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Stressed yeast paint a picture of dorian gray.

Roberts RG - PLoS Biol. (2014)

View Article: PubMed Central - PubMed

Affiliation: Public Library of Science, Cambridge, United Kingdom.

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Cells do the same thing when they divide; along with their newly replicated genomes and the vital cellular organelles, they also pass on a lifetime's worth of accrued rubbish... An important component of this is the legacy of insoluble aggregated protein that the parent cell has failed to deal with by the normal processes of degradation, and the amount that's passed on can affect the lifespan and wellbeing of the daughter cells... In the case of cells that divide asymmetrically, such as baker's yeast (Saccharomyces cerevisiae), the mother cell selflessly keeps the junk to herself, leaving her daughters pristine... In general the dilution that happens at cell division means that the progeny can cope with this burden, but it's been shown that when protein aggregation is dramatically increased by a stressful event, such as heat shock (think about the protein aggregation that occurs when you poach an egg), S. pombe switches to dividing up its aggregates asymmetrically... How does it do this? A new study by Miguel Coelho, Iva Tolić, and colleagues, just published in PLOS Biology, reveals that the yeast has found a surprisingly simple and elegant solution to the problem of waste management... The authors study what happens to protein aggregates in S. pombe, following their fate by using a fluorescently tagged version of the disaggregase enzyme Hsp104, which is known to associate with aggregated proteins... First the authors look at the basic behaviour of aggregates—they find that these seem to drift around the cell by diffusion alone, that the aggregates rarely split up, and that almost every encounter between two aggregates results in their fusion to form a single larger one... They light upon Hsp16, a small heat-shock protein known to associate with aggregated proteins during times of stress... They find that aggregates in cells lacking the Hsp16 gene undergo fewer fusion events overall, with only half of the encounters between aggregates resulting in fusion... Without Hsp16, fusion is less efficient, the number of aggregates per cell is higher after stress, partition of aggregates at cell division is more symmetrical, half as many cells are born without aggregates, and more cells die overall... During normal conditions, protein aggregates drift around, bump into each other and fuse occasionally, are shared more-or-less equally between daughter cells, and are sufficiently diluted by cell division not to interfere with a healthy existence... After one or two cell divisions, they all end up in one massive cluster, and this can only pass to one of the daughter cells; one cell is left as fresh and sparkling as a newborn baby, and the other takes the full hit of a history of aggregation... Thus when times get tough, simple diffusion, chaperoned fusion of particles and the vicissitudes of stochasticity can give rise to an adaptively valuable switch from symmetric division—two gracefully aging twins—to asymmetric division—the eternally young and beautiful Dorian Gray, and his corrupt and damaged portrait in the attic... doi:10.1371/journal.pbio.1001886

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Stress breeds asymmetry. In the normal situation (left-hand panel), aggregates are small and partitioned symmetrically. After thermal stress (right-hand panel), increased rates of aggregate fusion result in a smaller number of larger aggregates. By the second cell division (bottom of each panel), one cell inherits all, and is likely to die soon after.
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pbio-1001885-g001: Stress breeds asymmetry. In the normal situation (left-hand panel), aggregates are small and partitioned symmetrically. After thermal stress (right-hand panel), increased rates of aggregate fusion result in a smaller number of larger aggregates. By the second cell division (bottom of each panel), one cell inherits all, and is likely to die soon after.


Stressed yeast paint a picture of dorian gray.

Roberts RG - PLoS Biol. (2014)

Stress breeds asymmetry. In the normal situation (left-hand panel), aggregates are small and partitioned symmetrically. After thermal stress (right-hand panel), increased rates of aggregate fusion result in a smaller number of larger aggregates. By the second cell division (bottom of each panel), one cell inherits all, and is likely to die soon after.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4060992&req=5

pbio-1001885-g001: Stress breeds asymmetry. In the normal situation (left-hand panel), aggregates are small and partitioned symmetrically. After thermal stress (right-hand panel), increased rates of aggregate fusion result in a smaller number of larger aggregates. By the second cell division (bottom of each panel), one cell inherits all, and is likely to die soon after.

View Article: PubMed Central - PubMed

Affiliation: Public Library of Science, Cambridge, United Kingdom.

AUTOMATICALLY GENERATED EXCERPT
Please rate it.

Cells do the same thing when they divide; along with their newly replicated genomes and the vital cellular organelles, they also pass on a lifetime's worth of accrued rubbish... An important component of this is the legacy of insoluble aggregated protein that the parent cell has failed to deal with by the normal processes of degradation, and the amount that's passed on can affect the lifespan and wellbeing of the daughter cells... In the case of cells that divide asymmetrically, such as baker's yeast (Saccharomyces cerevisiae), the mother cell selflessly keeps the junk to herself, leaving her daughters pristine... In general the dilution that happens at cell division means that the progeny can cope with this burden, but it's been shown that when protein aggregation is dramatically increased by a stressful event, such as heat shock (think about the protein aggregation that occurs when you poach an egg), S. pombe switches to dividing up its aggregates asymmetrically... How does it do this? A new study by Miguel Coelho, Iva Tolić, and colleagues, just published in PLOS Biology, reveals that the yeast has found a surprisingly simple and elegant solution to the problem of waste management... The authors study what happens to protein aggregates in S. pombe, following their fate by using a fluorescently tagged version of the disaggregase enzyme Hsp104, which is known to associate with aggregated proteins... First the authors look at the basic behaviour of aggregates—they find that these seem to drift around the cell by diffusion alone, that the aggregates rarely split up, and that almost every encounter between two aggregates results in their fusion to form a single larger one... They light upon Hsp16, a small heat-shock protein known to associate with aggregated proteins during times of stress... They find that aggregates in cells lacking the Hsp16 gene undergo fewer fusion events overall, with only half of the encounters between aggregates resulting in fusion... Without Hsp16, fusion is less efficient, the number of aggregates per cell is higher after stress, partition of aggregates at cell division is more symmetrical, half as many cells are born without aggregates, and more cells die overall... During normal conditions, protein aggregates drift around, bump into each other and fuse occasionally, are shared more-or-less equally between daughter cells, and are sufficiently diluted by cell division not to interfere with a healthy existence... After one or two cell divisions, they all end up in one massive cluster, and this can only pass to one of the daughter cells; one cell is left as fresh and sparkling as a newborn baby, and the other takes the full hit of a history of aggregation... Thus when times get tough, simple diffusion, chaperoned fusion of particles and the vicissitudes of stochasticity can give rise to an adaptively valuable switch from symmetric division—two gracefully aging twins—to asymmetric division—the eternally young and beautiful Dorian Gray, and his corrupt and damaged portrait in the attic... doi:10.1371/journal.pbio.1001886

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