A first order phase transition mechanism underlies protein aggregation in mammalian cells
Abstract
The formation of misfolded protein aggregates is a hallmark of neurodegenerative diseases. The aggregate formation process exhibits an initial lag phase when precursor clusters spontaneously assemble. However, most experimental assays are blind to this lag phase. We develop a quantitative assay based on super-resolution imaging in fixed cells and light sheet imaging of living cells to study the early steps of aggregation in mammalian cells. We find that even under normal growth conditions mammalian cells have precursor clusters. The cluster size distribution is precisely that expected for a so-called super-saturated system in first order phase transition. This means there exists a nucleation barrier, and a critical size above which clusters grow and mature. Homeostasis is maintained through a Szilard model entailing the preferential clearance of super-critical clusters. We uncover a role for a putative chaperone (RuvBL) in this disassembly of large clusters. The results indicate early aggregates behave like condensates.
Additional Information
© 2019, Narayanan et al. This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited. Received: June 29, 2018. Accepted: December 17, 2018. Version of Record published: February 4, 2019 (version 1). We thank Ammon Possey (WUSTL), Assaf Amitai (MIT), Ben Sabari (MIT), Gene Wei Li (MIT), Geraldine Seydoux (Johns Hopkins), Jeff Gore (MIT), Jeong-Mo Choi (WUSTL), Kabir Ramola (Brandeis), Kandice Tanner (NCI/NIH), Kiersten Ruff (WUSTL), Miccah Hecht (MIT), Rick Young (MIT), Rohit Pappu (WUSTL), Sina Wittman (MPI-CBG, Dresden), Tony Hyman (MPI-CBG, Dresden), Vivien Siegel (MIT) and members of the Cissé lab at MIT for helpful comments and discussions. Research reported in this publication was supported by the National Cancer Institute and the National Institutes of Health through the NIH Director's New Innovator Award Number DP2CA195769 to IIC. We acknowledge HHMI for the license to build Lattice Light Sheet. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. This work was also supported by funds from the MIT Department of Physics. The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication. Data availability. All data generated or analyzed during this study are included in the manuscript and supporting files. Source data files have been provided for Figures 1, 2, 3 and 4. Author contributions. Arjun Narayanan, Conceptualization, Software, Formal analysis, Investigation, Methodology, Writing—original draft, Writing—review and editing; Anatoli Meriin, Resources, Investigation, Methodology, Writing—review and editing; J Owen Andrews, Software, Investigation, Writing—review and editing; Jan-Hendrik Spille, Conceptualization, Software, Investigation, Methodology, Writing—review and editing; Michael Y Sherman, Resources, Investigation, Methodology, Project administration, Writing—review and editing; Ibrahim I Cisse, Conceptualization, Formal analysis, Supervision, Funding acquisition, Methodology, Writing—original draft, Project administration, Writing—review and editing. The authors declare that no competing interests exist.Attached Files
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Additional details
- PMCID
- PMC6361590
- Eprint ID
- 106674
- Resolver ID
- CaltechAUTHORS:20201113-163228425
- NIH
- DP2CA195769
- Massachusetts Institute of Technology (MIT)
- Created
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2020-11-25Created from EPrint's datestamp field
- Updated
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2023-06-02Created from EPrint's last_modified field