Sykaras Alexandros G, Demenis Claire, Cheng Lei, Pisitkun Trairak, Mclaughlin John T, Fenton Robert A, Smith Craig P
Faculty of Life Sciences (A.G.S., C.D., C.P.S.) and School of Medicine (J.T.M.), The University of Manchester, Manchester, M13 9PT United Kingdom; Department of Biomedicine (L.C., T.P., R.A.F.), InterPrET Center and Membranes, Aarhus University, Aarhus, DK-800 Denmark; Faculty of Medicine (T.P.), Chulalongkorn University, Bangkok, 10330 Thailand; and Graduate Program Molecular Basis of Human Diseases (A.G.S.), University of Crete Medical School, 71003 Iraklion, Crete, Greece.
Endocrinology. 2014 Sep;155(9):3339-51. doi: 10.1210/en.2013-2165. Epub 2014 Jul 8.
Enteroendocrine (EEC) cells have a pivotal role in intestinal nutrient sensing and release hormones that orchestrate food digestion and regulate appetite. EEC cells are found scattered throughout the intestine and have typically been classified based on the primary hormone they contain. I cells represent a subset of EEC cells that secrete cholecystokinin (CCK) and are mainly localized to the duodenum. Recent studies have shown that I cells express mRNAs encoding several gut hormones. In this study, we investigated the hormonal profile of murine fluorescence-activated cell sorting-sorted duodenal I cells using semiquantitative RT-PCR, liquid chromatography tandem mass spectrometry, and immunostaining methods. We report that I cells are enriched in mRNA transcripts encoding CCK and also other key gut hormones, including neurotensin, glucose-dependent insulinotropic peptide (GIP), secretin, peptide YY, proglucagon, and ghrelin (Ghrl). Furthermore, liquid chromatography tandem mass spectrometry analysis of fluorescence-activated cell sorting-purified I cells and immunostaining confirmed the presence of these gut hormones in duodenal I cells. Immunostaining highlighted that subsets of I cells in both crypts and villi coexpress differential amounts of CCK, Ghrl, GIP, or peptide YY, indicating that a proportion of I cells contain several hormones during maturation and when fully differentiated. Our results reveal that although I cells express several key gut hormones, including GIP or proglucagon, and thus have a considerable overlap with classically defined K and L cells, approximately half express Ghrl, suggesting a potentially important subset of duodenal EEC cells that require further consideration.
肠内分泌（EEC）细胞在肠道营养感知中起关键作用，并释放协调食物消化和调节食欲的激素。EEC细胞散布于整个肠道，通常根据其所含的主要激素进行分类。I细胞是EEC细胞的一个亚群，分泌胆囊收缩素（CCK），主要定位于十二指肠。最近的研究表明，I细胞表达编码几种肠道激素的mRNA。在本研究中，我们使用半定量逆转录聚合酶链反应、液相色谱串联质谱和免疫染色方法，研究了小鼠荧光激活细胞分选法分选的十二指肠I细胞的激素谱。我们报告称，I细胞富含编码CCK以及其他关键肠道激素的mRNA转录本，这些激素包括神经降压素、葡萄糖依赖性促胰岛素多肽（GIP）、促胰液素、肽YY、胰高血糖素原和胃饥饿素（Ghrl）。此外，对荧光激活细胞分选法纯化的I细胞进行液相色谱串联质谱分析和免疫染色，证实了十二指肠I细胞中存在这些肠道激素。免疫染色突出显示，隐窝和绒毛中的I细胞亚群共表达不同量的CCK、Ghrl、GIP或肽YY，这表明一部分I细胞在成熟和完全分化时含有多种激素。我们的结果显示，尽管I细胞表达几种关键的肠道激素，包括GIP或胰高血糖素原，因此与经典定义的K细胞和L细胞有相当大的重叠，但约有一半表达Ghrl，这表明十二指肠EEC细胞中存在一个潜在重要的亚群，需要进一步研究。
