scholarly journals ANALYSIS OF THE CAPABILITIES OF THE PROGRAMS FIJI, IPLAB AND DARFI IN THE STUDY OF DNA REPAIR ABILITIES IN THE CELLS OF PATIENTS WITH A MOSAIC FORM OF ATAXIA TELANGIECTASIA

2020 ◽  
Author(s):  
Aleksandra Nozdracheva ◽  
Roman Ushakov ◽  
Nadezhda Pleskach ◽  
Mirya Kuranova
Keyword(s):  
Dna Repair ◽  
Ataxia Telangiectasia ◽  
Mosaic Form

Features of DNA repair in dermal fibroblasts in ataxia-telangiectasia patients with mosaic type of manifestation of active ATM kinase

2020 ◽  
Vol XV (1) ◽  
Author(s):  
M. Kuranova ◽  
A. Nozdracheva ◽  
R. Ushakov ◽  
T. Ledashcheva ◽  
L. Schugareva ◽  
...  
Keyword(s):  
Dna Repair ◽  
Ataxia Telangiectasia ◽  
Dermal Fibroblasts ◽  
Atm Kinase

The ionizing radiation-induced replication protein A phosphorylation response differs between ataxia telangiectasia and normal human cells

1993 ◽  
Vol 13 (12) ◽  
pp. 7222-7231
Author(s):  
V F Liu ◽  
D T Weaver
Keyword(s):  
Dna Repair ◽  
Ionizing Radiation ◽  
Gamma Irradiation ◽  
Ataxia Telangiectasia ◽  
Protein A ◽  
Replication Protein A ◽  
Replication Protein ◽  
Inherited Disease ◽  
Dna Replication And Repair ◽  
In Cells

Replication protein A (RPA), the trimeric single-stranded DNA-binding protein complex of eukaryotic cells, is important to DNA replication and repair. Phosphorylation of the p34 subunit of RPA is modulated by the cell cycle, occurring during S and G2 but not during G1. The function of phosphorylated p34 remains unknown. We show that RPA p34 phosphorylation is significantly induced by ionizing radiation. The phosphorylated form, p36, is similar if not identical to the phosphorylated S/G2 form. gamma-Irradiation-induced phosphorylation occurs without new protein synthesis and in cells in G1. Mutation of cdc2-type protein kinase phosphorylation sites in p34 eliminates the ionizing radiation response. The gamma-irradiation-induced phosphorylation of RPA p34 is delayed in cells from ataxia telangiectasia, a human inherited disease conferring DNA repair defects and early-onset tumorigenesis. UV-induced phosphorylation of RPA p34 occurs less rapidly than gamma-irradiation-induced phosphorylation but is kinetically similar between ataxia telangiectasia and normal cells. This is the first time that modification of a repair protein, RPA, has been linked with a DNA damage response and suggests that phosphorylation may play a role in regulating DNA repair pathways.

Kaempferol Induces DNA Damage and Inhibits DNA Repair Associated Protein Expressions in Human Promyelocytic Leukemia HL-60 Cells

2015 ◽  
Vol 43 (02) ◽  
pp. 365-382 ◽  
Author(s):  
Lung-Yuan Wu ◽  
Hsu-Feng Lu ◽  
Yu-Cheng Chou ◽  
Yung-Luen Shih ◽  
Da-Tian Bau ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Protein Expression ◽  
Ataxia Telangiectasia ◽  
Repair System ◽  
Dapi Staining ◽  
Viable Cells ◽  
Protein Expressions ◽  
Dose Dependent

Numerous evidences have shown that plant flavonoids (naturally occurring substances) have been reported to have chemopreventive activities and protect against experimental carcinogenesis. Kaempferol, one of the flavonoids, is widely distributed in fruits and vegetables, and may have cancer chemopreventive properties. However, the precise underlying mechanism regarding induced DNA damage and suppressed DNA repair system are poorly understood. In this study, we investigated whether kaempferol induced DNA damage and affected DNA repair associated protein expression in human leukemia HL-60 cells in vitro. Percentages of viable cells were measured via a flow cytometry assay. DNA damage was examined by Comet assay and DAPI staining. DNA fragmentation (ladder) was examined by DNA gel electrophoresis. The changes of protein levels associated with DNA repair were examined by Western blotting. Results showed that kaempferol dose-dependently decreased the viable cells. Comet assay indicated that kaempferol induced DNA damage (Comet tail) in a dose-dependent manner and DAPI staining also showed increased doses of kaempferol which led to increased DNA condensation, these effects are all of dose-dependent manners. Western blotting indicated that kaempferol-decreased protein expression associated with DNA repair system, such as phosphate-ataxia-telangiectasia mutated (p-ATM), phosphate-ataxia-telangiectasia and Rad3-related (p-ATR), 14-3-3 proteins sigma (14-3-3σ), DNA-dependent serine/threonine protein kinase (DNA-PK), O6-methylguanine-DNA methyltransferase (MGMT), p53 and MDC1 protein expressions, but increased the protein expression of p-p53 and p-H2AX. Protein translocation was examined by confocal laser microscopy, and we found that kaempferol increased the levels of p-H2AX and p-p53 in HL-60 cells. Taken together, in the present study, we found that kaempferol induced DNA damage and suppressed DNA repair and inhibited DNA repair associated protein expression in HL-60 cells, which may be the factors for kaempferol induced cell death in vitro.

