Disease relevance of DICER1

• We studied the expression level of the miRNA processing enzyme (DICER1, DGCR8, and RNASEN) in esophageal squamous cell carcinoma (ESCC) [1].
• We have generated mutations in human Dicer and Escherichia coli RNase III residues implicated in the catalysis, and studied their effect on RNA processing [2].
• The increased Dicer level in prostate adenocarcinoma correlated with clinical stage, lymph node status, and Gleason score [3].
• Immunohistochemical studies on a tissue microarray consisting of 232 prostate specimens confirmed up-regulation of Dicer in prostatic intraepithelial neoplasia and in 81% of prostate adenocarcinoma [3].
• Here we show that TRBP (the human immunodeficiency virus transactivating response RNA-binding protein), which contains three double-stranded, RNA-binding domains, is an integral component of a Dicer-containing complex [4].
• The Dicer-induced downregulation of the mutant transcript in myotonic dystrophy cells is accompanied by the downregulation of transcripts containing long complementary repeats [5].

High impact information on DICER1

• While Dicer, which produces small interfering RNAs, is currently the focus of intense interest, the structurally simpler bacterial RNase III serves as a paradigm for the entire family [6].
• Here we show that RISC is composed of Dicer, the double-stranded RNA binding protein TRBP, and Argonaute2 [7].
• Dicer is a multidomain ribonuclease that processes double-stranded RNAs (dsRNAs) to 21 nt small interfering RNAs (siRNAs) during RNA interference, and excises microRNAs from precursor hairpins [2].
• Based on these and other data, we propose that Dicer functions through intramolecular dimerization of its two RNase III domains, assisted by the flanking RNA binding domains, PAZ and dsRBD [2].
• At an early step in RNAi, an RNaseIII-related enzyme, Dicer (DCR-1), processes long-trigger dsRNA into small interfering RNAs (siRNAs) [8].

Biological context of DICER1

• RNA interference is triggered by double-stranded RNA that is processed into small interfering RNAs (siRNAs) by Dicer enzyme [9].
• The up-regulation upon Ago2 and Dicer knock-downs was moderate and we found no evidence, at the mRNA level, for activation of silenced genes [10].
• Effects of Dicer and Argonaute down-regulation on mRNA levels in human HEK293 cells [10].
• EXPERIMENTAL DESIGN: The expression levels of DICER1, DGCR8, and RNASEN mRNA in 73 ESCC tissues were compared with that in corresponding normal esophageal epithelium by Taqman real-time reverse-transcription PCR [1].
• The discrepancy between pri-miRNA and miR expression following overload was not explained by a change in the expression of components of the miRNA biogenesis pathway, since Drosha and Exportin-5 transcript levels were significantly increased by 50% in response to functional overload, whereas Dicer expression remained unchanged [11].

Anatomical context of DICER1

• We postulate that at least some members of the human Argonaute family may be involved in the development and maintenance of stem cells through the RNA-mediated gene-quelling mechanisms associated with DICER [12].
• We generated HEK293 cell lines depleted of Dicer or individual Ago proteins [10].
• Human Dicer expressed in mammalian cells colocalized with calreticulin, a resident protein of the endoplasmic reticulum [13].
• Our results suggest that Dicer is essential for turnover of a substantial subset of maternal transcripts that are normally lost during oocyte maturation [14].
• Dicer facilitates, in a cell-autonomous fashion, the development of T reg cells in the thymus and the efficient induction of Foxp3 by transforming growth factor beta [15].

Associations of DICER1 with chemical compounds

• However, over the last 2 years, great strides have been made towards elucidating how PPD proteins and Dicer regulate gene-silencing at the pre- and post-transcriptional levels [16].
• In this study, we demonstrate that siRNAs that have been generated in vitro by recombinant human Dicer (re-hDicer) significantly suppress not only the exogenous expression of a puromycin-resistance gene but also the endogenous expression of H-ras, c-jun and c-fos [17].
• Incorporation of an RNA aptamer for theophylline in the loop region of a short hairpin RNA (shRNA) designed to silence fluorescent reporter genes led to dose-dependent inhibition of RNAi by theophylline. shRNA cleavage experiments using recombinant Dicer demonstrated that theophylline inhibited cleavage of an aptamer-fused shRNA by Dicer in vitro [18].
• Specifically, dsRNA is responsible for stimulating important protective responses, such as the activation of dicer-related antiviral pathways, induction of type 1 IFN, and stimulation of dsRNA-activated protein kinase and oligoadenylate synthetase [19].
• Exp5 binds correctly processed pre-miRNAs directly and specifically, in a Ran guanosine triphosphate-dependent manner, but interacts only weakly with extended pre-miRNAs that yield incorrect miRNAs when processed by Dicer in vitro [20].

Physical interactions of DICER1

• In vitro reconstitution assays demonstrated that TRBP is required for the recruitment of Ago2 to the small interfering RNA (siRNA) bound by Dicer [4].
• In this work, we describe the identification of TRBP (human immunodeficiency virus (HIV-1) transactivating response (TAR) RNA-binding protein) as a protein partner of human Dicer [21].
• Such a study revealed that EB-3 cells possess 4-fold higher expression of Dicer gene coupled with 2-fold higher activity of RNA polymerase III than that observed in normal human lymphocytes. siRNAs derived from EB-3 cells had the inherent capacity to suppress c-myc gene expression in normal cells but not in native cells [22].
• It has been established that the double stranded short interfering RNAs (siRNAs) originate by the activity of a dsRNA-specific endonuclease, Dicer. siRNA in conjunction with a multiple enzyme complex called RNA-induced silencing complex (RISC) locates to the specific sites on mRNA and degrades it by endonuclease and exonuclease activities [23].

Regulatory relationships of DICER1

• Unexpectedly, binding of PPD proteins to Dicer inhibits the RNase activity of this enzyme in vitro [24].
• Instead, we find that intergenic transcripts of the beta-globin gene cluster are specifically upregulated in Dicer-deficient cells [25].

Other interactions of DICER1

• The 3'-untranslated region sequences of a few hundred transcripts that were commonly up-regulated upon Ago2 and Dicer knock-downs showed a significant enrichment of putative miRNA-binding sites [10].
• TAR RNA-binding protein, TRBP, was recently discovered to be an essential partner for Dicer and a crucial component of the RNA-induced silencing complex (RISC), a critical element of the RNA interference (RNAi) of the cell apparatus [26].
• Dicer and positive charge of proteins decrease the stability of RNA containing the AU-rich element of GM-CSF [27].
• Processing of the microRNA let-7 precursor by Dicer produced an apparently mature let-7 RNA [13].
• Comprehensive phylogenetic analyses of fungal Argonaute, Dicer, and RNA-dependent RNA polymerase-like proteins have been performed to gain insights into the diversification of RNA silencing pathways during the evolution of fungi [28].

Analytical, diagnostic and therapeutic context of DICER1

• Immunoprecipitation and affinity binding experiments using human HEK293 cells cotransfected with cDNAs for FLAG-tagged DICER, a member of the ribonuclease III family, and the His-tagged members of the Argonaute family suggested that the proteins from members of both subfamilies are associated with DICER [12].
• Western blot analysis of benign and neoplastic prostate cell lines further confirmed Dicer up-regulation in prostate adenocarcinoma [3].
• Molecular cloning and characterization of a novel human gene (HERNA) which encodes a putative RNA-helicase [29].
• Evaluation of the products of in vitro dicing reactions using electrospray ionization mass spectrometry reveals that a variety of products can be produced by Dicer cleavage [30].
• Crystallization and preliminary X-ray analysis of the C-terminal RNase III domain of human Dicer [31].

References