Histone ubiquitylation is a prominent response to DNA double-strand breaks (DSBs), but how these modifications are confined to DNA lesions is not understood. Here, we show that TRIP12 and UBR5, two HECT domain ubiquitin E3 ligases, control accumulation of RNF168, a rate-limiting component of a pathway that ubiquitylates histones after DNA breakage. We find that RNF168 can be saturated by increasing amounts of DSBs. Depletion of TRIP12 and UBR5 allows accumulation of RNF168 to supraphysiological levels, followed by massive spreading of ubiquitin conjugates and hyperaccumulation of ubiquitin-regulated genome caretakers such as 53BP1 and BRCA1. Thus, regulatory and proteolytic ubiquitylations are wired in a self-limiting circuit that promotes histone ubiquitylation near the DNA lesions but at the same time counteracts its excessive spreading to undamaged chromosomes. We provide evidence that this mechanism is vital for the homeostasis of ubiquitin-controlled events after DNA breakage and can be subverted during tumorigenesis. Copyright 2012 Elsevier Inc. All rights reserved.

• MeSH
• Alphapapillomavirus MeSH
• buněčné linie MeSH
• chromatin * metabolismus   MeSH
• dvouřetězcové zlomy DNA * MeSH
• genetická transkripce MeSH
• infekce papilomavirem metabolismus   patologie   MeSH
• intracelulární signální peptidy a proteiny metabolismus   MeSH
• lidé MeSH
• nádorové buněčné linie MeSH
• nádory metabolismus   patologie   virologie   MeSH
• oprava DNA * MeSH
• transportní proteiny * metabolismus   MeSH
• ubikvitinace MeSH
• ubikvitinligasy * metabolismus   MeSH
• umlčování genů MeSH
• Check Tag
• lidé MeSH

Completion of genome duplication is challenged by structural and topological barriers that impede progression of replication forks. Although this can seriously undermine genome integrity, the fate of DNA with unresolved replication intermediates is not known. Here, we show that mild replication stress increases the frequency of chromosomal lesions that are transmitted to daughter cells. Throughout G1, these lesions are sequestered in nuclear compartments marked by p53-binding protein 1 (53BP1) and other chromatin-associated genome caretakers. We show that the number of such 53BP1 nuclear bodies increases after genetic ablation of BLM, a DNA helicase associated with dissolution of entangled DNA. Conversely, 53BP1 nuclear bodies are partially suppressed by knocking down SMC2, a condensin subunit required for mechanical stability of mitotic chromosomes. Finally, we provide evidence that 53BP1 nuclear bodies shield chromosomal fragile sites sequestered in these compartments against erosion. Together, these data indicate that restoration of DNA or chromatin integrity at loci prone to replication problems requires mitotic transmission to the next cell generations. 2011 Macmillan Publishers Limited. All rights reserved.

• MeSH
• buněčné jádro * metabolismus   MeSH
• buněčný cyklus MeSH
• časové faktory MeSH
• chromatin metabolismus   MeSH
• chromozomy * ultrastruktura   MeSH
• DNA-helikasy metabolismus   MeSH
• DNA * genetika   metabolismus   MeSH
• intracelulární signální peptidy a proteiny * metabolismus   MeSH
• lidé MeSH
• malá interferující RNA metabolismus   MeSH
• mitóza * MeSH
• nádorové buněčné linie MeSH
• poškození DNA MeSH
• regulace genové exprese u nádorů MeSH
• replikace DNA * MeSH
• Check Tag
• lidé MeSH