1
|
Bessho T. Up-Regulation of Non-Homologous End-Joining by MUC1. Genes (Basel) 2024; 15:808. [PMID: 38927743 PMCID: PMC11203369 DOI: 10.3390/genes15060808] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Revised: 06/10/2024] [Accepted: 06/15/2024] [Indexed: 06/28/2024] Open
Abstract
Ionizing radiation (IR) and chemotherapy with DNA-damaging drugs such as cisplatin are vital cancer treatment options. These treatments induce double-strand breaks (DSBs) as cytotoxic DNA damage; thus, the DSB repair activity in each cancer cell significantly influences the efficacy of the treatments. Pancreatic cancers are known to be resistant to these treatments, and the overexpression of MUC1, a member of the glycoprotein mucins, is associated with IR- and chemo-resistance. Therefore, we investigated the impact of MUC1 on DSB repair. This report examined the effect of the overexpression of MUC1 on homologous recombination (HR) and non-homologous end-joining (NHEJ) using cell-based DSB repair assays. In addition, the therapeutic potential of NHEJ inhibitors including HDAC inhibitors was also studied using pancreatic cancer cell lines. The MUC1-overexpression enhances NHEJ, while partially suppressing HR. Also, MUC1-overexpressed cancer cell lines are preferentially killed by a DNA-PK inhibitor and HDAC1/2 inhibitors. Altogether, MUC1 induces metabolic changes that create an imbalance between NHEJ and HR activities, and this imbalance can be a target for selective killing by HDAC inhibitors. This is a novel mechanism of MUC1-mediated IR-resistance and will form the basis for targeting MUC1-overexpressed pancreatic cancer.
Collapse
Affiliation(s)
- Tadayoshi Bessho
- The Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, 986805 Nebraska Medical Center, Omaha, NE 68198, USA
| |
Collapse
|
2
|
Li Y, Wang F, Li X, Wang L, Yang Z, You Z, Peng A. The ATM-E6AP-MASTL axis mediates DNA damage checkpoint recovery. eLife 2023; 12:RP86976. [PMID: 37672026 PMCID: PMC10482428 DOI: 10.7554/elife.86976] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/07/2023] Open
Abstract
Checkpoint activation after DNA damage causes a transient cell cycle arrest by suppressing cyclin-dependent kinases (CDKs). However, it remains largely elusive how cell cycle recovery is initiated after DNA damage. In this study, we discovered the upregulated protein level of MASTL kinase hours after DNA damage. MASTL promotes cell cycle progression by preventing PP2A/B55-catalyzed dephosphorylation of CDK substrates. DNA damage-induced MASTL upregulation was caused by decreased protein degradation, and was unique among mitotic kinases. We identified E6AP as the E3 ubiquitin ligase that mediated MASTL degradation. MASTL degradation was inhibited upon DNA damage as a result of the dissociation of E6AP from MASTL. E6AP depletion reduced DNA damage signaling, and promoted cell cycle recovery from the DNA damage checkpoint, in a MASTL-dependent manner. Furthermore, we found that E6AP was phosphorylated at Ser-218 by ATM after DNA damage and that this phosphorylation was required for its dissociation from MASTL, the stabilization of MASTL, and the timely recovery of cell cycle progression. Together, our data revealed that ATM/ATR-dependent signaling, while activating the DNA damage checkpoint, also initiates cell cycle recovery from the arrest. Consequently, this results in a timer-like mechanism that ensures the transient nature of the DNA damage checkpoint.
