scholarly journals Recruitment of the Type B Histone Acetyltransferase Hat1p to Chromatin Is Linked to DNA Double-Strand Breaks

2006 ◽  
Vol 26 (9) ◽  
pp. 3649-3658 ◽  
Author(s):  
Song Qin ◽  
Mark R. Parthun
Keyword(s):  
Dna Damage ◽  
Molecular Mechanisms ◽  
Dna Damage Repair ◽  
Strand Break ◽  
Double Strand Break ◽  
Similar Distribution ◽  
Tail Domain ◽  
Type B ◽  
Direct Role ◽  
Damage Repair

ABSTRACT Type B histone acetyltransferases are thought to catalyze the acetylation of the NH2-terminal tails of newly synthesized histones. Although Hat1p has been implicated in cellular processes, such as telomeric silencing and DNA damage repair, the underlying molecular mechanisms by which it functions remain elusive. In an effort to understand how Hat1p is involved in the process of DNA double-strand break (DSB) repair, we examined whether Hat1p is directly recruited to sites of DNA damage. Following induction of the endonuclease HO, which generates a single DNA DSB at the MAT locus, we found that Hat1p becomes associated with chromatin near the site of DNA damage. The nuclear Hat1p-associated histone chaperone Hif1p is also recruited to an HO-induced DSB with a similar distribution. In addition, while the acetylation of all four histone H4 NH2-terminal tail domain lysine residues is increased following DSB formation, only the acetylation of H4 lysine 12, the primary target of Hat1p activity, is dependent on the presence of Hat1p. Kinetic analysis of Hat1p localization indicates that it is recruited after the phosphorylation of histone H2A S129 and concomitant with the recombinational-repair factor Rad52p. Surprisingly, Hat1p is still recruited to chromatin in strains that cannot repair an HO-induced double-strand break. These results indicate that Hat1p plays a direct role in DNA damage repair and is responsible for specific changes in histone modification that occur during the course of recombinational DNA repair.

Abstract 125: Proteome Analysis of a Regulatory Pathway of Pathologic Vascular Injury as Mediated by KLF5 and its Transcriptional Complexes

Circulation ◽  
2007 ◽  
Vol 116 (suppl_16) ◽  
Author(s):  
Kenichi Aizawa ◽  
Toru Suzuki ◽  
Takayoshi Mastumura ◽  
Nanae Kada ◽  
Daigo Sawaki ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Repair ◽  
Proteome Analysis ◽  
Strand Break ◽  
Double Strand Break ◽  
Chain Gene ◽  
Repair System ◽  
Peptide Mass ◽  
Damage Repair ◽  
A Chain

Background: Transcription factor Krüppel-like factor 5 (KLF5) is a key element linking external stress and cardiovascular remodeling by up-regulating platelet derived growth factor (PDGF)-A chain gene activity. However, the underlying mechanisms remain to be elucidated. The unambiguous and comprehensive identification of interacting proteins is crucial for understanding these mechanisms. In the present study, we identified interacting factors of KLF5 by proteomic analysis and characterized their regulation in the vascular pathogenic response. Methods&Results: Double-stranded oligonucleotide containing the binding sequence for KLF5 in the PDGF-A promoter was synthesized and attached to metal beads, to which cell nuclear extract was applied. SDS-PAGE visualized specific bands to the sequence, which were subjected to in-gel digestion and peptide mass fingerprinting by MALDI-TOF/MS spectrometry. Factors that are known to be important in the DNA damage/repair pathway were successively identified. We therefore examined the involvement of the complex in vascular pathologies. Double-strand break as determined by immunohistochemistry using γ-H2AX antibody, a marker of activation of the double-stranded DNA damage/repair response, was observed in pathogenically stimulated vascular endothelial cells (HUVEC) and neointimal tissues in rat carotid artery balloon injury model. Further, KLF5 was shown to mediate the response on γ-H2AX as shown by co-immunoprecipitation and confocal microscopy. Discussion: We show a hitherto unknown regulatory mechanism by DNA double-strand break/repair system involving KLF5 in the vascular pathogenic response. Our findings might provide a clue to understanding the initiation of pathological cell proliferation observed in atherosclerosis or restenosis after coronary intervention. This new pathway might also be a tempting target for therapeutic intervention aimed at modulating the activity of KLF5 upon PDGF-A chain and its associated pathologies in the cardiovascular system.

