Exploring microRNA Signatures of DNA Damage Response Using an Innovative System of Genotoxic Stress in Medicago truncatula Seedlings

One of the challenges that living organisms face is to promptly respond to genotoxic stress to avoid DNA damage. To this purpose, all organisms, including plants, developed complex DNA damage response (DDR) mechanisms. These mechanisms are highly conserved among organisms and need to be finely regulated. In this scenario, microRNAs (miRNAs) are emerging as active players, thus attracting the attention of the research community. The involvement of miRNAs in DDR has been investigated prominently in human cells whereas studies in plants are still scarce. To experimentally investigate the involvement of plant miRNAs in the regulation of DDR-associated pathways, an ad hoc system was developed, using the model legume Medicago truncatula. Specific treatments with camptothecin (CPT) and/or NSC120686 (NSC), targeting distinct components of DDR, namely topoisomerase I (TopI) and tyrosyl-DNA phosphodiesterase 1 (TDP1), were used. Phenotypic (germination percentage and speed, seedling growth) and molecular (cell death, DNA damage, and gene expression profiles) analyses demonstrated that the imposed treatments impact DDR. Our results show that these treatments do not influence the germination process but rather inhibit seedling development, causing an increase in cell death and accumulation of DNA damage. Moreover, treatment-specific changes in the expression of suppressor of gamma response 1 (SOG1), master-regulator of plant DDR, were observed. Additionally, the expression of multiple genes playing important roles in different DNA repair pathways and cell cycle regulation were differentially expressed in a treatment-specific manner. Subsequently, specific miRNAs identified from our previous bioinformatics approaches as putatively targeting genes involved in DDR processes were investigated alongside their targets. The obtained results indicate that under most conditions when a miRNA is upregulated the corresponding candidate target gene is downregulated, providing an indirect evidence of miRNAs action over these targets. Hence, the present study extends the present knowledge on the information available regarding the roles played by miRNAs in the post-transcriptional regulation of DDR in plants.

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The JNK Pathway Is a Significant Determinant of Sensitivity to DNA Damaging Agents in Pre-B ALL.

Blood ◽

10.1182/blood.v114.22.3786.3786 ◽

2009 ◽

Vol 114 (22) ◽

pp. 3786-3786

Author(s):

Philip O. Saunders ◽

Kenneth F Bradstock ◽

Linda J. Bendall

Keyword(s):

Cell Cycle ◽

Dna Damage ◽

Cell Death ◽

Dna Damage Response ◽

Genotoxic Stress ◽

Jnk Pathway ◽

Dna Damaging Agents ◽

Pathway Activation ◽

Damage Response ◽

Jnk Activation

Abstract Abstract 3786 Poster Board III-722 The JNK pathway is reported to facilitate AP1 binding and promote apoptosis depending on cell type and environmental conditions. We have previously reported RAD001 (16μM) induces JNK pathway activation in pre-B ALL cells. We sought to evaluate the impact of changes in JNK pathway activation on pre-B ALL viability in vitro. Using JNK inhibitor SP600125 titrated to inhibit c-Jun activation, we determined that cell death in pre-B ALL cells treated with RAD001 (16μM) alone was not JNK dependent. In contrast, combining RAD001 (16μM) with DNA damaging agents significantly enhanced JNK dependent death. This difference indicates that additional factors, including genotoxic stress, are required for JNK activation to induce pre-B ALL cell death. The JNK pathway is reported to suppress transcriptional activation of key mediators of the DNA damage response. We observed that JNK activation in cells treated with RAD001 (16μM) and DNA damaging agents was associated with suppression of p53 and p21 relative to DNA damage alone. This result was supported by the observation of enhanced p53 and p21 expression in pre-B ALL cells treated with DNA damaging agents in the presence of the JNK inhibitor SP600125. Analysis of DNA content and proliferation antigen expression in pre-B ALL cells treated with RAD001 (16μM) and DNA damaging agents revealed JNK activation was associated with a significant increase in the proportion of cells in S phase, relative to DNA damage alone, which caused a G1 and G2 cell cycle arrest. Further evidence that the JNK pathway impacts on the DNA damage response was provided by the observation that pre-B ALL cells treated with DNA damaging agents and JNK inhibitor SP600125 demonstrated reduced PCNA expression at G1 and G2 and reduced expression of mitotic antigen phospho-Histone–H3. This is consistent with enhanced regulation at G1-S and G2-M checkpoints. The results indicate changes in JNK pathway activation impact on the cell cycle response to DNA damage. In conclusion we have identified that the JNK pathway has a significant impact on the sensitivity of pre-B ALL cells to DNA damaging agents. JNK activation in the presence of genotoxic stress significantly enhanced pre-B ALL cell death, associated with suppression of key mediators of the DNA damage response, p53 and p21. We found that changes in JNK activation altered the cell cycle response to DNA damage. Further study is required to determine if changes in cell cycle regulation in the presence of DNA damage is causal to JNK dependent cell death. Additional studies to identify intracellular signal pathways which facilitate JNK dependent cell death are warranted. Our observations suggest combining agents which induce JNK activation with conventional chemotherapy or selected novel agents has the potential to enhance clinical responses in pre-B ALL. Disclosures: No relevant conflicts of interest to declare.

