Gregory J Hannon

..RNAi has been cultivated as a means to manipulate gene expression experimentally and to probe gene function on a whole-genome scale...

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..Maximal inhibition of target genes was achieved at lower concentrations and silencing at 24 h was often greater. These studies provide the basis for an improved approach to triggering experimental silencing via the RNAi pathway...

..Considered together, these results indicate a role for Pasha in miRNA maturation and miRNA-mediated gene regulation...

..Our findings indicate a function for pseudogenes in regulating gene expression by means of the RNA interference pathway and may, in part, explain the evolutionary pressure to conserve argonaute-mediated catalysis in mammals...

..These data reinforce the growing awareness that non-coding RNAs are key players in tumour development by placing miRNAs in a central role in a well-known tumour-suppressor network...

..These studies demonstrate that Argonaute proteins catalyze mRNA cleavage within RISC and provide a source of recombinant enzyme for detailed biochemical studies of the RNAi effector complex...

..These observations expand the repertoire of small RNAs in Drosophila, adding a class that blurs distinctions based on known biogenesis mechanisms and functional roles...

..Our studies identify Dicer as central to a regulatory network that controls oocyte gene expression programs and that promotes genomic integrity in a cell type notoriously susceptible to aneuploidy...

..Methylation, along with specific histone marks, was enriched in exonic regions, suggesting that chromatin states can foreshadow the content of mature mRNAs...

..These libraries are available to the scientific community...

..We achieved greater than 97% accuracy in these trials. The strategies reported here can be applied to a wide variety of biological problems, including the determination of genotypic variation within large populations of individuals...

..In practice, this primary microRNA-based short hairpin RNA vector system is markedly similar to cDNA overexpression systems and is a powerful tool for studying gene function in cells and animals...

..By leaving the target gene unaltered, this approach permits tissue-specific, reversible regulation of endogenous gene expression in vivo, with potential broad application in basic biology and drug target validation...

..Together, these studies indicate that non-coding RNAs, specifically microRNAs, can modulate tumour formation, and implicate the mir-17-92 cluster as a potential human oncogene...

..We find that specific members of the Dicer and Argonaute families have distinct biochemical activities, which provides insight into their roles within RNA silencing pathways in Arabidopsis...

..Platypus and echidna testes contain a robust Piwi-interacting (piRNA) system, which appears to be participating in ongoing transposon defense...

..Our results suggest that our large-scale RNAi library can be used in specific, genetic applications in mammals, and will become a valuable resource for gene analysis and discovery...

..Our findings link the conservation of Argonaute catalysis to a conserved mechanism of microRNA biogenesis that is important for vertebrate development...

..Library cassettes can be easily shuttled into vectors that contain different promoters and/or that provide different modes of viral delivery...

..The p53 network suppresses tumour formation through the coordinated activation of multiple transcriptional targets, and miR-34 may act in concert with other effectors to inhibit inappropriate cell proliferation...

..Recently, a related RNAse III enzyme, Drosha, has surfaced as another component of the RNAi pathway. In addition to biochemistry, protein structures have proven to be helpful in deciphering the enzymology of RNase III molecules...

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..Coupled with our inability to generate viable Dicer1-null embryonic stem (ES) cells, this suggests a role for Dicer, and, by implication, the RNAi machinery, in maintaining the stem cell population during early mouse development...

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..Although their function must still be resolved, the abundance of piRNAs in germline cells and the male sterility of Miwi mutants suggest a role in gametogenesis...

..Let-7 sensors can be used to prospectively enrich self-renewing populations, and enforced let-7 expression induces loss of self-renewing cells from mixed cultures...

..Our results establish the feasibility of in vivo RNAi screens and illustrate how combining cancer genomics, RNA interference, and mosaic mouse models can facilitate the functional annotation of the cancer genome...

..Second, AGO4 catalytic activity can be crucial for the generation of secondary siRNAs that reinforce its repressive effects...

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..This methodology provides an adaptable route toward rapid and efficient resequencing of any sizeable, non-repeat portion of the human genome...

..Tudor-SN is the first RISC subunit to be identified that contains a recognizable nuclease domain, and could therefore contribute to the RNA degradation observed in RNAi...

..In addition, intrinsic differences between individual shRNA expression vectors targeting the same gene can be used to create an 'epi-allelic series' for dissecting gene function in vivo...

..Alta-Cyclic substantially improved the number of accurate reads for sequencing runs up to 78 bases and reduced systematic biases, facilitating confident identification of sequence variants...

..Harnessed as an experimental tool, RNAi has revolutionized approaches to decoding gene function. It also has the potential to be exploited therapeutically, and clinical trials to test this possibility are already being planned...

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..Here, we discuss the diversity of Argonaute proteins from a structural and functional perspective...

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..Mutants defective in aerial development and antibiotic production exhibit altered tRNA cleavage profiles relative to wild-type strains...

..These findings demonstrate that antisense transcription and processing contributes to the functional diversification of miRNA genes...

..For mir-10 in particular, both arms show abundant processing, and both show highly conserved target sites in Hox genes, suggesting a possible cooperation of the two arms, and their role as a master Hox regulator...

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..Sequencing of this genome now provides a valuable resource for deep mammalian comparative analyses, as well as for monotreme biology and conservation...

..This implicates piRNAs as specificity determinants of DNA methylation in germ cells...

..A likely function of RNAi throughout that history is to protect the genome from both pathogenic and parasitic invaders...

..Furthermore, we show that piRNAs are Dicer independent and that their 3' end likely carries a 2'O-Methyl modification...

..Inducible and reversible regulation of RNA interference has broad applications in the areas of mammalian genetics and molecular therapeutics...

..In this review, some of the key features of RNAi in mammalian systems are discussed...

..These results provide a molecular explanation for the stability of the senescent state, as well as new insights into the action of Rb as a tumor suppressor...

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..The possibility that dFXR, and potentially FMRP, use, at least in part, an RNAi-related mechanism for target recognition suggests a potentially important link between RNAi and human disease...

..We describe methods for the construction and transfer of stable shRNA expressing vectors suitable for generating loss of function alleles in mammalian cells in vitro or in vivo...

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..Thus, our evidence supports a model in which Argonaute contributes "Slicer" activity to RISC, providing the catalytic engine for RNAi...

..An emerging theme is that miRNAs, and siRNAs to some extent, target mRNAs to the general eukaryotic machinery for mRNA degradation and translation control...

..Thus, our results support a functional link between cytoplasmic P-bodies and the ability of a microRNA to repress expression of a target mRNA...

..In this review, we discuss the recent developments in our understanding of plant RNAi mechanisms from a biochemical perspective...

..These results suggest that Aurora-A and p160ROCK act in a common genetic pathway that promotes and monitors progression through G(2)/M...

..We also provide methods that use shRNAs to permit different levels of gene expression. Additionally, we discuss some aspects important for constructing an information pipeline to support development of a large shRNA library...

..Purified RISC complexes contain short interfering RNAs and endogenously expressed miRNAs and will be useful for studying many aspects of the RNAi machinery...

..We also show the therapeutic potential of this technique by demonstrating effective targeting of a sequence from hepatitis C virus by RNA interference in vivo...