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UHRF1调控AMPK的分子机制和生物学功能研究
Mechanism and Functional Study for Regulation of AMPK Activity by UHRF1
【作者】 徐翔；
【导师】 翁杰敏；
【作者基本信息】 华东师范大学 ， 生物化学与分子生物学， 2021， 博士
【摘要】 UHRF1是至关重要的DNA甲基化调控因子,它参与DNA维持性甲基化过程的功能已经研究的比较清楚。另外,还有研究表明UHRF1参与DNA的损伤修复。但除此之外UHRF1是否还有其它全新的生物学功能尚不清楚。AMPK是细胞极为重要的能量感受器,当细胞处于能量匮乏的状态时AMPK会被激活,AMPK激活后可以磷酸化不同的下游底物从而促进分解代谢和抑制合成代谢,最终使细胞达到能量平衡状态。我们的研究发现UHRF1和AMPK存在着较强的相互作用,UHRF1能在不同细胞系中显著抑制AMPK的激酶活性,并且UHRF1对于AMPK活性的调控不依赖于它的E3泛素连接酶活性。我们还发现UHRF1可以通过AMPK调控细胞糖酵解和脂质代谢。进一步的实验表明UHRF1主要在细胞核内通过招募磷酸酶PP2A对AMPK进行去磷酸化从而负调控AMPK的活性,而AMPK又是核质动态穿梭的,所以UHRF1也能调控细胞质部分AMPK的活性。最后我们通过尾静脉注射腺病毒在小鼠肝脏内特异过表达UHRF1以及构建肝脏特异性过表达UHRF1的转基因动物模型发现,在肝脏特异性过表达UHRF1后,小鼠的整体代谢指标包括血糖、血脂、肝脏脂质水平有非常显著的改变,同时肝脏内的AMPK活性也被显著抑制,说明UHRF1在体内也能负调控AMPK的活性。总之,我们的研究发现了UHRF1的一个全新的生物学功能即通过调控AMPK的激酶活性从而调控细胞代谢。
【Abstract】 UHRF1 is an important regulatory factor for DNA methylation,and its function in DNA maintenance methylation has been well studied.In addition,other studies have shown that UHRF1 is involved in DNA damage repair,but whether there are other new biological functions of UHRF1 is unclear.AMPK is an important cell energy sensor.When the cell is in the state of energy shortage,AMPK will be activated.After activation,AMPK can phosphorylate different downstream substrates to promote catabolism and inhibit anabolism,and finally make the cell reach the state of energy balance.Our study found that UHRF1 can interact with AMPK.UHRF1 can significantly inhibit AMPK kinase activity in different cell lines and this regulation is independent of its E3 ubiquitin ligase activity.We also found that UHRF1 can regulate glycolysis and lipid metabolism through AMPK.Further experiments showed that UHRF1 can negatively control the activity of AMPK through recruiting phosphatase PP2 A to dephosphorylate AMPK in the nucleus.Since AMPK can shuttling between cytoplasm and nucleus,so UHRF1 can suppress AMPK activities both in nucleus and cytoplasm.Finally,we specifically overexpressed UHRF1 in the liver of mice by injecting adenovirus into the tail vein and found that the overall metabolic indexes of mice,including blood glucose,blood lipid and liver lipid levels,were significantly changed after overexpression of UHRF1.Meanwhile,the activity of AMPK in the liver was also significantly inhibited.We obtained similar results by constructing the transgenic mouse model of conditional overexpression of UHRF1 in the liver.These results indicated that UHRF1 could negatively regulate the activity of AMPK in vivo.In conclusion,our study found that UHRF1 can regulate cell metabolism through controlling AMPK kinase activity.