Center for Microbiology, VIB, Leuven-Heverlee, Flanders, Belgium; Functional Genomics and Proteomics Research Unit, Department of Biology, KU Leuven, Leuven, Flanders, Belgium.
Center for Microbiology, VIB, Leuven-Heverlee, Flanders, Belgium; Laboratory of Molecular Cell Biology, Institute of Botany and Microbiology, KU Leuven, Leuven-Heverlee, Flanders, Belgium.
Eur J Pharmacol. 2021 Apr 15;897:173925. doi: 10.1016/j.ejphar.2021.173925. Epub 2021 Feb 3.
Caco-2 cells are increasingly used to study the absorption of drugs and nutrients, including D-glucose, an important nutrient that mainly gets absorbed from the intestine by the sodium/glucose cotransporter 1 (SGLT1). However, disadvantages of Caco-2 cells for such studies have been reported, e.g., D-glucose cannot elicit translocation of the intracellular pool of SGLT1 to the apical membrane, the origin of the cells affects glucose uptake, and Caco-2 cells exhibit heterogeneity. This study aimed to characterize SGLT1-mediated glucose transport across Caco-2 cell monolayers. We found that at lower glucose concentrations (5 mM) SGLT1 contributes more to total glucose transport than at higher (10 mM) glucose concentrations, suggesting contributions by another transporter at higher glucose concentrations. This contrasts with the in vivo situation, where SGLT1 dominant glucose transporter at all glucose concentrations. We also tested whether known regulators like sugars or catecholamines can stimulate glucose transport across Caco-2 cell monolayers. Neither epinephrine nor 2-deoxy-D-glucose could stimulate glucose transport. Moreover, the epinephrine could not induce accumulation of cyclic adenosine monophosphate (cAMP) in Caco-2 cells, indicating the absence of a functional β-adrenoceptor in Caco-2 cells, which could explain the lack of epinephrine effect on glucose transport. Also, Caco-2 cells may lack some kinases required for increased SGLT1 transport. Overall, SGLT1-mediated glucose transport and its regulation in Caco-2 cells differ from that in vivo, and caution is advised when extrapolating glucose transport results obtained with this model to the in vivo situation.
Caco-2 细胞越来越多地被用于研究药物和营养素的吸收，包括 D-葡萄糖，这是一种重要的营养素，主要通过钠/葡萄糖协同转运蛋白 1（SGLT1）从肠道吸收。然而，已经报道了 Caco-2 细胞在这些研究中的一些缺点，例如，D-葡萄糖不能引起 SGLT1 的细胞内池向顶膜的易位，细胞的起源影响葡萄糖的摄取，并且 Caco-2 细胞表现出异质性。本研究旨在表征 SGLT1 介导的 Caco-2 细胞单层葡萄糖转运。我们发现，在较低的葡萄糖浓度（5 mM）下，SGLT1 对总葡萄糖转运的贡献大于较高的葡萄糖浓度（10 mM），表明在较高的葡萄糖浓度下存在另一种转运蛋白的贡献。这与体内情况相反，在所有葡萄糖浓度下 SGLT1 都是主要的葡萄糖转运体。我们还测试了已知的调节剂，如糖或儿茶酚胺是否可以刺激 Caco-2 细胞单层的葡萄糖转运。肾上腺素或 2-脱氧-D-葡萄糖都不能刺激葡萄糖转运。此外，肾上腺素不能在 Caco-2 细胞中诱导环腺苷酸（cAMP）的积累，表明 Caco-2 细胞中不存在功能性β-肾上腺素受体，这可以解释肾上腺素对葡萄糖转运没有影响。此外，Caco-2 细胞可能缺乏增加 SGLT1 转运所需的一些激酶。总的来说，Caco-2 细胞中 SGLT1 介导的葡萄糖转运及其调节与体内不同，在将该模型获得的葡萄糖转运结果外推到体内情况时应谨慎。
