Differentiated cytoplasmic granule formation in quiescent and non-quiescent cells upon chronological aging
Authors:Hsin-Yi Lee1,3,†, Kuo-Yu Cheng2,3,†, Jung-Chi Chao3 and Jun-Yi Leu3
doi: 10.15698/mic2016.03.484
Volume 3, pp. 109 to 119, published 03/03/2016.
1 Molecular and Cell Biology, Taiwan International Graduate Program, Graduate Institute of Life Sciences, National Defense Medical Center and Academia Sinica, Taipei, Taiwan.
2 Department of Life Sciences and Institute of Genome Sciences, National Yang-Ming University, Taipei, Taiwan.
3 Institute of Molecular Biology, Academia Sinica, Taipei, Taiwan.
† These authors contributed equally to this work.
Keywords:
stationary phase, chronological aging, quiescent cells, cytoplasmic granules, Hsp42.
Corresponding Author(s):
Conflict of interest statement:
The authors declare no conflict of interest.
Please cite this article as:
Hsin-Yi Lee, Kuo-Yu Cheng, Jung-Chi Chao and Jun-Yi Leu (2016). Differentiated cytoplasmic granule formation in quiescent and non-quiescent cells upon chronological aging. Microbial Cell 3(3): 109-119. doi: 10.15698/mic2016.03.484
© 2016 Lee et al. This is an open-access article released under the terms of the Creative Commons Attribution (CC BY) license, which allows the unrestricted use, distribution, and reproduction in any medium, provided the original author and source are acknowledged.
Abstract:
Stationary phase cultures represent a complicated cell population comprising at least two different cell types, quiescent (Q) and non-quiescent (NQ) cells. Q and NQ cells have different lifespans and cell physiologies. However, less is known about the organization of cytosolic protein structures in these two cell types. In this study, we examined Q and NQ cells for the formation of several stationary phase-prevalent granule structures including actin bodies, proteasome storage granules, stress granules, P-bodies, the compartment for unconventional protein secretion (CUPS), and Hsp42-associated stationary phase granules (Hsp42-SPGs). Most of these structures preferentially form in NQ cells, except for Hsp42-SPGs, which are enriched in Q cells. When nutrients are provided, NQ cells enter mitosis less efficiently than Q cells, likely due to the time requirement for reorganizing some granule structures. We observed that heat shock-induced misfolded proteins often colocalize to Hsp42-SPGs, and Q cells clear these protein aggregates more efficiently, suggesting that Hsp42-SPGs may play an important role in the stress resistance of Q cells. Finally, we show that the cell fate of NQ cells is largely irreversible even if they are allowed to reenter mitosis. Our results reveal that the formation of different granule structures may represent the early stage of cell type differentiation in yeast stationary phase cultures.