Linking Lipoxygenases with Essential Fatty Acids and Epidermal Barrier Formation

描述（由申请人提供）：本申请的长期目标是阐明两种脂氧合酶（LOX）及其必需脂肪酸（EFA）底物在形成表皮的不透水屏障中的作用，该屏障缺陷导致鱼鳞病并导致特应性皮炎。12 R-脂氧合酶（12 R-LOX）和表皮脂氧合酶-3（eLOX 3）是仅有的人类脂氧合酶，如果突变为失活形式，会导致疾病，一种常染色体隐性遗传性先天性鱼鳞病（ARCI）。ARCI的特征性鳞状皮肤也表现为必需脂肪酸（EFA）缺乏，这一事实表明EFA和两种LOX酶之间可能存在底物-酶关系。我们将测试一个新的假设，该假设将EFA、12 R-LOX和eLOX 3以及表皮水屏障的结构联系起来。我们认为这两种脂氧合酶是EFA的一种重要形式，亚油酸酯与独特的表皮酰基神经酰胺的极长链脂肪酸的ω-羟基酯化。我们进一步提出，需要这种氧合来促进（氧化的）亚油酸酯部分的水解，并使非常长链的脂肪酸ω-羟基游离以偶联到角质细胞包膜的交联蛋白质，这是角质形成细胞的关键步骤。 密封防水层具体目的是（1）使用动物模型在体内表征表皮中的12 R-LOX和eLOX 3活性，（2）评估LOX产物和神经酰胺在拯救鼠LOX-/-模型中的表型中的功效，（3）表征人表皮（包括ARCI患者）中的12 R-LOX和eLOX 3活性，（4）对酰基神经酰胺酯水解的氧化敏感步骤进行表征。本研究的结果将拼凑在一起的表皮水屏障的建设的一个重要方面，并允许一个合理的方法来使用氧化亚油酸酯及其类似物的未来治疗性干预的LOX依赖类鱼鳞病。如果屏障的生理学被正确理解，这就构成了任何屏障相关疗法的合理设计的坚实基础，并且使表皮水屏障的这些众所周知的关键组分的作用合理化是本项目的主要目标。

DESCRIPTION (provided by applicant): The long-term objective of this application is to elucidate the roles of two lipoxygenase (LOX) enzymes and their essential fatty acid (EFA) substrate in forming the water impermeable barrier of the epidermis, defects in which result in ichthyoses and contribute to atopic dermatitis. 12R-Lipoxygenase (12R-LOX) and Epidermal Lipoxygenase-3 (eLOX3) are the only human lipoxygenases that, if mutated to inactive forms, result in a disease, a form of autosomal recessive congenital ichthyosis (ARCI). The fact that the characteristic scaly skin of ARCI is also manifest in essential fatty acid (EFA) deficiency, suggests a possible substrate-enzyme relationship between EFA and the two LOX enzymes. We will test a new hypothesis that connects EFA, 12R- LOX and eLOX3, and the structure of the epidermal water barrier. We propose that the two lipoxygenases oxygenate a critical form of EFA, linoleate esterified to the omega-hydroxyl of the very long chain fatty acid of the unique epidermal acylceramides. We further propose that this oxygenation is required to facilitate hydrolysis of the (oxidized) linoleate moiety and leave the very long chain fatty acid omega-hydroxyl free for coupling to the cross-linked proteins of the corneocyte envelope, a vital step in sealing the water barrier. The Specific Aims are (1) To characterize 12R-LOX and eLOX3 activity in the epidermis in vivo using animal models, (2) To assess the efficacy of LOX products and ceramides in rescuing the phenotype in murine LOX-/- models, (3) To characterize 12R-LOX and eLOX3 activity in human epidermis including in ARCI patients, and (4) To characterize the putative oxidant-sensitive step of acylceramide ester hydrolysis. The results of this study wil piece together an important facet of construction of the epidermal water barrier and allow a rational approach to the use of oxidized linoleate and its analogs for future therapeutic interventions in the LOX- dependent classes of ichthyoses. If the physiology of the barrier is properly understood, this constitutes a firm foundation for the rational design of any barrier-related therapeutics, and it is to rationalize the role of these well-known key components of the epidermal water barrier that is the main goal of this project.