Collapse
Affiliation(s)
- Yanqiu Li
- Department of Oral Biology, University of Nebraska Medical CenterLincolnUnited States
| | - Feifei Wang
- Department of Oral Biology, University of Nebraska Medical CenterLincolnUnited States
| | - Xin Li
- Department of Oral Biology, University of Nebraska Medical CenterLincolnUnited States
| | - Ling Wang
- Department of Oral Biology, University of Nebraska Medical CenterLincolnUnited States
| | - Zheng Yang
- Department of Cell Biology and Physiology, School of Medicine, Washington University in St. LouisSt. LouisUnited States
| | - Zhongsheng You
- Department of Cell Biology and Physiology, School of Medicine, Washington University in St. LouisSt. LouisUnited States
| | - Aimin Peng
- Department of Oral Biology, University of Nebraska Medical CenterLincolnUnited States
| |
Collapse
|
3
|
Li Y, Wang F, Li X, Wang L, Yang Z, You Z, Peng A. The ATM-E6AP-MASTL axis mediates DNA damage checkpoint recovery. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.22.529521. [PMID: 36865136 PMCID: PMC9980089 DOI: 10.1101/2023.02.22.529521] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/24/2023]
Abstract
Checkpoint activation after DNA damage causes a transient cell cycle arrest by suppressing CDKs. However, it remains largely elusive how cell cycle recovery is initiated after DNA damage. In this study, we discovered the upregulated protein level of MASTL kinase hours after DNA damage. MASTL promotes cell cycle progression by preventing PP2A/B55-catalyzed dephosphorylation of CDK substrates. DNA damage-induced MASTL upregulation was caused by decreased protein degradation, and was unique among mitotic kinases. We identified E6AP as the E3 ubiquitin ligase that mediated MASTL degradation. MASTL degradation was inhibited upon DNA damage as a result of the dissociation of E6AP from MASTL. E6AP depletion reduced DNA damage signaling, and promoted cell cycle recovery from the DNA damage checkpoint, in a MASTL-dependent manner. Furthermore, we found that E6AP was phosphorylated at Ser-218 by ATM after DNA damage and that this phosphorylation was required for its dissociation from MASTL, the stabilization of MASTL, and the timely recovery of cell cycle progression. Together, our data revealed that ATM/ATR-dependent signaling, while activating the DNA damage checkpoint, also initiates cell cycle recovery from the arrest. Consequently, this results in a timer-like mechanism that ensures the transient nature of the DNA damage checkpoint.
Collapse
Affiliation(s)
- Yanqiu Li
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, Nebraska, USA
| | - Feifei Wang
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, Nebraska, USA
| | - Xin Li
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, Nebraska, USA
| | - Ling Wang
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, Nebraska, USA
| | - Zheng Yang
- Department of Cell Biology and Physiology, School of Medicine, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Zhongsheng You
- Department of Cell Biology and Physiology, School of Medicine, Washington University in St. Louis, St. Louis, Missouri, USA
| | - Aimin Peng
- Department of Oral Biology, University of Nebraska Medical Center, Lincoln, Nebraska, USA
| |
Collapse
|
4
|
A single XLF dimer bridges DNA ends during nonhomologous end joining. Nat Struct Mol Biol 2018; 25:877-884. [PMID: 30177755 PMCID: PMC6128732 DOI: 10.1038/s41594-018-0120-y] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Accepted: 07/05/2018] [Indexed: 01/09/2023]
Abstract
Non-homologous end joining (NHEJ) is the primary pathway of DNA double-strand break repair in vertebrate cells, yet it remains unclear how NHEJ factors assemble a synaptic complex that bridges DNA ends. To address the role of XRCC4-like factor (XLF) in synaptic complex assembly, we employed single-molecule fluorescence imaging in Xenopus laevis egg extract, a system that efficiently joins DNA ends. We find that a single XLF dimer binds to DNA substrates just prior to formation of a ligation-competent synaptic complex between DNA ends. The interaction of both globular head domains of the XLF dimer with XRCC4 is required for efficient formation of this synaptic complex. In contrast to a model in which filaments of XLF and XRCC4 bridge DNA ends, our results indicate that binding of a single XLF dimer facilitates the assembly of a stoichiometrically well-defined synaptic complex.
