Small RNA-mediated chromatin silencing directed to the 3′ region of the Arabidopsis gene encoding the developmental regulator, FLC
Small RNA-mediated chromatin silencing directed to the 3′ region of the Arabidopsis gene encoding the developmental regulator, FLC
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DOI：
10.1073/pnas.0611459104
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发表时间：
2007-02-27
影响因子：
11.1
通讯作者：
Dean, Caroline
中科院分区：
文献类型：
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作者：
Swiezewski, Szymon;Crevillen, Pedro;Dean, Caroline
小RNA介导的染色质沉默的特点是重复序列和转座子，但它在调节单拷贝内源基因的作用还不清楚。我们已经鉴定了两个小RNA（30和24个核苷酸），其对应于编码开花阻遏物的拟南芥基因FLOWARDINLOCUS C（FLC）的典型poly（A）位点3'的反向链。基因组搜索表明，这些RNA来源于缺乏重复序列的基因组区域中的FLC基因座。24-nt小RNA在发育中的果实中最丰富，但在RNA聚合酶IVa、RNA依赖性RNA聚合酶2和DICER-LIKE 3缺陷的突变体中不存在，这些缺陷是RNAi介导的染色质沉默所需的组分。相应的基因组区域显示组蛋白3赖氨酸9去甲基化，其在dc 12，3，4三重突变体中减少。对小RNA起源的研究揭示了覆盖3' FLC区域的聚合酶IVa依赖性剪接的反义转录物。通过T-DNA插入的该基因组区域的突变导致FLC错误表达和延迟开花，表明RNAi介导的染色质修饰是发挥抑制FLC表达的功能的内源性途径的重要组成部分。
Small RNA-mediated chromatin silencing is well characterized for repeated sequences and transposons, but its role in regulating single-copy endogenous genes is unclear. We have identified two small RNAs (30 and 24 nucleotides) corresponding to the reverse strand 3' to the canonical poly(A) site of FLOWERING LOCUS C(FLC), an Arabidopsis gene encoding a repressor of flowering. Genome searches suggest that these RNAs originate from the FLC locus in a genomic region lacking repeats. The 24-nt small RNA, which is most abundant in developing fruits, is absent in mutants defective in RNA polymerase IVa, RNA-DEPENDENT RNA POLYMERASE 2, and DICER-LIKE 3, components required for RNAi-mediated chromatin silencing. The corresponding genomic region shows histone 3 lysine 9 climethylation, which was reduced in a dc12,3,4 triple mutant. Investigations into the origins of the small RNAs revealed a polymerase IVa-depenclent spliced, antisense transcript covering the 3' FLC region. Mutation of this genomic region by T-DNA insertion led to FLC misexpression and delayed flowering, suggesting that RNAi-mediated chromatin modification is an important component of enclogenous pathways that function to suppress FLC expression.