A mechanism by which the osmotic laxative magnesium sulphate increases the intestinal aquaporin 3 expression in HT-29 cells
A mechanism by which the osmotic laxative magnesium sulphate increases the intestinal aquaporin 3 expression in HT-29 cells
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DOI：
10.1016/j.lfs.2010.11.013
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发表时间：
2011-01-17
期刊：
影响因子：
6.1
通讯作者：
Sugiyama, Kiyoshi
中科院分区：
文献类型：
--
作者：
Ikarashi, Nobutomo;Mochiduki, Toshihide;Sugiyama, Kiyoshi
目的：我们认为，渗透性泻药，硫酸镁（MgSO 4），可以作为一个泻药在一个非常合理的方式，通过增加水通道蛋白3（AQP 3）的表达水平，并通过改变渗透压在结肠。本研究以人结肠癌HT-29细胞株为实验对象，探讨MgSO 4对结肠癌细胞株肠上皮AQP 3表达的影响，主要方法：采用实时荧光定量PCR和蛋白质印迹法分别检测MgSO 4对结肠癌HT-29细胞AQP 3 mRNA和蛋白质表达的影响。测定细胞内Mg ~（2+）浓度、腺苷酸环化酶（AC）活性和蛋白激酶A（PKA）活性。Western blotting检测磷酸化cAMP反应元件结合蛋白（CREB）的表达水平。结果：MgSO 4处理后1 h，AQP 3 mRNA表达水平开始显著升高，9 h达到峰值，是对照组的3倍。AQP 3蛋白表达水平在添加后6小时开始增加，到12小时达到几乎是对照水平两倍的水平。在用MgSO 4处理的HT-29细胞中，细胞内Mg 2+浓度增加1.4倍，AC活性增加1.5倍，PKA活性增加1.6倍，CREB磷酸化显著增加。这些结果表明，AC激活引起的细胞内Mg 2+的增加，高浓度可能通过PICA激活CREB磷酸化，促进AQP 3基因转录。(C)2010年爱思唯尔公司All rights reserved.
Aims: We have suggested that an osmotic laxative, magnesium sulphate (MgSO4), may act as a cathartic in a very rational manner by increasing the aquaporin 3 (AQP3) expression level and by changing osmotic pressure in the colon. In this study, we examined the mechanism by which MgSO4 increases the intestinal AQP3 expression level by using the human colon cancer HT-29 cell line.Main methods: After the addition of MgSO4 to HT-29 cells, the expression levels of AQP3 mRNA and protein were measured using real-time RT-PCR and western blotting, respectively. The intracellular Mg2+ concentration, adenylate cyclase (AC) activity and protein kinase A (PKA) activity were also determined. The phosphorylated cAMP response element-binding protein (CREB) expression levels were determined by western blotting.Key findings: The AQP3 mRNA expression level started to increase significantly at 1 h after MgSO4 addition and peaked at 9 h, at a level 3 times as high as the control levels. The AQP3 protein expression level started to increase 6 h after the addition and reached a level almost twice as high as the control levels by hour 12. In the HT-29 cells treated with MgSO4, there was a 1.4-fold increase in the intracellular Mg2+ concentration, a 1.5-fold increase in AC activity, a 1.6-fold increase in PKA activity, and a significant increase in phosphorylation of the CREB.Significance: These results suggest that the AC activation caused by an increase in the intracellular Mg2+ concentration may trigger CREB phosphorylation through PICA activation and promote AQP3 gene transcription. (C) 2010 Elsevier Inc. All rights reserved.