Ataxia Telangiectasia

Blood ◽  
2011 ◽  
Vol 118 (21) ◽  
pp. SCI-7-SCI-7
Author(s):  
Richard A. Gatti
Keyword(s):  
Dna Repair ◽  
Ataxia Telangiectasia ◽  
Conflicts Of Interest ◽  
Severe Combined Immunodeficiency ◽  
Strand Break ◽  
Diagnostic Methods ◽  
Neurological Dysfunction ◽  
Single Strand Break ◽  
Atm Kinase ◽  
Clinical Radiosensitivity

Abstract Abstract SCI-7 Ataxia-telangiectasia (A-T) is the prototype for an expanded group of inherited radiation sensitive disorders that together define the XCIND syndrome: x-ray hypersensitivity, cancer, immunodeficiency, neurological dysfunction, and DNA repair deficiency. Although the clinical radiosensitivity of these disorders can be tested in the clinical laboratory, diagnostic methods remain limited and in need of further validation. Without exception, to date, sensitivity to ionizing radiation appears to be integrally associated with double strand break (DSB) repair defects and lymphoid cancer susceptibility, setting these disorders apart from single strand break repair disorders such as xeroderma pigmentosum. Responding within seconds to DSB damage are ATM kinase, the protein lacking in A-T, and the NMR complex (nibrin, Mre11, and Rad50). The latter three proteins are associated with three additional XCIND disorders (nibrin deficiency [aka nijmegen breakage syndrome], Mre11 deficiency [ATLD], and Rad50 deficiency). ATM kinase activates a myriad of other proteins that 1) halt DNA synthesis, replication, and the progression of the cell cycle; 2) form a complex protein “mesh” to physically stabilize the broken DNA strands; and 3) restore the integrity of the breaks before they unravel to create even larger chromosomal lesions and resulting malignancies. Another ATM-dependent cancer link involves the downregulation of ATM by microRNA-421. MicroRNA-421 is upregulated by the transcription factor N-myc. Despite this, neuroblastomas are not commonly observed in A-T or XCIND patients. Another subset of XCIND-associated disorders lacks proteins the drive the nonhomologous end joining pathway of DNA repair. Several of these diseases present in infancy as B−/T− severe combined immunodeficiency, or SCID, and are frequent candidates for stem cell transplantation. Attempts to ablate existing bone marrow prior to transplantation may further compromise such patients if they are inherently radiosensitive. Thus, attempts to preselect such patients and reduce radiation dosages may improve general post-transplantation survival. While most protein deficiencies can be diagnosed by immunoblots of appropriate cellular fractions, nonfunctional proteins are not detected by this platform. Colony survival assays (CSA) measure the ability of replicating cells (e.g., lymphoblasts or fibroblasts) to survive after exposure to radiation. Although causal proof that CSA can predict clinical radiosensitivity is lacking, the reduced percent survival fraction (i.e., radiosensitivity) of A-T, N-Bromosuccinimide, or Fanconi cell lines can be abrogated by introducing the mutated cognate gene. Other surrogate assays for radiosensitivity include kinetic studies, pre-irradiation and post-irradiation of γ-H2AX or SMC1 phosphorylation. Ultimately, DNA sequencing of a candidate gene can pinpoint the underlying pathogenesis of radiosensitivity in an XCIND disorder. Disclosures: No relevant conflicts of interest to declare.

scholarly journals ATM Kinase Dead: From Ataxia Telangiectasia Syndrome to Cancer

Cancers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 5498
Author(s):  
Sabrina Putti ◽  
Alessandro Giovinazzo ◽  
Matilde Merolle ◽  
Maria Laura Falchetti ◽  
Manuela Pellegrini
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Cancer Cells ◽  
Mouse Models ◽  
Ataxia Telangiectasia ◽  
Cancer Susceptibility ◽  
Residual Activity ◽  
In Vivo Models ◽  
Atm Kinase ◽  
Phosphoinositide 3 Kinase

ATM is one of the principal players of the DNA damage response. This protein exerts its role in DNA repair during cell cycle replication, oxidative stress, and DNA damage from endogenous events or exogenous agents. When is activated, ATM phosphorylates multiple substrates that participate in DNA repair, through its phosphoinositide 3-kinase like domain at the 3′end of the protein. The absence of ATM is the cause of a rare autosomal recessive disorder called Ataxia Telangiectasia characterized by cerebellar degeneration, telangiectasia, immunodeficiency, cancer susceptibility, and radiation sensitivity. There is a correlation between the severity of the phenotype and the mutations, depending on the residual activity of the protein. The analysis of patient mutations and mouse models revealed that the presence of inactive ATM, named ATM kinase-dead, is more cancer prone and lethal than its absence. ATM mutations fall into the whole gene sequence, and it is very difficult to predict the resulting effects, except for some frequent mutations. In this regard, is necessary to characterize the mutated protein to assess if it is stable and maintains some residual kinase activity. Moreover, the whole-genome sequencing of cancer patients with somatic or germline mutations has highlighted a high percentage of ATM mutations in the phosphoinositide 3-kinase domain, mostly in cancer cells resistant to classical therapy. The relevant differences between the complete absence of ATM and the presence of the inactive form in in vitro and in vivo models need to be explored in more detail to predict cancer predisposition of A-T patients and to discover new therapies for ATM-associated cancer cells. In this review, we summarize the multiple discoveries from humans and mouse models on ATM mutations, focusing into the inactive versus null ATM.

Sign in / Sign up

Export Citation Format

Share Document