GPR40, a free fatty acid receptor on pancreatic β cells, regulates insulin secretion
GPR40, a free fatty acid receptor on pancreatic β cells, regulates insulin secretion
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DOI：
10.1016/j.hepres.2005.09.028
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发表时间：
2005-10-01
影响因子：
4.2
通讯作者：
Hinuma, S
中科院分区：
文献类型：
--
作者：
Itoh, Y;Hinuma, S
GPR40最初是通过简并聚合酶链式反应从人基因组DNA中分离出来的。我们从不同物种中分离了GPR40cDNAs，并对其在大鼠组织中的表达进行了精确的分析，发现GPR40在大鼠胰岛的P细胞中高表达。与已知主要在胰岛β细胞表达的细胞表面受体(即舞蹈性激动素受体、胰高血糖素样肽-1受体和磺脲类受体)相比，GPR40的mRNA表达水平与这些受体相当。此外，我们检测的所有胰腺β细胞系都在显著水平上表达GPR40mRNA。在小鼠β细胞系MIN6中检测到其最高表达。为了揭示GPR40的功能，我们通过筛选1500多个化合物来寻找GPR40的配体。结果我们发现，表达GPR40的CHO细胞对游离脂肪酸(FFAs)有特异性的反应，即在这些细胞中检测到细胞内钙的升高。在所测试的脂肪酸中，在C12到16长度的饱和脂肪酸(例如月桂酸、肉豆蔻酸和棕榈酸)以及C18和C22长度的不饱和脂肪酸(例如油酸、榄香酸、亚油酸、a-亚麻酸、g-亚麻酸、花生四烯酸、二十碳五烯酸和二十二碳六烯酸)中都检测到了明显的刺激活性。我们发现在表达GPR40的CHO细胞中，游离脂肪酸诱导钙内流并激活MAPK。众所周知，细胞内钙离子的增加促进了胰岛素的分泌，我们预计通过GPR40刺激游离脂肪酸可以促进胰岛β细胞的胰岛素分泌。正如我们预期的那样，游离脂肪酸诱导了MIN6细胞葡萄糖刺激的胰岛素分泌(GSIS)。我们的结果表明，GPR40是FFAs的细胞表面受体，并调节胰岛β细胞的胰岛素分泌。众所周知，游离脂肪酸不仅作为身体营养物质提供重要的能量来源，而且在包括胰岛素分泌在内的各种细胞过程中扮演信号分子的角色。然而，胰岛素分泌和游离脂肪酸之间的关系背后的分子机制却知之甚少。我们相信，细胞表面FFA受体油胰腺β细胞的发现将为解决FFA与胰岛素分泌的关系提供线索，从而最终导致抗糖尿病药物的开发。(C)2005爱思唯尔爱尔兰有限公司。保留所有权利。
GPR40 was originally isolated from human genomic DNA by degenerate PCR. We isolated GPR40 cDNAs from various species, and precisely analyzed its mRNA expression in rat tissues, and found that GPR40 was highly expressed in P cells in the islets of rat pancreas. When compared to the cell-surface receptors (i.e., choresistokinin receptor, glucagon-like peptide-1 receptor, and sulfonylurea receptor) that are known to predominantly express in the pancreatic beta cells, GPR40 mRNA was comparable to these receptors in mRNA expression levels. In addition, all of pancreatic beta cell lines, which we examined, expressed GPR40 mRNA at significant levels. Its highest expression was detected in a mouse beta cell line MIN6. To reveal the function of GPR40, we searched for the ligands of GPR40 by screening more than 1500 compounds. As a result we found that CHO cells expressing GPR40 specifically responded to free fatty acids (FFAs), that is, elevation of intracellular Ca2+ was detected in these cells. Among FFAs tested, apparent stimulatory activities were detected in C12- to 16-length saturated FFAs (e.g., lauric acid, myristic acid, and palmitic acid) and in both C18- and C22-length unsaturated FFAs (e.g., oleic acid, elaidic acid, linoleic acid, a-linolenic acid, g-linolenic acid, arachidonic acid, eicosapetitaelloic acid, and docosahexaenoic acid) at EC50 of micro molar range. We found that FFAs induced Ca2+ influx and activated MAP kinase in CHO cells expressing GPR40. As it is known that the increase of intracellular Ca2+ promotes insulin secretion, we expected the stimulation of FFAs through GPR40 would promote insulin secretion from pancreatic beta cells. As we expected, FFAs induced glucose-stimulated insulin secretion (GSIS) in MIN6 cells. Our results indicate that GPR40 is a cell-surface receptor for FFAs and regulates insulin Secretion from pancreatic beta cells. FFAs are known not only to provide an important energy source as nutrients for the body but also to act as signaling molecules in various cellular processes including insulin secretion. However, the molecular mechanism behind the relationship between insulin secretion and FFAs is little understood. We believe that the discovery of a cell-surface FFA receptor oil pancreatic beta cells will provide a Clue to resolve the relation between FFAs and insulin secretion, and thus eventually lead to the development of anti-diabetic drugs. (c) 2005 Elsevier Ireland Ltd. All rights reserved.