PIG3 (p53-inducible gene 3), originally identified as one of a set of genes induced by p53 before the onset of apoptosis, was assumed to contribute to early cellular response to DNA damage. Here, we studied the relation between p53 status and the increased expression of PIG3 by ionizing radiation (IR), and the related clues regarding the involvement of PIG3 in the cellular response to IR-induced DNA damage signaling. We demonstrated that the pentanucleotide microsatellite sequence was responsible for the p53-dependent induction of PIG3 transcription after irradiation, while sequence upstream of PIG3 promoter could maintain the basal level of expression which was not inducible by irradiation. The interaction of PIG3 and the KRAB-ZFP-associated protein 1 (KAP1), a DNA damage response protein, was revealed. PIG3 nucleus foci were formed 15 min after γ-ray irradiation, and which were found to partially colocalize with the phospho-KAP-1 foci as well as γ-H2AX foci. Although the lac operator tagged EGFP based reporter system revealed that PIG3 does not remodel chromatin in large scale in the cells under normal growing condition, it indeed prompted the chromatin relaxation in the cellular response to DNA damage signaling. All these data suggest that PIG3 is involved in IR-induced DNA damage response, and which maybe partially attribute to its interaction with KAP1. The p53-inducible gene 3 (PIG3 or TP53I3) was originally identified as one of a set of genes induced by p53 before the onset of apoptosis [1]. The closest relative of PIG3 in mammals is zeta-Crystallin, an NADPH-quinone oxidoreductase and a potent generator of reactive oxygen species (ROS) [2]. As consistent with its classification in the quinine oxidoreductase (QOR) family, PIG3 was confirmed an activity of NADPH dependent reductase with orthoquinones [3]. In addition, in vitro activation and in vivo overexpression of PIG3 was demonstrated to accumulate reactive oxygen species (ROS), while an inactive PIG3 mutant (Ser151Val) did not produce ROS in cells, indicating that enzymatic active protein is necessary for its function [3]. PIG3 was also recently demonstrated to contribute to early cellular response to DNA damage induced by UV radiation and the DNA damaging-chemical neocarzinostatin through recruiting 53BP1, Mre11, Rad50 and Nbs1 to the sites of DNA break lesions and modulating intra-S and G2/M phase checkpoint [4]. A p53 dependent upregulation of PIG3 way demonstrated during p53-mediated growth arrest or under genotoxic stress [5]. Szak et al. [6] reported that increased p53 binding to PIG3, p21 and MDM2 promoters occurred in the human colorectal carcinoma cell line RKO within 2 h after p53 activation, but a lower p53 affinity was demonstrated for the consensus binding site in the PIG3 promoters compared to

Titanium dioxide (TiO2) coating was prepared through dipping stainless steel net into titanium dioxide sol and then extracting it. The photocatalytic activities for all titanium dioxide coatings were tested by methyl orange degradation under ultraviolet and visible light irradiation. The photo-absorption property was determined by UV-Vis spectrophotometer. The titanium dioxide coating is photo-catalytically reactive for the degradation of methyl orange. The photo-catalytic activity is influenced by extraction times, degradation time, doping element and light source. La-doped titanium dioxide exhibits the best photocatalytic activity in comparison with undoped, V-doped and La-V-codoped ones. The degradation rate of methyl orange by La-doped titanium dioxide coating reaches 92% after 70 minutes irradiation under ultraviolet light.