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The DNA damage inducible lncRNA SCAT7 regulates genomic integrity and topoisomerase 1 turnover in lung adenocarcinoma

NAR Cancer ◽

10.1093/narcan/zcab002 ◽

2021 ◽

Vol 3 (1) ◽

Author(s):

Luisa Statello ◽

Mohamad M Ali ◽

Silke Reischl ◽

Sagar Mahale ◽

Subazini Thankaswamy Kosalai ◽

...

Keyword(s):

Dna Damage ◽

Dna Damage Response ◽

Cancer Biology ◽

Topoisomerase I ◽

Cell Cycle Checkpoints ◽

Topoisomerase 1 ◽

Damage Response ◽

Promote Cell Survival

Abstract Despite the rapid improvements in unveiling the importance of lncRNAs in all aspects of cancer biology, there is still a void in mechanistic understanding of their role in the DNA damage response. Here we explored the potential role of the oncogenic lncRNA SCAT7 (ELF3-AS1) in the maintenance of genome integrity. We show that SCAT7 is upregulated in response to DNA-damaging drugs like cisplatin and camptothecin, where SCAT7 expression is required to promote cell survival. SCAT7 silencing leads to decreased proliferation of cisplatin-resistant cells in vitro and in vivo through interfering with cell cycle checkpoints and DNA repair molecular pathways. SCAT7 regulates ATR signaling, promoting homologous recombination. Importantly, SCAT7 also takes part in proteasome-mediated topoisomerase I (TOP1) degradation, and its depletion causes an accumulation of TOP1–cc structures responsible for the high levels of intrinsic DNA damage. Thus, our data demonstrate that SCAT7 is an important constituent of the DNA damage response pathway and serves as a potential therapeutic target for hard-to-treat drug resistant cancers.

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Depletion of the DarG antitoxin in Mycobacterium tuberculosis triggers the DNA‐damage response and leads to cell death

Molecular Microbiology ◽

10.1111/mmi.14571 ◽

2020 ◽

Vol 114 (4) ◽

pp. 641-652 ◽

Cited By ~ 1

Author(s):

Anisha Zaveri ◽

Ruojun Wang ◽

Laure Botella ◽

Ritu Sharma ◽

Linnan Zhu ◽

...

Keyword(s):

Dna Damage ◽

Cell Death ◽

Mycobacterium Tuberculosis ◽

Dna Damage Response ◽

Damage Response

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Punicalagin from pomegranate promotes human papillary thyroid carcinoma BCPAP cell death by triggering ATM-mediated DNA damage response

Nutrition Research ◽

10.1016/j.nutres.2017.09.001 ◽

2017 ◽

Vol 47 ◽

pp. 63-71 ◽

Cited By ~ 9

Author(s):

Xin Yao ◽

Xian Cheng ◽

Li Zhang ◽

Huixin Yu ◽

Jiandong Bao ◽

...

