Hint1 is a haploinsufficient tumor suppressor gene and the underlying molecular mechanisms for its tumor suppressor function are unknown. In this study we demonstrate that HINT1 participates in ionizing radiation (IR)-induced DNA damage responses. In response to IR, HINT1 is recruited to IR-induced foci (IRIF) and associates with gamma-H2AX and ATM. HINT1 deficiency does not affect the formatio...

We employed gene targeting to study H2AX, a histone variant phosphorylated in chromatin surrounding DNA double-strand breaks. Mice deficient for both H2AX and p53 (H(delta/delta)P(-/-)) rapidly developed immature T and B lymphomas and solid tumors. Moreover, H2AX haploinsufficiency caused genomic instability in normal cells and, on a p53-deficient background, early onset of various tumors inclu...

Introduction: The radiation induced bystander effect (BSE) is the induction of biological changes in unexposed cells, by signals transmitted from bystander cells that cause the spread of radiation toxicity to adjacent or far tissues. In addition, reactive oxygen species (ROS) and reactive nitrogen species (RNS) such as cytokines are involved in mediating mechanisms in bystande...

BACKGROUND The response of eukaryotic cells to double-strand breaks in genomic DNA includes the sequestration of many factors into nuclear foci. Recently it has been reported that a member of the histone H2A family, H2AX, becomes extensively phosphorylated within 1-3 minutes of DNA damage and forms foci at break sites. RESULTS In this work, we examine the role of H2AX phosphorylation in focus...

is phosphorylated and forms discrete foci immediately (within 5 min) after irradiation [5]; hence, it may represent an earlier signaling response than formation of the complex within 2 hr of irradiation, as detected by anti-hMRE11 antibody (Figure 2A). In the absence of NBS1, 5 Medical and Biological Laboratories Nagano 396-0002 hMRE11 protein was confined to the cytoplasm and did not form nucl...

At close hand to one's genomic material are the histones that make up the nucleosome. Standing guard, one variant stays hidden doubling as one of the core histones. But, thanks to its prime positioning, a variation in the tail of H2AX enables rapid modification of the histone code in response to DNA damage. A role for H2AX phosphorylation has been demonstrated in DNA repair, cell cycle checkpoi...

Cancer cells express survivin that facilitates tumorigenesis. Celecoxib has been shown to reduce human colorectal cancers. However, the role and regulation of survivin by celecoxib in colorectal carcinoma cells remain unclear. Treatment with 40-80 muM celecoxib for 24 h induced cytotoxicity and proliferation inhibition via a concentration-dependent manner in RKO colorectal carcinoma cells. Cele...

Histone H2AX is a histone H2A variant that is ubiquitously expressed throughout the genome. It plays a key role in the cellular response to DNA damage and has been designated as the histone guardian of the genome. Histone H2AX deficiency decreases genomic stability and increases tumor susceptibility of normal cells and tissues. However, the role of histone H2AX phosphorylation in malignant tran...

Several genes involved in the DNA damage response and in maintaining genomic stability have emerged as breast cancer susceptibility genes. These include BRCA1 and BRCA2, as well as other genes with smaller contributions to breast cancer aetiology, such as TP53, CHEK2, and ATM. Germline mutations in BRCA1 and BRCA2 increase sensitivity to DNA damage and decrease cellular capacity to repair doubl...

The presence of phosphorylated histone H2AX (γ-H2AX) is associated with the local activation of DNA-damage repair pathways. Although γ-H2AX deregulation in cancer has previously been reported, the molecular mechanism involved and its relationship with other histone modifications remain largely unknown. Here we find that the histone methyltransferase SUV39H2 methylates histone H2AX on lysine 134...