Spk1/Rad53 is regulated by Mec1-dependent protein phosphorylation in DNA replication and damage checkpoint pathways.

Sun, Zhaoxia; Fay, David S.; Marini, Federica; Foiani, Marco; Stern, David F.

doi:10.1101/gad.10.4.395

Cited by 297 publications

(330 citation statements)

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“…Cells were collected at various times and subjected to immunoblotting analysis with anti-HA antibodies. Rad53 phosphorylation can be detected as a slowly migrating form on immunoblots (Sanchez et al, 1996;Sun et al, 1996). In HO cells, phosphorylation became detectable 2 h after HO expression and persisted for at least 6 h. Rad53 was fully phosphorylated in TG-HO cells, but phosphorylation became less evident at 5 h and nearly undetectable at 6 h. Interestingly, phosphorylation was significantly inhibited in TG-HO-CA cells.…”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…Mec1 and Tel1 phosphorylate the Rad9 checkpoint mediator and in turn activate the CHK2-related Rad53 protein (Gilbert et al, 2001;Schwartz et al, 2002;Sweeney et al, 2005). Activated Rad53 becomes hyperphosphorylated and further phosphorylates downstream targets (Sanchez et al, 1996;Sun et al, 1996).The ends of chromosomes, termed telomeres, contain a double-stranded DNA region of tandem repeats (e.g., human, T 2 AG 3 ; budding yeast, TG [1][2][3] [TG]) and a 3Ј-protruding ssDNA region of the G-rich strand (Vega et al, 2003;Smogorzewska and de Lange, 2004). Due to the inability of the DNA replication machinery to copy the most distal telomere sequences, telomeric DNA progressively decreases in length as cells undergo successive cell divisions.…”

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Cdc13 Telomere Capping Decreases Mec1 Association but Does Not Affect Tel1 Association with DNA Ends

Hirano

Sugimoto

2007

MBoC

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Chromosome ends, known as telomeres, have to be distinguished from DNA breaks that activate DNA damage checkpoint. Two large protein kinases, ataxia-teleangiectasia mutated (ATM) and ATM-Rad3-related (ATR), control not only checkpoint activation but also telomere length. In budding yeast, Mec1 and Tel1 correspond to ATR and ATM, respectively. Here, we show that Cdc13-dependent telomere capping attenuates Mec1 association with DNA ends. The telomeric TG repeat sequence inhibits DNA degradation and decreases Mec1 accumulation at the DNA end. The TG-mediated degradation block requires binding of multiple Cdc13 proteins. The Mre11-Rad50-Xrs2 complex and Exo1 contribute to DNA degradation at DNA ends. Although the TG sequence impedes Exo1 association with DNA ends, it allows Mre11 association. Moreover, the TG sequence does not affect Tel1 association with the DNA end. Our results suggest that the Cdc13 telomere cap coordinates Mec1 and Tel1 accumulation rather than simply covering the DNA ends at telomeres. INTRODUCTIONDNA double-strand breaks (DSBs) are induced by exogenous DNA-damaging agents and carcinogens or by endogenous by-products, including reactive oxygen species (Friedberg et al., 2006). The repair of DSBs is crucial for maintaining genome stability. All organisms respond to DSBs by promptly launching the DNA damage response. This response involves the recruitment of DNA repair factors and the activation of signal transduction pathways, often termed DNA damage checkpoint pathways (Zhou and Elledge, 2000). Activation of the checkpoint pathway induces cell cycle arrest and expression of genes required for DNA repair.The checkpoint signals are initiated through two large protein kinases, ataxia-teleangiectasia mutated (ATM) and ATM-Rad3-related (ATR) (Zhou and Elledge, 2000;Abraham, 2001). ATM and ATR are highly conserved among eukaryotes. ATR is closely related to Mec1 in the budding yeast Saccharomyces cerevisiae and Rad3 in the fission yeast Schizosaccharomyces pombe. ATM homologues are termed Tel1 in both budding and fission yeasts. Current evidence indicates that the Mre11-Rad50 -Nbs1 (Xrs2 in budding yeast) complex is the primary sensor that recruits ATR/ Mec1 and ATM/Tel1 to DSBs (Nakada et al., 2003a(Nakada et al., , 2004Falck et al., 2005;You et al., 2005). In budding yeast, there is compelling evidence that the Mre11-Rad50 -Xrs2 (MRX) complex collaborates with exonuclease 1 (Exo1) in the generation of single-stranded DNA (ssDNA) at DSB ends (Krogh and Symington, 2004). ATM/Tel1 interacts with the C terminus of Nbs1/Xrs2 to localize to DNA ends (Nakada et al., 2003a;Falck et al., 2005;You et al., 2005). Meanwhile, the ssDNA that is generated at the DSB is covered with replication protein A (RPA) (Wold, 1997;Krogh and Symington, 2004). RPA-covered DNA recruits ATR/Mec1 to a region near the DSB end (Zou and Elledge, 2003;Nakada et al., 2005). ATM and ATR activate the downstream kinases CHK1 and CHK2 with assistance of checkpoint mediators, including 53BP1, BRCA1, and MDC1 (Zhou and Elledge, 2000;Bakke...