Effect of enzalutamide on sensitivity in prostate cancer cells to radiation by inhibition of DNA double strand break repair.

2017 ◽  
Vol 35 (6_suppl) ◽  
pp. 208-208 ◽  
Author(s):  
Maryam Ghashghaei ◽  
Thierry Muanza ◽  
Miltiadis Paliouras ◽  
Tamim Niazi
Keyword(s):  
Prostate Cancer ◽  
Dna Damage ◽  
Dna Damage Repair ◽  
Strand Break ◽  
Dependent Manner ◽  
Castration Resistance ◽  
Concurrent Administration ◽  
Damage Repair ◽  
Pathway Inhibition ◽  
Approved Drugs

208 Background: Prostate cancer is the second leading cause of cancer-related deaths amongst men in North America. Data suggests that, following radiation therapy (XRT), androgen receptor (AR) enhances DNA damage repair and contributes to resistance of prostate cancer (PCa) cells to XRT. At present AR-pathway inhibition is the mainstay treatment of metastatic castration resistance prostate cancer (mCRPC). Enzalutamide (ENZA), a potent AR inhibitor is one of the approved drugs in this setting. The purpose of this study was to assess the potential radiosensitization of ENZA and its mechanism of action in hormone resistant PCa cells. Methods: The effect of ENZA alone or in combination with XRT was assessed on hormone-sensitive, (HS: LNCaP, PC3-T877A) and insensitive PCa cells (HI: PC3, PC3-AR V7, C4-2) using viability and clonogenic assays, cell cycle arrest and DNA damage analysis. Results: MTT assay demonstrates that ENZA significantly inhibits the proliferation of HS PCa cells in a dose dependent manner whereas CRPC required ENZA in combination with ADT (androgen deprivation therapy). Additionally, clonogenic assay proves that concurrent administration of ENZA or ADT+ENZA and XRT led to a supra-additive antitumor effect with the dose enhancement factor of 1.76±0.008 in LNCaP, 1.65±0.01 in PC3-T877A and 1.35±0.003 in C4-2 respectively at surviving fraction of 0.1. This effect was not observed in PC3 and PC3-AR V7 cells pre-treated with ENZA (in all cases DEF = 1 at SF = 0.1). Additionally, the level of γH2AX increased in HS cells and CRPC cells treated with ENZA/ADT+ENZA and XRT when compared to XRT alone. The enhanced H2AX activity remained unchanged up to 24 hours after combination treatment. Furthermore, there is an initial inhibition of DNA-PKcs in HS and CRPC cells treated with ENZA/ADT+ENZA administered before XRT. Conclusions: Our data suggest that the higher efficacy of ENZA/ENZA+ADT and XRT could be partially due to inhibition of DNA damage repair. Our results demonstrated a significant enhancement of XRT efficacy and confirms the rational for the ongoing combination clinical trials with XRT.

scholarly journals Persistent DNA Double-Strand Breaks After Repeated Diagnostic CT Scans in Breast Epithelial Cells and Lymphocytes

2021 ◽  
Vol 11 ◽  
Author(s):  
Natalia V. Bogdanova ◽  
Nina Jguburia ◽  
Dhanya Ramachandran ◽  
Nora Nischik ◽  
Katharina Stemwedel ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Repair ◽  
Cell Types ◽  
Strand Break ◽  
Ct Scans ◽  
Breast Epithelial Cell ◽  
Damage Repair ◽  
Breast Epithelial ◽  
The Impact ◽  
Diagnostic Ct

DNA double-strand break (DSB) induction and repair have been widely studied in radiation therapy (RT); however little is known about the impact of very low exposures from repeated computed tomography (CT) scans for the efficiency of repair. In our current study, DSB repair and kinetics were investigated in side-by-side comparison of RT treatment (2 Gy) with repeated diagnostic CT scans (≤20 mGy) in human breast epithelial cell lines and lymphoblastoid cells harboring different mutations in known DNA damage repair proteins. Immunocytochemical analysis of well known DSB markers γH2AX and 53BP1, within 48 h after each treatment, revealed highly correlated numbers of foci and similar appearance/disappearance profiles. The levels of γH2AX and 53BP1 foci after CT scans were up to 30% of those occurring 0.5 h after 2 Gy irradiation. The DNA damage repair after diagnostic CT scans was monitored and quantitatively assessed by both γH2AX and 53BP1 foci in different cell types. Subsequent diagnostic CT scans in 6 and/or 12 weeks intervals resulted in elevated background levels of repair foci, more pronounced in cells that were prone to genomic instability due to mutations in known regulators of DNA damage response (DDR). The levels of persistent foci remained enhanced for up to 6 months. This “memory effect” may reflect a radiation-induced long-term response of cells after low-dose x-ray exposure.

