scholarly journals PARI Regulates Stalled Replication Fork Processing To Maintain Genome Stability upon Replication Stress in Mice

2017 ◽  
Vol 37 (23) ◽  
Author(s):  
Ayako L. Mochizuki ◽  
Ami Katanaya ◽  
Eri Hayashi ◽  
Mihoko Hosokawa ◽  
Emiko Moribe ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Replication ◽  
Genome Stability ◽  
Ex Vivo ◽  
Chromosome Instability ◽  
Embryonic Stem ◽  
Replication Stress ◽  
Genotoxic Stress ◽  
Origin Firing

ABSTRACT DNA replication is frequently perturbed by intrinsic, as well as extrinsic, genotoxic stress. At damaged forks, DNA replication and repair activities require proper coordination to maintain genome integrity. We show here that PARI antirecombinase plays an essential role in modulating the initial response to replication stress in mice. PARI is functionally dormant at replisomes during normal replication, but upon replication stress, it enhances nascent-strand shortening that is regulated by RAD51 and MRE11. PARI then promotes double-strand break induction, followed by new origin firing instead of replication restart. Such PARI function is apparently obstructive to replication but is nonetheless physiologically required for chromosome stability in vivo and ex vivo. Of note, Pari-deficient embryonic stem cells exhibit spontaneous chromosome instability, which is attenuated by differentiation induction, suggesting that pluripotent stem cells have a preferential requirement for PARI that acts against endogenous replication stress. PARI is a latent modulator of stalled fork processing, which is required for stable genome inheritance under both endogenous and exogenous replication stress in mice.

scholarly journals Replication Stress and Telomere Dysfunction Are Present in Cultured Human Embryonic Stem Cells

2015 ◽  
Vol 146 (4) ◽  
pp. 251-260 ◽  
Author(s):  
Christine Janson ◽  
Kristine Nyhan ◽  
John P. Murnane
Keyword(s):  
Stem Cells ◽  
Dna Damage ◽  
Embryonic Stem Cells ◽  
Human Embryonic Stem Cells ◽  
Chromosome Instability ◽  
Embryonic Stem ◽  
Replication Stress ◽  
Activin A ◽  
Fragile Sites ◽  
Telomere Dysfunction

Replication stress causes DNA damage at fragile sites in the genome. DNA damage at telomeres can initiate breakage-fusion-bridge cycles and chromosome instability, which can result in replicative senescence or tumor formation. Little is known about the extent of replication stress or telomere dysfunction in human embryonic stem cells (hESCs). hESCs are grown in culture with the expectation of being used therapeutically in humans, making it important to minimize the levels of replication stress and telomere dysfunction. Here, the hESC line UCSF4 was cultured in a defined medium with growth factor Activin A, exogenous nucleosides, or DNA polymerase inhibitor aphidicolin. We used quantitative fluorescence in situ hybridization to analyze individual telomeres for dysfunction and observed that it can be increased by aphidicolin or Activin A. In contrast, adding exogenous nucleosides relieved dysfunction, suggesting that telomere dysfunction results from replication stress. Whether these findings can be applied to other hESC lines remains to be determined. However, because the loss of telomeres can lead to chromosome instability and cancer, we conclude that hESCs grown in culture for future therapeutic purposes should be routinely checked for replication stress and telomere dysfunction.

scholarly journals Human Embryonic Stem Cells Fail to Activate CHK1 and Commit to Apoptosis in Response to DNA Replication Stress

Stem Cells ◽  
2012 ◽  
Vol 30 (7) ◽  
pp. 1385-1393 ◽  
Author(s):  
Joëlle A. Desmarais ◽  
Michele J. Hoffmann ◽  
Gregg Bingham ◽  
Mary E. Gagou ◽  
Mark Meuth ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dna Replication ◽  
Embryonic Stem Cells ◽  
Human Embryonic Stem Cells ◽  
Embryonic Stem ◽  
Replication Stress ◽  
Dna Replication Stress

scholarly journals Emerging functions of Fanconi anemia genes in replication fork protection pathways

2020 ◽  
Vol 29 (R2) ◽  
pp. R158-R164 ◽  
Author(s):  
Arun Mouli Kolinjivadi ◽  
Wayne Crismani ◽  
Joanne Ngeow
Keyword(s):  
Dna Replication ◽  
Fanconi Anemia ◽  
Replication Fork ◽  
Genome Stability ◽  
Chromosome Instability ◽  
Replication Stress ◽  
Short Review ◽  
Gene Products ◽  
Dna Double Strand Breaks ◽  
Variants Of Unknown Significance

