An energy supply network of nutrient absorption coordinated by calcium and T1R taste receptors in rat small intestine
An energy supply network of nutrient absorption coordinated by calcium and T1R taste receptors in rat small intestine
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DOI：
10.1113/jphysiol.2008.159616
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发表时间：
2009-01-01
影响因子：
5.5
通讯作者：
Foley, David
中科院分区：
文献类型：
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作者：
Mace, Oliver J.;Lister, Norma;Foley, David
T1 R味觉受体存在于整个胃肠道。葡萄糖吸收包括通过SGLT 1的主动吸收和通过顶膜中的GLUT 2的促进吸收。顶端GLUT 2的运输被葡萄糖和人工甜味剂快速上调，其通过T1 R2 + T1 R3/α-味蛋白激活PLC β 2和PKC β II。因此，我们研究是否非糖营养素的调节味觉受体在体内灌流大鼠空肠。在不同的条件下，我们观察到的H+/寡肽转运蛋白PepT 1和顶端GLUT 2之间的Ca 2+依赖的相互关系，反映了一个事实，即运输的PepT 1和GLUT 2的顶端膜抑制和激活PKC β II，分别。将l-谷氨酸或三氯蔗糖添加到含有低葡萄糖（20 mm）的灌注液中，各自激活PKC β II并降低顶端PepT 1水平和抗水解二肽l-Phe（Psi S）-l-Ala（1 mm）的吸收，同时在几分钟内增加顶端GLUT 2和葡萄糖吸收。将灌注从甘露醇切换为葡萄糖（75 mm）产生了类似的效果。L-谷氨酸诱导T1 R1、T1 R3和transducin的快速GPCR内化，而三氯蔗糖内化T1 R2、T1 R3和α-味觉蛋白。我们的结论是，l-谷氨酸通过氨基酸和葡萄糖通过甜味受体协调调节PepT 1和顶端GLUT 2通过一个共同的PKC β II肠细胞池。这些数据表明，存在一个更广泛的Ca 2+和味觉受体协调的运输网络，包括其他营养物质和/或其他刺激，能够激活PKC β II和其他转运蛋白，如天冬氨酸/谷氨酸转运蛋白，EAAC 1，其水平增加了一倍，l-谷氨酸。网络可以控制能量供应。
T1R taste receptors are present throughout the gastrointestinal tract. Glucose absorption comprises active absorption via SGLT1 and facilitated absorption via GLUT2 in the apical membrane. Trafficking of apical GLUT2 is rapidly up-regulated by glucose and artificial sweeteners, which act through T1R2 + T1R3/alpha-gustducin to activate PLC beta 2 and PKC beta II. We therefore investigated whether non-sugar nutrients are regulated by taste receptors using perfused rat jejunum in vivo. Under different conditions, we observed a Ca2+-dependent reciprocal relationship between the H+/oligopeptide transporter PepT1 and apical GLUT2, reflecting the fact that trafficking of PepT1 and GLUT2 to the apical membrane is inhibited and activated by PKC beta II, respectively. Addition of l-glutamate or sucralose to a perfusate containing low glucose (20 mm) each activated PKC beta II and decreased apical PepT1 levels and absorption of the hydrolysis-resistant dipeptide l-Phe(Psi S)-l-Ala (1 mm), while increasing apical GLUT2 and glucose absorption within minutes. Switching perfusion from mannitol to glucose (75 mm) exerted similar effects. l-Glutamate induced rapid GPCR internalization of T1R1, T1R3 and transducin, whereas sucralose internalized T1R2, T1R3 and alpha-gustducin. We conclude that l-glutamate acts via amino acid and glucose via sweet taste receptors to coordinate regulation of PepT1 and apical GLUT2 reciprocally through a common enterocytic pool of PKC beta II. These data suggest the existence of a wider Ca2+ and taste receptor-coordinated transport network incorporating other nutrients and/or other stimuli capable of activating PKC beta II and additional transporters, such as the aspartate/glutamate transporter, EAAC1, whose level was doubled by l-glutamate. The network may control energy supply.