Cell-to-cell propagation of infectious cytosolic protein aggregates

• Published in: Proceedings of the National Academy of Sciences - PNAS 2013-04, Vol.110 (15), p.5951-5956
• Main Authors: Hofmann, Julia P., Denner, Philip, Nussbaum-Krammer, Carmen, Kuhn, Peer-Hendrik, Suhre, Michael H., Scheibel, Thomas, Lichtenthaler, Stefan F., Schätzl, Hermann M., Bano, Daniele, Vorberg, Ina M.
• Format: Article
• Language: English
• Subjects: Animals; Astrocytes; Astrocytes - cytology; Biological Sciences; Brain diseases; Cell aggregates; Cell Communication; Cell lines; Cellular biology; Coculture Techniques; Cytoplasm; Cytoplasm - metabolism; Cytosol - metabolism; Daughter cells; Green Fluorescent Proteins - metabolism; Hippocampus - metabolism; Inductive reasoning; Mice; Microscopy, Confocal; Neurons; Peptide Termination Factors - metabolism; Prion Diseases; Prions; Prions - metabolism; Propagation; Protein Conformation; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - metabolism; Solar fibrils; Yeasts
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.1217321110

Prions are self-templating protein conformers that replicate by recruitment and conversion of homotypic proteins into growing protein aggregates. Originally identified as causative agents of transmissible spongiform encephalopathies, increasing evidence now suggests that prion-like phenomena are more common in nature than previously anticipated. In contrast to fungal prions that replicate in the cytoplasm, propagation of mammalian prions derived from the precursor protein PrP is confined to the cell membrane or endocytic vesicles. Here we demonstrate that cytosolic protein aggregates can also behave as infectious entities in mammalian cells. When expressed in the mammalian cytosol, protein aggregates derived from the prion domain NM of yeast translation termination factor Sup35 persistently propagate and invade neighboring cells, thereby inducing a self-perpetuating aggregation state of NM. Cell contact is required for efficient infection. Aggregates can also be induced in primary astrocytes, neurons, and organotypic cultures, demonstrating that this phenomenon is not specific to immortalized cells. Our data have important implications for understanding prion-like phenomena of protein aggregates associated with human diseases and for the growing number of amyloidogenic proteins discovered in mammals.