Prion diseases are among the most rapidly progressive neurodegenerative disorders and are characterized pathologically by extracellular prion aggregates, synaptic damage, neuronal loss, and severe astrogliosis in the brain and spinal cord. Prion aggregates spread through neuroanatomically connected brain regions, yet how prions physically spread from cell-to-cell is poorly understood. In vitro, prion aggregates form on the plasma membrane, in endosomes, and in multivesicular bodies, and are released in exosomes from chronically infected cells. A major goal of this application is to determine how intra-cellular vesicular prion trafficking contributes to inter-cellular prion spread through the central nervous system using in vitro and in vivo model systems. We have previously employed a broad range of approaches to track structurally diverse prions from axon terminals to neuronal cell bodies and have determined the biophysical properties of highly virulent prions that spread into the CNS. We discovered that small, subfibrillar and fibrillar prions were internalized by neurons through macropinocytosis. However, only the small, subfibrillar prions spread from extraneural sites into the brain. Thus, aggregate size underlies prion spread into the CNS. We also determined that post-translational modifications in the prion protein can alter aggregate packing arrangements and lead to the emergence of new prion strains. Finally, we found that autophagic clearance pathways were induced in muscle cells harboring prion aggregates. In this renewal, we aim to determine how the vesicular trafficking of prions in neurons and glia impacts prion spread through the CNS.
In Specific Aim 1, we will define the physical properties of a prion that govern packaging into exosomes.
In Specific Aim 2, we will identify key regulators of intracellular prion conversion and clearance in neurons and astrocytes by manipulating vesicular transit pathways. Additionally we will characterize vesicular regulatory protein expression in prion-infected humans and in mouse models.
In Specific Aim 3, we will determine how cell-specific repression of early and late stages of vesicular trafficking modifies prion disease progression. These experiments are the first to probe the contribution of intra-vesicular prion trafficking pathways to prion spread in vivo, and will help unravel how vesicular transport impacts prion conversion, clearance, and rapid spread through the brain. The proposed studies are particularly important with the growing recognition of endosomal and lysosomal dysfunction occurring in Alzheimer?s and other neurodegenerative diseases, and with potential opportunities arising for therapeutic intervention in protein aggregate clearance pathways.

Public Health Relevance

Prion diseases are rapidly progressive, fatal neurodegenerative disorders caused by the accumulation of aggregated prion protein. We have found that small prion aggregates efficiently spread into and through the central nervous system. We expect the proposed studies will reveal mechanisms underlying how prions transfer from cell-to-cell through the brain with a goal of identifying new therapeutic targets to block the spread of prions.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS076896-09
Application #
9910452
Study Section
Special Emphasis Panel (ZRG1)
Program Officer
Wong, May
Project Start
2012-09-15
Project End
2022-04-30
Budget Start
2020-05-01
Budget End
2021-04-30
Support Year
9
Fiscal Year
2020
Total Cost
Indirect Cost
Name
University of California, San Diego
Department
Pathology
Type
Schools of Medicine
DUNS #
804355790
City
La Jolla
State
CA
Country
United States
Zip Code
92093
Aguilar-Calvo, Patricia; Bett, Cyrus; Sevillano, Alejandro M et al. (2018) Generation of novel neuroinvasive prions following intravenous challenge. Brain Pathol 28:999-1011
Orrù, Christina D; Soldau, Katrin; Cordano, Christian et al. (2018) Prion Seeds Distribute throughout the Eyes of Sporadic Creutzfeldt-Jakob Disease Patients. MBio 9:
Kurt, Timothy D; Aguilar-Calvo, Patricia; Jiang, Lin et al. (2017) Asparagine and glutamine ladders promote cross-species prion conversion. J Biol Chem 292:19076-19086
Aguilar-Calvo, Patricia; Xiao, Xiangzhu; Bett, Cyrus et al. (2017) Post-translational modifications in PrP expand the conformational diversity of prions in vivo. Sci Rep 7:43295
Bett, Cyrus; Lawrence, Jessica; Kurt, Timothy D et al. (2017) Enhanced neuroinvasion by smaller, soluble prions. Acta Neuropathol Commun 5:32
Sikorska, Beata; Gajos, Agata; Bogucki, Andrzej et al. (2017) Electron microscopic and confocal laser microscopy analysis of amyloid plaques in chronic wasting disease transmitted to transgenic mice. Prion 11:431-439
Klionsky, Daniel J (see original citation for additional authors) (2016) Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition). Autophagy 12:1-222
Keene, C Dirk; Darvas, Martin; Kraemer, Brian et al. (2016) Neuropathological assessment and validation of mouse models for Alzheimer's disease: applying NIA-AA guidelines. Pathobiol Aging Age Relat Dis 6:32397
Kurt, Timothy D; Sigurdson, Christina J (2016) Cross-species transmission of CWD prions. Prion 10:83-91
Annamalai, Karthikeyan; Gührs, Karl-Heinz; Koehler, Rolf et al. (2016) Polymorphism of Amyloid Fibrils In Vivo. Angew Chem Int Ed Engl 55:4822-5

Showing the most recent 10 out of 29 publications