scholarly journals DNA-PKcs promotes chromatin decondensation to facilitate initiation of the DNA damage response

2019 ◽  
Vol 47 (18) ◽  
pp. 9467-9479 ◽  
Author(s):  
Huiming Lu ◽  
Janapriya Saha ◽  
Pauline J Beckmann ◽  
Eric A Hendrickson ◽  
Anthony J Davis
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Ataxia Telangiectasia ◽  
Cellular Response ◽  
Kinase Activity ◽  
Human Cell Line ◽  
Cell Cycle Checkpoint ◽  
Chromatin Decondensation ◽  
Damage Site ◽  
Damage Response

Abstract The DNA damage response (DDR) encompasses the cellular response to DNA double-stranded breaks (DSBs), and includes recognition of the DSB, recruitment of numerous factors to the DNA damage site, initiation of signaling cascades, chromatin remodeling, cell-cycle checkpoint activation, and repair of the DSB. Key drivers of the DDR are multiple members of the phosphatidylinositol 3-kinase-related kinase family, including ataxia telangiectasia mutated (ATM), ataxia telangiectasia and Rad3-related (ATR), and the DNA-dependent protein kinase catalytic subunit (DNA-PKcs). ATM and ATR modulate multiple portions of the DDR, but DNA-PKcs is believed to primarily function in the DSB repair pathway, non-homologous end joining. Utilizing a human cell line in which the kinase domain of DNA-PKcs is inactivated, we show here that DNA-PKcs kinase activity is required for the cellular response to DSBs immediately after their induction. Specifically, DNA-PKcs kinase activity initiates phosphorylation of the chromatin factors H2AX and KAP1 following ionizing radiation exposure and drives local chromatin decondensation near the DSB site. Furthermore, loss of DNA-PKcs kinase activity results in a marked decrease in the recruitment of numerous members of the DDR machinery to DSBs. Collectively, these results provide clear evidence that DNA-PKcs activity is pivotal for the initiation of the DDR.

scholarly journals Intersection of Two Checkpoints: Could Inhibiting the DNA Damage Response Checkpoint Rescue Immune Checkpoint-Refractory Cancer?

Cancers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 3415
Author(s):  
Peter H. Goff ◽  
Rashmi Bhakuni ◽  
Thomas Pulliam ◽  
Jung Hyun Lee ◽  
Evan T. Hall ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Tumor Immunity ◽  
Immune Checkpoint ◽  
Ataxia Telangiectasia ◽  
Management Strategies ◽  
Adaptive Immune Response ◽  
Cell Cycle Checkpoint ◽  
Damage Response ◽  
Cycle Checkpoint

Metastatic cancers resistant to immunotherapy require novel management strategies. DNA damage response (DDR) proteins, including ATR (ataxia telangiectasia and Rad3-related), ATM (ataxia telangiectasia mutated) and DNA-PK (DNA-dependent protein kinase), have been promising therapeutic targets for decades. Specific, potent DDR inhibitors (DDRi) recently entered clinical trials. Surprisingly, preclinical studies have now indicated that DDRi may stimulate anti-tumor immunity to augment immunotherapy. The mechanisms governing how DDRi could promote anti-tumor immunity are not well understood; however, early evidence suggests that they can potentiate immunogenic cell death to recruit and activate antigen-presenting cells to prime an adaptive immune response. Merkel cell carcinoma (MCC) is well suited to test these concepts. It is inherently immunogenic as ~50% of patients with advanced MCC persistently benefit from immunotherapy, making MCC one of the most responsive solid tumors. As is typical of neuroendocrine cancers, dysfunction of p53 and Rb with upregulation of Myc leads to the very rapid growth of MCC. This suggests high replication stress and susceptibility to DDRi and DNA-damaging agents. Indeed, MCC tumors are particularly radiosensitive. Given its inherent immunogenicity, cell cycle checkpoint deficiencies and sensitivity to DNA damage, MCC may be ideal for testing whether targeting the intersection of the DDR checkpoint and the immune checkpoint could help patients with immunotherapy-refractory cancers.