Keyword(s):

Dna Damage ◽

Cell Death ◽

Papillary Thyroid Carcinoma ◽

Thyroid Carcinoma ◽

Dna Damage Response ◽

Papillary Thyroid ◽

Damage Response

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RUNX Family Participates in the Regulation of p53-Dependent DNA Damage Response

International Journal of Genomics ◽

10.1155/2013/271347 ◽

2013 ◽

Vol 2013 ◽

pp. 1-12 ◽

Cited By ~ 22

Author(s):

Toshinori Ozaki ◽

Akira Nakagawara ◽

Hiroki Nagase

Keyword(s):

Cell Cycle ◽

Dna Damage ◽

Cell Death ◽

Cell Cycle Arrest ◽

Dna Damage Response ◽

Apoptotic Cell ◽

Genetic Alterations ◽

Apoptotic Cell Death ◽

Cycle Arrest ◽

Damage Response

A proper DNA damage response (DDR), which monitors and maintains the genomic integrity, has been considered to be a critical barrier against genetic alterations to prevent tumor initiation and progression. The representative tumor suppressor p53 plays an important role in the regulation of DNA damage response. When cells receive DNA damage, p53 is quickly activated and induces cell cycle arrest and/or apoptotic cell death through transactivating its target genes implicated in the promotion of cell cycle arrest and/or apoptotic cell death such asp21WAF1,BAX, andPUMA. Accumulating evidence strongly suggests that DNA damage-mediated activation as well as induction of p53 is regulated by posttranslational modifications and also by protein-protein interaction. Loss of p53 activity confers growth advantage and ensures survival in cancer cells by inhibiting apoptotic response required for tumor suppression. RUNX family, which is composed of RUNX1, RUNX2, and RUNX3, is a sequence-specific transcription factor and is closely involved in a variety of cellular processes including development, differentiation, and/or tumorigenesis. In this review, we describe a background of p53 and a functional collaboration between p53 and RUNX family in response to DNA damage.

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MORC2 regulates DNA damage response through a PARP1-dependent pathway

Nucleic Acids Research ◽

10.1093/nar/gkz545 ◽

2019 ◽

Vol 47 (16) ◽

pp. 8502-8520 ◽

Cited By ~ 4

Author(s):

Lin Zhang ◽

Da-Qiang Li

Keyword(s):

Dna Damage ◽

Zinc Finger ◽

Chromatin Remodeling ◽

Dna Damage Response ◽

Mammalian Cells ◽

Cellular Response ◽

Genotoxic Stress ◽

Underlying Mechanism ◽

Dna Lesions ◽

Damage Response

Abstract Microrchidia family CW-type zinc finger 2 (MORC2) is a newly identified chromatin remodeling enzyme with an emerging role in DNA damage response (DDR), but the underlying mechanism remains largely unknown. Here, we show that poly(ADP-ribose) polymerase 1 (PARP1), a key chromatin-associated enzyme responsible for the synthesis of poly(ADP-ribose) (PAR) polymers in mammalian cells, interacts with and PARylates MORC2 at two residues within its conserved CW-type zinc finger domain. Following DNA damage, PARP1 recruits MORC2 to DNA damage sites and catalyzes MORC2 PARylation, which stimulates its ATPase and chromatin remodeling activities. Mutation of PARylation residues in MORC2 results in reduced cell survival after DNA damage. MORC2, in turn, stabilizes PARP1 through enhancing acetyltransferase NAT10-mediated acetylation of PARP1 at lysine 949, which blocks its ubiquitination at the same residue and subsequent degradation by E3 ubiquitin ligase CHFR. Consequently, depletion of MORC2 or expression of an acetylation-defective PARP1 mutant impairs DNA damage-induced PAR production and PAR-dependent recruitment of DNA repair proteins to DNA lesions, leading to enhanced sensitivity to genotoxic stress. Collectively, these findings uncover a previously unrecognized mechanistic link between MORC2 and PARP1 in the regulation of cellular response to DNA damage.

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