A Lipoxygenase Pathway in Epidermal Differentiation

描述（由申请人提供）：脂氧合酶（LOX）家族的酶在炎症中具有明确的作用（5-LOX和白三烯），在细胞分化和增殖中的作用尚未完全确定。最近发现的人类遗传缺陷的两个LOX酶与遗传形式的鱼鳞病提供了一个机会，连接这些酶的功能与表皮分化的作用。遗传学鉴定了12 R-LOX和eLOX 3（表皮脂氧合酶-3）在所研究的家族中有缺陷，并且暗示在所有正常个体中起着关键和重要的作用。我们最近发现了一个合理的遗传生化解释：两个脂氧合酶，12 R-LOX和eLOX 3串联作用，将花生四烯酸转化为特定的环氧醇代谢物。在这里，我们建议调查的LOX途径的作用，追求的总体假设，它有一个重要的功能，在角质形成细胞分化，通过表征底物，中间体和产品的交织LOX活动，以及这些代谢产物的能力，激活或调节角质形成细胞的分化过程。具体目标是： 表征涉及12 R-LOX和eLOX 3的酶学和代谢途径; 通过分析12 R-LOX和eLOX 3在细胞和组织中的表达、活性和定位来确定它们之间的功能关系;确定12 R-LOX/eLOX 3衍生产物的生物活性角质形成细胞不能正确分化是严重皮肤病如银屑病或鱼鳞病的标志。这项研究的结果将有助于表征LOX酶活性在疾病的明确定义的人类背景下控制细胞分化的模型，以及揭示一类新的试剂，环氧醇及其衍生物的活性，具有未来治疗干预的潜力。

DESCRIPTION (provided by applicant): The lipoxygenase (LOX) family of enzymes has well established roles in inflammation (5-LOX and the leukotrienes), and yet-to-be fully defined roles in cell differentiation and proliferation. The recent finding of a human genetic defect in two LOX enzymes associated with an inherited form of ichthyosis presents an opportunity to connect the functioning of these enzymes with a role in epidermal differentiation. The genetics identifies both 12R-LOX and eLOX3 (epidermal lipoxygenase-3) as defective in the families studied, and by implication, as playing a critical and important role in all normal individuals. We recently found a plausible biochemical explanation for the genetics: the two lipoxygenases, 12R-LOX and eLOX3 act in tandem to convert arachidonic acid to a specific epoxyalcohol metabolite. Here we propose to investigate the role of this LOX pathway, pursuing the overall hypothesis that it has a vital function in keratinocyte differentiation, by characterizing substrates, intermediates, and products of the intertwined LOX activities, and the ability of these metabolites to activate or modulate the differentiation process in keratinocytes. The Specific Aims are: To characterize the enzymology and pathways of metabolism involving 12R-LOX and eLOX3; To determine the functional relationships between 12R-LOX and eLOX3 by analyses of their expression, activities and localization in cells and tissues; To determine the biological activities of the 12R-LOX/eLOX3-derived products The failure of keratinocytes to correctly differentiate is a hallmark of severe skin diseases like psoriasis or ichthyosis. The results of this study will help characterize a model for LOX enzyme activity in controlling cell differentiation in a well-defined human context of disease, as well as uncovering the activities of a new class of agents, epoxyalcohols and their derivatives, with the potential for future therapeutic interventions.