Disease relevance of DCL1

• RNA silencing of host transcripts by cauliflower mosaic virus requires coordinated action of the four Arabidopsis Dicer-like proteins [1].
• The short integument (sin1) mutation causes a female-specific infertility, and a defect in the control of time to flowering in Arabidopsis [2].

High impact information on DCL1

• 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 [3].
• These data support a model in which miRNA-guided formation of a 5' or 3' terminus within pre-ta-siRNA transcripts, followed by RDR6-dependent formation of dsRNA and Dicer-like processing, yields phased ta-siRNAs that negatively regulate other genes [4].
• Gain-of-function alleles cause exaggerated growth of the suspensor and can suppress embryonic development to a degree where no recognizable proembryo is formed [5].
• In loss-of-function mutants, the zygote does not elongate properly, and the cells of the basal lineage are eventually incorporated into the embryo instead of differentiating the extra-embryonic suspensor [5].
• We find that standard wheat germ extract contains Dicer-like enzymes that convert double-stranded RNA (dsRNA) into two classes of small interfering RNAs, as well as an RNA-dependent RNA polymerase activity that can convert exogenous single-stranded RNA into dsRNA [6].

Biological context of DCL1

• In Arabidopsis, point mutations in or short truncations of the nuclear DICER-LIKE1 (DCL1) or HEN1 protein reduce miRNA accumulation and increase uncleaved target mRNAs accumulation, resulting in developmental abnormalities [7].
• The interaction between DCL1 and HYL1 is important for efficient and precise processing of pri-miRNA in plant microRNA biogenesis [8].
• Expression of a DCL1 cDNA transgene (35S:DCL1) produced a mild gain-of-function phenotype and largely rescued dcl1 mutant phenotypes [9].
• Thus, CAF appears to suppress cell division in floral meristems [10].
• SHORT INTEGUMENTS1/SUSPENSOR1/CARPEL FACTORY, a Dicer homolog, is a maternal effect gene required for embryo development in Arabidopsis [11].

Anatomical context of DCL1

• A 3.3-kb region 5' of the SIN1/SUS1/CAF gene shows asymmetric parent-of-origin activity in the embryo: It confers transcriptional activation of a reporter gene in early embryos only when transmitted through the maternal gamete [11].
• The results also show that, at the time of hypophysis specification, the symplastic connectivity between suspensor and embryo is reduced or interrupted and that the embryo develops from a single symplast (globular and heart stage) to a mature embryo with new symplastic domains [12].

Associations of DCL1 with chemical compounds

• These results indicate that each HYL1/DRB family protein interacts with one specific partner among the four Dicer-like proteins [13].
• Mutations at a locus designated SIN1 also eliminate accumulation of the sinapic acid esters characteristic of seed tissues [14].
• As determined by in vivo radiotracer feeding experiments, precursor supplementation studies, and enzymatic assays, the defect in the sin1 mutants appears to block the conversion of ferulate to 5-hydroxyferulate in the general phenylpropanoid pathway [14].
• Because of increased transparency to UV light, the sin1 mutants exhibit a characteristic red fluorescence under UV light, whereas wild-type plants have a blue-green appearance due to the fluorescence of sinapoyl malate in the upper epidermis [14].
• A T-DNA insertion in the Arabidopsis thaliana DEK1 gene, encoding a calpain-like cysteine proteinase with a predicted membrane anchor, causes unorganized embryo development displaying irregular mitotic divisions in the embryo proper and suspensor [15].

Physical interactions of DCL1

• An immunoprecipitation assay using Agrobacterium-mediated transient expression in Nicotiana benthamiana showed that HYL1 was able to form a complex with wild-type DCL1 protein, but not with the dcl1-9 mutant protein [8].

Other interactions of DCL1

• Both sense and antisense RNAs corresponding to these miRNA targets accumulated in the ago1 and dcl1 backgrounds [16].
• In the present work we investigated the role of the Arabidopsis nuclear RNA-binding protein HYL1 and the nuclear RNase III enzyme DCL1 in processing of primary miRNA (pri-miR171a) [17].
• Using a series of insertion mutants of Arabidopsis thaliana, unique functions for three DCL proteins in miRNA (DCL1), endogenous siRNA (DCL3), and viral siRNA (DCL2) biogenesis were identified [18].
• Formation or activity of small RNAs requires factors belonging to gene families that encode DICER (or DICER-LIKE [DCL]) and ARGONAUTE proteins and, in the case of some siRNAs, RNA-dependent RNA polymerase (RDR) proteins [18].
• AGL15-specific antibodies and immunohistochemistry were used to demonstrate that AGL15 accumulates before fertilization in the cytoplasm in the cells of the egg apparatus and moves into the nucleus during early stages of development in the suspensor, embryo, and endosperms [19].

Analytical, diagnostic and therapeutic context of DCL1

• In situ hybridization experiments show that CAF RNA is expressed throughout all shoot tissues [10].

References