scholarly journals Mutations in DNA Replication Genes Reduce Yeast Life Span

2002 ◽  
Vol 22 (12) ◽  
pp. 4136-4146 ◽  
Author(s):  
Laura L. Mays Hoopes ◽  
Martin Budd ◽  
Wonchae Choe ◽  
Tao Weitao ◽  
Judith L. Campbell
Keyword(s):  
Dna Replication ◽  
Life Span ◽  
Genomic Instability ◽  
Replicative Senescence ◽  
Premature Aging ◽  
Wild Type ◽  
Cell Cycle Time ◽  
Replicative Stress ◽  
Age Related ◽  
In The Wild

ABSTRACT Surprisingly, the contribution of defects in DNA replication to the determination of yeast life span has never been directly investigated. We show that a replicative yeast helicase/nuclease, encoded by DNA2 and a member of the same helicase subfamily as the RecQ helicases, is required for normal life span. All of the phenotypes of old wild-type cells, for example, extended cell cycle time, age-related transcriptional silencing defects, and nucleolar reorganization, occur after fewer generations in dna2 mutants than in the wild type. In addition, the life span of dna2 mutants is extended by expression of an additional copy of SIR2 or by deletion of FOB1, which also increase wild-type life span. The ribosomal DNA locus and the nucleolus seem to be particularly sensitive to defects in dna2 mutants, although in dna2 mutants extrachromosomal ribosomal circles do not accumulate during the aging of a mother cell. Several other replication mutations, such as rad27Δ, encoding the FEN-1 nuclease involved in several aspects of genomic stability, also show premature aging. We propose that replication fork failure due to spontaneous, endogenous DNA damage and attendant genomic instability may contribute to replicative senescence. This may imply that the genomic instability, segmental premature aging symptoms, and cancer predisposition associated with the human RecQ helicase diseases, such as Werner, Bloom, and Rothmund-Thomson syndromes, are also related to replicative stress.

scholarly journals Electrophysiological Measures of Aging Pharynx Function in C. elegans Reveal Enhanced Organ Functionality in Older, Long-lived Mutants

2017 ◽  
Vol 74 (8) ◽  
pp. 1173-1179 ◽  
Author(s):  
Joshua Coulter Russell ◽  
Nikolay Burnaevskiy ◽  
Bridget Ma ◽  
Miguel Arenas Mailig ◽  
Franklin Faust ◽  
...  
Keyword(s):  
Caenorhabditis Elegans ◽  
Heat Shock ◽  
Life Span ◽  
Insulin Signaling ◽  
Model System ◽  
Wild Type ◽  
Organ Function ◽  
C Elegans ◽  
Age Related ◽  
The Relationship

Abstract The function of the pharynx, an organ in the model system Caenorhabditis elegans, has been correlated with life span and motility (another measure of health) since 1980. In this study, in order to further understand the relationship between organ function and life span, we measured the age-related decline of the pharynx using an electrophysiological approach. We measured and analyzed electropharyngeograms (EPG) of wild type animals, short-lived hsf-1 mutants, and long-lived animals with genetically decreased insulin signaling or increased heat shock pathway signaling; we recorded a total of 2,478 EPGs from 1,374 individuals. As expected, the long-lived daf-2(e1370) and hsf-1OE(uthIs235) animals maintained pharynx function relatively closer to the youthful state during aging, whereas the hsf-1(sy441) and wild type animals’ pharynx function deviated significantly further from the youthful state at advanced age. Measures of the amount of variation in organ function can act as biomarkers of youthful physiology as well. Intriguingly, the long-lived animals had greater variation in the duration of pharynx contraction at older ages.

scholarly journals Progerin Expression Induces Inflammation, Oxidative Stress and Senescence in Human Coronary Endothelial Cells

Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1201 ◽  
Author(s):  
Guillaume Bidault ◽  
Marie Garcia ◽  
Jacqueline Capeau ◽  
Romain Morichon ◽  
Corinne Vigouroux ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Endothelial Cells ◽  
Endothelial Cell ◽  
Endothelial Dysfunction ◽  
Premature Aging ◽  
Lamin A ◽  
Wild Type ◽  
Human Endothelial Cells ◽  
Endothelial Cell Function ◽  
Age Related

