Activation of APE1/Ref-1 is dependent on reactive oxygen species generated after purinergic receptor stimulation by ATP

Apurinic apyrimidinic endonuclease redox effector factor-1 (APE1/Ref-1) is involved both in the base excision repair (BER) of DNA lesions and in the eukaryotic transcriptional regulation. APE1/Ref-1 is regulated at both the transcriptional and post-translational levels, through control of subcellular localization and post-translational modification. In response to stress conditions, several cell types release ATP, which exerts stimulatory effects on eukaryotic cells via the purinergic receptors (P2) family. By using western blot and immunofluorescence analysis on a human tumour thyroid cell line (ARO), we demonstrate that purinergic stimulation by extracellular ATP induces quick cytoplasm to nucleus translocation of the protein at early times and its neosynthesis at later times. Continuous purinergic triggering by extracellular ATP released by ARO cells is responsible for the control of APE1/Ref-1 intracellular level. Interference with intracellular pathways activated by P2 triggering demonstrates that Ca(2+) mobilization and intracellular reactive oxygen species (ROS) production are responsible for APE1/Ref-1 translocation. The APE1/Ref-1 activities on activator protein-1 (AP-1) DNA binding and DNA repair perfectly match its nuclear enrichment upon ATP stimulation. The biological relevance of our data is reinforced by the observation that APE1/Ref-1 stimulation by ATP protects ARO cells by H(2)O(2)-induced cell death. Our data provide new insights into the complex mechanisms regulating APE1/Ref-1 functions

Identification of secondary targets of N-containing bisphosphonates in mammalian cells via parallel competition analysis of the barcoded yeast deletion collection

Growth competition assays using barcoded yeast deletion-mutants reveal the molecular targets of nitrogen containing bisphosphonates used for the treatment of bone cancers and osteoporosis

Short oligodeoxynucleotides with d(G-C)<SUB>n</SUB> sequence do not assume left-handed conformation in high salt conditions

d(G-C)n oligodeoxynucleotides (with n varying from 3 to 7) were studied by the circular dichroism technique in 5 M -NaCl. Contrary to what was previously found with the d(C-G)n series in the same solvent, the left-handed double-stranded Z-conformation appears less stable than the B-form for low n values. The influence of base sequence on the relative stability of B- and Z-conformations for the two series is discussed