Project description:High concentration of NaCl increases DNA breaks both in cell culture and in vivo. The breaks remain elevated as long as NaCl concentration remains high and are rapidly repaired when the concentration is lowered. Repair of the breaks after NaCl is reduced is accompanied by formation of foci containing phosphorylated H2AX (γH2AX), which occurs around DNA double-strand breaks and contributes to their repair. By chromatin immunoprecipitation using anti-γH2AX antibody, followed by massive parallel sequencing (ChIP-Seq), we find that during repair of double–strand breaks induced by high NaCl, γH2AX is predominantly localized to regions of the genome devoid of genes (“gene deserts”), indicating that the high NaCl-induced double-strand breaks are located there. Localization to gene deserts helps explain why the DNA breaks are less harmful than are the random breaks induced by genotoxic agents such as UV radiation, ionizing radiation and oxidants. We propose that the universal presence of NaCl around animal cells has directly influenced the evolution of the structure of their genomes.
Project description:High concentration of NaCl increases DNA breaks both in cell culture and in vivo. The breaks remain elevated as long as NaCl concentration remains high and are rapidly repaired when the concentration is lowered. Repair of the breaks after NaCl is reduced is accompanied by formation of foci containing phosphorylated H2AX (M-NM-3H2AX), which occurs around DNA double-strand breaks and contributes to their repair. By chromatin immunoprecipitation using anti-M-NM-3H2AX antibody, followed by massive parallel sequencing (ChIP-Seq), we find that during repair of doubleM-bM-^@M-^Sstrand breaks induced by high NaCl, M-NM-3H2AX is predominantly localized to regions of the genome devoid of genes (M-bM-^@M-^\gene desertsM-bM-^@M-^]), indicating that the high NaCl-induced double-strand breaks are located there. Localization to gene deserts helps explain why the DNA breaks are less harmful than are the random breaks induced by genotoxic agents such as UV radiation, ionizing radiation and oxidants. We propose that the universal presence of NaCl around animal cells has directly influenced the evolution of the structure of their genomes. ChIP-Seq experiment to find locations of M-NM-3H2AX in mouse genome
Project description:Repair of DNA double-strand breaks (DSBs) by non-homologous end-joining is critical for neural development, and brain cells frequently contain somatic genomic variations that might involve DSB intermediates. We now use an unbiased, high-throughput approach to identify genomic regions harboring recurrent DSBs in primary neural stem/progenitor cells (NSPCs). We identify 27 recurrent DSB clusters (RDCs) and, remarkably, all occur within gene bodies. Most of these NSPC RDCs were detected only upon mild, aphidicolin-induced replication stress, providing a nucleotide-resolution view of replication-associated genomic fragile sites. The vast majority of RDCs occur in long, transcribed, and late-replicating genes. Moreover, almost 90% of identified RDC-containing genes are involved in synapse function and/or neural cell adhesion, with a substantial fraction also implicated in tumor suppression and/or mental disorders. Our characterization of NSPC RDCs reveals a basis of gene fragility and suggests potential impacts of DNA breaks on neurodevelopment and neural functions. We performed high-throughput, genome-wide, translocation sequencing (HTGTS) and GRO-seq in primary mouse neural stem/progenitor cells of the indicated genotypes.
Project description:DallePazze2014 - Cellular senescene-induced
mitochondrial dysfunction
This model is described in the article:
Dynamic modelling of
pathways to cellular senescence reveals strategies for targeted
interventions.
Dalle Pezze P, Nelson G, Otten EG,
Korolchuk VI, Kirkwood TB, von Zglinicki T, Shanley DP.
PLoS Comput. Biol. 2014 Aug; 10(8):
e1003728
Abstract:
Cellular senescence, a state of irreversible cell cycle
arrest, is thought to help protect an organism from cancer, yet
also contributes to ageing. The changes which occur in
senescence are controlled by networks of multiple signalling
and feedback pathways at the cellular level, and the interplay
between these is difficult to predict and understand. To
unravel the intrinsic challenges of understanding such a highly
networked system, we have taken a systems biology approach to
cellular senescence. We report a detailed analysis of
senescence signalling via DNA damage, insulin-TOR, FoxO3a
transcription factors, oxidative stress response, mitochondrial
regulation and mitophagy. We show in silico and in vitro that
inhibition of reactive oxygen species can prevent loss of
mitochondrial membrane potential, whilst inhibition of mTOR
shows a partial rescue of mitochondrial mass changes during
establishment of senescence. Dual inhibition of ROS and mTOR in
vitro confirmed computational model predictions that it was
possible to further reduce senescence-induced mitochondrial
dysfunction and DNA double-strand breaks. However, these
interventions were unable to abrogate the senescence-induced
mitochondrial dysfunction completely, and we identified
decreased mitochondrial fission as the potential driving force
for increased mitochondrial mass via prevention of mitophagy.
Dynamic sensitivity analysis of the model showed the network
stabilised at a new late state of cellular senescence. This was
characterised by poor network sensitivity, high signalling
noise, low cellular energy, high inflammation and permanent
cell cycle arrest suggesting an unsatisfactory outcome for
treatments aiming to delay or reverse cellular senescence at
late time points. Combinatorial targeted interventions are
therefore possible for intervening in the cellular pathway to
senescence, but in the cases identified here, are only capable
of delaying senescence onset.
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Project description:Nucleic Acid Sequencing for the study of division induced double strand breaks in the terminus region of Escherichia coli cells lacking RecBCD DNA repair enzymes.