Hutchinson–Gilford progeria syndrome (HGPS) is a rare premature aging disorder notably characterized by precocious and deadly atherosclerosis. Almost 90% of HGPS patients carry a LMNA p.G608G splice variant that leads to the expression of a permanently farnesylated abnormal form of prelamin-A, referred to as progerin. Endothelial dysfunction is a key determinant of atherosclerosis, notably during aging. Previous studies have shown that progerin accumulates in HGPS patients’ endothelial cells but also during vascular physiological aging. However, whether progerin expression in human endothelial cells can recapitulate features of endothelial dysfunction is currently unknown. Herein, we evaluated the direct impact of exogenously expressed progerin and wild-type lamin-A on human endothelial cell function and senescence. Our data demonstrate that progerin, but not wild-type lamin-A, overexpression induces endothelial cell dysfunction, characterized by increased inflammation and oxidative stress together with persistent DNA damage, increased cell cycle arrest protein expression and cellular senescence. Inhibition of progerin prenylation using a pravastatin–zoledronate combination partly prevents these defects. Our data suggest a direct proatherogenic role of progerin in human endothelial cells, which could contribute to HGPS-associated early atherosclerosis and also potentially be involved in physiological endothelial aging participating to age-related cardiometabolic diseases.

Biomarkers of aging, life span and spontaneous carcinogenesis in the wild type and HER-2 transgenic FVB/N female mice

2015 ◽  
Vol 17 (2) ◽  
pp. 317-324 ◽  
Author(s):  
Andrey V. Panchenko ◽  
Irina G. Popovich ◽  
Alexandr P. Trashkov ◽  
Peter A. Egormin ◽  
Maria N. Yurova ◽  
...  
Keyword(s):  
Life Span ◽  
Wild Type ◽  
Female Mice ◽  
Biomarkers Of Aging ◽  
In The Wild ◽  
Her 2 ◽  
Spontaneous Carcinogenesis

Endothelial cells maintain a reduced redox environment even as mitochondrial function declines

2002 ◽  
Vol 283 (6) ◽  
pp. C1675-C1686 ◽  
Author(s):  
Ricarda Carlisle ◽  
Carol Ann Rhoads ◽  
Tak Yee Aw ◽  
Lynn Harrison
Keyword(s):  
Endothelial Cells ◽  
Oxygen Consumption ◽  
Genomic Instability ◽  
Mitochondrial Function ◽  
Replicative Senescence ◽  
Umbilical Vein ◽  
Nuclear Genome ◽  
Mitochondrial Mass ◽  
Atp Production ◽  
Age Related

Human umbilical vein endothelial cells (HUVECs) are an endothelial model of replicative senescence. Oxidative stress, possibly due to dysfunctional mitochondria, is believed to play a key role in replicative senescence and atherosclerosis, an age-related vascular disease. In this study, we determined the effect of cell division on genomic instability, mitochondrial function, and redox status in HUVECs that were able to replicate for ∼60 cumulative population doublings (CPD). After 20 CPD, the nuclear genome deteriorated and the protein content of the cell population increased. This indicated an increase in cell size, which was accompanied by an increase in oxygen consumption, ATP production, and mitochondrial genome copy number and ∼10% increase in mitochondrial mass. The antioxidant capacity increased, as seen by an increase in reduced glutathione, glutathione peroxidase, GSSG reductase, and glucose-6-phosphate dehydrogenase. However, by CPD 52, the latter two enzymes decreased, as well as the ratio of mitochondrial-to-nuclear genome copies, the mitochondrial mass, and the oxygen consumption per milligram of protein. Our results signify that HUVECs maintain a highly reducing (GSH) environment as they replicate despite genomic instability and loss of mitochondrial function.

scholarly journals Effects of oriC relocation on control of replication initiation in Bacillus subtilis

Microbiology ◽  
2009 ◽  
Vol 155 (9) ◽  
pp. 3070-3082 ◽  
Author(s):  
Shigeki Moriya ◽  
Yoshikazu Kawai ◽  
Sakiko Kaji ◽  
Adrian Smith ◽  
Elizabeth J. Harry ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Bacillus Subtilis ◽  
Dna Replication ◽  
Negative Control ◽  
Replication Initiation ◽  
Control Mechanisms ◽  
Bacterial Cells ◽  
Wild Type ◽  
Dna Replication Initiation ◽  
In The Wild

In bacteria, DNA replication initiation is tightly regulated in order to coordinate chromosome replication with cell growth. In Escherichia coli, positive factors and negative regulatory mechanisms playing important roles in the strict control of DNA replication initiation have been reported. However, it remains unclear how bacterial cells recognize the right time for replication initiation during the cell cycle. In the Gram-positive bacterium Bacillus subtilis, much less is known about the regulation of replication initiation, specifically, regarding negative control mechanisms which ensure replication initiation only once per cell cycle. Here we report that replication initiation was greatly enhanced in strains that had the origin of replication (oriC) relocated to various loci on the chromosome. When oriC was relocated to new loci further than 250 kb counterclockwise from the native locus, replication initiation became asynchronous and earlier than in the wild-type cells. In two oriC-relocated strains (oriC at argG or pnbA, 25 ° or 30 ° on the 36 ° chromosome map, respectively), DnaA levels were higher than in the wild-type but not enough to cause earlier initiation of replication. Our results suggest that the initiation capacity of replication is accumulated well before the actual time of initiation, and its release may be suppressed by a unique DNA structure formed near the native oriC locus.

