scholarly journals Cardiac-Specific Cre Induces Age-Dependent Dilated Cardiomyopathy (DCM) in Mice

Molecules ◽  
2019 ◽  
Vol 24 (6) ◽  
pp. 1189 ◽  
Author(s):  
Taha Rehmani ◽  
Maysoon Salih ◽  
Balwant Tuana
Keyword(s):  
Dna Damage ◽  
Dilated Cardiomyopathy ◽  
Protein Function ◽  
Mouse Genome ◽  
Model System ◽  
Dependent Manner ◽  
Cardiac Pathology ◽  
Damage Response ◽  
Age Dependent ◽  
Invaluable Tool

The genetic modification of the mouse genome using the cre-lox system has been an invaluable tool in deciphering gene and protein function in a temporal and/or spatial manner. However, it has its pitfalls, as researchers have shown that the unregulated expression of cre recombinase can cause DNA damage, the consequences of which can be very detrimental to mouse health. Previously published literature on the most utilized cardiac-specific cre, αMHC-cre, mouse model exhibited a nonlethal hypertrophic cardiomyopathy (HCM) with aging. However, using the same αMHC-cre mice, we observed a cardiac pathology, resulting in complete lethality by 11 months of age. Echocardiography and histology revealed that the αMHC-cre mice were displaying symptoms of dilated cardiomyopathy (DCM) by seven months of age, which ultimately led to their demise in the absence of any HCM at any age. Molecular analysis showed that this phenotype was associated with the DNA damage response through the downregulation of activated p38 and increased expression of JNK, p53, and Bax, known inducers of myocyte death resulting in fibrosis. Our data urges strong caution when interpreting the phenotypic impact of gene responses using αMHC-cre mice, since a lethal DCM was induced by the cre driver in an age-dependent manner in this commonly utilized model system.

scholarly journals ATF4-Mediated Upregulation of REDD1 and Sestrin2 Suppresses mTORC1 Activity during Prolonged Leucine Deprivation

2019 ◽  
Vol 150 (5) ◽  
pp. 1022-1030 ◽  
Author(s):  
Dandan Xu ◽  
Weiwei Dai ◽  
Lydia Kutzler ◽  
Holly A Lacko ◽  
Leonard S Jefferson ◽  
...  
Keyword(s):  
Amino Acids ◽  
Dna Damage ◽  
Amino Acid ◽  
Protein Kinase ◽  
Dna Damage Response ◽  
Dependent Manner ◽  
Mouse Embryo Fibroblasts ◽  
Damage Response ◽  
Mtorc1 Activation ◽  
In Cells

ABSTRACT Background The protein kinase target of rapamycin (mTOR) in complex 1 (mTORC1) is activated by amino acids and in turn upregulates anabolic processes. Under nutrient-deficient conditions, e.g., amino acid insufficiency, mTORC1 activity is suppressed and autophagy is activated. Intralysosomal amino acids generated by autophagy reactivate mTORC1. However, sustained mTORC1 activation during periods of nutrient insufficiency would likely be detrimental to cellular homeostasis. Thus, mechanisms must exist to prevent amino acids released by autophagy from reactivating the kinase. Objective The objective of the present study was to test whether mTORC1 activity is inhibited during prolonged leucine deprivation through ATF4-dependent upregulation of the mTORC1 suppressors regulated in development and DNA damage response 1 (REDD1) and Sestrin2. Methods Mice (8 wk old; C57Bl/6 × 129SvEV) were food deprived (FD) overnight and one-half were refed the next morning. Mouse embryo fibroblasts (MEFs) deficient in ATF4, REDD1, and/or Sestrin2 were deprived of leucine for 0–16 h. mTORC1 activity and ATF4, REDD1, and Sestrin2 expression were assessed in liver and cell lysates. Results Refeeding FD mice resulted in activation of mTORC1 in association with suppressed expression of both REDD1 and Sestrin2 in the liver. In cells in culture, mTORC1 exhibited a triphasic response to leucine deprivation, with an initial suppression followed by a transient reactivation from 2 to 4 h and a subsequent resuppression after 8 h. Resuppression occurred concomitantly with upregulated expression of ATF4, REDD1, and Sestrin2. However, in cells lacking ATF4, neither REDD1 nor Sestrin2 expression was upregulated by leucine deprivation, and resuppression of mTORC1 was absent. Moreover, in cells lacking either REDD1 or Sestrin2, mTORC1 resuppression was attenuated, and in cells lacking both proteins resuppression was further blunted. Conclusions The results suggest that leucine deprivation upregulates expression of both REDD1 and Sestrin2 in an ATF4-dependent manner, and that upregulated expression of both proteins is involved in resuppression of mTORC1 during prolonged leucine deprivation.

