Cao Yang, Cao Xun, Liu Xiao-Min
Department of Endocrinology, First Affiliated Hospital of Harbin Medical University, Harbin 150001, Heilongjiang Province, China.
Department of Endocrinology, First Affiliated Hospital of Harbin Medical University, Harbin 150001, Heilongjiang Province, China.
Acta Histochem. 2015 Mar;117(2):205-10. doi: 10.1016/j.acthis.2014.12.007. Epub 2015 Jan 15.
Gastrin is a gastrointestinal hormone secreted by G cells. Hypergastrinemia can improve blood glucose and glycosylated hemoglobin levels. These positive effects are primarily due to the trophic effects of gastrin on β-cells. In recent years, many receptors that regulate secretion of glucagon-like peptide 1 (GLP-1) have been identified in enteroendocrine L cell lines. This led us to hypothesize that, in addition to the trophic effects of gastrin on β-cells, L cells also express cholecystokinin2-receptor (CCK2R), which may regulate GLP-1 secretion and have synergistic effects on glucose homeostasis. Our research provides a preliminary analysis of CCK2R expression and the stimulating effect of gastrin treatment on GLP-1 secretion in a human endocrine L cell line, using RT-PCR, Western blot, immunocytochemistry, and ELISA analyses. The expression of proglucagon and prohormone convertase 3, which regulate GLP-1 biosynthesis, were also analyzed by real-time PCR. Double immunofluorescence labeling was utilized to assess the intracellular localization of CCK2R and GLP-1 in L cells harvested from rat colon tissue. Our results showed that CCK2R was expressed in both the human L cell line and the rat L cells. We also showed that treatment with gastrin, a CCK2R agonist, stimulated the secretion of GLP-1, and that this effect was likely due to increased expression of proglucagon and PCSK1 (also known as prohormone convertase 3 (PC3 gene)). These results not only provide a basis for the role gastrin may play in intestinal L cells, and may also provide the basis for the development of a method of gastrin-mediated glycemic regulation.
胃泌素是一种由G细胞分泌的胃肠激素。高胃泌素血症可改善血糖和糖化血红蛋白水平。这些积极作用主要归因于胃泌素对β细胞的营养作用。近年来，在肠内分泌L细胞系中已鉴定出许多调节胰高血糖素样肽1（GLP-1）分泌的受体。这使我们推测，除了胃泌素对β细胞的营养作用外，L细胞还表达胆囊收缩素2受体（CCK2R），其可能调节GLP-1分泌并对葡萄糖稳态产生协同作用。我们的研究使用逆转录聚合酶链反应（RT-PCR）、蛋白质免疫印迹法、免疫细胞化学和酶联免疫吸附测定（ELISA）分析，对人内分泌L细胞系中CCK2R的表达以及胃泌素处理对GLP-1分泌的刺激作用进行了初步分析。还通过实时聚合酶链反应分析了调节GLP-1生物合成的胰高血糖素原和激素原转化酶3的表达。利用双重免疫荧光标记评估从大鼠结肠组织收获的L细胞中CCK2R和GLP-1的细胞内定位。我们的结果表明，CCK2R在人L细胞系和大鼠L细胞中均有表达。我们还表明，用CCK2R激动剂胃泌素处理可刺激GLP-1的分泌，并且这种作用可能是由于胰高血糖素原和PCSK1（也称为激素原转化酶3（PC3基因））表达增加所致。这些结果不仅为胃泌素在肠道L细胞中可能发挥的作用提供了依据，也可能为开发胃泌素介导的血糖调节方法提供依据。