Molecular Mechanisms of Radiation Induced Dna Damage: H-Addition to Bases, Direct Ionization and Double Strand Break

1991 ◽  
Vol 13 (1) ◽  
pp. 465-467 ◽  
Author(s):  
R. Osman ◽  
L. Pardo ◽  
J. Banfelder ◽  
A. P. Mazurek ◽  
L. Shvartzman ◽  
...  
Keyword(s):  
Dna Damage ◽  
Molecular Mechanisms ◽  
Strand Break ◽  
Double Strand Break ◽  
Direct Ionization ◽  
Radiation Induced

scholarly journals Ablating Ku70 phosphorylation results in defective DNA damage repair and spontaneous induction of hepatocellular carcinoma

2021 ◽  
Author(s):  
Janapriya Saha ◽  
Jinsung Bae ◽  
Shih-Ya Wang ◽  
Lori J. Chappell ◽  
Purva Gopal ◽  
...  
Keyword(s):  
Hepatocellular Carcinoma ◽  
Dna Damage ◽  
Genomic Instability ◽  
Dna Damage Repair ◽  
Strand Break ◽  
Damage Repair ◽  
Dna End Resection ◽  
Non Homologous End Joining ◽  
Transformed Cell Lines ◽  
Dna Ends

SUMMARYMultiple pathways mediate the repair of DNA double-strand break (DSB), with numerous mechanisms responsible for driving choice between the pathways. Previously, we reported that phosphorylation of the non-homologous end joining (NHEJ) factor, Ku70, is required for the dissociation of the Ku heterodimer from DNA ends to allow DSB repair via homologous recombination (HR). A knock-in mouse, in which phosphorylation is ablated in the three conserved sites of Ku70 (Ku703A/3A), was generated in order to test the hypothesis that Ku70 phosphorylation is required for initiation of HR and that blocking this process results in enhanced genomic instability and tumorigenesis. Here, we show that Ku703A/3A mice develop spontaneous and have accelerated chemical-induced hepatocellular carcinoma (HCC) compared to wild-type (Ku70+/+) littermates. The HCC tumors from the Ku703A/3A mice have increased γH2AX and 8-oxo-G staining, suggesting DNA repair is decreased in these mice. Spontaneous transformed cell lines from Ku703A/3A mice are more radiosensitive, have a significant decrease in DNA end resection, and are more sensitive to the DNA cross-linking agent mitomycin C compared to cells from Ku70+/+ littermates. Collectively, these findings demonstrate that phosphorylation-mediated dissociation of Ku heterodimer from DNA ends is required for efficient DNA damage repair and disruption of this process results in genomic instability and accelerated development of HCC.

scholarly journals Deletions of 5q Promote Genome Instability in TP53-Mutant MDS/AML

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1244-1244
Author(s):  
Andreea Reilly ◽  
Stephanie Busch ◽  
Janis L. Abkowitz ◽  
Pamela S. Becker ◽  
Sergei Doulatov
Keyword(s):  
Dna Damage ◽  
Chromosomal Instability ◽  
Molecular Mechanisms ◽  
Genome Instability ◽  
Dna Damage Repair ◽  
Normal Karyotype ◽  
Complex Karyotype ◽  
Differentiation Potential ◽  
Tp53 Mutations ◽  
Damage Repair