scholarly journals Ribosomal protein L6 (RPL6) is recruited to DNA damage sites in a poly(ADP-ribose) polymerase–dependent manner and regulates the DNA damage response

2018 ◽  
Vol 294 (8) ◽  
pp. 2827-2838 ◽  
Author(s):  
Chuanzhen Yang ◽  
Weicheng Zang ◽  
Yapeng Ji ◽  
Tingting Li ◽  
Yongfeng Yang ◽  
...  
Keyword(s):  
Dna Damage ◽  
Ribosomal Protein ◽  
Dna Damage Response ◽  
Dependent Manner ◽  
Damage Response

Coordinated Chromatin-Association of Fanconi Anemia Network Proteins Requires Replication-Coupled DNA Damage Recognition.

Blood ◽  
2004 ◽  
Vol 104 (11) ◽  
pp. 723-723
Author(s):  
Alexandra Sobeck ◽  
Stacie Stone ◽  
Bendert deGraaf ◽  
Vincenzo Costanzo ◽  
Johan deWinter ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Replication ◽  
Dna Damage Response ◽  
Fanconi Anemia ◽  
Bone Marrow Failure ◽  
S Phase ◽  
Dependent Manner ◽  
Core Complex ◽  
Damage Response ◽  
Crosslinking Agents

Abstract Fanconi anemia (FA) is a genetic disorder characterized by hypersensitivity to DNA crosslinking agents and diverse clinical symptoms, including developmental anomalies, progressive bone marrow failure, and predisposition to leukemias and other cancers. FA is genetically heterogeneous, resulting from mutations in any of at least eleven different genes. The FA proteins function together in a pathway composed of a mulitprotein core complex that is required to trigger the DNA-damage dependent activation of the downstream FA protein, FANCD2. This activation is thought to be the key step in a DNA damage response that functionally links FA proteins to major breast cancer susceptibility proteins BRCA1 and BRCA2 (BRCA2 is FA gene FANCD1). The essential function of the FA proteins is unknown, but current models suggest that FA proteins function at the interface between cell cycle checkpoints, DNA repair and DNA replication, and are likely to play roles in the DNA damage response during S phase. To provide a platform for dissecting the key functional events during S-phase, we developed cell-free assays for FA proteins based on replicating extracts from Xenopus eggs. We identified the Xenopus homologs of human FANCD2 (xFANCD2) and several of the FA core complex proteins (xCCPs), and biochemically characterized these proteins in replicating cell-free extracts. We found that xCCPs and a modified isoform of xFANCD2 become associated with chromatin during normal and disrupted DNA replication. Blocking initiation of replication with geminin demonstrated that association of xCCPs and xFANCD2 with chromatin occurs in a strictly replication-dependent manner that is enhanced following DNA damage by crosslinking agents or by addition of aphidicolin, an inhibitor of replicative DNA polymerases. In addition, chromatin binding of xFANCD2, but not xBRCA2, is abrogated when xFANCA is quantitatively depleted from replicating extracts suggesting that xFANCA promotes the loading of xFANCD2 on chromatin. The chromatin-association of xFANCD2 and xCCPs is diminished in the presence of caffeine, an inhibitor of checkpoint kinases. Taken together, our data suggest a model in which the ordered loading of FA proteins on chromatin is required for processing a subset of DNA replication-blocking lesions that are resolved during late stages of replication.

scholarly journals ATM regulates a DNA damage response posttranscriptional RNA operon in lymphocytes

