scholarly journals Characterization of a Knock-In Mouse Model with a Huntingtin Exon 1 Deletion

2021 ◽  
pp. 1-20
Author(s):  
Elise M. Braatz ◽  
Emily A. André ◽  
Jeh-Ping Liu ◽  
Scott O. Zeitlin
Keyword(s):  
Dna Damage ◽  
Critical Role ◽  
Motor Tasks ◽  
Female Ratio ◽  
Damage Repair ◽  
Exon 1 ◽  
Male To Female ◽  
Terminal Domains

Background: The Huntingtin (HTT) N-terminal domains encoded by Huntingtin’s (HTT) exon 1 consist of an N17 domain, the polyglutamine (polyQ) stretch and a proline-rich region (PRR). These domains are conserved in mammals and have been hypothesized to modulate HTT’s functions in the developing and adult CNS, including DNA damage repair and autophagy. Objective: This study longitudinally characterizes the in vivo consequences of deleting the murine Htt N-terminal domains encoded by Htt exon 1. Methods: Knock-in mice with a deletion of Htt exon 1 sequences (Htt ΔE1) were generated and bred into the C57BL/6J congenic genetic background. Their behavior, DNA damage response, basal autophagy, and glutamatergic synapse numbers were evaluated. Results: Progeny from Htt ΔE1/+ intercrosses are born at the expected Mendelian frequency but with a distorted male to female ratio in both the Htt ΔE1/ΔE1 and Htt  +/+ offspring. Htt ΔE1/ΔE1 adults exhibit a modest deficit in accelerating rotarod performance, and an earlier increase in cortical and striatal DNA damage with elevated neuronal pan-nuclear 53bp1 levels compared to Htt  +/+ mice. However, a normal response to induced DNA damage, normal levels of basal autophagy markers, and no significant differences in corticocortical, corticostriatal, thalamocortical, or thalamostriatal synapses numbers were observed compared to controls. Conclusion: Our results suggest that deletion of the Htt N-terminus encoded by the Htt exon 1 does not affect Htt’s critical role during embryogenesis, but instead, may have a modest effect on certain motor tasks, basal levels of DNA damage in the brain, and Htt function in the testis.

scholarly journals LINC-PINT impedes DNA repair and enhances radiotherapeutic response by targeting DNA-PKcs in nasopharyngeal cancer

2021 ◽  
Vol 12 (5) ◽  
Author(s):  
You-hong Wang ◽  
Zhen Guo ◽  
Liang An ◽  
Yong Zhou ◽  
Heng Xu ◽  
...  
Keyword(s):  
Dna Damage ◽  
Nasopharyngeal Cancer ◽  
Noncoding Rnas ◽  
Dependent Protein Kinase ◽  
Damage Repair ◽  
Dependent Protein ◽  
Cancer Tissues

AbstractRadioresistance continues to be the leading cause of recurrence and metastasis in nasopharyngeal cancer. Long noncoding RNAs are emerging as regulators of DNA damage and radioresistance. LINC-PINT was originally identified as a tumor suppressor in various cancers. In this study, LINC-PINT was significantly downregulated in nasopharyngeal cancer tissues than in rhinitis tissues, and low LINC-PINT expressions showed poorer prognosis in patients who received radiotherapy. We further identified a functional role of LINC-PINT in inhibiting the malignant phenotypes and sensitizing cancer cells to irradiation in vitro and in vivo. Mechanistically, LINC-PINT was responsive to DNA damage, inhibiting DNA damage repair through ATM/ATR-Chk1/Chk2 signaling pathways. Moreover, LINC-PINT increased radiosensitivity by interacting with DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and negatively regulated the expression and recruitment of DNA-PKcs. Therefore, these findings collectively support the possibility that LINC-PINT serves as an attractive target to overcome radioresistance in NPC.

scholarly journals PAICS contributes to gastric carcinogenesis and participates in DNA damage response by interacting with histone deacetylase 1/2

