A role for ATR in the DNA damage-induced phosphorylation of p53

Tibbetts, Randal S.; Brumbaugh, Kathryn M.; Williams, Josie M.; Sarkaria, Jann N.; Cliby, William A.; Shieh, Sheau‐Yann; Taya, Yoichi; Prives, Carol; Abraham, Robert T.

doi:10.1101/gad.13.2.152

Cited by 955 publications

(798 citation statements)

References 30 publications

(45 reference statements)

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“…In contrast, the phosphorylation status of p53 at Ser-15 and Ser-37 was dramatically enhanced as the concentrations of okadaic acid and calyculin A were increased to block PP-1 activity (panels 2 and 3 of Figure 2a and b). It is well established that hyperphosphorylation of p53 at Ser-15 and Ser-37 enhances its transcriptional activity (Shieh et al, 1997;Tibbetts et al, 1999;Bakkenist and Kastan, 2003). To test this possibility, we have analysed the expression levels of two Bcl-2 family members, Bcl-2 and Bax, downstream targets of p53.…”

Section: Resultsmentioning

confidence: 99%

“…Phosphorylation of p53 at different sites has an important impact on its function. For example, phosphorylation at Ser-15 has been shown to disrupt the interaction of p53 with the Mdm2 protein, leading to stabilization and an increase in protein levels and transcriptional activity (Shieh et al, 1997;Tibbetts et al, 1999). Phosphorylation of p53 at Ser-15 and Ser-37 also impairs the ability of MDM2 to inhibit p53-dependent transactivation (Shieh et al, 1997).…”

Section: Introductionmentioning

confidence: 99%

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Protein serine/threonine phosphatase-1 dephosphorylates p53 at Ser-15 and Ser-37 to modulate its transcriptional and apoptotic activities

et al. 2006

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We have previously demonstrated that the serine/threonine protein phosphatase-1 (PP-1) plays an important role in promoting cell survival. However, the molecular mechanisms by which PP-1 promotes survival remain largely unknown. In the present study, we provide evidence to show that PP-1 can directly dephosphorylate a master regulator of apoptosis, p53, to negatively modulate its transcriptional and apoptotic activities, and thus to promote cell survival. As a transcriptional factor, the function of p53 can be greatly regulated by phosphorylation and dephosphorylation. While the kinases responsible for phosphorylation of the 17 serine/threonine sites have been identified, the dephosphorylation of these sites remains largely unknown. In the present study, we demonstrate that PP-1 can dephosphorylate p53 at Ser-15 and Ser-37 through co-immunoprecipitation, in vitro and in vivo dephosphorylation assays, overexpression and silence of the gene encoding the catalytic subunit for PP-1. We further show that mutations mimicking constitutive dephosphorylation or phosphorylation of p53 at these sites attenuate or enhance its transcriptional activity, respectively. As a result of the changed p53 activity, expression of the downstream apoptosis-related genes such as bcl-2 and bax is accordingly altered and the apoptotic events are either largely abrogated or enhanced. Thus, our results demonstrate that PP-1 directly dephosphorylates p53, and dephosphorylation of p53 has as important impact on its functions as phosphorylation does. In addition, our results reveal that one of the molecular mechanisms by which PP-1 promotes cell survival is to dephosphorylate p53, and thus negatively regulate p53-dependent death pathway.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Protein serine/threonine phosphatase-1 dephosphorylates p53 at Ser-15 and Ser-37 to modulate its transcriptional and apoptotic activities

et al. 2006

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“…Precedent for PIKKs to sequentially respond to different lesions comes from studies showing that ATM rapidly responds to ionizing radiation while ATR responds later presumably due to replication fork stalling caused by damaged DNA (Tibbetts et al, 1999;Bakkenist and Kastan, 2003). Additional studies are required to clarify why hSMG-1 activation precedes that of ATM in hyperoxia.…”

Section: Discussionmentioning

confidence: 99%

“…ATM becomes activated in response to DNA lesions or perhaps by alterations in chromatin structure through intermolecular autophosphorylation on Ser1981 (Bakkenist and Kastan, 2003). On the other hand, ATR regulates the cellular response to ultraviolet (UV) radiationinduced damage and stalled DNA replication forks and also participates in the late response to IR (Tibbetts et al, 1999;Guo et al, 2000). Activation of ATR proceeds through its association with ATR-interacting protein (Cortez et al, 2001).…”

Section: Introductionmentioning

confidence: 99%

“…Of particular importance to checkpoint activation is p53 phosphorylation on serine 15. ATM can directly phosphorylate p53 (Ser15) in response to IR while ATR is critical in the same response to UV (Canman et al, 1998;Tibbetts et al, 1999). Additionally, p53 is phosphorylated on Ser20 by Chk1 or Chk2, which are targets for ATR and ATM signaling, respectively, although some cross-talk exists between the pathways (Bartek and Lukas, 2003).…”

Section: Introductionmentioning

confidence: 99%

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hSMG-1 and ATM sequentially and independently regulate the G1 checkpoint during oxidative stress

et al. 2008

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Genotoxic stress activates the phosphatidylinositol 3-kinase-like kinases (PIKKs) that phosphorylate proteins involved in cell cycle arrest, DNA repair and apoptosis. Previous work showed that the PIKK ataxia telangiectasia mutated (ATM) but not ATM and Rad3 related phosphorylates p53 (Ser15) during hyperoxia, a model of prolonged oxidative stress and DNA damage. Here, we show hSMG-1 is responsible for the rapid and early phosphorylation of p53 (Ser15) and that ATM helps maintain phosphorylation after 24 h. Despite reduced p53 phosphorylation and abundance in cells depleted of hSMG-1 or ATM, levels of the p53 target p21 were still elevated and the G 1 checkpoint remained intact. Conditional overexpression of p21 in p53-deficient cells revealed that hyperoxia also stimulates wortmannin-sensitive degradation of p21. siRNA depletion of hSMG-1 or ATM restored p21 stability and the G 1 checkpoint during hyperoxia. These findings establish hSMG-1 as a proximal regulator of DNA damage signaling and reveal that the G 1 checkpoint is tightly regulated during prolonged oxidative stress by both PIKK-dependent synthesis and proteolysis of p21.

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