Blood ◽  
2011 ◽  
Vol 117 (8) ◽  
pp. 2441-2450 ◽  
Author(s):  
Krystyna Mazan-Mamczarz ◽  
Patrick R. Hagner ◽  
Yongqing Zhang ◽  
Bojie Dai ◽  
Elin Lehrmann ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Damage ◽  
Dna Damage Response ◽  
Ataxia Telangiectasia ◽  
Rna Binding ◽  
Critical Role ◽  
Cell Cycle Checkpoints ◽  
Dependent Manner ◽  
Damage Response ◽  
Multiple Cell

Abstract Maintenance of genomic stability depends on the DNA damage response, a biologic barrier in early stages of cancer development. Failure of this response results in genomic instability and high predisposition toward lymphoma, as seen in patients with ataxia-telangiectasia mutated (ATM) dysfunction. ATM activates multiple cell-cycle checkpoints and DNA repair after DNA damage, but its influence on posttranscriptional gene expression has not been examined on a global level. We show that ionizing radiation modulates the dynamic association of the RNA-binding protein HuR with target mRNAs in an ATM-dependent manner, potentially coordinating the genotoxic response as an RNA operon. Pharmacologic ATM inhibition and use of ATM-null cells revealed a critical role for ATM in this process. Numerous mRNAs encoding cancer-related proteins were differentially associated with HuR depending on the functional state of ATM, in turn affecting expression of encoded proteins. The findings presented here reveal a previously unidentified role of ATM in controlling gene expression posttranscriptionally. Dysregulation of this DNA damage response RNA operon is probably relevant to lymphoma development in ataxia-telangiectasia persons. These novel RNA regulatory modules and genetic networks provide critical insight into the function of ATM in oncogenesis.

scholarly journals Hof1 plays a checkpoint-related role in MMS-induced DNA damage response in Candida albicans

2020 ◽  
Vol 31 (5) ◽  
pp. 348-359 ◽  
Author(s):  
Jinrong Feng ◽  
Amjad Islam ◽  
Bjorn Bean ◽  
Jia Feng ◽  
Samantha Sparapani ◽  
...  
Keyword(s):  
Dna Damage ◽  
Candida Albicans ◽  
Mutant Strain ◽  
Dna Damage Response ◽  
Genotoxic Stress ◽  
Dependent Manner ◽  
Damage Response

Fifty-six strains from the GRACE collection were found to be sensitive to MMS upon repression. Deletion of the HOF1 gene renders sensitivity to genotoxic stress. Hof1 is genetically linked to the Rad53 pathway and is down-regulated in a Rad53-dependent manner. The importance of Hof1 in MMS response is reduced in a Rad23 or Rad4 mutant strain.

scholarly journals TFEB Modulates p21/WAF1/CIP1 during the DNA Damage Response

Cells ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 1186 ◽  
Author(s):  
Sandra Pisonero-Vaquero ◽  
Chiara Soldati ◽  
Marcella Cesana ◽  
Andrea Ballabio ◽  
Diego Luis Medina
Keyword(s):  
Dna Damage ◽  
Cancer Cell ◽  
Dna Damage Response ◽  
Cell Types ◽  
Dependent Manner ◽  
Cancer Cell Growth ◽  
Direct Role ◽  
Growth And Survival ◽  
Damage Response ◽  
P21 Waf1

The MiT/TFE family of transcription factors (MITF, TFE3, and TFEB), which control transcriptional programs for autophagy and lysosome biogenesis have emerged as regulators of energy metabolism in cancer. Thus, their activation increases lysosomal catabolic function to sustain cancer cell growth and survival in stress conditions. Here, we found that TFEB depletion dramatically reduces basal expression levels of the cyclin-dependent kinase (CDK) inhibitor p21/WAF1 in various cell types. Conversely, TFEB overexpression increases p21 in a p53-dependent manner. Furthermore, induction of DNA damage using doxorubicin induces TFEB-mediated activation of p21, delays G2/M phase arrest, and promotes cell survival. Pharmacological inhibition of p21, instead, abrogates TFEB-mediated protection during the DNA damage response. Together, our findings uncover a novel and direct role of TFEB in the regulation of p21 expression in both steady-state conditions and during the induction of DNA-damage response (DDR). Our observations might open novel therapeutic strategies to promote cancer cell death by targeting the TFEB-p21 pathway in the presence of genotoxic agents.

