Mapping MKP-3/FOXO1 interaction and evaluating the effect on gluconeogenesis.
Mapping MKP-3/FOXO1 interaction and evaluating the effect on gluconeogenesis.
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DOI：
10.1371/journal.pone.0041168
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发表时间：
2012
期刊：
影响因子：
3.7
通讯作者：
Xu H
中科院分区：
文献类型：
--
作者：
Jiao P;Feng B;Xu H
已知MAP激酶磷酸酶3（MKP-3）减弱ERK信号传导途径。最近已经证明，MKP-3也通过与FOXO 1相互作用并激活FOXO 1而在肥胖状态下促进肝葡萄糖输出中起作用。肝脏MKP-3表达的降低足以降低饮食诱导和遗传性肥胖小鼠的血糖水平。本研究利用MKP-3和FOXO 1腺病毒载体，在Fao肝癌细胞中研究了MKP-3/FOXO 1相互作用的机制及其对促癌基因转录和葡萄糖分泌的影响。结果表明，MKP-3磷酸酶活性不是MKP-3/FOXO 1相互作用所必需的，但对于FOXO 1核转位和MKP-3促进细胞异生是必需的。与GFP对照（1±0.38）相比，MKP-3使G6 β基因表达增加242%（3.42±0.62），而失活的MKP-3不改变G6 β基因表达（0.98±0.17）。MKP-3的200-260位残基和FOXO 1的360-456位残基对于介导MKP-3/FOXO 1相互作用是必需的。有趣的是，ERK磷酸化缺陷但Akt磷酸化缺陷的FOXO 1突变体失去了与MKP-3的相互作用。此外，体内实验表明，Akt磷酸化抗性FOXO 1 3A突变体足以挽救瘦小鼠肝脏中MKP-3敲低引起的低血糖（从141±6.78至209±14.64 mg/dL）。1)已经鉴定了介导MKP-3/FOXO 1相互作用的关键残基; 2）ERK磷酸化缺陷型FOXO 1突变体在激活促血管生成基因转录方面与Akt磷酸化缺陷型FOXO 1突变体一样有效; 3）组成型活性FOXO 1可以挽救体内由肝脏MKP-3表达降低引起的降血糖作用。
MAP kinase phosphatase 3 (MKP-3) is known to attenuate the ERK signaling pathway. It has been recently demonstrated that MKP-3 is also a player in promoting hepatic glucose output in obese state by interacting and activating FOXO1. Reduction of hepatic MKP-3 expression is sufficient to reduce blood glucose levels in both diet-induced and genetically obese mice. In current study, the mechanism of MKP-3/FOXO1 interaction and the effects on transcription of gluconeogenic gene and glucose output was investigated in Fao hepatoma cells by using mutated MKP-3 and FOXO1 adenoviral constructs. The results indicate that MKP-3 phosphatase activity is not required for MKP-3/FOXO1 interaction but is essential for FOXO1 nuclear translocation and MKP-3 promoted gluconeogenesis. Compared to GFP control (1±0.38), MKP-3 increased G6Pase gene expression by 242% (3.42±0.62) while inactive MKP-3 does not change G6Pase expression (0.98±0.17). The residues 200–260 of MKP-3 and the residues 360–456 of FOXO1 are essential for mediating MKP-3/FOXO1 interaction. Interestingly, ERK phosphorylation deficient but not Akt phosphorylation deficient FOXO1 mutant lost interaction with MKP-3. Furthermore, in vivo experiments showed that Akt phosphorylation resistant FOXO1 3A mutant is sufficient to rescue the hypoglycemia caused by MKP-3 knock down in the liver of lean mice (from 141±6.78 to 209±14.64 mg/dL). 1) Critical residues mediating MKP-3/FOXO1 interaction have been identified; 2) ERK phosphorylation deficient FOXO1 mutant is as potent as Akt phosphorylation deficient FOXO1 mutant in activating transcription of gluconeogenic genes; 3) Constitutively active FOXO1 can rescue the hypoglycemic effect caused by reduced hepatic MKP-3 expression in vivo.
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