DNA-PK: A dynamic enzyme in a versatile DSB repair pathway

Davis, Anthony J.; Chen, Benjamin P.C.; Chen, David J.

doi:10.1016/j.dnarep.2014.02.020

Cited by 289 publications

(299 citation statements)

References 148 publications

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“…As a third example, DNA-dependent protein kinase, which is well established to play a central role in the nonhomologous end joining pathway of DNA repair (66), is also reported to interact with DNA in the cytoplasm and to be essential for the full induction of innate immune responses to DNA and DNA viruses in fibroblasts (61,67,68). Ferguson et al found that the DNA-dependent protein kinase subunit Ku70 is in a complex with STING in resting cells, but this interaction is abrogated following DNA stimulation (61).…”

Section: Interactions Between the Cgas-cgamp-sting Pathway And Othermentioning

confidence: 99%

Activation and Regulation of DNA-Driven Immune Responses

Paludan

2015

Microbiol Mol Biol Rev

103

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SUMMARY The innate immune system provides early defense against infections and also plays a key role in monitoring alterations of homeostasis in the body. DNA is highly immunostimulatory, and recent advances in this field have led to the identification of the innate immune sensors responsible for the recognition of DNA as well as the downstream pathways that are activated. Moreover, information on how cells regulate DNA-driven immune responses to avoid excessive inflammation is now emerging. Finally, several reports have demonstrated how defects in DNA sensing, signaling, and regulation are associated with susceptibility to infections or inflammatory diseases in humans and model organisms. In this review, the current literature on DNA-stimulated innate immune activation is discussed, and important new questions facing this field are proposed.

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Section: Interactions Between the Cgas-cgamp-sting Pathway And Othermentioning

confidence: 99%

Activation and Regulation of DNA-Driven Immune Responses

Paludan

2015

Microbiol Mol Biol Rev

103

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“…Previous NHEJ models suggested that after binding of Ku to DNA ends, DNA-PKcs binds Ku:DNA to form a DNA-PK holoenzyme and bridges the broken ends (15)(16)(17)(18); however, recent experiments indicate that DNAPKcs may have different roles in NHEJ, such as the stabilization of core NHEJ factors, recruitment and retention of accessory factors, involvement in the DDR signaling cascade, and repair of complex and clustered DSBs (19)(20)(21)(22)(23)(24)(25). In addition, recent structural studies have shown that XRCC4 and XLF form filamentous structures in vitro (26)(27)(28).…”

mentioning

confidence: 99%

Organization and dynamics of the nonhomologous end-joining machinery during DNA double-strand break repair