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cdc13 Telomere Capping Decreases Mec1 Association but Does Not Affect Tel1 Association with DNA Ends

Hirano

Sugimoto

2007

MBoC

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“…While the major role of Dun1 sc is thought to be downstream of Rad53 sc in transcriptional induction of repair genes, dun1 sc Δ cells do have a partial checkpoint arrest defect which may or may not be related to the role of Dun1 sc in transcription [54,55]. Rad53 sc is phosphorylated in response to DNA damage and this phosphorylation is dependent on Mec1 sc , Rad9 sc , and the proteins of the Rad24 sc epistasis group [52,56]. Whether Rad53 sc is a direct substrate of Mec1 sc remains to be determined.…”

Section: The Schizosaccharomyces Pombe G 2 Dna Damage Checkpointmentioning

confidence: 99%

Mitotic DNA damage and replication checkpoints in yeast

Rhind

Russell

1998

Current Opinion in Cell Biology

176

129

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“…These results suggest that functions that determine the latter two phenotypes in human cells may reside in ATM domains that require a higher degree of homology than is present in the yeast Tel1 protein, or, alternatively, may reside in other functional yeast homologues. In this regard, it has been shown that Mec1p in S. cerevisiae and Rad3p in S. pombe, which are yeast homologues of ATM and putative partners of Tel1p, are involved in cell cycle regula-tion and radiosensitivity, thus sharing functional properties with ATM that are different from those of Tel1p (Jimenez et al, 1992;Bentley et al, 1996;Siede et al, 1996;Sun et al, 1996;Gatti, 1998).…”

Section: Tel1 Expression Leads To Telomere Lengthening In A-t Cellsmentioning

confidence: 99%

The YeastTEL1Gene Partially Substitutes for HumanATMin Suppressing Hyperrecombination, Radiation-Induced Apoptosis and Telomere Shortening in A-T Cells

Fritz¹,

Friedl²,

Zwacka

et al. 2000

MBoC

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Homozygous mutations in the human ATM gene lead to a pleiotropic clinical phenotype of ataxia-telangiectasia (A-T) patients and correlating cellular deficiencies in cells derived from A-T donors. Saccharomyces cerevisiae tel1 mutants lacking Tel1p, which is the closest sequence homologue to the ATM protein, share some of the cellular defects with A-T. Through genetic complementation of A-T cells with the yeast TEL1 gene, we provide evidence that Tel1p can partially compensate for ATM in suppressing hyperrecombination, radiation-induced apoptosis, and telomere shortening. Complementation appears to be independent of p53 activation. The data provided suggest that TEL1 is a functional homologue of human ATM in yeast, and they help to elucidate different cellular and biochemical pathways in human cells regulated by the ATM protein.

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Spk1/Rad53 is regulated by Mec1-dependent protein phosphorylation in DNA replication and damage checkpoint pathways.

Cited by 297 publications

References 48 publications

Cdc13 Telomere Capping Decreases Mec1 Association but Does Not Affect Tel1 Association with DNA Ends

Cdc13 Telomere Capping Decreases Mec1 Association but Does Not Affect Tel1 Association with DNA Ends

Mitotic DNA damage and replication checkpoints in yeast

The YeastTEL1Gene Partially Substitutes for HumanATMin Suppressing Hyperrecombination, Radiation-Induced Apoptosis and Telomere Shortening in A-T Cells

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