The polarisome is required for segregation and retrograde transport of protein aggregates.
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.
Department of Cell and Molecular Biology, University of Gothenburg, Medicinaregatan 9C, 413 90 Göteborg, Sweden.
Beidong
B
Liu
Lisa
L
Larsson
Antonio
A
Caballero
Xinxin
X
Hao
David
D
Oling
Julie
J
Grantham
Thomas
T
Nyström
D000199:Actins / Q000378:metabolism; D018833:Chaperonins / Q000378:metabolism; D006360:Heat-Shock Proteins / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D008938:Mitosis; D015388:Organelles / Q000378:metabolism; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae / Q000378:metabolism; D056565:Sirtuin 2 / Q000378:metabolism
D000199:Actins; C105191:Bni1 protein, S cerevisiae; D006360:Heat-Shock Proteins; D008840:Microfilament Proteins; D029701:Saccharomyces cerevisiae Proteins; D038281:Silent Information Regulator Proteins, Saccharomyces cerevisiae; C070972:HsP104 protein, S cerevisiae; C087778:SIR2 protein, S cerevisiae; D056565:Sirtuin 2; D018833:Chaperonins