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Updated: Jun 16, 2026

Assays for the Degradation of Misfolded Proteins in Cells
Published on: August 28, 2016
The polarisome is required for segregation and retrograde transport of protein aggregates
Beidong Liu1, Lisa Larsson, Antonio Caballero
1Department of Cell and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, 413 90 Göteborg, Sweden.
Abstract:
The paradigm sirtuin, Sir2p, of budding yeast is required for establishing cellular age asymmetry, which includes the retention of damaged and aggregated proteins in mother cells. By establishing the global genetic interaction network of SIR2 we identified the polarisome, the formin Bni1p, and myosin motor protein Myo2p as essential components of the machinery segregating protein aggregates during mitotic cytokinesis. Moreover, we found that daughter cells can clear themselves of damage by a polarisome- and tropomyosin-dependent polarized flow of aggregates into the mother cell compartment. The role of Sir2p in cytoskeletal functions and polarity is linked to the CCT chaperonin in sir2Delta cells being compromised in folding actin. We discuss the findings in view of recent models hypothesizing that polarity may have evolved to avoid clonal senescence by establishing an aging (soma-like) and rejuvenated (germ-like) lineage.
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