Reid

Keegan

Leo‐Macias

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

150

164

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Nonhomologous end-joining (NHEJ) is a major repair pathway for DNA double-strand breaks (DSBs), involving synapsis and ligation of the broken strands. We describe the use of in vivo and in vitro single-molecule methods to define the organization and interaction of NHEJ repair proteins at DSB ends. Super-resolution fluorescence microscopy allowed the precise visualization of XRCC4, XLF, and DNA ligase IV filaments adjacent to DSBs, which bridge the broken chromosome and direct rejoining. We show, by singlemolecule FRET analysis of the Ku/XRCC4/XLF/DNA ligase IV NHEJ ligation complex, that end-to-end synapsis involves a dynamic positioning of the two ends relative to one another. Our observations form the basis of a new model for NHEJ that describes the mechanism whereby filament-forming proteins bridge DNA DSBs in vivo. In this scheme, the filaments at either end of the DSB interact dynamically to achieve optimal configuration and end-to-end positioning and ligation.genomic integrity | DNA repair | nonhomologous end-joining | super-resolution microscopy | single-molecule FRET C hromosomal double-strand breaks (DSBs), considered the most cytotoxic form of DNA damage, occur as a result of normal cellular processes (1, 2) as well as cancer therapies (3-5). The cellular DNA damage response (DDR) and repair pathways responsible for maintaining genomic integrity are highly regulated and synchronized processes, both temporally and spatially, involving the coordinated recruitment, assembly, and disassembly of numerous macromolecular complexes (6, 7). In mammalian cells, nonhomologous end-joining (NHEJ) is the primary DSB repair pathway; it is active throughout the cell cycle and is crucial for viability. Dysfunctional NHEJ is associated with several clinical conditions, including LIG4 syndrome and severe combined immunodeficiency (1,8). Despite its importance, however, the details of how the NHEJ complex assembles at DSBs, brings together a pair of breaks, and organizes subsequent catalytic repair steps remain unknown.In NHEJ, DSBs are initially recognized by the Ku 70/80 heterodimer (Ku), which encircles dsDNA ends (Ku:DNA) and serves as a molecular scaffold for recruitment of DNA-dependent protein kinase catalytic subunit (DNA-PKcs), XRCC4 (X-ray repair cross-complementing protein 4), XLF (XRCC4 like factor), and DNA ligase IV (LigIV) (1,(9)(10)(11)(12)(13)(14). Previous NHEJ models suggested that after binding of Ku to DNA ends, DNA-PKcs binds Ku:DNA to form a DNA-PK holoenzyme and bridges the broken ends (15-18); however, recent experiments indicate that DNAPKcs may have different roles in NHEJ, such as the stabilization of core NHEJ factors, recruitment and retention of accessory factors, involvement in the DDR signaling cascade, and repair of complex and clustered . In addition, recent structural studies have shown that XRCC4 and XLF form filamentous structures in vitro (26-28). Whether such filaments mediate repair in vivo has not yet been determined.Our present understanding of the cellular NHEJ response to DSBs ...

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“…DNA-PK has a versatile role in NHEJ by forming complexes with other proteins and by its kinase activity (8,9). However, the importance of the catalytic subunit of this protein kinase, DNA-PKcs, during the NHEJ-dependent process of CSR has been uncertain.…”

Section: Discussionmentioning

confidence: 99%

“…Nonetheless, other than DNA-PKcs selfphosphorylation, the functional relevance of its kinase activity is not fully understood (4,8). Furthermore, other kinases, such as ATM, have the ability to phosphorylate many of these proteins (9).…”

mentioning

confidence: 99%

DNA-PKcs Is Involved in Ig Class Switch Recombination in Human B Cells

Björkman

Felgentreff

et al. 2015

The Journal of Immunology

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Nonhomologous end-joining (NHEJ) is one of the major DNA double-strand break repair pathways in mammalian cells and is required for both V(D)J recombination and class switch recombination (CSR), two Ig gene–diversification processes occurring during B cell development. DNA-dependent protein kinase, catalytic subunit (DNA-PKcs) is a component of the classical NHEJ machinery and has a critical function during V(D)J recombination. However, its role in CSR has been controversial. In this study, we examined the pattern of recombination junctions from in vivo–switched B cells from two DNA-PKcs–deficient patients. One of them harbored mutations that did not affect DNA-PKcs kinase activity but caused impaired Artemis activation; the second patient had mutations resulting in diminished DNA-PKcs protein expression and kinase activity. These results were compared with those from DNA-PKcs–deficient mouse B cells. A shift toward the microhomology-based alternative end-joining at the recombination junctions was observed in both human and mouse B cells, suggesting that the classical NHEJ pathway is impaired during CSR when DNA-PKcs is defective. Furthermore, cells from the second patient showed additional or more severe alterations in CSR and/or NHEJ, which may suggest that DNA-PKcs and/or its kinase activity have additional, Artemis-independent functions during these processes.

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DNA-PK: A dynamic enzyme in a versatile DSB repair pathway

Cited by 289 publications

References 148 publications

Activation and Regulation of DNA-Driven Immune Responses

Activation and Regulation of DNA-Driven Immune Responses

Organization and dynamics of the nonhomologous end-joining machinery during DNA double-strand break repair

DNA-PKcs Is Involved in Ig Class Switch Recombination in Human B Cells

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