Impact of Neprilysin on Islet Function

脑啡肽酶对胰岛功能的影响

基本信息

批准号：
8883516
负责人：
Sakeneh Zraika
金额：
$ 29.36万
依托单位：
SEATTLE INST FOR BIOMEDICAL/CLINICAL RES
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-09-01 至 2016-06-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8883516
关键词：
Ablation Address Binding Biological Preservation Blood Circulation C-terminal Calcium Capsaicin Cell Culture Techniques Cell membrane Cell physiology Cells Cleaved cell Data Deafferentation procedure Diabetes Mellitus Diet Dietary Fats Dipeptidyl Peptidases Dose Exposure to Failure Fatty acid glycerol esters Functional disorder Gastric Inhibitory Polypeptide Genetic Glucagon Glucose Half-Life Health Hepatic Human Hyperglycemia Hyperlipidemia In Vitro Insulin Insulin Resistance Intestines Islet Cell L Cells Link Maintenance Measures Mediating Modeling Mus Neprilysin Neurons Non-Insulin-Dependent Diabetes Mellitus Normal Cell Oral Oral Administration Palmitates Pancreas Peptide Hydrolases Peptides Peripheral Production Relative (related person)Role Signal Transduction Site Somatostatin Streptozocin Testing Therapeutic Transplantation Vagotomy Wit blood glucose regulation comparative efficacy diabetic feeding genetic approach glucagon-like peptide glucagon-like peptide 1 glucose tolerance improved in vivo in vivo Model inhibitor/antagonist insulin secretion islet neuromechanism neurotransmission novel overexpression paracrine receptor receptor binding research study response therapeutic development villin

项目摘要

DESCRIPTION (provided by applicant): Type 2 diabetes is characterized by islet �-cell failure, contributed to by hyperglycemia and hyperlipidemia. Neprilysin (NEP) is a widely expressed plasma membrane peptidase that we have shown is increased in islets with prolonged exposure to elevated glucose and fat. Like dipeptidyl peptidase-4 (DPP-4), NEP can degrade and inactivate glucagon-like peptide-1 (GLP-1), a glucose-dependent insulinotropic peptide secreted by intestinal L cells and islet ? cells. Our preliminary data show that under conditions of increased dietary fat, NEP ablation in mice enhances active GLP-1 levels thereby contributing to increased glucose-stimulated insulin secretion (GSIS) and improved glucose tolerance. Thus in this proposal, we will test the hypothesis that increased NEP activity limits the beneficial effect of GLP-1 on insulin secretion and glucose homeostasis. To address this hypothesis, the following specific aims have been identified: 1) To determine the contribution of islet NEP to reduced GSIS via its ability to degrade active GLP-1. First, an in vitro culture model will be utilized to measure active GLP-1 levels in human and mouse islets cultured with or without palmitate or high glucose to determine whether GLP-1 levels are reduced in conditions associated with increased NEP activity. Islets with pharmacological inhibition or genetic ablation of NEP will be used for comparison. Second, an in vivo model will be utilized in which wild-type or NEP-/- islets will be transplanted into streptozocin-diabetic wild-type or NEP-/- syngeneic recipients to evaluate the contribution of islet NEP to the maintenance of active GLP-1 levels and normal �-cell function following transplantation. 2) To determine the contribution of intestinal NEP to reduced GSIS via its ability to degrade active GLP- 1. GLP-1 released from L cells facilitates GSIS directly via the systemic circulation and indirectly via neural signals from vagal afferents. We will assess whether selective reduction of NEP activity in mouse intestine using pharmacologic and genetic (NEPflox ? Villin-Cre) approaches increases portal and peripheral active GLP- 1 levels and thereby enhances GSIS. The contribution of neural signaling to enhanced GSIS will be determined using selective hepatic vagotomies or capsaicin to block activation of pancreatic vagal efferents. 3) To compare the efficacy of NEP versus DPP-4 inhibition in enhancing active GLP-1 levels and improving fat-induced insulin secretory dysfunction in vivo. NEP, DPP-4 or both will be pharmacologically inhibited in wild-type control mice fed a low or high fat diet for 18 weeks. Active GLP-1 levels and GSIS will be measured to determine the relative contributions of each peptidase to preservation of �-cell function in mice fed a high fat diet. Dual peptidase inhibition will test whether any beneficial effect observed wit NEP inhibition can be augmented with concurrent DPP-4 inhibition. These studies will delineate a novel role for islet and intestinal NEP in modulating �-cell function, and will have significant implications for development of therapeutics to treat �-cell dysfunction in diabetes.

描述（由申请人提供）：2 型糖尿病的特点是胰岛β细胞衰竭，由高血糖和高脂血症引起，脑啡肽酶 (NEP) 是一种广泛表达的质膜肽酶，我们已经证明，随着长期暴露于升高的胰岛中，该酶会增加。与二肽基肽酶 4 (DPP-4) 一样，NEP 可以降解并灭活胰高血糖素样肽-1。 (GLP-1)，一种由肠道 L 细胞和胰岛细胞分泌的葡萄糖依赖性促胰岛素肽，我们的初步数据表明，在饮食脂肪增加的条件下，小鼠体内的 NEP 消除会增强活性 GLP-1 水平，从而导致葡萄糖-1 水平增加。因此，在本提案中，我们将测试 NEP 活性增加限制 GLP-1 对胰岛素分泌和葡萄糖稳态的有益作用的假设。已确定具体目标： 1) 确定胰岛 NEP 通过其降解活性 GLP-1 的能力对减少 GSIS 的贡献首先，将利用体外培养模型来测量人和小鼠胰岛中的活性 GLP-1 水平。在有或没有棕榈酸盐或高葡萄糖的情况下培养，以确定在与 NEP 活性增加相关的条件下 GLP-1 水平是否降低，将使用具有 NEP 药物抑制或遗传消除的胰岛进行比较。哪些野生型或 NEP-/- 胰岛将被移植到链脲佐菌素糖尿病野生型或 NEP-/- 同基因受体中，以评估胰岛 NEP 对维持活性 GLP-1 水平和正常 β-细胞功能的贡献2) 确定肠道 NEP 通过其降解活性 GLP-1 的能力对减少 GSIS 的贡献。L 细胞释放的 GLP-1 直接通过体循环促进 GSIS，并通过神经间接促进 GSIS信号来自我们将评估使用药理学和遗传 (NEPflox? Villin-Cre) 方法选择性降低小鼠肠道中的 NEP 活性是否会增加门静脉和外周活性 GLP-1 水平，从而增强 GSIS 神经信号传导对增强 GSIS 的贡献。使用选择性肝迷走神经切断术或辣椒素阻断胰腺迷走神经传出神经的激活来确定 3) 比较 NEP 与 DPP-4 抑制的功效。在喂食低脂肪或高脂肪饮食 18 周的野生型对照小鼠中，增强活性 GLP-1 水平并改善脂肪诱导的体内胰岛素分泌功能障碍将受到药理学抑制。将测量 GSIS，以确定每种肽酶对高脂肪饮食小鼠的 β 细胞功能保存的相对贡献，将测试双肽酶抑制是否可以通过同时进行 NEP 抑制来增强观察到的任何有益效果。 DPP-4 抑制。这些研究将阐明胰岛和肠道 NEP 在调节 β 细胞功能中的新作用，并将对治疗糖尿病 β 细胞功能障碍的疗法的开发产生重大影响。