2020 ◽  
Vol 11 (7) ◽  
Author(s):  
Nan Huang ◽  
Chang Xu ◽  
Liang Deng ◽  
Xue Li ◽  
Zhixuan Bian ◽  
...  
Keyword(s):  
Dna Damage ◽  
Histone Deacetylase ◽  
Dna Damage Response ◽  
De Novo ◽  
Dna Damage Repair ◽  
Histone Deacetylase 1 ◽  
Damage Repair ◽  
Damage Response

AbstractPhosphoribosylaminoimidazole carboxylase, phosphoribosylaminoimidazole succinocarboxamide synthetase (PAICS), an essential enzyme involved in de novo purine biosynthesis, is connected with formation of various tumors. However, the specific biological roles and related mechanisms of PAICS in gastric cancer (GC) remain unclear. In the present study, we identified for the first time that PAICS was significantly upregulated in GC and high expression of PAICS was correlated with poor prognosis of patients with GC. In addition, knockdown of PAICS significantly induced cell apoptosis, and inhibited GC cell growth both in vitro and in vivo. Mechanistic studies first found that PAICS was engaged in DNA damage response, and knockdown of PAICS in GC cell lines induced DNA damage and impaired DNA damage repair efficiency. Further explorations revealed that PAICS interacted with histone deacetylase HDAC1 and HDAC2, and PAICS deficiency decreased the expression of DAD51 and inhibited its recruitment to DNA damage sites by impairing HDAC1/2 deacetylase activity, eventually preventing DNA damage repair. Consistently, PAICS deficiency enhanced the sensitivity of GC cells to DNA damage agent, cisplatin (CDDP), both in vitro and in vivo. Altogether, our findings demonstrate that PAICS plays an oncogenic role in GC, which act as a novel diagnosis and prognostic biomarker for patients with GC.

scholarly journals A Critical Role for Fas Ligand in the Active Suppression of Systemic Immune Responses by Ultraviolet Radiation

1999 ◽  
Vol 189 (8) ◽  
pp. 1285-1294 ◽  
Author(s):  
Laurie L. Hill ◽  
Vijay K. Shreedhar ◽  
Margaret L. Kripke ◽  
Laurie B. Owen-Schaub
Keyword(s):  
Dna Damage ◽  
Immune Responses ◽  
Immune Suppression ◽  
Fas Ligand ◽  
Critical Role ◽  
Cell Activity ◽  
Contact Hypersensitivity ◽  
Delayed Type Hypersensitivity ◽  
Intact Cells

Induction of antigen-specific suppression elicited by environmental insults, such as ultraviolet (UV)-B radiation in sunlight, can inhibit an effective immune response in vivo and may contribute to the outgrowth of UV-induced skin cancer. Although UV-induced DNA damage is known to be an initiating event in the immune suppression of most antigen responses, the underlying mechanism(s) of such suppression remain undefined. In this report, we document that Fas ligand (FasL) is critical for UV-induced systemic immune suppression. Normal mice acutely exposed to UV exhibit a profound suppression of both contact hypersensitivity and delayed type hypersensitivity (DTH) reactions and the development of transferable antigen-specific suppressor cells. FasL-deficient mice exposed to UV lack both transferable suppressor cell activity and primary suppression to all antigens tested, with the exception of the DTH response to allogeneic spleen cells. Interestingly, suppression of this response is also known to occur independently of UV-induced DNA damage. Delivery of alloantigen as protein, rather than intact cells, restored the requirement for FasL in UV-induced immune suppression of this response. These results substantiate that FasL/Fas interactions are essential for systemic UV-induced suppression of immune responses that involve host antigen presentation and suggest an interrelationship between UV-induced DNA damage and FasL in this phenomenon. Collectively, our results suggest a model whereby UV-induced DNA damage disarms the immune system in a manner similar to that observed in immunologically privileged sites.

