AMPK improves gut epithelial differentiation and barrier function via regulating Cdx2 expression
AMPK improves gut epithelial differentiation and barrier function via regulating Cdx2 expression
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DOI：
10.1038/cdd.2017.14
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发表时间：
2017-05-01
影响因子：
12.4
通讯作者：
Zhu, Mei-Jun
中科院分区：
文献类型：
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作者：
Sun, Xiaofei;Yang, Qiyuan;Zhu, Mei-Jun
肠道上皮完整性和屏障功能受损与许多疾病有关。肠屏障的稳态基于上皮增殖和分化的微妙调节。 AMP 激活蛋白激酶 (AMPK) 是能量代谢的主要调节因子，细胞代谢物本质上参与控制细胞分化的表观遗传修饰。我们的目的是评估 AMPK 对肠上皮发育和屏障功能的调节作用。在这项研究中，AMPK 激活剂 (AICAR) 改善了 Caco-2 细胞的屏障功能，表现为跨上皮电阻增加和细胞旁 FITC-葡聚糖渗透性降低；一致地，AICAR 增强了上皮分化和紧密连接形成。用AMPKWT质粒转染Caco-2细胞，增强AMPK活性，改善上皮屏障功能和上皮分化，而K45R（AMPK显性失活突变体）受损；这些变化与尾部型同源盒 2 (CDX2) 的表达相关，CDX2 是使细胞分化为肠上皮谱系的关键转录因子。 CDX2 缺陷消除了 AMPK 激活促进的肠道分化。从机制上讲，AMPK 失活与多梳抑制复合物 2 调节的 H3K27me3 富集（抑制性组蛋白修饰）以及赖氨酸特异性组蛋白去甲基化酶 1 介导的 H3K4me3（一种允许性组蛋白修饰）减少相关。这些组蛋白修饰提供了 AMPK 和 CDX2 表达之间的机制联系。一致地，体内上皮 AMPK 敲除降低了 CDX2 表达，损害了肠道屏障功能、紧密连接的完整性和超微结构以及上皮细胞迁移，促进了肠道增殖并加剧了葡聚糖硫酸钠诱导的结肠炎。总之，AMPK 通过促进 CDX2 表达来增强肠屏障功能和上皮分化，这部分是由 Cdx2 启动子中组蛋白修饰的改变介导的。
Impairment in gut epithelial integrity and barrier function is associated with many diseases. The homeostasis of intestinal barrier is based on a delicate regulation of epithelial proliferation and differentiation. AMP-activated protein kinase (AMPK) is a master regulator of energy metabolism, and cellular metabolites are intrinsically involved in epigenetic modifications governing cell differentiation. We aimed to evaluate the regulatory role of AMPK on intestinal epithelial development and barrier function. In this study, AMPK activator (AICAR) improved the barrier function of Caco-2 cells as indicated by increased transepithelial electrical resistance and reduced paracellular FITC-dextran permeability; consistently, AICAR enhanced epithelial differentiation and tight junction formation. Transfection of Caco-2 cells with AMPKWT plasmid, which enhances AMPK activity, improved epithelial barrier function and epithelial differentiation, while K45R (AMPK dominant negative mutant) impaired; these changes were correlated with the expression of caudal type homeobox 2 (CDX2), the key transcription factor committing cells to intestinal epithelial lineage. CDX2 deficiency abolished intestinal differentiation promoted by AMPK activation. Mechanistically, AMPK inactivation was associated with polycomb repressive complex 2 regulated enrichment of H3K27me3, the inhibitory histone modification, and lysine-specific histone demethylase-1-mediated reduction of H3K4me3, a permissive histone modification. Those histone modifications provide a mechanistic link between AMPK and CDX2 expression. Consistently, epithelial AMPK knockout in vivo reduced CDX2 expression, impaired intestinal barrier function, integrity and ultrastructure of tight junction, and epithelial cell migration, promoted intestinal proliferation and exaggerated dextran sulfate sodium-induced colitis. In summary, AMPK enhances intestinal barrier function and epithelial differentiation via promoting CDX2 expression, which is partially mediated by altered histone modifications in the Cdx2 promoter.