López-Yoldi M, Castilla-Madrigal R, Lostao M P, Barber A, Prieto J, Martínez J A, Bustos M, Moreno-Aliaga M J
Department of Nutrition, Food Science and Physiology, University of Navarra, Pamplona, Navarra, Spain.
Centre for Nutrition Research, University of Navarra, Pamplona, Navarra, Spain.
Acta Physiol (Oxf). 2016 Jul;217(3):217-26. doi: 10.1111/apha.12674. Epub 2016 Apr 7.
Cardiotrophin-1 (CT-1) is a member of the IL-6 family of cytokines with a key role in glucose and lipid metabolism. In the current investigation, we examined the in vivo and in vitro effects of CT-1 treatment on intestinal sugar absorption in different experimental models.
rCT-1 effects on α-Methyl-D-glucoside uptake were assessed in everted intestinal rings from wild-type and CT-1(-/-) mice and in Caco-2 cells. rCT-1 actions on SGLT-1 expression in brush border membrane vesicles and the identification of the potential signalling pathways involved were determined by Western blot.
In vivo administration (0.2 mg kg(-1) ) of rCT-1 caused a significant decrease on α-Methyl-D-glucoside uptake in everted intestinal rings from wild-type and CT-1(-/-) mice after short-term and long-term treatments. Similarly, in vitro treatment (1-50 ng mL(-1) ) with rCT-1 reduced α-Methyl-D-glucoside uptake in everted intestinal rings. In Caco-2 cells, rCT-1 treatment (20 ng mL(-1) , 1 and 24 h) lowered apical uptake of α-Methyl-D-glucoside in parallel with a decrease on SGLT-1 protein expression. rCT-1 promoted the phosphorylation of STAT-3 after 5 and 15 min treatment, but inhibited the activation by phosphorylation of AMPK after 30 and 60 min. Interestingly, pre-treatment with the JAK/STAT inhibitor (AG490) and with the AMPK activator (AICAR) reversed the inhibitory effects of rCT-1 on α-Methyl-D-glucoside uptake. AICAR also prevented the inhibition of SGLT-1 observed in rCT-1-treated cells.
CT-1 inhibits intestinal sugar absorption by the reduction of SGLT-1 levels through the AMPK pathway, which could also contribute to explain the hypoglycaemic and anti-obesity properties of CT-1.
心肌营养素-1（CT-1）是细胞因子白细胞介素-6家族的成员，在葡萄糖和脂质代谢中起关键作用。在本研究中，我们在不同实验模型中检测了CT-1治疗对肠道糖吸收的体内和体外作用。
在野生型和CT-1基因敲除（CT-1(-/-)）小鼠的外翻肠环以及Caco-2细胞中评估重组CT-1（rCT-1）对α-甲基-D-葡萄糖苷摄取的影响。通过蛋白质印迹法确定rCT-1对刷状缘膜囊泡中钠-葡萄糖协同转运蛋白1（SGLT-1）表达的作用以及所涉及的潜在信号通路。
短期和长期给予野生型和CT-1(-/-)小鼠rCT-1（0.2mg/kg(-1)）后，外翻肠环中α-甲基-D-葡萄糖苷的摄取显著减少。同样，用rCT-1进行体外处理（1-50ng/mL(-1)）可降低外翻肠环中α-甲基-D-葡萄糖苷的摄取。在Caco-2细胞中，rCT-1处理（20ng/mL(-1)，1小时和24小时）降低了α-甲基-D-葡萄糖苷的顶端摄取，同时SGLT-1蛋白表达减少。rCT-1处理5分钟和15分钟后促进信号转导和转录激活因子3（STAT-3）的磷酸化，但在30分钟和60分钟后抑制腺苷酸活化蛋白激酶（AMPK）磷酸化激活。有趣的是，用JAK/STAT抑制剂（AG490）和AMPK激活剂（AICAR）预处理可逆转rCT-1对α-甲基-D-葡萄糖苷摄取的抑制作用。AICAR还可防止在rCT-1处理的细胞中观察到的SGLT-1抑制。
CT-1通过AMPK途径降低SGLT-1水平来抑制肠道糖吸收，这也有助于解释CT-1的降血糖和抗肥胖特性。