scholarly journals Dephosphorylation of the C-terminal Tyrosyl Residue of the DNA Damage-related Histone H2A.X Is Mediated by the Protein Phosphatase Eyes Absent

2009 ◽  
Vol 284 (24) ◽  
pp. 16066-16070 ◽  
Author(s):  
Navasona Krishnan ◽  
Dae Gwin Jeong ◽  
Suk-Kyeong Jung ◽  
Seong Eon Ryu ◽  
Andrew Xiao ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Mammalian Cells ◽  
Protein Tyrosine Phosphatases ◽  
Histone H2a ◽  
Eyes Absent ◽  
Damage Repair ◽  
Damage Response

In mammalian cells, the DNA damage-related histone H2A variant H2A.X is characterized by a C-terminal tyrosyl residue, Tyr-142, which is phosphorylated by an atypical kinase, WSTF. The phosphorylation status of Tyr-142 in H2A.X has been shown to be an important regulator of the DNA damage response by controlling the formation of γH2A.X foci, which are platforms for recruiting molecules involved in DNA damage repair and signaling. In this work, we present evidence to support the identification of the Eyes Absent (EYA) phosphatases, protein-tyrosine phosphatases of the haloacid dehalogenase superfamily, as being responsible for dephosphorylating the C-terminal tyrosyl residue of histone H2A.X. We demonstrate that EYA2 and EYA3 displayed specificity for Tyr-142 of H2A.X in assays in vitro. Suppression of eya3 by RNA interference resulted in elevated basal phosphorylation and inhibited DNA damage-induced dephosphorylation of Tyr-142 of H2A.X in vivo. This study provides the first indication of a physiological substrate for the EYA phosphatases and suggests a novel role for these enzymes in regulation of the DNA damage response.

scholarly journals The emerging role of RNAs in DNA damage repair

2017 ◽  
Vol 24 (4) ◽  
pp. 580-587 ◽  
Author(s):  
Ben R Hawley ◽  
Wei-Ting Lu ◽  
Ania Wilczynska ◽  
Martin Bushell
Keyword(s):  
Dna Damage ◽  
Dna Repair ◽  
Critical Role ◽  
Repair Process ◽  
Rna Molecules ◽  
Processing Enzymes ◽  
Damage Repair ◽  
New Findings ◽  
Integral Role ◽  
Repair Mechanisms

Abstract Many surveillance and repair mechanisms exist to maintain the integrity of our genome. All of the pathways described to date are controlled exclusively by proteins, which through their enzymatic activities identify breaks, propagate the damage signal, recruit further protein factors and ultimately resolve the break with little to no loss of genetic information. RNA is known to have an integral role in many cellular pathways, but, until very recently, was not considered to take part in the DNA repair process. Several reports demonstrated a conserved critical role for RNA-processing enzymes and RNA molecules in DNA repair, but the biogenesis of these damage-related RNAs and their mechanisms of action remain unknown. We will explore how these new findings challenge the idea of proteins being the sole participants in the response to DNA damage and reveal a new and exciting aspect of both DNA repair and RNA biology.

scholarly journals Imaging DNA Damage Repair In Vivo After 177Lu-DOTATATE Therapy

2019 ◽  
Vol 61 (5) ◽  
pp. 743-750 ◽  
Author(s):  
Edward O’Neill ◽  
Veerle Kersemans ◽  
P. Danny Allen ◽  
Samantha Y.A. Terry ◽  
Julia Baguña Torres ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Repair ◽  
Damage Repair

scholarly journals SIRT7-mediated ATM deacetylation is essential for its deactivation and DNA damage repair

2019 ◽  
Vol 5 (3) ◽  
pp. eaav1118 ◽  
Author(s):  
Ming Tang ◽  
Zhiming Li ◽  
Chaohua Zhang ◽  
Xiaopeng Lu ◽  
Bo Tu ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Repair ◽  
Class Iii ◽  
Ataxia Telangiectasia Mutated ◽  
Damage Repair ◽  
Damage Response ◽  
Late Stages

