Multi-generational silencing dynamics control cell aging

Abstract

Significance:Aging is an inevitable consequence of living, and with it comes increased morbidity and mortality. Novel approaches to mitigating age-related chronic diseases demand a better understanding of the biology of aging. Studies in model organisms have identified many peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission.The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/102210 doi: bioRxiv preprint first posted online Jan. 22, 2017; 3 conserved molecular factors that influence aging. The emerging challenge is to understand how these factors interact and change dynamically to drive aging. Using multidisciplinary technologies, we have revealed a sirtuin-dependent intermittent pattern of chromatin silencing during yeast aging that is crucial for longevity. Our findings highlight the important role of silencing dynamics in aging, which deserves careful consideration when designing schemes to delay or reverse aging by modulating sirtuins and silencing. Main Text: /bodyCellular aging is generally driven by the accumulation of genetic and cellular damage (1, 2). Although much progress has been made in identifying molecular factors that influence lifespan, what remains sorely missing is an understanding of how these factors interact and change dynamically during the aging process. This is in part due to the fact that aging is a complex process wherein isogenic cells have various intrinsic causes of aging and widely different rates of aging. As a result, static population-based approaches could be insufficient to fully reveal sophisticated dynamic changes during aging. Recent developments in single-cell analyses to unravel the interplay of cellular dynamics and variability hold the promise to answer that challenge (3-5). Here we chose the replicative aging of yeast S.cerevisiae as a model and exploited novel quantitative biology technologies to study the dynamics of molecular processes that control aging at the single-cell level. ResultsReplicative aging of yeast is measured as the number of daughter cells produced before the death of a mother cell (6). The conventional method for studying yeast aging requires laborious manual separation of daughter cells from mother cells after each division and does not peer-reviewed) is the author/funder. All rights reserved. No reuse allowed without permission.The copyright holder for this preprint (which was not . http://dx.doi.org/10.1101/102210 doi: bioRxiv preprint first posted online Jan. 22, 2017; 4 allow tracking of molecular processes over multiple generations during aging (7). Recent advances in microfluidics technology have automated cell separation and enabled continuous single-cell measurements during aging (8)(9)(10)(11)(12)(13)(14). Building upon these efforts, we developed a new microfluidic aging device. The device traps mother cells at the bottom of finger-shaped chambers, allowing them to bud continuously, while daughter cells are removed via a waste port.Each chamber also has a smal...

Enhanced cellular longevity arising from environmental fluctuations

“…To further define the lifespan-extending effect of the optimal CR conditions, we monitored rDNA silencing loss and heme depletion, two major age-induced deterioration processes that regulate lifespan (Li et al, 2020;Zhou et al, 2023). To track rDNA silencing, we used a GFP reporter inserted within the rDNA (rDNA-GFP) (Li et al, 2017). Because expression of the reporter is subject to silencing, increased reporter fluorescence indicates reduced silencing, whereas decreased fluorescence indicates enhanced silencing.…”

“…iRFP reporter (NH268) and the strain with both nuc. iRFP and the NTS1 silencing reporters (NH270) was made as previously described (Li et al, 2017).…”

“…To this end, we set out to quantify and model replicative aging of the budding yeast Saccharomyces cerevisiae, a genetically tractable model for aging of mitotic cell types in mammals, such as stem cells. Using microfluidics coupled with time-lapse microscopy (O'Laughlin et al, 2020), we quantitatively tracked the aging processes in a large number of single yeast cells and found that isogenic cells age with two different types of phenotypic changes (Jin et al, 2019;Li et al, 2020;Li et al, 2017;Paxman et al, 2022): about half of cells continuously produced daughters with an elongated morphology during later stages of life (designated as "Mode 1" aging). In contrast, the other half produced small, round daughter cells until death (designated as "Mode 2" aging).…”

Microfluidics for long-term single-cell time-lapse microscopy: Advances and applications

“…The classic MM architecture has been used to study archaea and symmetrically-dividing yeast organisms such as Halobacterium salinarum (Darnell et al, 2020) and Schizosaccharomyces pombe (Nakaoka and Wakamoto, 2017), respectively, by scaling up device dimensions. The ability of the budding yeast Saccharomyces cerevisiae to switch budding orientation over the course of its lifespan necessitated the trapping and retention of mother cells in trenches open on both ends to flowing media (Li et al, 2017). This accommodates the removal of daughter cells produced by budding in either orientation (Figure 4B).…”

“…(B) Maintaining an opening at either end of each cell trench in a modified MM device enables removal of S. cerevisiae daughter cells produced from budding in either orientation into perpendicular media channels. Schematic representation inspired fromLi et al (2017).…”