Circadian Clock- and Transcription-controlled Genome-wide Excision Repair of UV Damage in Arabidopsis. Circadian Clock- and Transcription-controlled Genome-wide Excision Repair of UV Damage in Arabidopsis

We used the recently developed Excision Repair-sequencing (XR-seq) method to study genome-wide repair of UV-induced DNA damage in Arabidopsis. We found that the repair of cyclobutane pyrimidine dimers for a large fraction of the genome is controlled by the joint actions of the circadian clock and transcription by RNA polymerase II. Arabidopsis has a relatively compact genome, and a large fraction of the genes are controlled by the circadian clock. Our data on the interface of these two global regulatory systems reveal very strong repair preference of the transcribed strands of Arabidopsis genes, 10 to 30% of which are circadian time-dependent. Thus, throughout the day, Arabidopsis exhibits enormous dynamic range in repair to cope with exposure to sunlight. Overall design: Examination of excision repair throughout the circadian cycle with 2 experiments each of which having 8 samples collected at ZT2, ZT5, ZT8, ZT11, ZT14, ZT17, ZT20, ZT23

我们采用新近开发的切除修复测序（Excision Repair-sequencing, XR-seq）技术，针对拟南芥体内紫外线诱导DNA损伤的全基因组修复情况开展研究。研究发现，基因组中绝大多数区域的环丁烷嘧啶二聚体（cyclobutane pyrimidine dimers, CPD）修复过程，由昼夜节律钟与RNA聚合酶II介导的转录共同调控。拟南芥基因组相对紧凑，且多数基因的表达受昼夜节律钟调控。基于这两类全局调控系统相互作用的研究数据，我们发现拟南芥基因的转录链存在极强的修复偏好性，其中10%至30%的修复事件呈现昼夜节律时间依赖性。因此，在全天的不同时段，拟南芥的DNA修复能力展现出极大的动态变化范围，以应对持续的日光暴露。
实验设计：对整个昼夜周期中的切除修复过程进行检测，共开展2组独立实验，每组分别于授时因子时间（Zeitgeber Time, ZT）2、ZT5、ZT8、ZT11、ZT14、ZT17、ZT20、ZT23共8个时间点采集样本。