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

摘要 胰岛β细胞功能和/或质量缺陷是糖耐量受损向 弗兰克糖尿病既有1型糖尿病，也有2型糖尿病。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类炎症的酶 β细胞中的介质。12-LOX活性的二十烷类产物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，脂氧合酶生物学中的一个挑战是 人和小鼠在β细胞中表达不同的12-LOX亚型(由Alox12和Alox15编码， 分别)，每种异构体显示不同的活性中心特征。此应用程序的强大之处在于 多PI博士R.Mirmira(胰岛炎症途径方面的专家)和R. Kulkarni(胰岛生长因子信号转导专家)和合作调查员J.Nadler(二十烷类化合物专家 生物学)，他们将集体带来他们的专业知识和独特的试剂-包括基因敲除和人类基因 显示人类异构体激活、人类12-LOX选择性抑制物和主要 人体细胞--研究12-LOX及其炎症产物的生物学。我们假设在 胰岛素抵抗β细胞中12-LOX的激活通过受体介导促进β细胞功能障碍 通过其下游产品12-HETE发出信号。为了验证这一假设，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-脂氧合酶活性和 细胞功能障碍。 目的2：确定12-LOX活性在胰岛素环境下β细胞功能障碍中的作用 体内抗药性。 目的3：确定12-HETE受体GPR31在介导下游β细胞功能障碍中的作用 12-LOX。 到目前为止，还没有工具和试剂来询问人类12-LOX和12-HETE的生物学。这个 这项提议的主要影响将是为预期的治疗靶向奠定基础 人类12-LOX通路在胰岛素抵抗/β细胞功能障碍中的作用，并在12-LOX通路中寻找潜在的新靶点。 HETE G蛋白偶联受体GPR31。

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.