the structural properties of yeast prions, their mutual interactions, and their interactions with other cellular factors, particularly, with molecular chaperones. We have recently discovered that the yeast heat-shock transcription factor (HSF), a master regulator of molecular chaperones’ production, plays an important role in governing the de novo formation and “strain” determination of yeast prion [PSI+]. We are working toward to identify novel cellular factors that are HSF targets and important for yeast prion formation and inheritance. The function of HSF is evolutionally conserved from yeast to human. We hope results from our yeast prion study will provide valuable information on the complex etiology of the devastating prion diseases.
Our laboratory is also interested in investigating how common is the prion phenomenon in biology. We wish to identify potential prion proteins from yeast and other non-yeast model organisms through a combined approach of bioinformatics and genetic screenings. Our ultimate goal is to uncover the mechanisms governing the prion conformational switch and to understand the biological significance of the protein conformation based prion-like inheritance.