Proteasomes and Proteasome Activator 200 kDa (PA200) Accumulate on Chromatin in Response to Ionizing Radiation

Blickwedehl, Jennifer; McEvoy, Sarah; Wong, Irene; Kousis, Philaretos C.; Clements, James L.; Elliott, Rosemary W.; Cresswell, Peter; Liang, Ping; Bangia, Naveen

doi:10.1667/rr0690.1

Cited by 49 publications

(54 citation statements)

References 78 publications

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“…Redistribution of PA200 in the nucleus of c-irradiated HeLa cells to punctuate patterns, reminding to the reactions of many DNA repairing proteins, suggest a participation of the protein in DNA repair, confirmed by experiments showing a hypersensitivity of yeast having PA200 mutations to bleomycin (82); in between 20S-PA200 complexes attached to chromatin after c-irradiation have been shown as well (82). Until now, three different forms of PA200 are identified via their mRNA: PA200i, ii, and iii, but only PA200i seems to bind the 20S ''core'' proteasome (88).…”

Section: Regulators Of the 20s ''Core'' Proteasomementioning

confidence: 85%

The proteasome and its role in the degradation of oxidized proteins

2008

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SummaryThe generation of free radicals and the resulting oxidative modification of cell structures are omnipresent in mammalian cells. This includes the permanent oxidation of proteins leading to the disruption of the protein structure and an impaired functionality. In consequence, these oxidized proteins have to be removed in order to prevent serious metabolic disturbances. The most important cellular proteolytic system responsible for the removal of oxidized proteins is the proteasomal system. For normal functioning, the proteasomal system needs the coordinated interaction of numerous components. This review describes the fundamental functions of the 20S ''core'' proteasome, its regulators, and the roles of the proteasomal system beyond the removal of oxidized proteins in mammalian cells. IUBMBIUBMB Life, 60(11): 743-752, 2008

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Section: Regulators Of the 20s ''Core'' Proteasomementioning

confidence: 85%

The proteasome and its role in the degradation of oxidized proteins

2008

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“…All cell lines were maintained in DMEM supplemented with 10% serum (20,36). The ATM inhibitor KU-55933 and the DNA-PK inhibitor NU7026 have been described (26,37).…”

Section: Methodsmentioning

confidence: 99%

“…The ATM inhibitor KU-55933 and the DNA-PK inhibitor NU7026 have been described (26,37). The following antibodies have been described: anti-PA200 antisera, MCP20 (anti-core proteasome subunit, ␣6), anti-histone H1-H4, KU70, and RC23V (anti-flu peptide) (20). The antibodies specific for the following proteins were purchased: 19S proteasome (subunit S10B) from Calbiochem; Rad51 (clone 3C10) and phosphorylated (Ser-10) histone H3 from Millipore; NBS1 and P-NBS1 from Novus Biologicals; human p53 (DO-1) from Sigma; murine p53 (pAb240) from Abcam; PUMA (Ab-1) from Calbiochem; and ␣-tubulin (DM 1A) from Sigma.…”

Section: Methodsmentioning

confidence: 99%

“…1A). Given that PA200 associates with the end of core proteasomes and within cells, virtually all detectable PA200 is associated with core proteasomes (18)(19)(20)22) the observed association of PA200 with 19S caps likely reflects a hybrid proteasome comprising a core proteasome with a 19S cap on one end and a PA200 cap on the other end. To confirm the existence of PA200-19S hybrid proteasomes, we immunoprecipitated the complex by using an antibody specific for a 19S cap subunit (S10B) and assessed the associated proteins for PA200-core proteasome complexes by immunoprecipitation of core proteasomes followed by Western blotting for PA200 (Fig.…”

Section: Elevated Levels Of Pa200-19s Hybrid Proteasomes After Ir Expmentioning

confidence: 97%

“…Both mammalian PA200 and its ortholog in Saccharomyces cerevisiae (known as Blm10) are reported to form hybrid proteasomes consisting of one 19S cap on one end and one Blm10/PA200 cap on the other end of a core proteasome (4,19). PA200 forms nuclear foci and accumulates on chromatin after IR exposure, indicating that PA200 responds to damage induced by IR and may function in DNA repair (4,20). However, two observations challenge the idea that PA200 plays a role in DNA repair.…”

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confidence: 99%

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Role for proteasome activator PA200 and postglutamyl proteasome activity in genomic stability

Blickwedehl

Agarwal

Seong

et al. 2008

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

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Proteasome activator PA200 enhances proteasome-mediated cleavage after acidic residues in vitro; however, its role within cells is not known. Here, we show that, in response to ionizing radiation, PA200 forms hybrid proteasomes with 19S caps and 20S core proteasomes that accumulate on chromatin, leading to an increase in proteolytic activity. Unlike many other proteins that respond to DNA damage, the response of PA200 appears to be independent of Ataxia Telangiectasia Mutated and p53, but dependent on DNAdependent protein kinase activity. Nonetheless, PA200 is critical because PA200-knockdown cells show genomic instability and reduced survival after exposure to ionizing radiation. This phenotype is reproduced by specific inhibition of postglutamyl activity of proteasomes, but combined treatment with PA200 siRNA and postglutamyl inhibitor does not show additive effects on survival. Together, these data suggest a unique role for PA200 in genomic stability that is likely mediated through its ability to enhance postglutamyl cleavage by proteasomes.ATM ͉ chromatin ͉ DNA-dependent protein kinase ͉ ionizing radiation ͉ DNA damage

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