Meiotic DNA Repair in the Nucleolus Employs a Non-homologous End Joining Mechanism

编号 040020305

推送时间 20190909

研究领域 森林培育 

年份 2019 

类型 期刊 

语种 英语

标题 Meiotic DNA Repair in the Nucleolus Employs a Non-homologous End Joining Mechanism

来源期刊 Plant Cell

期 第203期

发表时间 20190702

关键词 rDNA;  NHEJ;  Nucleolus;  DSB;  homologous recombination; 

摘要 Ribosomal RNA genes are arranged in large arrays with hundreds of rDNA units in tandem. These highly repetitive DNA elements pose a risk to genome stability since they can undergo non-allelic exchanges. During meiosis DNA double strand breaks (DSBs) are induced as part of the regular program to generate gametes. Meiotic DSBs initiate homologous recombination (HR) which subsequently ensures genetic exchange and chromosome disjunction. In Arabidopsis thaliana we demonstrate that all 45S rDNA arrays become transcriptionally active and are recruited into the nucleolus early in meiosis. This shields the rDNA from acquiring canonical meiotic chromatin modifications and meiotic cohesin and allows only very limited meiosis-specific DSB formation. DNA lesions within the rDNA arrays are repaired in a RAD51-independent, but LIG4-dependent manner, establishing that it is non-homologous end joining (NHEJ) that maintains rDNA integrity during meiosis. Utilizing ectopically integrated rDNA repeats we validate our findings and demonstrate that the rDNA constitutes a HR-refractory genome environment.

服务人员 孙小满

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