Activation of AMP-activated protein kinase reduces cAMP-mediated epithelial chloride secretion
Activation of AMP-activated protein kinase reduces cAMP-mediated epithelial chloride secretion
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DOI：
10.1152/ajpgi.00077.2003
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发表时间：
2003-11-01
影响因子：
4.5
通讯作者：
Madsen, KL
中科院分区：
文献类型：
--
作者：
Walker, J;Jijon, HB;Madsen, KL
AMP激活的蛋白激酶(AMPK)被激活，以响应氧化应激引起的细胞能量状态的波动。它的靶点之一是囊性纤维化跨膜电导调节因子(CFTR)，这是结肠组织中主要的氯离子分泌通道。本研究的目的是确定AMPK在氧化应激和慢性炎症条件下对结肠氯分泌的调节作用。研究了成年IL-10基因缺陷小鼠和野生型129Sv/EV小鼠在存在和不存在药理AMPK抑制剂和激活剂的情况下，结肠组织的氯离子分泌和AMPK活性。在刷状缘膜泡中测量CFTR的表达水平。人结肠T84单层细胞培养研究检测了过氧化氢和AMPK的药理激活对Forsklin刺激的氯离子分泌的影响。IL-10缺乏的小鼠的发炎结肠对Forsklin刺激表现出低反应性，与表面CFTR表达减少和AMPK活性增加有关。在野生型小鼠中，抑制AMPK恢复了对Forsklin的组织反应性，而用5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside(AICAR)刺激AMPK导致组织低反应性。T84细胞暴露于过氧化氢后，AMPK活性呈时间依赖性增加，Forsklin刺激的氯离子分泌减少。抑制AMPK可阻止氯的分泌减少。用AMPK激活剂AICAR处理细胞后，氯的分泌减少。总之，AMPK的激活与cAMP介导的上皮氯离子流量的减少有关，可能是慢性炎症条件下出现低反应的一个因素。
AMP-activated protein kinase ( AMPK) is activated in response to fluctuations in cellular energy status caused by oxidative stress. One of its targets is the cystic fibrosis transmembrane conductance regulator ( CFTR), which is the predominant Cl- secretory channel in colonic tissue. The aim of this study was to determine the role of AMPK in the modulation of colonic chloride secretion under conditions of oxidative stress and chronic inflammation. Chloride secretion and AMPK activity were examined in colonic tissue from adult IL-10-deficient and wild-type 129 Sv/Ev mice in the presence and absence of pharmacological AMPK inhibitors and activators, respectively. Apical levels of CFTR were measured in brush-border membrane vesicles. Cell culture studies in human colonic T84 monolayers examined the effect of hydrogen peroxide and pharmacological activation of AMPK on forskolin-stimulated chloride secretion. Inflamed colons from IL-10-deficient mice exhibited hyporesponsiveness to forskolin stimulation in association with reductions in surface CFTR expression and increased AMPK activity. Inhibition of AMPK restored tissue responsiveness to forskolin, whereas stimulation of AMPK with 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside ( AICAR) induced tissue hyporesponsivness in wild-type mice. T84 cells exposed to hydrogen peroxide demonstrated a time-dependent increase in AMPK activity and reduction of forskolin-stimulated chloride secretion. Inhibition of AMPK prevented the reduction in chloride secretion. Treatment of cells with the AMPK activator, AICAR, resulted in a decreased chloride secretion. In conclusion, AMPK activation is linked with reductions in cAMP-mediated epithelial chloride flux and may be a contributing factor to the hyporesponsiveness seen under conditions of chronic inflammation.