A Cryptic Modifier Causing Transient Self-Incompatibility in Arabidopsis thaliana
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- 作者：Pei Liu ; Susan Sherman-Broyles ; Mikhail E. Nasrallah ; June B. Nasrallah
- 关键词：RNA
- 刊名：Current Biology
- 出版年：2007
- 出版时间：1 May 2007
- 年：2007
- 卷：17
- 期：9
- 页码：824
- 全文大小：16 K
文摘
MicroRNAs (miRNAs) are important for regulating gene expression in muticellular organisms. MiRNA processing is a two-step process. In animal cells, the first step is nuclear and the second step cytoplasmic, whereas in plant cells, both steps occur in the nucleus via the enzyme Dicer-like1 (DCL1) bbib1"">bib1"">[1] and bbib2"">bib2"">[2] and other proteins including the zinc-finger-domain protein Serrate (SE) bbib3"">bib3"">[3] and bbib4"">bib4"">[4] and a double-stranded RNA (dsRNA) binding-domain protein, Hyponastic Leaves1 (HYL1) bbib5"">bib5"">[5], bbib6"">bib6"">[6] and bbib7"">bib7"">[7]. Furthermore, plant miRNAs are methylated by Hua Enhancer (HEN1) at their 3′ ends bbib8"">bib8"">[8] and loaded onto Argonaute1 (AGO1) bbib9"">bib9"">[9]. However, little is known about the cellular basis of miRNA biogenesis. Using live-cell imaging, we show here that DCL1 and HYL1 colocalize in discrete nuclear bodies in addition to being present in a low-level diffuse nucleoplasmic distribution. These bodies, which we refer to as nuclear dicing bodies (D-bodies), differ from Cajal bodies bbib10"">bib10"">[10] and bbib11"">bib11"">[11]. A mutated DCL1 with impaired function in miRNA processing fails to target to D-bodies, and an introduced primary (pri)-miRNA transcript is recruited to D-bodies. Furthermore, bimolecular fluorescence complementation (BiFC) shows that DCL1, HYL1, and SE interact in D-bodies. On the basis of these data, we propose that D-bodies are crucial for orchestrating pri-miRNA processing and/or storage/assembly of miRNA-processing complexes in the nuclei of plant cells.