Regulation of Nox Enzymes by Calcium and Novel Subunits

钙和新亚基对 Nox 酶的调节

• 批准号: 7069094
• 负责人: John David Lambeth
• 金额: $ 24.5万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-01 至 2009-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7069094
• 关键词: NAD(P)H dehydrogenase; RNA splicing; calcium; calcium binding protein; cell growth regulation; chimeric proteins; cytochromes; enzyme activity; enzyme structure; free radical oxygen; guanosinetriphosphatases; intermolecular interaction; molecular assembly /self assembly; neoplasm /cancer; site directed mutagenesis

DESCRIPTION (provided by applicant): We recently described a family of NADP H-oxidases, the Nox enzymes that have been implicated in cancer, particularly colon and prostate cancers. The enzymes are flavocytochromes that produce reactive oxygen species (ROS) and one of these, hydrogen peroxide, has functions as a signal molecule, stimulating mitosis and angiogenesis. Aberrant epithelial expression or activation of these enzymes has therefore been proposed to play a role in cancer progression. However, to date, little is known about how the activity of these enzymes is regulated. This application therefore focuses on the molecular mechanisms of regulation of Nox1, Nox3, Nox4 and Nox5. The Nox enzymes are homologs of gp91phox, the catalytic subunit of the phagocyte respiratory burst oxidase. The latter is regulated by catalytic subunits p47phox and p67phox, and we recently identified novel homologs of these subunits termed NOXO1 (Nox Organizing Protein 1) and NOXA1 (Nox Activating Protein 1) from colon and testis cDNA libraries. Evidence points to these proteins as regulatory subunits of the Noxl and possibly Nox5. We have identified 4 isoforms (splice forms) of NOXO1 and 5 splice forms of NOXAI. In addition, NOXO1 and NOXA1 contain Src-homology 3 (SH3) domains and proline-rich regions, and NOXA1 contains a 4 tandem copies of a TPR motif that is proposed to participate in heterodimer formation with Rac or another small GTP-binding protein. Thus, the role of these subunits and their interaction domains in the regulated assembly/activation of Noxl-5, and the role of small GTPases will be investigated. Nox5 contains a domain similar to the recoverin group of calcium-binding proteins, and is presumed to be regulated by calcium. In addition, Nox5 contains a proline-rich motif that is predicted to interact with an SH3 domain like the one in NOXO1. The role of regulatory subunits and calcium as alternative or synergistic mechanisms for regulating Nox5 will be investigated. These studies are expected to have implications with regard to both normal and aberrant generation of ROS signals relevant to cell growth and cancer.

描述（由申请人提供）：我们最近描述了NADP家族 H-氧化酶，即与癌症，特别是结肠癌和前列腺癌有关的Nox酶。这些酶是产生活性氧（ROS）的黄细胞色素，其中之一，过氧化氢，具有信号分子的功能，刺激有丝分裂和血管生成。因此，已经提出这些酶的异常上皮表达或活化在癌症进展中起作用。然而，迄今为止，人们对这些酶的活性是如何调节的知之甚少。因此，本申请集中于调节Nox 1、Nox 3、Nox 4和Nox 5的分子机制。Nox酶是gp 91 phox的同系物，gp 91 phox是吞噬细胞呼吸爆发氧化酶的催化亚基。后者是由催化亚基p47 phox和p67 phox，我们最近确定了新的同系物，这些亚基称为NOXO 1（Nox Organizing Protein 1）和NOXA 1（Nox Activating Protein 1）从结肠和睾丸cDNA文库。有证据表明这些蛋白质是Noxl和可能的Nox 5的调节亚基。我们已经鉴定了NOXO 1的4种同种型（剪接形式）和NOXAI的5种剪接形式。此外，NOXO 1和NOXA 1含有Src同源3（SH 3）结构域和富含脯氨酸的区域，NOXA 1含有TPR基序的4个串联拷贝，该基序被认为参与与Rac或另一种小GTP结合蛋白的异二聚体形成。因此，将研究这些亚基及其相互作用结构域在Noxl-5的调节组装/活化中的作用，以及小GTP酶的作用。Nox 5含有一个类似于钙结合蛋白recoverin组的结构域，并被推测为受钙调节。此外，Nox 5含有一个富含脯氨酸的基序，预计与NOXO 1中的SH 3结构域相互作用。调节亚基和钙作为替代或协同机制调节Nox 5的作用将被研究。这些研究预计将对与细胞生长和癌症相关的ROS信号的正常和异常产生影响。