The activation of ataxia-telangiectasia mutated (ATM) upon DNA damage involves a cascade of reactions, including acetylation by TIP60 and autophosphorylation. However, how ATM is progressively deactivated after completing DNA damage repair remains obscure. Here, we report that sirtuin 7 (SIRT7)–mediated deacetylation is essential for dephosphorylation and deactivation of ATM. We show that SIRT7, a class III histone deacetylase, interacts with and deacetylates ATM in vitro and in vivo. In response to DNA damage, SIRT7 is mobilized onto chromatin and deacetylates ATM during the late stages of DNA damage response, when ATM is being gradually deactivated. Deacetylation of ATM by SIRT7 is prerequisite for its dephosphorylation by its phosphatase WIP1. Consequently, depletion of SIRT7 or acetylation-mimic mutation of ATM induces persistent ATM phosphorylation and activation, thus leading to impaired DNA damage repair. Together, our findings reveal a previously unidentified role of SIRT7 in regulating ATM activity and DNA damage repair.

scholarly journals Characterization of Trypanosoma cruzi Sirtuins as Possible Drug Targets for Chagas Disease

2015 ◽  
Vol 59 (8) ◽  
pp. 4669-4679 ◽  
Author(s):  
Nilmar Silvio Moretti ◽  
Leonardo da Silva Augusto ◽  
Tatiana Mordente Clemente ◽  
Raysa Paes Pinto Antunes ◽  
Nobuko Yoshida ◽  
...  
Keyword(s):  
Trypanosoma Cruzi ◽  
Chagas Disease ◽  
Drug Targets ◽  
Wild Type ◽  
Content Type ◽  
Damage Repair ◽  
Lysine Deacetylases

ABSTRACTAcetylation of lysine is a major posttranslational modification of proteins and is catalyzed by lysine acetyltransferases, while lysine deacetylases remove acetyl groups. Among the deacetylases, the sirtuins are NAD+-dependent enzymes, which modulate gene silencing, DNA damage repair, and several metabolic processes. As sirtuin-specific inhibitors have been proposed as drugs for inhibiting the proliferation of tumor cells, in this study, we investigated the role of these inhibitors in the growth and differentiation ofTrypanosoma cruzi, the agent of Chagas disease. We found that the use of salermide during parasite infection prevented growth and initial multiplication after mammalian cell invasion byT. cruziat concentrations that did not affect host cell viability. In addition,in vivoinfection was partially controlled upon administration of salermide. There are two sirtuins inT. cruzi, TcSir2rp1 and TcSir2rp3. By using specific antibodies and cell lines overexpressing the tagged versions of these enzymes, we found that TcSir2rp1 is localized in the cytosol and TcSir2rp3 in the mitochondrion. TcSir2rp1 overexpression acts to impair parasite growth and differentiation, whereas the wild-type version of TcSir2rp3 and not an enzyme mutated in the active site improves both. The effects observed with TcSir2rp3 were fully reverted by adding salermide, which inhibited TcSir2rp3 expressed inEscherichia coliwith a 50% inhibitory concentration (IC50) ± standard error of 1 ± 0.5 μM. We concluded that sirtuin inhibitors targeting TcSir2rp3 could be used in Chagas disease chemotherapy.

scholarly journals KALRN mutations promote antitumor immunity and immunotherapy response in cancer

2020 ◽  
Vol 8 (2) ◽  
pp. e000293
Author(s):  
Mengyuan Li ◽  
Yuxiang Ma ◽  
You Zhong ◽  
Qian Liu ◽  
Canping Chen ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
Immune Checkpoint ◽  
Antitumor Immunity ◽  
Immune Checkpoint Blockade ◽  
Patients With Cancer ◽  
In Vivo Experiments ◽  
Damage Repair

