REGULATION OF ACTIVITY AND EXPRESSION OF NO SYNTHASE

拟议研究的主要目的是阐明 一氧化氮合成酶调节一氧化氮(NO)产生的机制 哺乳动物细胞。近些年来，NO研究领域几乎呈爆炸式增长 岁月和NO，自然界中最简单的分子之一，已经发展成 最普遍和最多方面的生物介体之一 生理学和病理生理学。鉴于……的广泛行动 内源性NO作为血管扩张剂、血小板抑制物和 非肾上腺素-非胆碱能的白细胞功能、神经递质 神经元和靶细胞损伤的病理生理介质， NO的生物合成和代谢是需要 理解。一氧化氮在生物组织中是化学不稳定的， 因此，影响意志力生物行为的因素 这在很大程度上取决于影响NO产量的因素。这个 中心假说是血管平滑合成NO 肌肉和内皮细胞、肺泡巨噬细胞和肝细胞 受到内源性因素的严格调控，影响两种酶 一氧化氮合酶的活性和转录表达。最近的这方面的研究 实验室研究表明，NO、亚硝基可改变一氧化氮合酶活性 化合物、四氢生物蝶呤的可用性和氧化还原试剂，以及 干扰核因子kappaB活性的化合物 核因子-kB抑制细胞因子激活的诱导型一氧化氮合酶的表达 巨噬细胞。更多的实验表明，NO可以下调 诱导型一氧化氮合酶的转录。因此，建议的 一氧化氮合酶活性和表达调控的研究进展 哺乳动物细胞。为实现这一目标，提出了五个具体目标： (1)阐明一氧化氮抑制神经细胞和神经细胞生长的机制 内皮一氧化氮合酶；(2)确定巨噬细胞诱生一氧化氮合酶的原因 抵抗NO的抑制作用；(3)阐明 钙调素促进钙调素催化反应的机制(S) 一氧化氮合酶的各种亚型；(4)确定所需的条件 通过一氧化氮合酶亚型产生活性氧物种；及(5) 阐明核因子-kB和活性氧作为血管紧张素转换酶的介体的作用 早期反应基因激活在诱导型一氧化氮合酶表达中的作用 巨噬细胞和肝细胞。这项拟议的研究代表着一项持续的 长期努力了解影响人类健康的生物因素 一氧化氮在哺乳动物细胞中在健康和疾病中的作用。

The principal objective of the proposed research is to elucidate the mechanisms of regulation of nitric oxide (NO) production by NO synthase in mammalian cells. The field of NO research has virtually exploded in recent years and NO, one of the simplest molecules in nature, has developed into one of the most ubiquitous and multifaceted biological mediators in physiology and pathophysiology. In view of the widespread actions of endogenously generated NO as a vasodilator, inhibitor of platelet and leukocyte function, neurotransmitter in nonadrenergic-noncholinergic neurons, and pathophysiological mediator of target cell injury, the biosynthesis and metabolism of NO are critical processes that require understanding. NO is chemically labile in biological tissues and, therefore, the factors that influence the biological actions of NO will depend largely on the factors that affect the production of NO. The central hypothesis is that the biosynthesis of NO by vascular smooth muscle and endothelial cells, alveolar macrophages, and hepatocytes is tightly regulated by endogenous factors influencing both the enzymatic activity and transcriptional expression of NOS. Recent studies from this laboratory indicate that NOS activity can be altered by NO, nitroso compounds, tetrahydrobiopterin availability, and redox agents, and that compounds which interfere with the activation of nuclear factor kappa B (NF-kB) inhibit expression of inducible NOS in cytokine-activated macrophages. Additional experiments indicate that NO can down-regulate the transcription of mRNA for inducible NOS. Therefore, the proposed studies focus on the regulation of NOS activity and expression in mammalian cells. Five specific aims are proposed to achieve the objective: (1) to elucidate the mechanism by which NO inhibits neuronal and endothelial NOS; (2) to determine the reasons why macrophage inducible NOS is resistant to the inhibitory action of NO; (3) to elucidate the mechanism(s) by which calmodulin promotes the catalytic reaction of various isoforms of NOS; (4) to determine the conditions required for the production of reactive oxygen species by NOS isoforms; and (5) to elucidate the roles for NF-kB and reactive oxygen species as mediators of early response gene activation in the expression of inducible NOS in macrophages and hepatocytes. The proposed research represents a continuing long-term effort to understand the biological factors that influence the actions of NO in mammalian cells in both health and disease.