2118-P: Regulation of Ataxia-Telangiectasia and Rad3-Related (ATR)–Dependent DNA Damage Response by Nitric Oxide in ß-Cells

Diabetes ◽  
2020 ◽  
Vol 69 (Supplement 1) ◽  
pp. 2118-P
Author(s):  
CHAY TENG YEO ◽  
BRYNDON OLESON ◽  
JOHN A. CORBETT ◽  
JAMIE K. SCHNUCK
Keyword(s):  
Nitric Oxide ◽  
Dna Damage ◽  
Dna Damage Response ◽  
Ataxia Telangiectasia ◽  
Damage Response

scholarly journals MORC2 regulates DNA damage response through a PARP1-dependent pathway

2019 ◽  
Vol 47 (16) ◽  
pp. 8502-8520 ◽  
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.

scholarly journals DNA‑PKcs PARylation regulates DNA‑PK kinase activity in the DNA damage response

2019 ◽  
Author(s):  
Yang Han ◽  
Feng Jin ◽  
Ying Xie ◽  
Yike Liu ◽  
Sai Hu ◽  
...  
Keyword(s):  
Dna Damage ◽  
Dna Damage Response ◽  
Kinase Activity ◽  
Damage Response

scholarly journals Phosphorylation of PLK3 Is Controlled by Protein Phosphatase 6

Cells ◽  
2020 ◽  
Vol 9 (6) ◽  
pp. 1506 ◽  
Author(s):  
Cecilia Aquino Perez ◽  
Matous Palek ◽  
Lenka Stolarova ◽  
Patrick von Morgen ◽  
Libor Macurek
Keyword(s):  
Dna Damage ◽  
Stress Response ◽  
Osmotic Stress ◽  
Dna Damage Response ◽  
Protein Phosphatase ◽  
Gene Editing ◽  
Kinase Activity ◽  
Cell Cycle Control ◽  
Damage Response ◽  
Transformed Cell Lines

Polo-like kinases play essential roles in cell cycle control and mitosis. In contrast to other members of this kinase family, PLK3 has been reported to be activated upon cellular stress including DNA damage, hypoxia and osmotic stress. Here we knocked out PLK3 in human non-transformed RPE cells using CRISPR/Cas9-mediated gene editing. Surprisingly, we find that loss of PLK3 does not impair stabilization of HIF1α after hypoxia, phosphorylation of the c-Jun after osmotic stress and dynamics of DNA damage response after exposure to ionizing radiation. Similarly, RNAi-mediated depletion of PLK3 did not impair stress response in human transformed cell lines. Exposure of cells to various forms of stress also did not affect kinase activity of purified EGFP-PLK3. We conclude that PLK3 is largely dispensable for stress response in human cells. Using mass spectrometry, we identify protein phosphatase 6 as a new interacting partner of PLK3. Polo box domain of PLK3 mediates the interaction with the PP6 complex. Finally, we find that PLK3 is phosphorylated at Thr219 in the T-loop and that PP6 constantly dephosphorylates this residue. However, in contrast to PLK1, phosphorylation of Thr219 does not upregulate enzymatic activity of PLK3, suggesting that activation of both kinases is regulated by distinct mechanisms.

scholarly journals INTS3 controls the hSSB1-mediated DNA damage response

2009 ◽  
Vol 187 (1) ◽  
pp. 25-32 ◽  
Author(s):  
Jeffrey R. Skaar ◽  
Derek J. Richard ◽  
Anita Saraf ◽  
Alfredo Toschi ◽  
Emma Bolderson ◽  
...  
Keyword(s):  
Dna Damage ◽  
Signaling Pathway ◽  
Dna Damage Response ◽  
Ataxia Telangiectasia ◽  
Binding Protein ◽  
Ataxia Telangiectasia Mutated ◽  
Uncharacterized Protein ◽  
Damage Response ◽  
Atm Signaling Pathway ◽  
Atm Signaling

Human SSB1 (single-stranded binding protein 1 [hSSB1]) was recently identified as a part of the ataxia telangiectasia mutated (ATM) signaling pathway. To investigate hSSB1 function, we performed tandem affinity purifications of hSSB1 mutants mimicking the unphosphorylated and ATM-phosphorylated states. Both hSSB1 mutants copurified a subset of Integrator complex subunits and the uncharacterized protein LOC58493/c9orf80 (henceforth minute INTS3/hSSB-associated element [MISE]). The INTS3–MISE–hSSB1 complex plays a key role in ATM activation and RAD51 recruitment to DNA damage foci during the response to genotoxic stresses. These effects on the DNA damage response are caused by the control of hSSB1 transcription via INTS3, demonstrating a new network controlling hSSB1 function.

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