scholarly journals Spi-1/PU.1 Accelerates Replication Fork Elongation through PP1a Phosphatase-Associated Dephosphorylation of CHK1 in Erythroleukemic Cells

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 2193-2193
Author(s):  
Pauline Rimmelé ◽  
Jean-Hugues Guervilly ◽  
Filippo Rosselli ◽  
Françoise Moreau-Gachelin ◽  
Christel Guillouf
Keyword(s):  
Dna Replication ◽  
Genomic Instability ◽  
Genetic Instability ◽  
High Speed ◽  
Conflicts Of Interest ◽  
Leukemic Cells ◽  
Chain Elongation ◽  
Origin Firing ◽  
Replicative Stress ◽  
Dna Chain

Abstract The multistage process of leukemic formation is driven by the progressive acquisition of somatic mutations. Replication stress creates genomic instability in mammals. Oncogenes and tumor suppressors trigger a replicative stress, that will consequently participates to the progression of cancer partly through this increased genetic instability. Thus, determining how cells cope with replicative stress should help understanding leukemogenesis and lead to the identification of new targets for antitumor treatments. Using a multistep leukemia model driven by Spi-1/PU.1 overexpression, we investigated the relationship between DNA replication and cancer progression. We have previously identified that the constitutive overexpression of the oncogenic transcription factor Spi-1/PU.1 is associated with an increased speed of DNA chain elongation favoring genetic instability without inducing DNA strand breaks. The Spi-1-induced replicative stress is peculiar because, in contrast to most of stress triggered by oncogenes or tumor suppressor, it is associated with an increase fork progression speed instead of alteration in the program of origin firing. Here, we bring evidence that the S phase checkpoint protein, CHK1, is maintained in the inactive dephosphorylated form in Spi-1/PU.1 overexpressing pre-leukemic cells inducing and/or maintaining the observed high speed of DNA chain elongation. CHK1 under-phosphorylation is not due to defects in ATR signaling, its main regulator. Moreover, pharmacological inhibition of the kinases, ATM and DNA-PK, did not decrease CHK1 phosphorylation in the preleukemic cells overexpressing Spi-1. These findings are not consistent with an involvement of DNA damage response kinases in Spi-1-mediated modulation of CHK1 phosphorylation.We found that PP1a expression is increased in Spi-1/PU.1 overexpressing pre-leukemic cells compared to cells in which Spi-1/PU.1 was down-regulated. Two functional assays bring arguments that PP1 activity mediates the Spi-1/PU.1 effect on CHK1 dephosphorylation. Indeed, inhibition of PP1activity in cells overexpressing Spi-1 promoted the phosphorylation of CHK1, while the overexpression of PP1a led to the loss of a correlation between CHK1 phosphorylation and Spi-1 expression. In addition, PP1a inhibition and overexpression, not only acted on the CHK1 phosphorylation status controlled by Spi-1 but also inversely modified the progression of replication. Altogether, these results support the existence of a pathway linking Spi-1/PU.1 expression to acceleration of DNA replication via a PP1-mediated control of CHK1 phosphorylation in the pre-leukemic cells. These results identified a new pathway by which an oncogene influences replicative stress and favors the leukemic progression by fostering the incidence of genomic instability. Disclosures No relevant conflicts of interest to declare.

scholarly journals Longevity mutation in SCH9 prevents recombination errors and premature genomic instability in a Werner/Bloom model system

2008 ◽  
Vol 180 (1) ◽  
pp. 67-81 ◽  
Author(s):  
Federica Madia ◽  
Cristina Gattazzo ◽  
Min Wei ◽  
Paola Fabrizio ◽  
William C. Burhans ◽  
...  
Keyword(s):  
Genomic Instability ◽  
Population Expansion ◽  
Fold Increase ◽  
Model System ◽  
Premature Aging ◽  
Initial Population ◽  
G1 Arrest ◽  
Age Related ◽  
Age Dependent ◽  
Premature Aging Syndromes

