Hyperoxia is known to produce elevated levels of reactive oxygen species (ROS) that can damage DNA. The cellular response to DNA damage is complex and involves gene-products that recognize DNA damage and transduce the signal to various sensors, which, in turn, inhibit proliferation, stimulate repair or induce apoptosis. Although the DNA damage response induced by oxidants such as hydrogen peroxide (H202) or other peroxides have been studied, less is known about how cells respond to DNA damage in hyperoxia. Elucidating how lung cells respond to hyperoxic DNA damage is critical for understanding pulmonary oxygen toxicity. ATM (ataxia telangiecea) and ATR (ATM-Rad3-related) are members of the phosphatidylinositol 3-kinase-related kinases (PIKK) family of proteins that have been shown to transduce DNA damage signals in response to exposure to genotoxic agents. The experiments proposed here test the hypothesis that ATR transduces hyperoxia-mediated DNA damage signals by activating checkpoint proteins p53 and/or checkpoint kinase1 (Chk1). This results in inactivation of cdc25C, which inhibits cdc2 kinase activity, thereby preventing cell cycle progression. First, we will determine whether ATR is activated in hyperoxia in lung cells. This will be achieved using inhibitors for PIKKs, and by genetic approaches involving dominant-negative constructs of ATR or ATM, and the use of ATM+/+ or ATM-/- cells (Aim 1). Next we will determine the nature of DNA damage induced in hyperoxia and how that differs from H202 or UV (Aim 2). In our next specific aim we will determine whether hyperoxia specifically activates Chk1 directly or in an ATR-dependent manner resulting in cdc25C inactivation. We will use specific inhibitors of Chk1 and genetic approaches to delineate the role of Chk1 and cdc25C in DNA damage signaling in hyperoxia (Aim 3). In our next specific aim (Aim 4) we will determine the mechanisms of inactivation of cdc2 kinase activity. We will use various kinase and phosphatase assays and genetic and inhibitor studies to define the mechanisms of inhibition of cdc2 in hyperoxia. Using these molecular approaches, we will define the mechanisms of DNA damage signaling n hyperoxia, which will significantly improve our understanding of pulmonary oxygen toxicity in lung cells ? ?

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
5R01HL071558-03
Application #
7027689
Study Section
Alcohol and Toxicology Subcommittee 4 (ALTX)
Program Officer
Harabin, Andrea L
Project Start
2004-04-01
Project End
2008-02-29
Budget Start
2006-03-01
Budget End
2007-02-28
Support Year
3
Fiscal Year
2006
Total Cost
$277,326
Indirect Cost
Name
University of Arkansas for Medical Sciences
Department
Pathology
Type
Schools of Medicine
DUNS #
122452563
City
Little Rock
State
AR
Country
United States
Zip Code
72205
Das, Kumuda C (2015) Thioredoxin-deficient mice, a novel phenotype sensitive to ambient air and hypersensitive to hyperoxia-induced lung injury. Am J Physiol Lung Cell Mol Physiol 308:L429-42
Das, Kumuda C; Wasnick, John D (2014) Biphasic response of checkpoint control proteins in hyperoxia: exposure to lower levels of oxygen induces genome maintenance genes in experimental baboon BPD. Mol Cell Biochem 395:187-98
Das, Kumuda C; Muniyappa, Harish (2010) c-Jun-NH2 terminal kinase (JNK)-mediates AP-1 activation by thioredoxin: phosphorylation of cJun, JunB, and Fra-1. Mol Cell Biochem 337:53-63
Muniyappa, Harish; Song, Shiwei; Mathews, Christopher K et al. (2009) Reactive oxygen species-independent oxidation of thioredoxin in hypoxia: inactivation of ribonucleotide reductase and redox-mediated checkpoint control. J Biol Chem 284:17069-81
Muniyappa, Harish; Das, Kumuda C (2008) Activation of c-Jun N-terminal kinase (JNK) by widely used specific p38 MAPK inhibitors SB202190 and SB203580: a MLK-3-MKK7-dependent mechanism. Cell Signal 20:675-83
Ravi, Dashnamoorthy; Muniyappa, Harish; Das, Kumuda C (2008) Caffeine inhibits UV-mediated NF-kappaB activation in A2058 melanoma cells: an ATM-PKCdelta-p38 MAPK-dependent mechanism. Mol Cell Biochem 308:193-200
Ravi, Dashnamoorthy; Muniyappa, Harish; Das, Kumuda C (2005) Endogenous thioredoxin is required for redox cycling of anthracyclines and p53-dependent apoptosis in cancer cells. J Biol Chem 280:40084-96
Ravi, Dashnamoorthy; Das, Kumuda C (2004) Redox-cycling of anthracyclines by thioredoxin system: increased superoxide generation and DNA damage. Cancer Chemother Pharmacol 54:449-58