Crosstalk between BER and NHEJ in XRCC4-Deficient Cells Depending on hTERT Overexpression.

Targeting DNA repair pathways is an important strategy in anticancer therapy. However, the unrevealed interactions between different DNA repair systems may interfere with the desired therapeutic effect. Among DNA repair systems, BER and NHEJ protect genome integrity through the entire cell cycle.

The role of Sp1 in the detection and elimination of cells with persistent DNA strand breaks.

Maintenance of genome stability suppresses cancer and other human diseases and is critical for organism survival. Inevitably, during a life span, multiple DNA lesions can arise due to the inherent instability of DNA molecules or due to endogenous or exogenous DNA damaging factors. To avoid malignant transformation of cells with damaged DNA, multiple mechanisms have evolved to repair DNA or to detect and eradicate cells accumulating unrepaired DNA damage.

Sp1-independent downregulation of NHEJ in response to BER deficiency.

Base excision repair (BER) is the major repair pathway that removes DNA single strand breaks (SSBs) arising spontaneously due to the inherent instability of DNA. Unrepaired SSBs promote cell-cycle delay, which facilitates DNA repair prior to replication. On the other hand, in response to persistent DNA strand breaks, ATM-dependent degradation of transcription factor Sp1 leads to downregulation of BER genes expression, further accumulation of SSBs and renders cells susceptible to elimination via apoptosis.

Stability and reactivity of free radicals: a physicochemical perspective with biological implications.

Several factors control the reactivity of radicals and can provide the strategies to convert highly reactive species into more persistent species that are easier to detect in an experiment. A reaction can only proceed if sufficient mobility and thermodynamic driving force are provided and the reaction is allowed by steric considerations and by electronic states of the reagents and products. A violation of at least one of these conditions can make the radical relatively stable.

Kinetic magnetic-field effect involving the small biologically relevant inorganic radicals NO and O2(·-).

Oxidation of dihydrorhodamine 123 (DHR) to rhodamine 123 (RH) by oxoperoxonitrite (ONOO(-)), formed through recombination of NO and O(2)(·-) radicals resulting from thermal decomposition of 3-morpholinosydnonimine (SIN-1) in buffered aerated aqueous solution at pH 7.6, represents a kinetic model system of the reactivity of NO and O(2)(·-) in biochemical systems. A magnetic-field effect (MFE) on the yield of RH detected in this system is explored in the full range of fields between 0 and 18 T.

19F NMR measurements of NO production in hypertensive ISIAH and OXYS rats.

Recently we demonstrated the principal possibility of application of 19F NMR spin-trapping technique for in vivo *NO detection [Free Radic. Biol. Med.