核糖体是由核糖体RNA和核糖体蛋白组成的复合体,其功能是参与蛋白质合成.SUMO化修饰的底物蛋白对核糖体的形成有重要调控作用.前期研究发现,KRAB型锌指蛋白Apak能特异地抑制p53所介导的凋亡通路.进一步研究发现,在核仁应激及癌基因激活...核糖体是由核糖体RNA和核糖体蛋白组成的复合体,其功能是参与蛋白质合成.SUMO化修饰的底物蛋白对核糖体的形成有重要调控作用.前期研究发现,KRAB型锌指蛋白Apak能特异地抑制p53所介导的凋亡通路.进一步研究发现,在核仁应激及癌基因激活条件下,抑癌蛋白ARF促进Apak发生SUMO化修饰并促使其移位于核仁.为了进一步探讨SUMO化修饰的Apak对核糖体RNA合成的调控功能,本研究通过Northern blot检测SUMO化修饰的Apak对核糖体RNA合成的影响,实时定量PCR检测核糖体RNA转录水平,RNA-Ch IP方法检测核糖体RNA与Apak蛋白的相互作用,结果表明,SUMO化修饰的Apak抑制47S核糖体RNA前体的合成且抑制RNA聚合酶Ⅰ介导转录的18S和5.8S r RNA的合成;在放线菌素D以及癌基因诱导下,促进Apak与18S,5.8S r RNA相互作用.本研究对理解Apak的功能和作用机制提供了新的依据,为深入研究KRAB型锌指蛋白家族分子对核糖体RNA的调控奠定了基础.展开更多
Ribosomes are among the most fundamental molecular machines in all cells,as they are required for protein synthesis.Most structural rRNA components are generated in the nucleolus and assembled into pre-ribosomal parti...Ribosomes are among the most fundamental molecular machines in all cells,as they are required for protein synthesis.Most structural rRNA components are generated in the nucleolus and assembled into pre-ribosomal particles.Here we show Apak,a previously identified p53 inhibitor,as a novel ribosomal stress response protein.In unstressed cells,Apak is bound to the deSUMOylase SENP1 in the nucleoplasm and targeted for proteasomal degradation by MDM2 ubiquitin ligase.Upon ribosomal stress,SENP1 dissociates fromApak and the tumor suppressor protein ARF couplesUbc9 with Apak to promote Apak SUMOylation on zinc fingers.This results in Apak protein stabilization and translocation to the nucleolus,where Apak inhibits the pre-rRNA synthesis.These findings provide a molecular mechanism whereby ARF coordinates Apak to regulate ribosome biogenesis upon cellular stress.展开更多
文摘核糖体是由核糖体RNA和核糖体蛋白组成的复合体,其功能是参与蛋白质合成.SUMO化修饰的底物蛋白对核糖体的形成有重要调控作用.前期研究发现,KRAB型锌指蛋白Apak能特异地抑制p53所介导的凋亡通路.进一步研究发现,在核仁应激及癌基因激活条件下,抑癌蛋白ARF促进Apak发生SUMO化修饰并促使其移位于核仁.为了进一步探讨SUMO化修饰的Apak对核糖体RNA合成的调控功能,本研究通过Northern blot检测SUMO化修饰的Apak对核糖体RNA合成的影响,实时定量PCR检测核糖体RNA转录水平,RNA-Ch IP方法检测核糖体RNA与Apak蛋白的相互作用,结果表明,SUMO化修饰的Apak抑制47S核糖体RNA前体的合成且抑制RNA聚合酶Ⅰ介导转录的18S和5.8S r RNA的合成;在放线菌素D以及癌基因诱导下,促进Apak与18S,5.8S r RNA相互作用.本研究对理解Apak的功能和作用机制提供了新的依据,为深入研究KRAB型锌指蛋白家族分子对核糖体RNA的调控奠定了基础.
基金This research was supported by grants from the National Basic Research Program of China(2011CB910802,2013CB910803,2012CB910702)the National Natural Science Foundation of China(31125010,81221004).
文摘Ribosomes are among the most fundamental molecular machines in all cells,as they are required for protein synthesis.Most structural rRNA components are generated in the nucleolus and assembled into pre-ribosomal particles.Here we show Apak,a previously identified p53 inhibitor,as a novel ribosomal stress response protein.In unstressed cells,Apak is bound to the deSUMOylase SENP1 in the nucleoplasm and targeted for proteasomal degradation by MDM2 ubiquitin ligase.Upon ribosomal stress,SENP1 dissociates fromApak and the tumor suppressor protein ARF couplesUbc9 with Apak to promote Apak SUMOylation on zinc fingers.This results in Apak protein stabilization and translocation to the nucleolus,where Apak inhibits the pre-rRNA synthesis.These findings provide a molecular mechanism whereby ARF coordinates Apak to regulate ribosome biogenesis upon cellular stress.
