scholarly journals Mechanisms that Link Chronological Aging to Cellular Quiescence in Budding Yeast

2020 ◽  
Vol 21 (13) ◽  
pp. 4717
Author(s):  
Karamat Mohammad ◽  
Jennifer Anne Baratang Junio ◽  
Tala Tafakori ◽  
Emmanuel Orfanos ◽  
Vladimir I. Titorenko
Keyword(s):  
Caloric Restriction ◽  
Budding Yeast ◽  
Yeast Cells ◽  
Yeast Culture ◽  
Chronological Aging ◽  
Quiescent Cells ◽  
Cellular Events ◽  
Age Related ◽  
Calorie Diet ◽  
Cellular Quiescence

After Saccharomyces cerevisiae cells cultured in a medium with glucose consume glucose, the sub-populations of quiescent and non-quiescent cells develop in the budding yeast culture. An age-related chronology of quiescent and non-quiescent yeast cells within this culture is discussed here. We also describe various hallmarks of quiescent and non-quiescent yeast cells. A complex aging-associated program underlies cellular quiescence in budding yeast. This quiescence program includes a cascade of consecutive cellular events orchestrated by an intricate signaling network. We examine here how caloric restriction, a low-calorie diet that extends lifespan and healthspan in yeast and other eukaryotes, influences the cellular quiescence program in S. cerevisiae. One of the main objectives of this review is to stimulate an exploration of the mechanisms that link cellular quiescence to chronological aging of budding yeast. Yeast chronological aging is defined by the length of time during which a yeast cell remains viable after its growth and division are arrested, and it becomes quiescent. We propose a hypothesis on how caloric restriction can slow chronological aging of S. cerevisiae by altering the chronology and properties of quiescent cells. Our hypothesis posits that caloric restriction delays yeast chronological aging by targeting four different processes within quiescent cells.

scholarly journals In S. cerevisiae hydroxycitric acid antagonizes chronological aging and apoptosis regardless of citrate lyase

APOPTOSIS ◽  
2020 ◽  
Vol 25 (9-10) ◽  
pp. 686-696
Author(s):  
Maurizio D. Baroni ◽  
Sonia Colombo ◽  
Olivier Libens ◽  
Rani Pallavi ◽  
Marco Giorgio ◽  
...  
Keyword(s):  
Caloric Restriction ◽  
Mechanistic Model ◽  
Yeast Cells ◽  
Signal Pathways ◽  
Atp Citrate Lyase ◽  
Chronological Aging ◽  
Hydroxycitric Acid ◽  
Age Related ◽  
Citrate Lyase ◽  
Bona Fide

Abstract Caloric restriction mimetics (CRMs) are promising molecules to prevent age-related diseases as they activate pathways driven by a true caloric restriction. Hydroxycitric acid (HCA) is considered a bona fide CRM since it depletes acetyl-CoA pools by acting as a competitive inhibitor of ATP citrate lyase (ACLY), ultimately repressing protein acetylation and promoting autophagy. Importantly, it can reduce inflammation and tumour development. In order to identify phenotypically relevant new HCA targets we have investigated HCA effects in Saccharomyces cerevisiae, where ACLY is lacking. Strikingly, the drug revealed a powerful anti-aging effect, another property proposed to mark bona fide CRMs. Chronological life span (CLS) extension but also resistance to acetic acid of HCA treated cells were associated to repression of cell apoptosis and necrosis. HCA also largely prevented cell deaths caused by a severe oxidative stress. The molecule could act widely by negatively modulating cell metabolism, similarly to citrate. Indeed, it inhibited both growth reactivation and the oxygen consumption rate of yeast cells in stationary phase. Genetic analyses on yeast CLS mutants indicated that part of the HCA effects can be sensed by Sch9 and Ras2, two conserved key regulators of nutritional and stress signal pathways of primary importance. Our data together with published biochemical analyses indicate that HCA may act with multiple mechanisms together with ACLY repression and allowed us to propose an integrated mechanistic model as a basis for future investigations.

DEK terminates diapause by activation of quiescent cells in the crustacean Artemia

2019 ◽  
Vol 476 (12) ◽  
pp. 1753-1769
Author(s):  
Wen-Huan Jia ◽  
An-Qi Li ◽  
Jing-Yi Feng ◽  
Yan-Fu Ding ◽  
Sen Ye ◽  
...  
Keyword(s):  
Rna Sequences ◽  
Quiescent Cells ◽  
P53 Signaling ◽  
Cellular Events ◽  
Short Period ◽  
Cell Quiescence ◽  
Cellular Quiescence ◽  
P53 Signaling Pathway ◽  
Insight Into ◽  
Mcf 7

Abstract To cope with harsh environments, the Artemia shrimp produces gastrula embryos in diapause, a state of obligate dormancy, having cellular quiescence and suppressed metabolism. The mechanism behind these cellular events remains largely unknown. Here, we study the regulation of cell quiescence using diapause embryos of Artemia. We found that Artemia DEK (Ar-DEK), a nuclear factor protein, was down-regulated in the quiescent cells of diapause embryos and enriched in the activated cells of post-diapause embryos. Knockdown of Ar-DEK induced the production of diapause embryos whereas the control Artemia released free-swimming nuaplii. Our results indicate that Ar-DEK correlated with the termination of cellular quiescence via the increase in euchromatin and decrease in heterochromatin. The phenomena of quiescence have many implications beyond shrimp ecology. In cancer cells, for example, knockdown of DEK also induced a short period of cellular quiescence and increased resistance to environmental stress in MCF-7 and MKN45 cancer cell lines. Analysis of RNA sequences in Artemia and in MCF-7 revealed that the Wnt and AURKA signaling pathways were all down-regulated and the p53 signaling pathway was up-regulated upon inhibition of DEK expression. Our results provide insight into the functions of Ar-DEK in the activation of cellular quiescence during diapause formation in Artemia.