Purpose TP53 mutations in myeloid neoplasms (MDS/AML) are associated with high-risk disease, poor outcome, and complex karyotype. The molecular mechanisms which lead to global chromosomal instability remain poorly understood. Loss of 5q [del(5q)] is the most frequent cytogenetic abnormality associated with TP53 mutations suggesting that haploinsufficiency of genes on 5q contributes to chromosomal instability. Methods We reprogrammed MDS/AML patient samples to establish genetically accurate iPSC lines from preleukemic subclones. We generated iPSCs with TP53 mutations and del(5q), differentiated them to hematopoietic progenitors (HPCs), and determined the contribution of del(5q) to genome instability. Results By reprogramming MDS/AML complex karyotype patient samples, we identified iPSCs with heterozygous TP53 mutations (TP53-only), as well as iPSCs with TP53 mutations and del5(q22-q31) (TP53;del5q), and an otherwise normal karyotype. HPCs derived from TP53;del5q iPSCs had decreased multilineage differentiation potential compared to the TP53-only HPCs. Gene expression analysis of TP53;del5q HPCs revealed downregulation of genes involved in chromosome segregation and DNA damage repair. Following irradiation TP53;del5q cells had significantly delayed DNA damage repair kinetics. In order to evaluate the effects of TP53 and del(5q) on chromosomal segregation during stress, we arrested the cells in mitosis by disrupting the mitotic spindle and quantified the induction of micronuclei, a marker of chromosomal instability that occurs due to lagging chromosomes. TP53;del5q cells had an increased frequency of micronuclei formation compared to TP53-only cells. We also detected micronuclei in primary AML patient samples. Micronuclei in iPSC-HPCs and primary patient cells had disrupted nuclear envelope and DNA damage marked by y-H2AX. Conclusions Our reprogramming approach revealed that TP53 mutations are disease-initiating and frequently followed by 5q loss. We propose that del(5q) cooperates with mutant TP53 to promote genome instability via two distinct mechanisms: classical double-stranded break repair and micronuclei formation. The latter is associated with global chromosomal instability, aneuploidy, and chromothripsis. We propose that loss of 5q accelerates genome instability in TP53-mutant cells which over time impedes normal hematopoietic differentiation and leads to complex karyotype. Disclosures Becker: The France Foundation: Honoraria; Accordant Health Services/Caremark: Consultancy; AbbVie, Amgen, Bristol-Myers Squibb, Glycomimetics, Invivoscribe, JW Pharmaceuticals, Novartis, Trovagene: Research Funding.

scholarly journals Interactome Analysis Reveals a Novel Role for RAD6 in the Regulation of Proteasome Activity and Localization in Response to DNA Damage

2016 ◽  
Vol 37 (6) ◽  
Author(s):  
Hongli An ◽  
Lu Yang ◽  
Chen Wang ◽  
Zhixue Gan ◽  
Haihui Gu ◽  
...  
Keyword(s):  
Dna Damage ◽  
Molecular Mechanisms ◽  
Nuclear Translocation ◽  
Dna Damage Repair ◽  
Repair Process ◽  
Proteasome Activity ◽  
Nuclear Antigen ◽  
Ppi Networks ◽  
Damage Repair ◽  
Repair Pathways

ABSTRACT RAD6, an E2 ubiquitin-conjugating enzyme, is a key node for determining different DNA damage repair pathways, controlling both the error-prone and the error-free DNA damage repair pathways through differential regulation of the ubiquitination of the proliferating cell nuclear antigen (PCNA) protein. However, whether other pathways are involved in the RAD6-mediated regulation of DNA damage repair is still unclear. To deeply understand the molecular mechanisms of RAD6 in DNA damage repair, we performed a proteomic analysis and identified the changes of the protein-protein interaction (PPI) networks of RAD6 before and after X-ray irradiation. Furthermore, our study indicated that a proteasome-related event is likely involved in the DNA damage repair process. Moreover, we found that RAD6 promotes proteasome activity and nuclear translocation by enhancing the degradation of PSMF1 and the lamin B receptor (LBR). Therefore, we provide a novel pathway that is employed by RAD6 in response to DNA damage.

scholarly journals Nuclear localization of Beclin 1 promotes radiation-induced DNA damage repair independent of autophagy

2017 ◽  
Vol 7 (1) ◽  
Author(s):  
Fei Xu ◽  
Yixuan Fang ◽  
Lili Yan ◽  
Lan Xu ◽  
Suping Zhang ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Repair ◽  
Strand Break ◽  
Beclin 1 ◽  
Dsb Repair ◽  
Dna Topoisomerase ◽  
Damage Repair ◽  
Dna Double Strand Break ◽  
Radiation Induced

