Role of perlecan in islet amyloid formation

描述(由申请人提供)： 大约90%的2型糖尿病受试者胰岛淀粉样蛋白沉积，并导致胰岛β细胞质量和功能的进行性丧失，这是该病的特征。了解胰岛淀粉样蛋白沉积背后的机制(S)将有助于开发防止其形成和由此导致的β细胞丢失和功能障碍的方法。胰岛淀粉样蛋白由胰岛淀粉样多肽(IAPP，Amylin)和硫酸乙酰肝素蛋白多糖组成。Perlecan可能通过其硫酸乙酰肝素糖胺聚糖(HS GAG)侧链结合致淀粉样人IAPP(HIAPP)来刺激胰岛淀粉样蛋白的形成。我们最近发现，胰岛β细胞表达Perlecan，并且β细胞Perlecan通过其HS Gag链与hIAPP结合。我们还表明，从表达缺乏HS Gag链的Perlecan的小鼠分离的胰岛，在体外显示出显著的胰岛淀粉样沉积。因此，我们假设Perlecan HS GAG对胰岛淀粉样蛋白沉积及其导致β细胞丢失和功能障碍的作用至关重要。将进行以下研究，以确定是否： 1.体外和体内胰岛淀粉样蛋白的形成需要Perlecan HS GAG。表达突变形式的Perlecan的小鼠将与我们的hIAPP转基因小鼠胰岛淀粉样蛋白形成模型杂交。我们预计，突变Perlecan的表达将减少胰岛淀粉样蛋白的形成，并在培养7天的孤立胰岛和喂养12个月高脂饮食的小鼠中改善胰岛素释放和β细胞体积。 2.淀粉样蛋白对移植后胰岛移植物失败的影响需要Perlecan HS GAG。上述小鼠将被用作胰岛移植的供体和受体。我们先前已经证明，移植hIAPP转基因胰岛会导致胰岛淀粉样蛋白的形成，高血糖的复发和移植胰岛移植物中的β细胞体积减少。我们期望突变型Perlecan的表达将阻止胰岛淀粉样蛋白的形成，并提高胰岛移植物的存活率。 3.Perlecan HS GAG促进淀粉样蛋白形成的机制。我们将鉴定β细胞Perlecan的HS GAG组成，以及它在体外结合hIAPP和刺激hIAPP纤维形成的能力。这项申请的成功资助将为我提供工资和受保护的研究时间，以实现我成为2型糖尿病领域的独立研究员的职业目标。

DESCRIPTION (provided by applicant): Islet amyloid deposition occurs in approximately approximately 90% of subjects with type 2 diabetes and contributes to the progressive loss of islet beta-cell mass and function that characterize the disease. Understanding the mechanism(s) that underlie islet amyloid deposition will allow the development of approaches to prevent its formation and the resulting beta-cell loss and dysfunction. Islet amyloid comprises the beta-cell peptide islet amyloid polypeptide (IAPP, amylin) and the heparan sulfate proteoglycan perlecan. Perlecan may stimulate islet amyloid formation by binding amyloidogenic human IAPP (hIAPP) through its heparan sulfate glycosaminoglycan (HS GAG) side chains. We have recently shown that islet beta-cells express perlecan and that beta-cell perlecan binds hIAPP through its HS GAG chains. We have also shown that isolated islets, from mice expressing perlecan that lacks HS GAG chains, show a marked reduction in islet amyloid deposition in vitro. Thus, we hypothesize that perlecan HS GAGs are critical for islet amyloid deposition and its effects to cause beta-cell loss and dysfunction. The following studies will be performed to determine whether: 1. Perlecan HS GAGs are required for islet amyloid formation in vitro and in vivo. Mice expressing a mutant form of perlecan will be cross-bred with our hIAPP transgenic mouse model of islet amyloid formation. We expect expression of mutant perlecan to reduce islet amyloid formation and improve both insulin release and beta-cell volume in isolated islets cultured for seven days and in mice fed a high fat diet for 12 months. 2. Perlecan HS GAGs are required for the effect of amyloid to cause islet graft failure following transplantation. The mice described above will be used here as islet transplant donors and recipients. We have previously shown that transplantation of hIAPP transgenic islets results in islet amyloid formation, recurrence of hyperglycemia and reduced beta-cell volume in the transplanted islet graft. We expect that expression of mutant perlecan will prevent islet amyloid formation and improve islet graft survival. 3. The mechanism by which perlecan HS GAGs enhance amyloid formation. We will characterize the HS GAG composition of beta-cell perlecan and its ability to bind hIAPP and stimulate hIAPP fibril formation in vitro. Successful funding of this application will provide me with salary and protected research time in order to achieve my career goal of becoming an independent investigator in the field of type 2 diabetes.