Degradation of amylin by insulin-degrading enzyme
Degradation of amylin by insulin-degrading enzyme
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DOI：
10.1074/jbc.m006170200
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发表时间：
2000-11-24
影响因子：
4.8
通讯作者：
Hamel, FG
中科院分区：
文献类型：
--
作者：
Bennett, RG;Duckworth, WC;Hamel, FG
2型糖尿病的一个病理特征是胰岛沉积，主要由胰淀素(胰岛淀粉样多肽)组成。虽然淀粉酶的表达和分泌已经引起了人们的广泛关注，但对淀粉蛋白周转所涉及的酶却知之甚少。最近的报道表明，胰岛素降解酶(IDE)可能对淀粉样蛋白具有特异性，因此我们试图确定胰淀素是否是IDE底物。通过几个层析步骤，与IDE共纯化大鼠肌肉中的淀粉素降解活性。金属蛋白酶抑制剂使淀粉酶降解活性失活，其模式与IDE的酶特性一致，而酸性和丝氨酸蛋白酶、钙蛋白酶和蛋白酶体的抑制剂无效。胰岛素以剂量依赖方式抑制胰淀素的降解，而胰淀素则抑制胰岛素的降解。IDE的其他底物，如心钠素和胰升糖素，也竞争性地抑制淀粉素的降解。放射性标记的胰淀素和胰岛素都与一个110 kDa的蛋白质共价交联，这种结合被未标记的胰岛素或胰淀素竞争性地抑制。最后，一种抗IDE的单抗免疫沉淀了胰岛素和胰淀素的降解活性。这些数据有力地表明，IDE是一种淀粉降解酶，在清除淀粉蛋白和防止胰岛淀粉样蛋白形成方面发挥着重要作用。
A pathological feature of Type 2 diabetes is deposits in the pancreatic islets primarily composed of amylin (islet amyloid polypeptide). Although much attention has been paid to the expression and secretion of amylin, little is known about the enzymes involved in amylin turnover. Recent reports suggest that insulin-degrading enzyme (IDE) may have specificity for amyloidogenic proteins, and therefore we sought to determine whether amylin is an IDE substrate. Amylin-degrading activity co-purified with IDE from rat muscle through several chromatographic steps. Metalloproteinase inhibitors inactivated amylin-degrading activity with a pattern consistent with the enzymatic properties of IDE, whereas inhibitors of acid and serine proteases, calpains, and the proteasome were ineffective. Amylin degradation was inhibited by insulin in a dose-dependent manner, whereas insulin degradation was inhibited by amylin. Other substrates of IDE such as atrial natriuretic peptide and glucagon also competitively inhibited amylin degradation. Radiolabeled amylin and insulin were both covalently cross-linked to a protein of 110 kDa, and the binding was competitively inhibited by either unlabeled insulin or amylin. Finally, a monoclonal anti-IDE antibody immunoprecipitated both insulin- and amylin-degrading activities. The data strongly suggest that IDE is an amylin-degrading enzyme and plays an important role in the clearance of amylin and the prevention of islet amyloid formation.