Novo Nordisk Foundation Center for Basic Metabolic Research, Section for Metabolic Receptology and Enteroendocrinology, Faculty of Health Sciences, University of Copenhagen, 2200 Denmark.
Endocrinology. 2012 Dec;153(12):5782-95. doi: 10.1210/en.2012-1595. Epub 2012 Oct 12.
Enteroendocrine cells such as duodenal cholecystokinin (CCK cells) are generally thought to be confined to certain segments of the gastrointestinal (GI) tract and to store and release peptides derived from only a single peptide precursor. In the current study, however, transgenic mice expressing enhanced green fluorescent protein (eGFP) under the control of the CCK promoter demonstrated a distribution pattern of CCK-eGFP positive cells that extended throughout the intestine. Quantitative PCR and liquid chromatography-mass spectrometry proteomic analyses of isolated, FACS-purified CCK-eGFP-positive cells demonstrated expression of not only CCK but also glucagon-like peptide 1 (GLP-1), gastric inhibitory peptide (GIP), peptide YY (PYY), neurotensin, and secretin, but not somatostatin. Immunohistochemistry confirmed this expression pattern. The broad coexpression phenomenon was observed both in crypts and villi as demonstrated by immunohistochemistry and FACS analysis of separated cell populations. Single-cell quantitative PCR indicated that approximately half of the duodenal CCK-eGFP cells express one peptide precursor in addition to CCK, whereas an additional smaller fraction expresses two peptide precursors in addition to CCK. The coexpression pattern was further confirmed through a cell ablation study based on expression of the human diphtheria toxin receptor under the control of the proglucagon promoter, in which activation of the receptor resulted in a marked reduction not only in GLP-1 cells, but also PYY, neurotensin, GIP, CCK, and secretin cells, whereas somatostatin cells were spared. Key elements of the coexpression pattern were confirmed by immunohistochemical double staining in human small intestine. It is concluded that a lineage of mature enteroendocrine cells have the ability to coexpress members of a group of functionally related peptides: CCK, secretin, GIP, GLP-1, PYY, and neurotensin, suggesting a potential therapeutic target for the treatment and prevention of diabetes and obesity.
肠内分泌细胞，如十二指肠胆囊收缩素（CCK）细胞，通常被认为局限于胃肠道（GI）的某些节段，并且仅存储和释放来自单个肽前体的肽。然而，在当前的研究中，表达增强型绿色荧光蛋白（eGFP）的转基因小鼠在 CCK 启动子的控制下表现出 CCK-eGFP 阳性细胞的分布模式，该模式延伸到整个肠道。对分离的、FACS 纯化的 CCK-eGFP 阳性细胞进行定量 PCR 和液相色谱-质谱蛋白质组学分析表明，不仅表达 CCK，还表达胰高血糖素样肽 1（GLP-1）、胃抑制肽（GIP）、肽 YY（PYY）、神经降压素和分泌素，但不表达生长抑素。免疫组织化学证实了这种表达模式。免疫组织化学和分离细胞群体的 FACS 分析均证实，这种广泛的共表达现象既存在于隐窝中，也存在于绒毛中。单细胞定量 PCR 表明，大约一半的十二指肠 CCK-eGFP 细胞除了 CCK 之外还表达一种肽前体，而另外一小部分细胞除了 CCK 之外还表达两种肽前体。通过基于前胰高血糖素启动子表达人白喉毒素受体的细胞消融研究进一步证实了这种共表达模式，其中受体的激活不仅导致 GLP-1 细胞，而且还导致 PYY、神经降压素、GIP、CCK 和分泌素细胞显著减少，而生长抑素细胞则幸免。免疫组织化学双重染色在人小肠中证实了共表达模式的关键要素。结论是，成熟肠内分泌细胞的谱系具有共表达一组功能相关肽的成员的能力：CCK、分泌素、GIP、GLP-1、PYY 和神经降压素，这表明治疗和预防糖尿病和肥胖症的潜在治疗靶点。
