DNA Replication Factor C1 Mediates Genomic Stability and Transcriptional Gene Silencing in Arabidopsis
DNA Replication Factor C1 Mediates Genomic Stability and Transcriptional Gene Silencing in Arabidopsis
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DOI：
10.1105/tpc.110.076349
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发表时间：
2010-07-01
期刊：
影响因子：
11.6
通讯作者：
Gong, Zhizhong
中科院分区：
文献类型：
--
作者：
Liu, Qian;Wang, Junguo;Gong, Zhizhong
基因筛选鉴定了ros 1 -1的抑制子，其为沉默抑制子1（ROS 1;编码DNA去甲基化蛋白）的突变体。抑制基因是编码复制因子C最大亚基（RFC 1）的基因突变。RFC 1的这种突变重新激活了在ros 1中沉默的未连接的35 S-NPTII转基因，并且还以DNA甲基化独立的方式增加了称为转录沉默信息的近着丝粒Athila逆转录转座子的表达。rfc 1比野生型对DNA损伤剂甲基甲烷磺酸盐和DNA内部和内部交联剂顺铂更敏感。rfc 1突变体组成型表达G2/M特异性细胞周期蛋白CycB 1;1和其他DNA修复相关基因。用DNA损伤剂处理模拟rfc 1突变释放沉默的35 S-NPTII，这表明自发诱导的基因组不稳定性引起的rfc 1突变可能部分有助于释放的转录基因沉默（TGS）。在rfc 1突变体中，体细胞同源重组的频率显著增加。有趣的是，ros 1突变体显示端粒长度增加，而rfc 1突变体显示端粒长度减少和端粒酶表达减少。我们的研究结果表明，RFC 1有助于介导基因组的稳定性和拟南芥TGS。
Genetic screening identified a suppressor of ros1-1, a mutant of REPRESSOR OF SILENCING1 (ROS1; encoding a DNA demethylation protein). The suppressor is a mutation in the gene encoding the largest subunit of replication factor C (RFC1). This mutation of RFC1 reactivates the unlinked 35S-NPTII transgene, which is silenced in ros1 and also increases expression of the pericentromeric Athila retrotransposons named transcriptional silent information in a DNA methylation-independent manner. rfc1 is more sensitive than the wild type to the DNA-damaging agent methylmethane sulphonate and to the DNA inter-and intra-cross-linking agent cisplatin. The rfc1 mutant constitutively expresses the G2/M-specific cyclin CycB1;1 and other DNA repair-related genes. Treatment with DNA-damaging agents mimics the rfc1 mutation in releasing the silenced 35S-NPTII, suggesting that spontaneously induced genomic instability caused by the rfc1 mutation might partially contribute to the released transcriptional gene silencing (TGS). The frequency of somatic homologous recombination is significantly increased in the rfc1 mutant. Interestingly, ros1 mutants show increased telomere length, but rfc1 mutants show decreased telomere length and reduced expression of telomerase. Our results suggest that RFC1 helps mediate genomic stability and TGS in Arabidopsis thaliana.