Genotoxin-induced Rad9-Hus1-Rad1 (9-1-1) Chromatin Association Is an Early Checkpoint Signaling Event

Roos-Mattjus, Pia; Vroman, Benjamin T.; Burtelow, Matthew A.; Rauen, Matthew; Eapen, Alex; Karnitz, Larry M.

doi:10.1074/jbc.m207272200

Cited by 70 publications

(45 citation statements)

References 28 publications

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“…In agreement with several previous reports (16,22,27,34,36,37), the constitutively phosphorylated hRad9 protein underwent hyperphosphorylation under various conditions (Fig. 3B, top panel).…”

Section: Hrad9 Phosphorylation and Checkpoint Controlsupporting

confidence: 81%

A Role for the Phosphorylation of hRad9 in Checkpoint Signaling

St.Onge

Besley

Pelley

et al. 2003

Journal of Biological Chemistry

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The integrity of the human genome is preserved by signal transduction pathways called checkpoints, which delay progression through the cell cycle when DNA damage is present. Three checkpoint proteins, hRad9, hRad1, and hHus1, form a proliferating cell nuclear antigen-like, heterotrimeric complex that has been proposed to function in the initial detection of DNA structural abnormalities. hRad9 is highly modified by phosphorylation, in a constitutive manner and in response to both DNA damage and cell cycle position. Here we present evidence that Cell cycle checkpoints are signal transduction pathways that maintain the proper order of cell cycle events (1). Several checkpoints preserve the integrity of DNA by sensing genetic anomalies and delaying progression through the cell cycle so that enough time is provided for these anomalies to be corrected. The contribution of checkpoints to human health is illustrated by a growing list of checkpoint genes that are mutated in cancer and cancer predisposition syndromes (2-8).The hRad9 protein is the human homologue of Schizosaccharomyces pombe Rad9, a member of the checkpoint Rad family of proteins. In fission yeast, the checkpoint rad genes (rad1 ϩ , rad3 ϩ , rad9 ϩ , rad17 ϩ , rad26 ϩ , and hus1 ϩ ) are required for the S phase (DNA replication) and G 2 (DNA damage) checkpoints (9 -13). Yeasts lacking these genes fail to inactivate Cdc2 and enter premature, lethal mitosis when challenged with agents that inhibit DNA synthesis or damage DNA (14, 15). Like its yeast counterpart, hRad9 forms a ring-shaped, heterotrimeric complex with the hRad1 and hHus1 proteins (16 -18). Each member of the hRad9-hRad1-hHus1 complex (also known as the 9-1-1 complex), shares sequence homology with PCNA, 1 a homotrimer that encircles DNA and tethers DNA polymerase ␦ during DNA synthesis (19). PCNA is loaded onto DNA by the pentameric protein complex replication factor C (RFC), which is composed of one large subunit and four smaller subunits (20). In a manner analogous to PCNA and RFC, 9-1-1 is loaded onto DNA by a complex between hRad17 and the four smallest subunits of RFC (21). Since DNA damage induces hRad17-dependent association of 9-1-1 with chromatin, the 9-1-1 complex is believed to be involved in the direct recognition of DNA lesions during the initial stages of the checkpoint response (22). Also involved in this recognition are two phosphatidylinositol 3-kinase-related kinases, ATM and ATR, that regulate several cell cycle transitions and are central components of the cell checkpoint machinery (23). Even though these kinases appear to respond to different types of DNA lesions, they share a long list of common checkpoint substrates, including hRad17 (24 -26) and hRad9 (27). In fission yeast, Rad3 (which shares homology with both ATR and ATM) requires Rad9, Rad1, Hus1, and Rad17 to phosphorylate certain substrates (28). Similarly, in human cells, phosphorylation of hRad17 by ATR requires hHus1 (22). These findings support a model in which the 9-1-1 complex recruits substrates for ATM or...