Collapse
|
5
|
Zhu S, Fisher LA, Bessho T, Peng A. Protein phosphatase 1 and phosphatase 1 nuclear targeting subunit-dependent regulation of DNA-dependent protein kinase and non-homologous end joining. Nucleic Acids Res 2017; 45:10583-10594. [PMID: 28985363 PMCID: PMC5737533 DOI: 10.1093/nar/gkx686] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Accepted: 07/28/2017] [Indexed: 12/29/2022] Open
Abstract
DNA-dependent protein kinase catalytic subunit (DNA-PKcs) plays a key role in mediating non-homologous end joining (NHEJ), a major repair pathway for DNA double-strand breaks (DSBs). The activation, function and dynamics of DNA-PKcs is regulated largely by its reversible phosphorylation at numerous residues, many of which are targeted by DNA-PKcs itself. Interestingly, these DNA-PKcs phosphorylation sites function in a distinct, and sometimes opposing manner, suggesting that they are differentially regulated via complex actions of both kinases and phosphatases. In this study we identified several phosphatase subunits as potential DSB-associated proteins. In particular, protein phosphatase 1 (PP1) is recruited to a DSB-mimicking substrate in Xenopus egg extracts and sites of laser microirradiation in human cells. Depletion of PP1 impairs NHEJ in both Xenopus egg extracts and human cells. PP1 binds multiple motifs of DNA-PKcs, regulates DNA-PKcs phosphorylation, and is required for DNA-PKcs activation after DNA damage. Interestingly, phosphatase 1 nuclear targeting subunit (PNUTS), an inhibitory regulator of PP1, is also recruited to DNA damage sites to promote NHEJ. PNUTS associates with the DNA-PK complex and is required for DNA-PKcs phosphorylation at Ser-2056 and Thr-2609. Thus, PNUTS and PP1 together fine-tune the dynamic phosphorylation of DNA-PKcs after DNA damage to mediate NHEJ.
Collapse
Affiliation(s)
- Songli Zhu
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA
| | - Laura A Fisher
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA
| | - Tadayoshi Bessho
- Eppley Institute for Research in Cancer and Allied Diseases, Fred & Pamela Buffett Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198, USA
| | - Aimin Peng
- Department of Oral Biology, College of Dentistry, University of Nebraska Medical Center, Lincoln, NE 68583, USA
| |
Collapse
|
6
|
Graham TGW, Walter JC, Loparo JJ. Ensemble and Single-Molecule Analysis of Non-Homologous End Joining in Frog Egg Extracts. Methods Enzymol 2017. [PMID: 28645371 DOI: 10.1016/bs.mie.2017.03.020] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Non-homologous end joining (NHEJ) repairs the majority of DNA double-strand breaks in human cells, yet the detailed order of events in this process has remained obscure. Here, we describe how to employ Xenopus laevis egg extract for the study of NHEJ. The egg extract is easy to prepare in large quantities, and it performs efficient end joining that requires the core end joining proteins Ku, DNA-PKcs, XLF, XRCC4, and DNA ligase IV. These factors, along with the rest of the soluble proteome, are present at endogenous concentrations, allowing mechanistic analysis in a system that begins to approximate the complexity of cellular end joining. We describe an ensemble assay that monitors covalent joining of DNA ends and fluorescence assays that detect joining of single pairs of DNA ends. The latter assay discerns at least two discrete intermediates in the bridging of DNA ends.
Collapse
Affiliation(s)
| | - Johannes C Walter
- Harvard Medical School, Boston, MA, United States; Howard Hughes Medical Institute, Harvard Medical School, Boston, MA, United States.
| | | |
Collapse
|
7
|
Shen S, Loh TJ, Shen H, Zheng X, Shen H. CRISPR as a strong gene editing tool. BMB Rep 2017; 50:20-24. [PMID: 27616359 PMCID: PMC5319660 DOI: 10.5483/bmbrep.2017.50.1.128] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 08/16/2016] [Accepted: 09/07/2016] [Indexed: 11/20/2022] Open
Abstract
Clustered regularly-interspaced short palindromic repeats (CRISPR) is a new and effective genetic editing tool. CRISPR was initially found in bacteria to protect it from virus invasions. In the first step, specific DNA strands of virus are identified by guide RNA that is composed of crRNA and tracrRNA. Then RNAse III is required for producing crRNA from pre-crRNA. In The second step, a crRNA:tracrRNA:Cas9 complex guides RNase III to cleave target DNA. After cleavage of DNA by CRISPR-Cas9, DNA can be fixed by Non- Homologous End Joining (NHEJ) and Homology Directed Repair (HDR). Whereas NHEJ is simple and random, HDR is much more complex and accurate. Gene editing by CRISPR is able to be applied to various biological field such as agriculture and treating genetic diseases in human. [BMB Reports 2017; 50(1): 20-24].
Collapse
Affiliation(s)
- Shengfu Shen
- Willston Northampton School, Easthampton, MA 01027,
USA
| | - Tiing Jen Loh
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 61005,
Korea
| | - Hongling Shen
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 61005,
Korea
| | - Xuexiu Zheng
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 61005,
Korea
| | - Haihong Shen
- School of Life Sciences, Gwangju Institute of Science and Technology, Gwangju 61005,
Korea
| |
Collapse
|