Henderson Ian R, Zhang Xiaoyu, Lu Cheng, Johnson Lianna, Meyers Blake C, Green Pamela J, Jacobsen Steven E
Department of Molecular, Cell and Developmental Biology, University of California, Los Angeles, California 90095, USA.
Nat Genet. 2006 Jun;38(6):721-5. doi: 10.1038/ng1804. Epub 2006 May 14.
Small RNAs have several important biological functions. MicroRNAs (miRNAs) and trans-acting small interfering RNAs (tasiRNAs) regulate mRNA stability and translation, and siRNAs cause post-transcriptional gene silencing of transposons, viruses and transgenes and are important in both the establishment and maintenance of cytosine DNA methylation. Here, we study the role of the four Arabidopsis thaliana DICER-LIKE genes (DCL1-DCL4) in these processes. Sequencing of small RNAs from a dcl2 dcl3 dcl4 triple mutant showed markedly reduced tasiRNA and siRNA production and indicated that DCL1, in addition to its role as the major enzyme for processing miRNAs, has a previously unknown role in the production of small RNAs from endogenous inverted repeats. DCL2, DCL3 and DCL4 showed functional redundancy in siRNA and tasiRNA production and in the establishment and maintenance of DNA methylation. Our studies also suggest that asymmetric DNA methylation can be maintained by pathways that do not require siRNAs.
小RNA具有多种重要的生物学功能。微小RNA（miRNA）和顺式作用小干扰RNA（tasiRNA）调节mRNA的稳定性和翻译，而小干扰RNA（siRNA）导致转座子、病毒和转基因的转录后基因沉默，并且在胞嘧啶DNA甲基化的建立和维持过程中都发挥着重要作用。在此，我们研究了拟南芥中四个Dicer样基因（DCL1 - DCL4）在这些过程中的作用。对dcl2 dcl3 dcl4三突变体的小RNA进行测序，结果显示tasiRNA和siRNA的产生显著减少，这表明DCL1除了作为加工miRNA的主要酶之外，在内源反向重复序列产生小RNA的过程中还具有此前未知的作用。DCL2、DCL3和DCL4在siRNA和tasiRNA的产生以及DNA甲基化的建立和维持方面表现出功能冗余。我们的研究还表明，不对称DNA甲基化可以通过不需要siRNA的途径来维持。