Establishing a model to demonstrate physical and mathematical properties of chromatin fibres in fission yeast cells - Research in the Molecular Biophysics Lab at Hiroshima University

Impact ◽  
2018 ◽  
Vol 2018 (3) ◽  
pp. 89-91
Author(s):  
Shin-ichi Tate
Keyword(s):  
Molecular Biology ◽  
Yeast Cells ◽  
Molecular Architecture ◽  
Ministry Of Education ◽  
Cellular Functions ◽  
Sports Science ◽  
Cellular Events ◽  
And Function ◽  
Education Culture ◽  
Open The Doors

The field of molecular biology has provided great insights into the structure and function of key molecules. Thanks to this area of research, we can now grasp the biological details of DNA and have characterised an enormous number of molecules in massive data bases. These 'biological periodic tables' have allowed scientists to connect molecules to particular cellular events, furthering scientific understanding of biological processes. However, molecular biology has yet to answer questions regarding 'higher-order' molecular architecture, such as that of chromatin. Chromatin is the molecular material that serves as the building block for chromosomes, the structures that carry an organism's genetic information inside of the cell's nucleus. Understanding the physical properties of chromatin is crucial in developing a more thorough picture of how chromatin's structure relate to its key cellular functions. Moreover, by establishing a physical model of chromatin, scientists will be able to open the doors into the true inner workings of the cell nucleus. Professor Shin-ichi Tate and his team of researchers at Hiroshima University's Research Center for the Mathematics on Chromatin Live Dynamics (RcMcD), are attempting to do just that. Through a five-year grant funded by the Platform for Dynamic Approaches to Living Systems from the Ministry of Education, Culture, Sports, Science and Technology, Tate is aiming to gain a clearer understanding of the structure and dynamics of chromatin.

scholarly journals DNA methylation differs extensively between strains of the same geographical origin and changes with age in Daphnia magna

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Jack Hearn ◽  
Fiona Plenderleith ◽  
Tom J. Little
Keyword(s):  
Dna Methylation ◽  
Caloric Restriction ◽  
Daphnia Magna ◽  
Single Gene ◽  
Methylation Status ◽  
Strain Differences ◽  
Life History Trait ◽  
Food Level ◽  
Epigenetic Clock ◽  
Age Related

Abstract Background Patterns of methylation influence lifespan, but methylation and lifespan may also depend on diet, or differ between genotypes. Prior to this study, interactions between diet and genotype have not been explored together to determine their influence on methylation. The invertebrate Daphnia magna is an excellent choice for testing the epigenetic response to the environment: parthenogenetic offspring are identical to their siblings (making for powerful genetic comparisons), they are relatively short lived and have well-characterised inter-strain life-history trait differences. We performed a survival analysis in response to caloric restriction and then undertook a 47-replicate experiment testing the DNA methylation response to ageing and caloric restriction of two strains of D. magna. Results Methylated cytosines (CpGs) were most prevalent in exons two to five of gene bodies. One strain exhibited a significantly increased lifespan in response to caloric restriction, but there was no effect of food-level CpG methylation status. Inter-strain differences dominated the methylation experiment with over 15,000 differently methylated CpGs. One gene, Me31b, was hypermethylated extensively in one strain and is a key regulator of embryonic expression. Sixty-one CpGs were differentially methylated between young and old individuals, including multiple CpGs within the histone H3 gene, which were hypermethylated in old individuals. Across all age-related CpGs, we identified a set that are highly correlated with chronological age. Conclusions Methylated cytosines are concentrated in early exons of gene sequences indicative of a directed, non-random, process despite the low overall DNA methylation percentage in this species. We identify no effect of caloric restriction on DNA methylation, contrary to our previous results, and established impacts of caloric restriction on phenotype and gene expression. We propose our approach here is more robust in invertebrates given genome-wide CpG distributions. For both strain and ageing, a single gene emerges as differentially methylated that for each factor could have widespread phenotypic effects. Our data showed the potential for an epigenetic clock at a subset of age positions, which is exciting but requires confirmation.

scholarly journals EXO1 Plays a Role in Generating Type I and Type II Survivors in Budding Yeast

Genetics ◽  
2004 ◽  
Vol 166 (4) ◽  
pp. 1641-1649
Author(s):  
Laura Maringele ◽  
David Lydall
Keyword(s):  
Homologous Recombination ◽  
Budding Yeast ◽  
Human Cells ◽  
Telomere Maintenance ◽  
Recombination Process ◽  
Yeast Cells ◽  
Type I ◽  
Type Ii ◽  
Recombination Proteins

Abstract Telomerase-defective budding yeast cells escape senescence by using homologous recombination to amplify telomeric or subtelomeric structures. Similarly, human cells that enter senescence can use homologous recombination for telomere maintenance, when telomerase cannot be activated. Although recombination proteins required to generate telomerase-independent survivors have been intensively studied, little is known about the nucleases that generate the substrates for recombination. Here we demonstrate that the Exo1 exonuclease is an initiator of the recombination process that allows cells to escape senescence and become immortal in the absence of telomerase. We show that EXO1 is important for generating type I survivors in yku70Δ mre11Δ cells and type II survivors in tlc1Δ cells. Moreover, in tlc1Δ cells, EXO1 seems to contribute to the senescence process itself.

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