肠上皮细胞对糖的感知结合了极性、膜结合探测器和糖代谢。

Sugar sensing by enterocytes combines polarity, membrane bound detectors and sugar metabolism.

作者信息

Le Gall Maude, Tobin Vanessa, Stolarczyk Emilie, Dalet Véronique, Leturque Armelle, Brot-Laroche Edith

机构信息

INSERM, UMR S 872, Centre de Recherche des Cordeliers, Paris, France.

出版信息

J Cell Physiol. 2007 Dec;213(3):834-43. doi: 10.1002/jcp.21245.

Abstract

Sugar consumption and subsequent sugar metabolism are known to regulate the expression of genes involved in intestinal sugar absorption and delivery. Here we investigate the hypothesis that sugar-sensing detectors in membranes facing the intestinal lumen or the bloodstream can also modulate intestinal sugar absorption. We used wild-type and GLUT2-null mice, to show that dietary sugars stimulate the expression of sucrase-isomaltase (SI) and L-pyruvate kinase (L-PK) by GLUT2-dependent mechanisms, whereas the expression of GLUT5 and SGLT1, did not rely on the presence of GLUT2. By providing sugar metabolites, sugar transporters, including GLUT2, fuelled a sensing pathway. In Caco2/TC7 enterocytes, we could disconnect the sensing triggered by detector from that produced by metabolism, and found that GLUT2 generated a metabolism-independent pathway to stimulate the expression of SI and L-PK. In cultured enterocytes, both apical and basolateral fructose could increase the expression of GLUT5, conversely, basolateral sugar administration could stimulate the expression of GLUT2. Finally, we located the sweet-taste receptors T1R3 and T1R2 in plasma membranes, and we measured their cognate G alpha Gustducin mRNA levels. Furthermore, we showed that a T1R3 inhibitor altered the fructose-induced expression of SGLT1, GLUT5, and L-PK. Intestinal gene expression is thus controlled by a combination of at least three sugar-signaling pathways triggered by sugar metabolites and membrane sugar receptors that, according to membrane location, determine sugar-sensing polarity. This provides a rationale for how intestine adapts sugar delivery to blood and dietary sugar provision.

摘要

已知糖的消耗及随后的糖代谢可调节参与肠道糖吸收和转运的基因表达。在此,我们探究这样一种假说,即面向肠腔或血流的细胞膜中的糖感应探测器也可调节肠道糖吸收。我们使用野生型和GLUT2基因敲除小鼠,结果显示膳食糖类通过依赖GLUT2的机制刺激蔗糖酶 - 异麦芽糖酶(SI)和L - 丙酮酸激酶(L - PK)的表达,而GLUT5和SGLT1的表达并不依赖于GLUT2的存在。通过提供糖代谢产物,包括GLUT2在内的糖转运蛋白为一种感应途径提供了动力。在Caco2/TC7肠上皮细胞中,我们能够将探测器触发的感应与代谢产生的感应分开,并发现GLUT2产生了一条不依赖代谢的途径来刺激SI和L - PK的表达。在培养的肠上皮细胞中,顶端和基底外侧的果糖均可增加GLUT5的表达,相反,基底外侧给予糖类可刺激GLUT2的表达。最后,我们在质膜中定位了甜味受体T1R3和T1R2,并测量了它们同源的Gα味导蛋白mRNA水平。此外,我们还表明T1R3抑制剂改变了果糖诱导的SGLT1、GLUT5和L - PK的表达。因此,肠道基因表达受至少三种由糖代谢产物和膜糖受体触发的糖信号通路的组合控制,这些通路根据膜的位置决定糖感应极性。这为肠道如何使糖转运与血液供应及膳食糖供应相适应提供了理论依据。

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