Apical and basolateral localisation of GLUT2 transporters in human lung epithelial cells
Apical and basolateral localisation of GLUT2 transporters in human lung epithelial cells
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DOI：
10.1007/s00424-008-0459-8
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发表时间：
2008-08-01
影响因子：
4.5
通讯作者：
Baines, Deborah L.
中科院分区：
文献类型：
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作者：
Kalsi, Kameljit K.;Baker, Emma H.;Baines, Deborah L.
正常人气道表面液体的葡萄糖浓度比血糖浓度低12.5倍，表明上皮细胞的葡萄糖摄取可能在维持肺葡萄糖稳态中起作用。因此，我们研究了非极化和极化H441人气道上皮细胞和支气管活检中潜在的葡萄糖摄取机制。我们在非极化细胞中检测到葡萄糖转运蛋白2（GLUT 2）和葡萄糖转运蛋白4（GLUT 4）的mRNA和蛋白，但在质膜中未检测到GLUT 4。在极化细胞中，GLUT 2蛋白在顶侧和基底侧膜中检测到。此外，GLUT 2蛋白定位于人支气管粘膜活检的上皮细胞。在非极化的H441细胞中，D-葡萄糖和脱氧葡萄糖的摄取是相似的。根皮素抑制两者的摄取，表明葡萄糖的摄取是通过GLUT介导的运输。根皮素敏感的运输仍然是葡萄糖摄取的主要途径，在极化细胞的顶端和基底侧膜，并在5-10 mM葡萄糖最大。我们不能最终证明钠/葡萄糖转运蛋白介导的非极化或极化细胞的运输。我们的研究提供了第一个证据表明，在人体气道上皮细胞在体外和体内葡萄糖转运利用GLUT 2转运蛋白。我们推测，这些转运蛋白可能有助于葡萄糖摄取/人体气道内的稳态。
Glucose concentrations of normal human airway surface liquid are similar to 12.5 times lower than blood glucose concentrations indicating that glucose uptake by epithelial cells may play a role in maintaining lung glucose homeostasis. We have therefore investigated potential glucose uptake mechanisms in non-polarised and polarised H441 human airway epithelial cells and bronchial biopsies. We detected mRNA and protein for glucose transporter type 2 (GLUT2) and glucose transporter type 4 (GLUT4) in non-polarised cells but GLUT4 was not detected in the plasma membrane. In polarised cells, GLUT2 protein was detected in both apical and basolateral membranes. Furthermore, GLUT2 protein was localised to epithelial cells of human bronchial mucosa biopsies. In non-polarised H441 cells, uptake of D-glucose and deoxyglucose was similar. Uptake of both was inhibited by phloretin indicating that glucose uptake was via GLUT-mediated transport. Phloretin-sensitive transport remained the predominant route for glucose uptake across apical and basolateral membranes of polarised cells and was maximal at 5-10 mM glucose. We could not conclusively demonstrate sodium/glucose transporter-mediated transport in non-polarised or polarised cells. Our study provides the first evidence that glucose transport in human airway epithelial cells in vitro and in vivo utilises GLUT2 transporters. We speculate that these transporters could contribute to glucose uptake/homeostasis in the human airway.