Background：Nucleolin （NCL） is the most abundant RNA-binding protein in the cell nucleolus and plays an important role in chromatin stability,ribosome assembly,ribosomal RNA maturation,ribosomal DNA transcription,nucleocytoplasmic transport,and regulation of RNA stability and translation efficiency.In addition to its anti-apoptotic properties,the underlying mechanisms associated with NCL-related roles in different cellular processes remain unclear.In this study,the effect of NCL on microRNA （miRNA） expression was evaluated by generating transgenic mice with myocardial overexpression of NCL and by analyzing microarrays of mature and precursor miRNAs from mice.Methods：Using microinjection ofalpha-MyHc clone 26-NCL plasmids,we generated transgenic mice with myocardial overexpression of NCL firstly,and then mature and precursor miRNAs expression profiles were analyzed in NCL transgenic mice （n =3） and wild-type （WT） mice （n =3） by miRNA microarrays.Statistical Package for the Social Sciences version 16.0 software （SPSS,Inc.,Chicago,IL,USA） was used to perform Student＇s t-test,and statistical significance was determined at P 〈 0.05.Results：Several miRNAs were found to be differentially expressed,of which 11 were upregulated and 4 were downregulated in transgenic mice with myocardial overexpression of NCL compared to those in WT mice.Several differentially expressed miRNAs were subsequently confirmed and quantified by real-time quantitative reverse transcription-polymerase chain reaction.Bioinformatics analysis was used for the prediction of miRNA targets.Furthermore,in vitro experiments showed that NCL regulated miR-21 expression following hydrogen peroxide preconditioning.Conclusions：Myocardial-protection mechanisms exerted by NCL might be mediated by the miRNAs identified in this study.
目的:探讨腹主动脉缩窄致压力负荷增加大鼠心肌肥厚模型中核仁素的表达情况.方法:采用体质量180～220 g SD大鼠40只,随机分为假手术组和腹主动脉缩窄模型组,利用腹主动脉缩窄法制备压力负荷增加心肌肥厚模型,分别于术后2周、4周观察心脏质量指数、左心室质量指数;采用RT-PCR检测心肌组织中β-MHC mRNA的表达;采用Western印迹检测心肌、脑、肾组织中核仁素的表达情况.结果:腹主动脉缩窄模型组4周以后心脏质量指数、左心室质量指数较假手术组显著增加(P＜0.01);4周以后心肌组织中β-MHC mRNA的表达较假手术组显著升高(P＜0.05);2周以后心肌组织中核仁素蛋白的表达较假手术组显著升高(P＜0.05),而在脑、肾组织中无明显升高.结论:核仁素蛋白在大鼠压力负荷增加心肌肥厚模型中的表达上调,表明核仁素可能参与了压力负荷增加心肌肥厚的发生发展.
