Genetic defects in the repair of DNA single-strand breaks (SSBs) can result in neurological disease triggered by toxic activity of the single-strand-break sensor protein PARP1. However, the mechanism(s) by which this toxic PARP1 activity triggers cellular dysfunction are unclear. Here we show that human cells lacking XRCC1 fail to rapidly recover transcription following DNA base damage, a phenotype also observed in patient-derived fibroblasts with XRCC1 mutations and Xrcc1-/- mouse neurons. This defect is caused by excessive/aberrant PARP1 activity during DNA base excision repair, resulting from the loss of PARP1 regulation by XRCC1. We show that aberrant PARP1 activity suppresses transcriptional recovery during base excision repair by promoting excessive recruitment and activity of the ubiquitin protease USP3, which as a result reduces the level of monoubiquitinated histones important for normal transcriptional regulation. Importantly, inhibition and/or deletion of PARP1 or USP3 restores transcriptional recovery in XRCC1-/- cells, highlighting PARP1 and USP3 as possible therapeutic targets in neurological disease.

• MeSH
• DNA genetika   MeSH
• genetická transkripce genetika   MeSH
• histony metabolismus   MeSH
• jednořetězcové zlomy DNA * MeSH
• lidé MeSH
• myši knockoutované MeSH
• myši MeSH
• nádorové buněčné linie MeSH
• oprava DNA genetika   MeSH
• oxidační stres genetika   MeSH
• peroxid vodíku toxicita   MeSH
• poly(ADP-ribosa)polymerasa 1 genetika   metabolismus   MeSH
• protein XRCC1 genetika   metabolismus   MeSH
• specifické proteázy ubikvitinu metabolismus   MeSH
• ubikvitinace fyziologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA MeSH
• histony MeSH
• PARP1 protein, human MeSH Prohlížeč
• peroxid vodíku MeSH
• poly(ADP-ribosa)polymerasa 1 MeSH
• protein XRCC1 MeSH
• specifické proteázy ubikvitinu MeSH
• USP3 protein, human MeSH Prohlížeč
• XRCC1 protein, human MeSH Prohlížeč

Defects in DNA single-strand break repair (SSBR) are linked with neurological dysfunction but the underlying mechanisms remain poorly understood. Here, we show that hyperactivity of the DNA strand break sensor protein Parp1 in mice in which the central SSBR protein Xrcc1 is conditionally deleted (Xrcc1Nes-Cre ) results in lethal seizures and shortened lifespan. Using electrophysiological recording and synaptic imaging approaches, we demonstrate that aberrant Parp1 activation triggers seizure-like activity in Xrcc1-defective hippocampus ex vivo and deregulated presynaptic calcium signalling in isolated hippocampal neurons in vitro. Moreover, we show that these defects are prevented by Parp1 inhibition or deletion and, in the case of Parp1 deletion, that the lifespan of Xrcc1Nes-Cre mice is greatly extended. This is the first demonstration that lethal seizures can be triggered by aberrant Parp1 activity at unrepaired SSBs, highlighting PARP inhibition as a possible therapeutic approach in hereditary neurological disease.

• Klíčová slova
• DNA strand break, XRCC1, neurodegeneration, poly(ADP-ribose) polymerase, seizures,
• MeSH
• DNA vazebné proteiny * genetika   metabolismus   MeSH
• DNA MeSH
• myši MeSH
• neurony metabolismus   MeSH
• oprava DNA genetika   MeSH
• poly(ADP-ribosa)polymerasa 1 genetika   metabolismus   MeSH
• vápník * MeSH
• záchvaty genetika   MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA vazebné proteiny * MeSH
• DNA MeSH
• poly(ADP-ribosa)polymerasa 1 MeSH
• vápník * MeSH

Tyrosyl DNA phosphodiesterase 2 (TDP2) facilitates the repair of topoisomerase II (TOP2)-linked DNA double-strand breaks and, as a consequence, is required for cellular resistance to TOP2 "poisons". Recently, a deazaflavin series of compounds were identified as potent inhibitors of TDP2, in vitro. Here, however, we show that while some deazaflavins can induce cellular sensitivity to the TOP2 poison etoposide, they do so independently of TDP2 status. Consistent with this, both the cellular level of etoposide-induced TOP2 cleavage complexes and the intracellular concentration of etoposide was increased by incubation with deazaflavin, suggesting an impact of these compounds on etoposide uptake/efflux. In addition, deazaflavin failed to increase the level of TOP2 cleavage complexes or sensitivity induced by m-AMSA, which is a different class of TOP2 poison to which TDP2-defective cells are also sensitive. In conclusion, while deazaflavins are potent inhibitors of TDP2 in vitro, their limited cell permeability and likely interference with etoposide influx/efflux limits their utility in cells.

• MeSH
• aza sloučeniny chemie   MeSH
• biologický transport MeSH
• buněčné linie MeSH
• DNA vazebné proteiny antagonisté a inhibitory   MeSH
• etoposid farmakokinetika   MeSH
• flaviny chemie   farmakokinetika   farmakologie   MeSH
• fosfodiesterasy MeSH
• inhibitory topoisomerasy II farmakokinetika   MeSH
• knihovny malých molekul farmakologie   MeSH
• kur domácí MeSH
• lidé MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• aza sloučeniny MeSH
• DNA vazebné proteiny MeSH
• etoposid MeSH
• flaviny MeSH
• fosfodiesterasy MeSH
• inhibitory topoisomerasy II MeSH
• knihovny malých molekul MeSH
• TDP2 protein, human MeSH Prohlížeč