scholarly journals Poly(ADP-ribose)-dependent chromatin unfolding facilitates the association of DNA-binding proteins with DNA at sites of damage

2019 ◽  
Vol 47 (21) ◽  
pp. 11250-11267 ◽  
Author(s):  
Rebecca Smith ◽  
Théo Lebeaupin ◽  
Szilvia Juhász ◽  
Catherine Chapuis ◽  
Ostiane D’Augustin ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Binding ◽  
Chromatin Remodeling ◽  
Direct Interaction ◽  
Dna Lesions ◽  
Dependent Manner ◽  
Binding Domains ◽  
Damage Response ◽  
Direct Binding ◽  
Dnase Hypersensitivity

Abstract The addition of poly(ADP-ribose) (PAR) chains along the chromatin fiber due to PARP1 activity regulates the recruitment of multiple factors to sites of DNA damage. In this manuscript, we investigated how, besides direct binding to PAR, early chromatin unfolding events controlled by PAR signaling contribute to recruitment to DNA lesions. We observed that different DNA-binding, but not histone-binding, domains accumulate at damaged chromatin in a PAR-dependent manner, and that this recruitment correlates with their affinity for DNA. Our findings indicate that this recruitment is promoted by early PAR-dependent chromatin remodeling rather than direct interaction with PAR. Moreover, recruitment is not the consequence of reduced molecular crowding at unfolded damaged chromatin but instead originates from facilitated binding to more exposed DNA. These findings are further substantiated by the observation that PAR-dependent chromatin remodeling at DNA lesions underlies increased DNAse hypersensitivity. Finally, the relevance of this new mode of PAR-dependent recruitment to DNA lesions is demonstrated by the observation that reducing the affinity for DNA of both CHD4 and HP1α, two proteins shown to be involved in the DNA-damage response, strongly impairs their recruitment to DNA lesions.

scholarly journals Haploinsufficiency of Tmem43 in cardiac myocytes activates the DNA damage response pathway leading to a late-onset senescence-associated pro-fibrotic cardiomyopathy

2020 ◽  
Author(s):  
Leila Rouhi ◽  
Sirisha M Cheedipudi ◽  
Suet Nee Chen ◽  
Siyang Fan ◽  
Raffaella Lombardi ◽  
...  
Keyword(s):  
Dna Damage ◽  
Nuclear Envelope ◽  
Cardiac Myocytes ◽  
Myocardial Fibrosis ◽  
Dna Damage Response ◽  
Envelope Protein ◽  
Alternative Methods ◽  
Damage Response ◽  
Age Dependent ◽  
Tp53 Pathway

Abstract Aims Arrhythmogenic cardiomyopathy (ACM) encompasses a genetically heterogeneous group of myocardial diseases whose manifestations are sudden cardiac death, cardiac arrhythmias, heart failure, and in a subset fibro-adipogenic infiltration of the myocardium. Mutations in the TMEM43 gene, encoding transmembrane protein 43 (TMEM43) are known to cause ACM. The purpose of the study was to gain insights into the molecular pathogenesis of ACM caused by TMEM43 haploinsufficiency. Methods and results The Tmem43 gene was specifically deleted in cardiac myocytes by crossing the Myh6-Cre and floxed Tmem43 mice. Myh6-Cre:Tmem43W/F mice showed an age-dependent phenotype characterized by an increased mortality, cardiac dilatation and dysfunction, myocardial fibrosis, adipogenesis, and apoptosis. Sequencing of cardiac myocyte transcripts prior to and after the onset of cardiac phenotype predicted early activation of the TP53 pathway. Increased TP53 activity was associated with increased levels of markers of DNA damage response (DDR), and a subset of senescence-associated secretary phenotype (SASP). Activation of DDR, TP53, SASP, and their selected downstream effectors, including phospho-SMAD2 and phospho-SMAD3 were validated by alternative methods, including immunoblotting. Expression of SASP was associated with epithelial–mesenchymal transition and age-dependent expression of myocardial fibrosis and apoptosis in the Myh6-Cre:Tmem43W/F mice. Conclusion TMEM43 haploinsufficiency is associated with activation of the DDR and the TP53 pathways, which lead to increased expression of SASP and an age-dependent expression of a pro-fibrotic cardiomyopathy. Given that TMEM43 is a nuclear envelope protein and our previous data showing deficiency of another nuclear envelope protein, namely lamin A/C, activates the DDR/TP53 pathway, we surmise that DNA damage is a shared mechanism in the pathogenesis of cardiomyopathies caused by mutations involving nuclear envelope proteins.

