van Eyll B, Lankat-Buttgereit B, Bode H P, Göke R, Göke B
Clinical Research Unit for Gastrointestinal Endocrinology, Philipps University of Marburg, Germany.
FEBS Lett. 1994 Jul 4;348(1):7-13. doi: 10.1016/0014-5793(94)00553-2.
GLP-1 (glucagon-like peptide 1 (7-36) amide) plays an important role in the regulation of insulin secretion and proinsulin gene expression of pancreatic beta-cells. Patients with insulinoma tumors show uncontrolled insulin hypersecretion. This study demonstrates the molecular cloning of a cDNA for the GLP-1 receptor from a human insulinoma employing a lambda-gt11 cDNA library. The cloned cDNA encoded a seven transmembrane domain protein of 463 amino acids which showed high homology to the GLP-1 receptor in normal human pancreas. Four amino acid exchanges were found in comparison to a receptor sequence obtained from regular pancreatic islets. When transfected transiently into COS-7 or stably into fibroblast CHL cells a high affinity receptor was expressed which coupled to the adenylate cyclase with normal basal cAMP and increasing intracellular cAMP levels under GLP-1 stimulation. The receptor accepted GLP-1 and the non-mammalian agonist exendin-4 as high affinity ligands. In transfected COS-7 cells, GLP-1 did not influence intracellular calcium, whereas in the stably transfected fibroblasts GLP-1 transiently increased intracellular calcium to a small extent. The understanding of GLP-1 receptor regulation and signal transduction will aid in the discovery of compounds that act as agonists of the GLP-1 receptor for potential use in the treatment of diabetes and will facilitate the understanding of its expression under normal and pathophysiological conditions.
胰高血糖素样肽-1（GLP-1，即胰高血糖素样肽1(7 - 36)酰胺）在调节胰岛素分泌及胰岛β细胞胰岛素原基因表达方面发挥着重要作用。胰岛素瘤患者表现出不受控制的胰岛素分泌过多。本研究利用λ - gt11 cDNA文库从人胰岛素瘤中克隆了GLP-1受体的cDNA。克隆得到的cDNA编码一个由463个氨基酸组成的七跨膜结构域蛋白，该蛋白与正常人类胰腺中的GLP-1受体具有高度同源性。与从正常胰岛获得的受体序列相比，发现了四个氨基酸置换。当将其瞬时转染到COS-7细胞或稳定转染到成纤维细胞CHL中时，会表达出一种高亲和力受体，该受体在基础cAMP正常的情况下与腺苷酸环化酶偶联，并在GLP-1刺激下使细胞内cAMP水平升高。该受体可接受GLP-1和非哺乳动物激动剂艾塞那肽-4作为高亲和力配体。在转染的COS-7细胞中，GLP-1不影响细胞内钙，而在稳定转染的成纤维细胞中，GLP-1会使细胞内钙短暂小幅升高。对GLP-1受体调节和信号转导的理解将有助于发现作为GLP-1受体激动剂的化合物，这些化合物可能用于治疗糖尿病，并有助于理解其在正常和病理生理条件下的表达。
