The role of neprilysin in pancreatic beta-cell dysfunction and death

胰岛β细胞衰竭是2型糖尿病发展的核心，并由两者共同促成。 高血糖和高脂血症。肾素-血管紧张素系统的一种成分--Neprilysin (RAS)，已被证明在非胰岛组织中随着慢性血糖和脂肪的升高而上调 在2型糖尿病中出现的水平。虽然还没有研究neprilysin在胰岛中的作用，但我们已经 数据表明，它在胰岛合成并活跃，可能在β细胞功能的调节中发挥作用 对胰岛应激源的反应。因此，这项建议的总体目标是阐明neprilysin在 与β细胞功能受损相关的条件，即脂肪和葡萄糖增加。我们假设 在脂肪和葡萄糖长期升高的状态下，neprilysin的活性被上调，从而促进 β细胞功能障碍。 在该奖项的K99阶段，进行了研究以确定neprilysin对 由慢性脂肪升高引起的胰岛素分泌受损。我们的发现表明奈普利辛是 确实，在慢性脂肪升高的情况下上调，这与葡萄糖估测的降低有关 胰岛素的体外分泌。此外，喂食高脂饮食的NEP-KO小鼠 防止高脂饮食导致体内葡萄糖刺激的胰岛素分泌减少。 在该奖项的Roo阶段，将进行以下研究以确定： 1)neprilysin在慢性高血糖所致的胰岛素分泌障碍中的作用。我们的 初步数据表明，在高糖条件下，neprilysin也可能上调，从而 可能参与氧化应激的诱导。首先，NEP-KO小鼠将接受48小时的葡萄糖输注 诱导高血糖，然后胰岛素分泌将！在活体内进行测量。其次，从海岛中分离出胰岛 小鼠将在高糖环境中培养，胰岛素分泌将在体外进行检测。 2)RAS在慢性高脂高糖状态下调节Neprilysin效应中的作用 条件。由于neprilysin是RAS的一个组成部分，分离的胰岛将被用来确定 Neprilysin在这一途径中的活动是导致β细胞功能受损的原因。

Islet beta-cell failure is central to the development of type 2 diabetes and is contributed to by both hyperglycemia and hyperlipidemia. The protein neprilysin, a component ofthe renin-angiotensin system (RAS), has been shown in non-islet tissues to be upregulated with the chronically elevated glucose and fat levels seen in type 2 diabetes. While the function of neprilysin in islets has not been investigated, we have data that show it is synthesized and active in islets and may play a role in the modulation of beta-cell function in response to islet stressors. Thus, the overall aim of this proposal is to elucidate the role of neprilysin under conditions associated with impaired beta-cell function, namely increased fat and glucose. We hypothesize that in states of chronically elevated fat and glucose, neprilysin activity is upregulated thereby promoting beta-cell dysfunction. During the K99 phase of this award, studies were conducted to determine the contribution of neprilysin to impaired insulin secretion induced by chronically elevated fat. Our findings demonstrate that neprilysin is indeed upregulated under conditions of chronically elevated fat and this is associated with reduced glucosestimulated insulin secretion in vitro. Moreover, neprilysin deficient (NEP-KO) mice fed a high fat diet are protected from high fat diet-induced reductions in glucose-stimulated insulin secretion in vivo. During the ROO phase of this award, the following studies will be performed to determine: 1) The role of neprilysin in the impairment Of insulin secretion induced by chronically elevated glucose. Our preliminary data suggest that neprilysin may also be upregulated under high glucose conditions and thereby may mediate the induction of oxidative stress. Firstly, NEP-KO mice will receive a 48-hour glucose infusion to induce hyperglycemia, then insulin secretion wil! be measured in vivo. Secondly, isolated islets from NEPKO mice will be cultured in high glucose and insulin secretion will be examined in vitro. 2) The role ofthe RAS in mediating neprilysin's effects under chronically elevated fat and glucose conditions. Since neprilysin is a component of the RAS, isolated islets will be used to determine whether neprilysin's activity in this pathway is responsible for impaired beta-cell function.