Abstract Germline mutations in Fanconi anemia (FA) genes predispose to chromosome instability syndromes, such as FA and cancers. FA gene products have traditionally been studied for their role in interstrand cross link (ICL) repair. A fraction of FA gene products are classical homologous recombination (HR) factors that are involved in repairing DNA double-strand breaks (DSBs) in an error-free manner. Emerging evidence suggests that, independent of ICL and HR repair, FA genes protect DNA replication forks in the presence of replication stress. Therefore, understanding the precise function of FA genes and their role in promoting genome stability in response to DNA replication stress is crucial for diagnosing FA and FA-associated cancers. Moreover, molecular understanding of the FA pathway will greatly help to establish proper functional assays for variants of unknown significance (VUS), often encountered in clinics. In this short review, we discuss the recently uncovered molecular details of FA genes in replication fork protection pathways. Finally, we examine how novel FA variants predispose to FA and cancer, due to defective replication fork protection activity.

scholarly journals Effect of chromosome instability on the maintenance and differentiation of human embryonic stem cells in vitro and in vivo

2011 ◽  
Vol 6 (1) ◽  
pp. 50-59 ◽  
Author(s):  
Sung-Hwan Moon ◽  
Jong-Soo Kim ◽  
Soon-Jung Park ◽  
Joa-Jin Lim ◽  
Hye-Jin Lee ◽  
...  
Keyword(s):  
Stem Cells ◽  
Embryonic Stem Cells ◽  
Human Embryonic Stem Cells ◽  
Chromosome Instability ◽  
Embryonic Stem

Ex Vivo Treatment of Human Cord Blood with dmPGE2 Can Safely Increase the Potential for Hematopoietic Engraftment.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 1190-1190
Author(s):  
Trista E. North ◽  
Wolfram Goessling ◽  
Myriam Armant ◽  
Grace S. Kao ◽  
Leslie E. Silberstein ◽  
...  
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Cord Blood ◽  
Ex Vivo ◽  
Embryonic Stem ◽  
Relative Distribution ◽  
Human Cord Blood ◽  
Hematopoietic Stem

Abstract Hematopoietic stem cells (HSCs) are commonly used in transplantation therapy to rescue the hematopoietic and immune systems following systemic chemotherapy or irradiation. However, some patients receive inadequate numbers of HSCs and this often results in delayed reconstitution of hematopoiesis and immune function and associated toxicities. We previously demonstrated that a stabilized derivative of prostaglandin (PG) E2 increases vertebrate HSCs both in vivo and in vitro. 16,16-dimethyl PGE2 (dmPGE2) significantly increased HSCs during zebrafish embryogenesis and in the adult marrow following injury. Incubation of murine embryonic stem cells with dmPGE2 during embryoid body differentiation resulted in a dose-dependent increase in hematopoietic colonies, demonstrating that the function of PGE2 in HSC regulation is conserved in mammals. Finally, ex vivo treatment of murine bone marrow with dmPGE2 resulted in a 2-fold increase in engrafting cells in a limiting dilution competitive repopulation assay. No negative effects on serial transplantability of HSCs were observed in these animal models. To investigate the therapeutic potential of PGE2 for the amplification of blood stem cells, we exposed human cord blood (hCB) cells to dmPGE2 in vitro and measured the effects on stem and progenitor populations both in vitro and in vivo. Red cell depleted umbilical cord blood specimens, cryopreserved for clinical use, were thawed and divided for parallel processing. Ex vivo treatment of hCB cells for 1 hour with dmPGE2 in dextran/albumin had no negative impact on absolute cell count or the viability and relative distribution of both CD45 and CD34 positive cells compared to vehicle treated control hCB cells. Significantly, hCB treated with dmPGE2 produced enhanced numbers of GM and GEMM colonies in methylcellose CFU-C assays compared to controls. Human CB cells treated ex vivo with dmPGE2 for 1 hour and transplanted at a dose of 20 million live CD45+ cells per recipient were capable of repopulating NOD/SCID mice after sublethal irradiation. In comparative studies at 6 weeks post transplantation, human CD34+ and CD45+ cells could be detected in the marrow (>2%) of dmPGE2 treated (4/8) and control treated (1/6) recipients. Long-term and competitive transplantation experiments to assess the effect of dmPGE2 treatment on functional HSCs are currently in progress. Our data suggests that treatment of human cord blood products with dmPGE2 will be both safe and effective in achieving expansion of hematopoietic stem cells for transplantation in the clinical setting. TE North and W Goessling contributed equally to this work.

scholarly journals FBH1 promotes DNA double-strand breakage and apoptosis in response to DNA replication stress