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Section: Hrad9 Phosphorylation and Checkpoint Controlsupporting

confidence: 81%

A Role for the Phosphorylation of hRad9 in Checkpoint Signaling

St.Onge

Besley

Pelley

et al. 2003

Journal of Biological Chemistry

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“…The transient treatment with caffeine affects DNA synthesis at APBs but has no significant effects on global nuclear DNA synthesis or localization of at least two components (hRad9 (Table VI) and NBS1 2 ) at APBs. Consistently, it was previously reported that the chromatin association of neither hRad9 nor NBS1 depends on ATM or ATR (52,53). Because the overall progression of S phase was normal in ALT cells with or without caffeine treatment, it was unlikely that the inactivation of ATM and ATR by caffeine treatment led to reduced DNA synthesis at APB through activating the genome-wide checkpoint mechanism.…”

Section: Percentages Of Cells With Apbs and Brdurd Foci In Caffeine Tsupporting

confidence: 58%

Localization of hRad9, hHus1, hRad1, and hRad17 and Caffeine-sensitive DNA Replication at the Alternative Lengthening of Telomeres-associated Promyelocytic Leukemia Body

Nabetani

Yokoyama

Ishikawa

2004

Journal of Biological Chemistry

100

101

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Telomere maintenance is essential for continued cell proliferation. Although most cells accomplish this by activating telomerase, a subset of immortalized tumors and cell lines do so in a telomerase-independent manner, a process called alternative lengthening of telomeres (ALT). DNA recombination has been shown to be involved in ALT, but the precise mechanisms remain unknown. A fraction of cells in a given ALT population contain a unique nuclear structure called APB (ALTassociated promyelocytic leukemia (PML) body), which is characterized by the presence of telomeric DNA in the PML body. Here we describe that hRad9, hHus1, and hRad1, which form a DNA clamp complex that is associated with DNA damage, as well as its clamp loader, hRad17, are constitutive components of APB. Phosphorylated histone H2AX (␥-H2AX), a molecular marker of double-strand breaks (DSBs), also colocalizes with some APBs. The results suggest that telomeric DNAs at APBs are recognized as DSBs. PML staining and fluorescence in situ hybridization analyses of mitotic ALT cells revealed that telomeric DNAs present at APBs are of both extrachromosomal and native telomere origins. Furthermore, we demonstrated that DNA synthesis occurs at APBs and is significantly inhibited by caffeine, an inhibitor of phosphatidylinositol 3-kinase-related kinases. Taken together, we suggest that telomeric DNAs at APBs are recognized and processed as DSBs, leading to telomeric DNA synthesis and thereby contributing to telomere maintenance in ALT cells.

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“…RDS may reflect an impairment in this process. However, a recent finding suggested that the loading of the 9-1-1 complex onto chromatin is independent of ATM/ATR, implying that any regulatory aspects of PIKKs must be a proximal event in checkpoint signaling (Roos-Mattjus et al, 2002). Whereas it is quite clear that PIKKs and the 9-1-1 complex are required for CHK1 activation and the G2 checkpoint, it is not presently known what association the 9-1-1 complex has with DSB repair.…”

Section: Signal Transduction Pathways Regulating Dsb Repairmentioning

confidence: 94%

Regulation and mechanisms of mammalian double-strand break repair

2003

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The double-strand break (DSB) is believed to be one of the most severe types of DNA damage, and if left unrepaired is lethal to the cell. Several different types of repair act on the DSB. The most important in mammalian cells are nonhomologous end-joining (NHEJ) and homologous recombination repair (HRR). NHEJ is the predominant type of DSB repair in mammalian cells, as opposed to lower eucaryotes, but HRR has recently been implicated in critical cell signaling and regulatory functions that are essential for cell viability. Whereas NHEJ repair appears constitutive, HRR is regulated by the cell cycle and inducible signal transduction pathways. More is known about the molecular details of NHEJ than HRR in mammalian cells. This review focuses on the mechanisms and regulation of DSB repair in mammalian cells, the signaling pathways that regulate these processes and the potential crosstalk between NHEJ and HRR, and between repair and other stress-induced pathways with emphasis on the regulatory circuitry associated with the ataxia telangiectasia mutated (ATM) protein.

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Genotoxin-induced Rad9-Hus1-Rad1 (9-1-1) Chromatin Association Is an Early Checkpoint Signaling Event

Cited by 70 publications

References 28 publications

A Role for the Phosphorylation of hRad9 in Checkpoint Signaling

A Role for the Phosphorylation of hRad9 in Checkpoint Signaling

Localization of hRad9, hHus1, hRad1, and hRad17 and Caffeine-sensitive DNA Replication at the Alternative Lengthening of Telomeres-associated Promyelocytic Leukemia Body

Regulation and mechanisms of mammalian double-strand break repair

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