Backgroundkalirin RhoGEF kinase (KALRN) is mutated in a wide range of cancers. Nevertheless, the association between KALRN mutations and the pathogenesis of cancer remains unexplored. Identification of biomarkers for cancer immunotherapy response is crucial because immunotherapies only show beneficial effects in a subset of patients with cancer.MethodsWe explored the correlation between KALRN mutations and antitumor immunity in 10 cancer cohorts from The Cancer Genome Atlas program by the bioinformatics approach. Moreover, we verified the findings from the bioinformatics analysis with in vitro and in vivo experiments. We explored the correlation between KALRN mutations and immunotherapy response in five cancer cohorts receiving immune checkpoint blockade therapy.ResultsAntitumor immune signatures were more enriched in KALRN-mutated than KALRN-wildtype cancers. Moreover, KALRN mutations displayed significant correlations with increased tumor mutation burden and the microsatellite instability or DNA damage repair deficiency genomic properties, which may explain the high antitumor immunity in KALRN-mutated cancers. Also, programmed cell death 1 ligand (PD-L1) expression was markedly upregulated in KALRN-mutated versus KALRN-wildtype cancers. The increased antitumor immune signatures and PD-L1 expression in KALRN-mutated cancers may favor the response to immune checkpoint blockade therapy in this cancer subtype, as evidenced in five cancer cohorts receiving antiprogrammed cell death protein 1 (PD-1)/PD-L1/cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) immunotherapy. Furthermore, the significant association between KALRN mutations and increased antitumor immunity was associated with the fact that KALRN mutations compromised the function of KALRN in targeting Rho GTPases for the regulation of DNA damage repair pathways. In vitro and in vivo experiments validated the association of KALRN deficiency with antitumor immunity and the response to immune checkpoint inhibitors.ConclusionsThe KALRN mutation is a useful biomarker for predicting the response to immunotherapy in patients with cancer.

scholarly journals Pie1, a Protein Interacting with Mec1, Controls Cell Growth and Checkpoint Responses in Saccharomyces cerevisiae

2001 ◽  
Vol 21 (3) ◽  
pp. 755-764 ◽  
Author(s):  
Tatsushi Wakayama ◽  
Tae Kondo ◽  
Seiko Ando ◽  
Kunihiro Matsumoto ◽  
Katsunori Sugimoto
Keyword(s):  
Dna Damage ◽  
Cell Growth ◽  
Kinase Activity ◽  
Critical Role ◽  
Kinase Domain ◽  
Protein Kinase Activity ◽  
Replication Checkpoint ◽  
Family Protein ◽  
Replication Block

ABSTRACT In eukaryotes, the ATM and ATR family proteins play a critical role in the DNA damage and replication checkpoint controls. These proteins are characterized by a kinase domain related to the phosphatidylinositol 3-kinase, but they have the ability to phosphorylate proteins. In budding yeast, the ATR family protein Mec1/Esr1 is essential for checkpoint responses and cell growth. We have isolated the PIE1 gene in a two-hybrid screen for proteins that interact with Mec1, and we show that Pie1 interacts physically with Mec1 in vivo. Like MEC1, PIE1is essential for cell growth, and deletion of the PIE1 gene causes defects in the DNA damage and replication block checkpoints similar to those observed in mec1Δ mutants. Rad53 hyperphosphorylation following DNA damage and replication block is also decreased in pie1Δ cells, as in mec1Δcells. Pie1 has a limited homology to fission yeast Rad26, which forms a complex with the ATR family protein Rad3. Mutation of the region in Pie1 homologous to Rad26 results in a phenotype similar to that of thepie1Δ mutation. Mec1 protein kinase activity appears to be essential for checkpoint responses and cell growth. However, Mec1 kinase activity is unaffected by the pie1Δ mutation, suggesting that Pie1 regulates some essential function other than Mec1 kinase activity. Thus, Pie1 is structurally and functionally related to Rad26 and interacts with Mec1 to control checkpoints and cell proliferation.

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