Nox/Duox enzymes - NADPH-oxidases that generate superoxide and secondary reactive oxygen species (ROS) - participate in normal physiology including cell signaling, innate immunity, thyroid hormone synthesis, and gravity perception. Over-production of ROS by these enzymes is associated with molecular damage and aberrant signaling in disease classes such as hyperproliferative disorders (e.g., cancer, hypertension, atherosclerosis), fibrotic disease (pulmonary fibrosis, cirrhosis, diabetic nephropathy), inflammatory disorders (ARDS, arthritis, atherosclerosis), and reperfusion injury (stroke, myocardial infarction, organ transplantation). The seven human Nox isoenzymes reflect three modes of regulation: 1) constitutively active (Nox4);2) activation by assembly with regulatory subunits (Nox1, Nox2 and Nox3);and 3) calcium-activated (Nox5, Duox1 and Duox2). We will study the molecular mechanisms of regulation of the catalytic subunits, using Nox2 as representative of subunit-regulated Noxes, Nox4 as a constitutively active Nox, and Nox5 as a Ca2+regulated Nox. The underlying hypothesis to be explored is that all three activation mechanisms induce the same active conformation in the catalytic moiety, allowing electron flow from NADPH to form ROS. Regions on the catalytic subunit involved in responding to calcium or subunits will be identified and characterized, and information will be integrated using a newly developed homology structural model of the Nox catalytic subunit. We will explore the possibility of catalytically essential dimerization, and will investigate the roles of key conserved protein regions identified by an evolutionary comparison of more than 100 Nox enzymes in multiple species. A molecular understanding of the regulation of Nox/Duox enzymes will provide key information that will be key to preventing excess or inappropriate ROS generation and mitigating the course of these diseases.
Nox/Duox enzymes generate a form of free radical referred to as reactive oxygen species (ROS), which is used in normal biological processes to regulate many types of cells and to play a role in the ability of white blood cells to fight infections, the thyroid to produce hormones, and many other normal functions. However, in disease, overproduction of ROS by these enzymes causes both tissue damage and abnormalities in basic cellular functions, and plays a key role in some cancers, complications of diabetes, stroke, cardiovascular diseases, and many other diseases. In order to prevent the progression of these diseases, it is essential to understand the molecular changes that turn on these enzymes to produce too much ROS. This proposal centers on understanding the fundamentals of this process, and has direct implications, for example in our ability to design new classes of drugs that treat these diseases by targeting Nox/Duox enzymes.
|Diebold, Becky A; Smith, Susan M E; Li, Yang et al. (2015) NOX2 As a Target for Drug Development: Indications, Possible Complications, and Progress. Antioxid Redox Signal 23:375-405|
|Nisimoto, Yukio; Diebold, Becky A; Cosentino-Gomes, Daniela et al. (2014) Nox4: a hydrogen peroxide-generating oxygen sensor. Biochemistry 53:5111-20|
|Li, Hong; Cao, Zehong; Moore, D Ray et al. (2012) Microbicidal activity of vascular peroxidase 1 in human plasma via generation of hypochlorous acid. Infect Immun 80:2528-37|
|Smith, Susan M E; Min, Jaeki; Ganesh, Thota et al. (2012) Ebselen and congeners inhibit NADPH oxidase 2-dependent superoxide generation by interrupting the binding of regulatory subunits. Chem Biol 19:752-63|
|Kawahara, Tsukasa; Jackson, Heather M; Smith, Susan M E et al. (2011) Nox5 forms a functional oligomer mediated by self-association of its dehydrogenase domain. Biochemistry 50:2013-25|
|Takac, Ina; SchrÃ¶der, Katrin; Zhang, Leilei et al. (2011) The E-loop is involved in hydrogen peroxide formation by the NADPH oxidase Nox4. J Biol Chem 286:13304-13|
|Liu, Rui-Ming; Choi, Jinah; Wu, Jian-He et al. (2010) Oxidative modification of nuclear mitogen-activated protein kinase phosphatase 1 is involved in transforming growth factor beta1-induced expression of plasminogen activator inhibitor 1 in fibroblasts. J Biol Chem 285:16239-47|
|Nisimoto, Yukio; Jackson, Heather M; Ogawa, Hisamitsu et al. (2010) Constitutive NADPH-dependent electron transferase activity of the Nox4 dehydrogenase domain. Biochemistry 49:2433-42|
|Aguirre, Jesus; Lambeth, J David (2010) Nox enzymes from fungus to fly to fish and what they tell us about Nox function in mammals. Free Radic Biol Med 49:1342-53|
|de Mochel, Nabora Soledad Reyes; Seronello, Scott; Wang, Shelley Hsiuying et al. (2010) Hepatocyte NAD(P)H oxidases as an endogenous source of reactive oxygen species during hepatitis C virus infection. Hepatology 52:47-59|
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