Biochemistry and Pharmacology - Research Publications

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End date: 2018 × Author: Hatters, Daniel × Author: Haynes, Angelique × Author: MOHAMED RAMDZAN, YASMIN ×

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    Tracking protein aggregation and mislocalization in cells with flow cytometry
    Ramdzan, YM ; Polling, S ; Chia, CPZ ; Ng, IHW ; Ormsby, AR ; Croft, NP ; Purcell, AW ; Bogoyevitch, MA ; Ng, DCH ; Gleeson, PA ; Hatters, DM (NATURE PUBLISHING GROUP, 2012-05)
    We applied pulse-shape analysis (PulSA) to monitor protein localization changes in mammalian cells by flow cytometry. PulSA enabled high-throughput tracking of protein aggregation, translocation from the cytoplasm to the nucleus and trafficking from the plasma membrane to the Golgi as well as stress-granule formation. Combining PulSA with tetracysteine-based oligomer sensors in a cell model of Huntington's disease enabled further separation of cells enriched with monomers, oligomers and inclusion bodies.
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    A Platform to View Huntingtin Exon 1 Aggregation Flux in the Cell Reveals Divergent Influences from Chaperones hsp40 and hsp70
    Ormsby, AR ; Ramdzan, YM ; Mok, Y-F ; Jovanoski, KD ; Hatters, DM (AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC, 2013-12-27)
    Our capacity for tracking how misfolded proteins aggregate inside a cell and how different aggregation states impact cell biology remains enigmatic. To address this, we built a new toolkit that enabled the high throughput tracking of individual cells enriched with polyglutamine-expanded Htt exon 1 (Httex1) monomers, oligomers, and inclusions using biosensors of aggregation state and flow cytometry pulse shape analysis. Supplemented with gel filtration chromatography and fluorescence-adapted sedimentation velocity analysis of cell lysates, we collated a multidimensional view of Httex1 aggregation in cells with respect to time, polyglutamine length, expression levels, cell survival, and overexpression of protein quality control chaperones hsp40 (DNAJB1) and hsp70 (HSPA1A). Cell death rates trended higher for Neuro2a cells containing Httex1 in inclusions than with Httex1 dispersed through the cytosol at time points of expression over 2 days. hsp40 stabilized monomers and suppressed inclusion formation but did not otherwise change Httex1 toxicity. hsp70, however, had no major effect on aggregation of Httex1 but increased the survival rate of cells with inclusions. hsp40 and hsp70 also increased levels of a second bicistronic reporter of Httex1 expression, mKate2, and increased total numbers of cells in culture, suggesting these chaperones partly rectify Httex1-induced deficiencies in quality control and growth rates. Collectively, these data suggest that Httex1 overstretches the protein quality control resources and that the defects can be partly rescued by overexpression of hsp40 and hsp70. Importantly, these effects occurred in a pronounced manner for soluble Httex1, which points to Httex1 aggregation occurring subsequently to more acute impacts on the cell.