The Role of Repair Mechanisms in the Variations of Ultraviolet and γ-Radiation Sensitivity during the Cell Cycle of Schizosaccharomyces pombe

1973 ◽  
Vol 56 (3) ◽  
pp. 528 ◽  
Author(s):  
F. Fabre
2019 ◽  
Vol 105 (3) ◽  
pp. 839-853
Author(s):  
Aglaia Kyrilli ◽  
David Gacquer ◽  
Vincent Detours ◽  
Anne Lefort ◽  
Frédéric Libert ◽  
...  

Abstract Background The early molecular events in human thyrocytes after 131I exposure have not yet been unravelled. Therefore, we investigated the role of TSH in the 131I-induced DNA damage response and gene expression in primary cultured human thyrocytes. Methods Following exposure of thyrocytes, in the presence or absence of TSH, to 131I (β radiation), γ radiation (3 Gy), and hydrogen peroxide (H2O2), we assessed DNA damage, proliferation, and cell-cycle status. We conducted RNA sequencing to profile gene expression after each type of exposure and evaluated the influence of TSH on each transcriptomic response. Results Overall, the thyrocyte responses following exposure to β or γ radiation and to H2O2 were similar. However, TSH increased 131I-induced DNA damage, an effect partially diminished after iodide uptake inhibition. Specifically, TSH increased the number of DNA double-strand breaks in nonexposed thyrocytes and thus predisposed them to greater damage following 131I exposure. This effect most likely occurred via Gα q cascade and a rise in intracellular reactive oxygen species (ROS) levels. β and γ radiation prolonged thyroid cell-cycle arrest to a similar extent without sign of apoptosis. The gene expression profiles of thyrocytes exposed to β/γ radiation or H2O2 were overlapping. Modulations in genes involved in inflammatory response, apoptosis, and proliferation were observed. TSH increased the number and intensity of modulation of differentially expressed genes after 131I exposure. Conclusions TSH specifically increased 131I-induced DNA damage probably via a rise in ROS levels and produced a more prominent transcriptomic response after exposure to 131I.


2009 ◽  
Vol 29 (16) ◽  
pp. 4341-4351 ◽  
Author(s):  
Vanesa Lafarga ◽  
Ana Cuadrado ◽  
Isabel Lopez de Silanes ◽  
Rocio Bengoechea ◽  
Oscar Fernandez-Capetillo ◽  
...  

ABSTRACT Activation of p38 mitogen-activated protein kinase (MAPK) plays an important role in the G2/M cell cycle arrest induced by DNA damage, but little is known about the role of this signaling pathway in the G1/S transition. Upregulation of the cyclin-dependent kinase inhibitor p21Cip1 is thought to make a major contribution to the G1/S cell cycle arrest induced by γ radiation. We show here that inhibition of p38 MAPK impairs p21Cip1 accumulation and, as a result, the ability of cells to arrest in G1 in response to γ radiation. We found that p38 MAPK induces p21Cip1 mRNA stabilization, without affecting its transcription or the stability of the protein. In particular, p38 MAPK phosphorylates the mRNA binding protein HuR on Thr118, which results in cytoplasmic accumulation of HuR and its enhanced binding to the p21Cip1 mRNA. Our findings help to understand the emerging role of p38 MAPK in the cellular responses to DNA damage and reveal the existence of p53-independent networks that cooperate in modulating p21Cip1 levels at the G1/S checkpoint.


2020 ◽  
Vol 25775790 ◽  
pp. 1-1
Author(s):  
Vidhula R Ahire ◽  
◽  
Amit Kumar ◽  
Sushma Bhosle ◽  
Kaushala Prasad Mishra ◽  
...  

Ellagic acid (EA) is a polyphenol found in grapes, pomegranates, walnuts, etc. exhibits anti-cancer properties. The current study was conducted to understand the radiosensitizing role of EA on HeLa cells. Monotherapy of EA and radiation was initially studied on HeLa cells. The addition of EA before the radiation treatment subsequently made DNA more susceptible to damage thereby developing DNA beaks, which are known to be lethal for cell survival. This was evaluated by performing comet and γ-foci formation assay. Other assays which included cell-cycle distribution, clonogenic cell survival assay, mitochondrial membrane drop, and apoptosis were performed to evaluate the effect of EA with radiation. Our results demonstrate that, when cells were exposed to the combinatorial treatment of EA (10µM) and 2Gy of γ-radiation there was augmented cell death, lesser cell-proliferation, reduction in the colony-forming ability, increased DNA tail length, more number of γ-foci persisting even after 24h, enhanced apoptosis, augmented drop in the mitochondrial membrane potential and a G1 cell-cycle arrest. These results suggest that EA exhibits not only anti-cancer properties in terms of cell-death but also exhibits a radiosensitizing effect when given in combination with γ-radiation. Thus, it can be concluded that EA not only exhibits anticancer effects but also has potential in radiosensitizing HeLa cells.


Genetics ◽  
1975 ◽  
Vol 79 (4) ◽  
pp. 573-582
Author(s):  
A Nasim ◽  
B P Smith

ABSTRACT Genetic analysis of a large number of radiation-sensitive mutants of S. pombe, isolated in different laboratories, showed that these isolates represent 22 non-allelic loci. The mutants were shown to fall into three distinct classes concerning response to UV and ionizing radiation, including two mutants which are primarily sensitive to ionizing radiation but not to UV. Single-gene mutants were crossed to obtain supersensitive double mutants. Such double mutants showed a marked increase in sensitivity to a variety of inactivating agents as compared to the parental strains. The isolation of three classes of radiation-sensitive mutants and the construction of double mutants implies the presence of multiple pathways in S. pombe for repair of radiation-induced damage. The bearing of these data on cellular repair mechanisms in eukaryotes is discussed.


2008 ◽  
Vol 181 (1) ◽  
pp. 79-88 ◽  
Author(s):  
Dawn M. Clifford ◽  
Benjamin A. Wolfe ◽  
Rachel H. Roberts-Galbraith ◽  
W. Hayes McDonald ◽  
John R. Yates ◽  
...  

Cdc14 phosphatases antagonize cyclin-dependent kinase–directed phosphorylation events and are involved in several facets of cell cycle control. We investigate the role of the fission yeast Cdc14 homologue Clp1/Flp1 in cytokinesis. We find that Clp1/Flp1 is tethered at the contractile ring (CR) through its association with anillin-related Mid1. Fluorescent recovery after photobleaching analyses indicate that Mid1, unlike other tested CR components, is anchored at the cell midzone, and this physical property is likely to account for its scaffolding role. By generating a mutation in mid1 that selectively disrupts Clp1/Flp1 tethering, we reveal the specific functional consequences of Clp1/Flp1 activity at the CR, including dephosphorylation of the essential CR component Cdc15, reductions in CR protein mobility, and CR resistance to mild perturbation. Our evidence indicates that Clp1/Flp1 must interact with the Mid1 scaffold to ensure the fidelity of Schizosaccharomyces pombe cytokinesis.


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