2013 ◽  
Vol 200 (2) ◽  
pp. 141-149 ◽  
Author(s):  
Yeon-Tae Jeong ◽  
Mario Rossi ◽  
Lukas Cermak ◽  
Anita Saraf ◽  
Laurence Florens ◽  
...  
Keyword(s):  
Dna Replication ◽  
Genome Stability ◽  
Protein A ◽  
Replication Stress ◽  
Genotoxic Stress ◽  
Dna Helicase ◽  
Dna Lesions ◽  
Physical Interaction ◽  
Helicase Activity ◽  
Dna Replication Stress

Proper resolution of stalled replication forks is essential for genome stability. Purification of FBH1, a UvrD DNA helicase, identified a physical interaction with replication protein A (RPA), the major cellular single-stranded DNA (ssDNA)–binding protein complex. Compared with control cells, FBH1-depleted cells responded to replication stress with considerably fewer double-strand breaks (DSBs), a dramatic reduction in the activation of ATM and DNA-PK and phosphorylation of RPA2 and p53, and a significantly increased rate of survival. A minor decrease in ssDNA levels was also observed. All these phenotypes were rescued by wild-type FBH1, but not a FBH1 mutant lacking helicase activity. FBH1 depletion had no effect on other forms of genotoxic stress in which DSBs form by means that do not require ssDNA intermediates. In response to catastrophic genotoxic stress, apoptosis prevents the persistence and propagation of DNA lesions. Our findings show that FBH1 helicase activity is required for the efficient induction of DSBs and apoptosis specifically in response to DNA replication stress.

Strategies to Protect Hematopoietic Stem Cells from Culture-Induced Stress Conditions

2020 ◽  
Vol 15 ◽  
Author(s):  
Fatima Aerts-Kaya
Keyword(s):  
Stem Cells ◽  
Hematopoietic Stem Cells ◽  
Ex Vivo ◽  
Stress Conditions ◽  
Stress Factors ◽  
Hematopoietic Stem ◽  
Induced Stress

: In contrast to their almost unlimited potential for expansion in vivo and despite years of dedicated research and optimization of expansion protocols, the expansion of Hematopoietic Stem Cells (HSCs) in vitro remains remarkably limited. Increased understanding of the mechanisms that are involved in maintenance, expansion and differentiation of HSCs will enable the development of better protocols for expansion of HSCs. This will allow procurement of HSCs with long-term engraftment potential and a better understanding of the effects of the external influences in and on the hematopoietic niche that may affect HSC function. During collection and culture of HSCs, the cells are exposed to suboptimal conditions that may induce different levels of stress and ultimately affect their self-renewal, differentiation and long-term engraftment potential. Some of these stress factors include normoxia, oxidative stress, extra-physiologic oxygen shock/stress (EPHOSS), endoplasmic reticulum (ER) stress, replicative stress, and stress related to DNA damage. Coping with these stress factors may help reduce the negative effects of cell culture on HSC potential, provide a better understanding of the true impact of certain treatments in the absence of confounding stress factors. This may facilitate the development of better ex vivo expansion protocols of HSCs with long-term engraftment potential without induction of stem cell exhaustion by cellular senescence or loss of cell viability. This review summarizes some of available strategies that may be used to protect HSCs from culture-induced stress conditions.

scholarly journals mRNA-Driven Generation of Transgene-Free Neural Stem Cells from Human Urine-Derived Cells

Cells ◽  
2019 ◽  
Vol 8 (9) ◽  
pp. 1043 ◽  
Author(s):  
Phil Jun Kang ◽  
Daryeon Son ◽  
Tae Hee Ko ◽  
Wonjun Hong ◽  
Wonjin Yun ◽  
...  
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Human Urine ◽  
Neurological Disorders ◽  
Therapeutic Potential ◽  
Embryonic Stem ◽  
Global Gene Expression ◽  
Patient Specific ◽  
Human Neural Stem Cells

Human neural stem cells (NSCs) hold enormous promise for neurological disorders, typically requiring their expandable and differentiable properties for regeneration of damaged neural tissues. Despite the therapeutic potential of induced NSCs (iNSCs), a major challenge for clinical feasibility is the presence of integrated transgenes in the host genome, contributing to the risk for undesired genotoxicity and tumorigenesis. Here, we describe the advanced transgene-free generation of iNSCs from human urine-derived cells (HUCs) by combining a cocktail of defined small molecules with self-replicable mRNA delivery. The established iNSCs were completely transgene-free in their cytosol and genome and further resembled human embryonic stem cell-derived NSCs in the morphology, biological characteristics, global gene expression, and potential to differentiate into functional neurons, astrocytes, and oligodendrocytes. Moreover, iNSC colonies were observed within eight days under optimized conditions, and no teratomas formed in vivo, implying the absence of pluripotent cells. This study proposes an approach to generate transplantable iNSCs that can be broadly applied for neurological disorders in a safe, efficient, and patient-specific manner.

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