Werner and Bloom syndromes are human diseases characterized by premature age-related defects including elevated cancer incidence. Using a novel Saccharomyces cerevisiae model system for aging and cancer, we show that cells lacking the RecQ helicase SGS1 (WRN and BLM homologue) undergo premature age-related changes, including reduced life span under stress and calorie restriction (CR), G1 arrest defects, dedifferentiation, elevated recombination errors, and age-dependent increase in DNA mutations. Lack of SGS1 results in a 110-fold increase in gross chromosomal rearrangement frequency during aging of nondividing cells compared with that generated during the initial population expansion. This underscores the central role of aging in genomic instability. The deletion of SCH9 (homologous to AKT and S6K), but not CR, protects against the age-dependent defects in sgs1Δ by inhibiting error-prone recombination and preventing DNA damage and dedifferentiation. The conserved function of Akt/S6k homologues in lifespan regulation raises the possibility that modulation of the IGF-I–Akt–56K pathway can protect against premature aging syndromes in mammals.

scholarly journals Topoisomerase 1 dependent R-loop deficiency as a mechanism underlying oncogene-induced replication stress and genomic instability

2020 ◽  
Author(s):  
Dan Sarni ◽  
Alon Shtrikman ◽  
Yifat S. Oren ◽  
Batsheva Kerem
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Genomic Instability ◽  
Cancer Progression ◽  
Replication Stress ◽  
Genome Integrity ◽  
Replication Rate ◽  
Topoisomerase 1 ◽  
Replicative Stress ◽  
Complex Process

AbstractDNA replication is a complex process that is tightly regulated to ensure faithful genome duplication, and its perturbation leads to DNA damage and genomic instability. Oncogene expression triggers replicative stress that can lead to genetic instability, driving cancer progression. Thus, revealing the molecular basis for oncogene-induced replication stress is important for understanding of oncogenesis. Here we show that the activation of mutated HRAS leads to a non-canonical replication stress characterized by accelerated replication rate, inducing DNA damage. Mutated HRAS increases topoisomerase 1 (TOP1) expression, which leads to reduced levels of RNA-DNA hybrids (R-loops), driving fork acceleration and damage formation. Restoration of the perturbed replication either by restoration of TOP1 levels or directly by mild replication inhibition results in a dramatic reduction in DNA damage. The findings highlight the importance of TOP1 equilibrium in the regulation of R-loop homeostasis to ensure faithful DNA replication and genome integrity that when dysregulated can be a mechanism of oncogene-induced DNA damage.

Nucleoside diphosphokinase and cell cycle control in the fission yeast Schizosaccharomyces pombe

1983 ◽  
Vol 60 (1) ◽  
pp. 355-365
Author(s):  
J.R. Dickinson
Keyword(s):  
Cell Cycle ◽  
Protein Synthesis ◽  
Enzyme Activity ◽  
Dna Replication ◽  
Schizosaccharomyces Pombe ◽  
S Phase ◽  
Restrictive Temperature ◽  
Wild Type ◽  
Synchronous Cultures ◽  
In The Wild

Centrifugal elutriation was used to prepare synchronous cultures of Schizosaccharomyces pombe. Nucleoside diphosphokinase activity was measured throughout the cell cycle. In the wild-type strain (972) nucleoside diphosphokinase activity doubled in a stepwise fashion. The midpoint of the rise in enzyme activity was at 0.65 of a cycle, 0.29 of a cycle before the next S phase. Synchronous cultures of the mutant wee 1–6 were also prepared. In this strain S phase is delayed, occurring about 0.3 cycle later than in the wild-type. In wee 1–6 the midpoint of the stepwise doubling in nucleoside diphosphokinase activity occurred at 0.084; showing that the rise in enzyme activity is also delayed. Addition of cycloheximide to an exponentially growing culture caused an immediate inhibition of protein synthesis, yet nucleoside diphosphokinase activity continued to increase exponentially for a further 300 min. This indicates that the stepwise doubling of nucleoside diphosphokinase activity during the cell cycle is not achieved by a simple control on protein synthesis. Two temperature-sensitive cdc- mutants were also used: cdc2-33, a mutant whose single genetic lesion results in the twin defects of a loss of mitotic control and a loss of commitment to the cell cycle; and cdc 10–129, which has a defect in DNA replication. In both mutants a temperature shift-up of an asynchronously growing culture from the permissive (25 degrees C) to the restrictive temperature (36.5 degrees C) results in a rapid inhibition of DNA replication. In both mutants nucleoside diphosphokinase continues to increase exponentially. Therefore, although nucleoside diphosphokinase is required for DNA replication, apparently DNA replication is not required for an increase in nucleoside diphosphokinase activity.

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