scholarly journals Biphasic Functional Interaction between the Adenovirus E4orf4 Protein and DNA-PK

2019 ◽  
Vol 93 (10) ◽  
Author(s):  
Keren Nebenzahl-Sharon ◽  
Hassan Shalata ◽  
Rakefet Sharf ◽  
Jana Amer ◽  
Hanan Khoury-Haddad ◽  
...  
Keyword(s):  
Dna Damage ◽  
Cell Death ◽  
Virus Replication ◽  
Dna Damage Response ◽  
Late Phase ◽  
Direct Interaction ◽  
Dependent Manner ◽  
Functional Interaction ◽  
Cancer Cell Death ◽  
Damage Response

ABSTRACTThe adenovirus (Ad) E4orf4 protein contributes to virus-induced inhibition of the DNA damage response (DDR) by reducing ATM and ATR signaling. Consequently, E4orf4 inhibits DNA repair and sensitizes transformed cells to killing by DNA-damaging drugs. Inhibition of ATM and ATR signaling contributes to the efficiency of virus replication and may provide one explanation for the cancer selectivity of cell death induced by the expression of E4orf4 alone. In this report, we investigate a direct interaction of E4orf4 with the DDR. We show that E4orf4 physically associates with the DNA-dependent protein kinase (DNA-PK), and we demonstrate a biphasic functional interaction between these proteins, wherein DNA-PK is required for ATM and ATR inhibition by E4orf4 earlier during infection but is inhibited by E4orf4 as infection progresses. This biphasic process is accompanied by initial augmentation and a later inhibition of DNA-PK autophosphorylation as well as by colocalization of DNA-PK with early Ad replication centers and distancing of DNA-PK from late replication centers. Moreover, inhibition of DNA-PK improves Ad replication more effectively when a DNA-PK inhibitor is added later rather than earlier during infection. When expressed alone, E4orf4 is recruited to DNA damage sites in a DNA-PK-dependent manner. DNA-PK inhibition reduces the ability of E4orf4 to induce cancer cell death, likely because E4orf4 is prevented from arriving at the damage sites and from inhibiting the DDR. Our results support an important role for the E4orf4–DNA-PK interaction in Ad replication and in facilitation of E4orf4-induced cancer-selective cell death.IMPORTANCESeveral DNA viruses evolved mechanisms to inhibit the cellular DNA damage response (DDR), which acts as an antiviral defense system. We present a novel mechanism by which the adenovirus (Ad) E4orf4 protein inhibits the DDR. E4orf4 interacts with the DNA damage sensor DNA-PK in a biphasic manner. Early during infection, E4orf4 requires DNA-PK activity to inhibit various branches of the DDR, whereas it later inhibits DNA-PK itself. Furthermore, although both E4orf4 and DNA-PK are recruited to virus replication centers (RCs), DNA-PK is later distanced from late-phase RCs. Delayed DNA-PK inhibition greatly contributes to Ad replication efficiency. When E4orf4 is expressed alone, it is recruited to DNA damage sites. Inhibition of DNA-PK prevents both recruitment and the previously reported ability of E4orf4 to kill cancer cells. Our results support an important role for the E4orf4–DNA-PK interaction in Ad replication and in facilitation of E4orf4-induced cancer-selective cell death.

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