Abstract Beclin 1 is a well-established core mammalian autophagy protein that is embryonically indispensable and has been presumed to suppress oncogenesis via an autophagy-mediated mechanism. Here, we show that Beclin 1 is a prenatal primary cytoplasmic protein but rapidly relocated into the nucleus during postnatal development in mice. Surprisingly, deletion of beclin1 in in vitro human cells did not block an autophagy response, but attenuated the expression of several DNA double-strand break (DSB) repair proteins and formation of repair complexes, and reduced an ability to repair DNA in the cells exposed to ionizing radiation (IR). Overexpressing Beclin 1 improved the repair of IR-induced DSB, but did not restore an autophagy response in cells lacking autophagy gene Atg7, suggesting that Beclin 1 may regulate DSB repair independent of autophagy in the cells exposed to IR. Indeed, we found that Beclin 1 could directly interact with DNA topoisomerase IIβ and was recruited to the DSB sites by the interaction. These findings reveal a novel function of Beclin 1 in regulation of DNA damage repair independent of its role in autophagy particularly when the cells are under radiation insult.

scholarly journals Autism-associated vigilin depletion impairs DNA damage repair

2021 ◽  
Author(s):  
Shahid Banday ◽  
Raj K. Pandita ◽  
Arjamand Mushtaq ◽  
Albino Bacolla ◽  
Ulfat Syed Mir ◽  
...  
Keyword(s):  
Dna Damage ◽  
Rna Binding ◽  
Dna Damage Repair ◽  
Strand Break ◽  
Autism Spectrum ◽  
Heterochromatin Formation ◽  
Replicative Stress ◽  
Damage Repair ◽  
Dna End Resection ◽  
Fork Stalling

Vigilin (Vgl1) is essential for heterochromatin formation, chromosome segregation, mRNA stability and is associated with autism-spectrum disorders and cancer, vigilin, for example, can suppress proto-oncogene c-fms expression in breast cancer. Conserved from yeast to humans, vigilin is an RNA-binding protein with 14 tandemly arranged nonidentical hnRNP K type homology (KH) domains. Here we report that vigilin depletion increased cell sensitivity to cisplatin- or ionizing radiation (IR)-induced cell death and genomic instability due to defective DNA repair. Vigilin depletion delayed dephosphorylation of IR-induced γ-H2AX, elevated levels of residual 53BP1 and RIF1 foci, while reducing Rad51 and BRCA1 foci formation, DNA end resection and double strand break (DSB) repair. We show that vigilin interacts with the DNA damage response (DDR) proteins RAD51 and BRCA1, and vigilin depletion impairs their recruitment to DSB sites. Transient hydroxyurea (HU) induced replicative stress in vigilin-depleted cells increased replication fork stalling and blocked restart of DNA synthesis. Furthermore, histone acetylation promoted vigilin recruitment to DSBs preferentially in transcriptionally active genome. These findings uncover a novel vigilin role in DNA damage repair with implications for autism and cancer related disorders.

scholarly journals DNA Damage Repair and DNA Methylation in the Kidney

2019 ◽  
Vol 50 (2) ◽  
pp. 81-91 ◽  
Author(s):  
Kaori Hayashi ◽  
Akihito Hishikawa ◽  
Hiroshi Itoh
Keyword(s):  
Dna Methylation ◽  
Dna Damage ◽  
Dna Repair ◽  
Methylation Status ◽  
Dna Damage Repair ◽  
Strand Break ◽  
Repair System ◽  
Damage Repair ◽  
Dna Double Strand Break ◽  
Cell Type Specific

The DNA repair system is essential for the maintenance of genome integrity and is mainly investigated in the areas of aging and cancer. The DNA repair system is strikingly cell-type specific, depending on the expression of DNA repair factors; therefore, different DNA repair systems may exist in each type of kidney cell. Importance of DNA repair in the kidney is suggested by renal phenotypes caused by both genetic mutations in the DNA repair pathway and increased stimuli of DNA damage. Recently, we reported the importance of DNA double-strand break repair in glomerular podocytes and its involvement in the alteration of DNA methylation status, which regulates podocyte phenotypes. In this review, we summarize the roles of the DNA repair system in the kidneys and possible associations with altered kidney DNA methylation, which have been infrequently reported together. Investigations of DNA damage repair and epigenetic changes in the kidneys may achieve a profound understanding of kidney aging and diseases.

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