DNA double-strand breaks (DSBs) arise through both replication errors and from exogenous events such as exposure to ionizing radiation. DSBs are potentially lethal, and cells have evolved a highly conserved mechanism to detect and repair these lesions. This mechanism involves phosphorylation of histone H2AX (γH2AX) and the loading of DNA repair proteins onto the chromatin adjacent to the DSB. I...

Double-strand break (DSB) repair and DNA replication are tightly linked in the life cycle of bacteriophage T4. Indeed, the major mode of phage DNA replication depends on recombination proteins and can be stimulated by DSBs. DSB-stimulated DNA replication is dramatically demonstrated when T4 infects cells carrying two plasmids that share homology. A DSB on one plasmid triggered extensive replica...

Ionizing radiations deposit a wide range of energies in and around DNA and this leads to a corresponding spectrum of complexity of the lesions induced. The relationships between the amount of energy deposited and the yields and types of damage induced are important in modelling the physical and chemical stages of radiation effect and linking them to biological outcome. To study these relationsh...

The signaling cascade initiated in response to DNA double-strand breaks (DSBs) has been extensively investigated in interphase cells. Here, we show that mitotic cells treated with DSB-inducing agents activate a "primary" DNA damage response (DDR) comprised of early signaling events, including activation of the protein kinases ataxia telangiectasia mutated (ATM) and DNA-dependent protein kinase ...

Activation-induced cytidine deaminase (AID) likely initiates immunoglobulin gene-conversion (GC) by deaminating cytidines within the V-region of chicken B-cells. However, the intervening DNA lesion required to initiate GC remains elusive. GC could be initiated by a single strand break or a double strand break (DSB). To distinguish between these possibilities, we examined GC in the chicken DT40 ...

Using the method of filter elution of double stranded DNA under neutral conditions we have shown that most of gamma-ray induced double strand breaks (DSB) are rejoined in both mammalian and bacterial cells. Rejoining also occurs in the G1 phase in V79 Chinese hamster cells and under different growth conditions. Within 8 minutes at 37 C, half the breaks are rejoined. The rejoining in E. coli is ...

ownloade C regulates a myriad of genes controlling cell proliferation, metabolism, differentiation, and apoptosis. lso controls the expression of DNA double-strand break (DSB) repair genes and therefore may be a ial target for anticancer therapy to sensitize cancer cells to DNA damage or prevent genetic instability. report, we studied whether MYC binds to DSB repair gene promoters and modulates...

DNA non-homologous end joining (NHEJ) and homologous recombination (HR) function to repair DNA double-strand breaks (DSBs) in G2 phase with HR preferentially repairing heterochromatin-associated DSBs (HC-DSBs). Here, we examine the regulation of repair pathway usage at two-ended DSBs in G2. We identify the speed of DSB repair as a major component influencing repair pathway usage showing that DN...

Purpose The complex relationship between linear energy transfer (LET) and cellular response to radiation is not yet fully elucidated. To better characterize DNA damage after irradiations with therapeutic protons, we monitored formation disappearance of double-strand breaks (DNA DSB) as a function LET time. Comparisons conventional ?-rays high carbon ions were also performed.Materials Methods In...

In 2005, two reports, one on analysis of 5'-RACE PCR products of p53 transcripts in human normal tissues [1] and the other on analysis of a zebrafish genetic mutant def hi429 [2], described the discovery of p53 isoforms. Since then it has raised tremendous interest in the cancer research community to unravel the function and regulation of these isoforms due to the fact that p53 (TP53) is the mo...