Analysis of upstream glucokinase promoter activity in transgenic mice and identification of glucokinase in rare neuroendocrine cells in the brain and gut.
Analysis of upstream glucokinase promoter activity in transgenic mice and identification of glucokinase in rare neuroendocrine cells in the brain and gut.
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DOI：
10.1016/s0021-9258(17)41910-7
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发表时间：
1994-02
期刊：
影响因子：
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通讯作者：
T. Jetton;Yin Liang;C. C. Pettepher-C.;Elisabeth C Zimmerman;F. Cox;K. Horváth;F. Matschinsky;M. Mag
中科院分区：
文献类型：
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作者：
T. Jetton;Yin Liang;C. C. Pettepher-C.;Elisabeth C Zimmerman;F. Cox;K. Horváth;F. Matschinsky;M. Mag
由连接到人生长激素基因的编码序列的上游葡糖激酶（GK）启动子片段组成的转基因在小鼠的胰腺、垂体、脑、肠、甲状腺和肺的某些神经内分泌细胞中表达。在胰腺中，转基因在β细胞中以不均匀的方式表达，并且在其他胰岛细胞类型的可变但相当大的部分中表达。在垂体中，它在促皮质激素中表达，在脑中，它在内侧下丘脑的细胞中表达。在肠道内，在胃和十二指肠上皮的肠内分泌细胞亚群中检测到转基因表达，其中一些也表现出胰高血糖素样多肽-1免疫反应性。在甲状腺中，在新生动物的C细胞中观察到转基因表达，而在肺中，它在支气管粘膜的罕见内分泌细胞中表达。人生长激素mRNA的RNA聚合酶链反应分析证实了组织特异性转基因表达模式。通过在特定神经内分泌细胞中发现转基因表达，我们试图确定GK mRNA和GK本身是否也在大脑和肠道中表达，这些组织以前与这种酶的表达无关。使用大鼠组织，GK mRNA的检测RNA聚合酶链反应在大脑和肠道和定位于特定的细胞在下丘脑和肠粘膜原位杂交。从分离的大鼠空肠肠上皮细胞中检测到高Km葡萄糖磷酸化活性，其显示与肝GK相同的色谱洗脱曲线。GK免疫反应检测到下丘脑内侧的细胞与许多相同的细胞也显示GLUT 2免疫反应。总之，这些研究提供的证据上游GK启动子活性，GK mRNA，和GK本身在某些神经内分泌细胞胰岛外，并导致我们建议，GK可能发挥更广泛的作用，葡萄糖传感神经内分泌细胞比以前认为的。
A transgene consisting of an upstream glucokinase (GK) promoter fragment linked to coding sequences of the human growth hormone gene was expressed in certain neuroendocrine cells of the pancreas, pituitary, brain, gut, thyroid, and lungs of mice. In pancreas, the transgene was expressed in a nonuniform manner among beta cells and in a variable but substantial fraction of the other islet cell types. In pituitary, it was expressed in corticotropes, and in brain, it was expressed in cells of the medial hypothalamus. Within the gut transgene expression was detected in a subset of enteroendocrine cells of the stomach and duodenal epithelium, some of which also exhibited glucagon-like polypeptide-1 immunoreactivity. In thyroid, transgene expression was observed in C cells of neonatal animals, whereas in the lung, it was expressed among rare endocrine cells of the bronchopulmonary mucosa. RNA polymerase chain reaction analysis of human growth hormone mRNA corroborated the tissue-specific transgene expression pattern. Prompted by the finding of transgene expression in specific neuroendocrine cells, we sought to determine whether GK mRNA and GK itself was also expressed in the brain and gut, tissues not previously associated with the expression of this enzyme. Using rat tissues, GK mRNA was detected by RNA polymerase chain reaction in both the brain and intestine and was localized to specific cells in the hypothalamus and enteric mucosa by in situ hybridization. A high Km glucose phosphorylating activity was detected from isolated rat jejunal enterocytes that displayed a chromatographic elution profile identical to hepatic GK. GK immunoreactivity was detected in cells of the medial hypothalamus with many of the same cells also displaying GLUT2 immunoreactivity. Together, these studies provide evidence for upstream GK promoter activity, GK mRNA, and GK itself in certain neuroendocrine cells outside the pancreatic islet and lead us to suggest that GK may play a broader role in glucose sensing by neuroendocrine cells than was thought previously.