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（5-LOX和白三烯）中有很好的作用，但在细胞分化和增殖中的作用尚未完全确定。最近发现的两种与遗传性鱼鳞病相关的LOX酶的人类遗传缺陷，为将这些酶的功能与表皮分化中的作用联系起来提供了机会。遗传学鉴定出12R-LOX和eLOX3（表皮脂氧合酶-3）在研究的家族中都有缺陷，这意味着在所有正常个体中都起着关键和重要的作用。我们最近发现了一种合理的遗传生化解释：两种脂氧合酶，12R-LOX和eLOX3协同作用，将花生四烯酸转化为特定的环氧醇代谢物。在这里，我们建议研究这种LOX通路的作用，通过表征LOX相互交织的底物、中间体和产物，以及这些代谢物激活或调节角化细胞分化过程的能力，追求它在角化细胞分化中具有重要功能的总体假设。具体目标是：

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.