Role of 12-lipoxygenase and 12-HETE signaling in beta-cell dysfunction

摘要 胰岛β细胞功能和/或质量的缺陷是从糖耐量受损向糖耐量异常转变的核心。 1型糖尿病和2型糖尿病的发病原因脂氧合酶（LOX）代表一个家族 催化细胞多不饱和脂肪酸氧化形成脂质炎症的酶 β细胞中的介质。12-LOX活性的类二十烷酸产物，12-羟基二十碳四烯酸（12-HETE）， 在β细胞内施加炎症和氧化应激。然而，脂氧合酶生物学的一个挑战是， 人和小鼠在β细胞中表达不同的12-LOX同种型（由ALOX 12和Alox 15编码， 分别），每种同种型表现出不同的活性位点特征。该应用程序的优势在于 多PI博士之间的合作努力。Mirmira（胰岛炎症通路专家）和R。 Kulkarni（胰岛生长因子信号传导专家）和共同研究者J. Nadler（类花生酸专家 生物学），他们将共同带来他们的专业知识和独特的试剂-包括敲除和人类基因 显示人同种型活化、人12-LOX选择性抑制剂和原发性 人细胞-与12-LOX及其炎症产物的生物学有关。我们假设， 胰岛素抵抗β细胞中12-LOX的活化通过受体介导的胰岛素抵抗促进β细胞功能障碍。 通过其下游产物12-HETE进行信号传导。为了检验这一假设，我们提出了以下具体目标： 目的1：阐明β细胞胰岛素抵抗与12-LOX活性的关系， 细胞功能障碍 目的2：确定在胰岛素环境中12-LOX活性对β细胞功能障碍的贡献 体内抗性。 目的3：确定12-HETE受体GPR 31在介导β细胞功能障碍下游的作用 12-LOX 到目前为止，还没有研究人类12-LOX和12-HETE生物学的工具和试剂。的 该提案的主要影响将是为治疗靶向的预期奠定基础。 人12-LOX途径在胰岛素抵抗/β细胞功能障碍中的作用，并确定12-LOX途径中潜在的新靶点。 HETE G蛋白偶联受体GPR 31。

Abstract Deficiencies in islet β-cell function and/or mass are central in the transition from impaired glucose tolerance to frank diabetes in the setting of both type 1 and type 2 diabetes. The lipoxygenases (LOXs) represent a family of enzymes that catalyzes the oxygenation of cellular poly-unsaturated fatty acids to form lipid inflammatory mediators in β-cells. The eicosanoid product of 12-LOX activity, 12-hydoxyeicosatetraenoic acid (12-HETE), imposes inflammatory and oxidative stress within β cells. A challenge in lipoxygenase biology, however, is that humans and mice express different isoforms of 12-LOX in β cells (encoded by ALOX12 and Alox15, respectively), with each isoform exhibiting different active-site characteristics. The strength of this application is the collaborative effort between Multi-PIs Drs. R. Mirmira (an expert in islet inflammation pathways) and R. Kulkarni (an expert in growth factor signaling in the islet), and coinvestigator J. Nadler (an expert in eicosanoid biology), who will collectively bring their expertise and unique reagents—including knockout and human gene knock-in mouse models that show human isoform activation, human 12-LOX-selective inhibitors, and primary human cells—to bear on the biology of 12-LOX and its inflammatory products. We hypothesize that during insulin resistance the activation of 12-LOX in β-cells promotes β cell dysfunction through receptor-mediated signaling by its downstream product 12-HETE. To test this hypothesis, we propose the following specific aims: Aim 1: Elucidate the molecular mechanisms linking β-cell insulin resistance to 12-LOX activity and cellular dysfunction. Aim 2: Determine the contribution of 12-LOX activity to β cell dysfunction in the setting of insulin resistance in vivo. Aim 3: Determine the role of the 12-HETE receptor GPR31 in mediating β-cell dysfunction downstream of 12-LOX. Until now, tools and reagents to interrogate the biology of human 12-LOX and 12-HETE did not exist. The primary impact of this proposal will be to set the stage for the expectations of therapeutically targeting the human 12-LOX pathway in insulin resistance/β-cell dysfunction, and to identify a potential new target in the 12- HETE G protein-coupled receptor GPR31.