Project Summary
Research into the proteins that cause neurodegenerative diseases is undergoing a remarkable
transformation with the detailed identification of biochemical and biophysical pathways that drive
neuron stress and dysfunction. This MIRA project focuses on the cellular prion protein (PrPC), a
ubiquitous glycoprotein protein of the central nervous system and peripheral tissues. Misfolding
of PrPC to its scrapie form, PrPSc, causes a range of diseases including Creutzfeldt-Jakob
disease (CJD), Fatal Familial Insomnia and Kuru. In addition, PrPC is now identified as a primary
receptor for Aβ peptide oligomers that drive cytotoxicity in Alzheimer’s disease. PrPC is a
Cu2+/Zn2+-binding protein that controls the anatomical distribution of these essential metal ions
in the brain. Our program, initially supported by grant R01 GM065790, elucidated the
coordination features of the metal ion binding sites, evaluated the detailed binding
thermodynamics, and developed new concepts for understanding inherited prion diseases.
Discoveries supported by this current MIRA grant find that copper and zinc promote an inter-
domain interaction in PrPC that regulates neurotoxicity, pointing to fundamentally new molecular
mechanisms of neurodegeneration. With immediate relevance to Alzheimer’s disease, we
further showed that PrPC transports monomeric Aβ to the cell interior through endocytosis. We
also developed a method for artificially glycosylating uniformly 15N-labeled PrPC and new results
show that glycans exhibit surprising control over PrPC structure. The stage is now set for us to
move in four critical directions, all with broad and profound relevance towards understanding the
molecular processes that lead to neurodegeneration and dementia. First, we will elucidate the
specific interactions between disease relevant forms of Aβ and their PrPC binding surfaces, with
particular emphasis on the unexplored role of copper. Second, we plan to use the new method
of microenvironment mapping to clearly identify membrane proteins adjacent to PrPC on the cell
surface. Third, we will develop biophysical approaches geared towards understanding how PrPC
disrupts membrane structure and compromises transmembrane voltages. Finally, we will apply
methods learned from our research on the cystinosin transporter to interrogate the structure and
mechanism of the Mitochondrial Pyruvate Carrier (MPC), recently implicated in AD.