76
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Seitz H. Fall 1253. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1236256] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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77
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Seitz H. Fall 1271. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1236282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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78
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Seitz H. Fall 1247. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1236248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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79
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Seitz H. Fall 1257. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1236261] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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80
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Seitz H. Fall 1263. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1236271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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81
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Seitz H. Fall 1665. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1235682] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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82
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Seitz H. Fall 1689. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1235717] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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83
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Seitz H. Fall 1673. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1235693] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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84
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Seitz H. Fall 1659. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1235673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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85
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Seitz H. Fall 1655. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1235668] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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86
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Seitz H. Fall 1371. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1236422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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87
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Seitz H. Fall 1359. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1236406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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88
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Seitz H. Fall 1355. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1236400] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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89
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Seitz H. Fall 1363. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1236412] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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90
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Seitz H. Fall 1367. Dtsch Med Wochenschr 2009. [DOI: 10.1055/s-0029-1236416] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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91
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Seitz H, Schwendenwein I, Vécsei V, Losert U. Die Biokompatibilität von Polyäthylenterephthalat-PET-(Trevira® hochfest) Eine tierexperimentelle Studie am Schafknie. BIOMED ENG-BIOMED TE 2009. [DOI: 10.1515/bmte.1995.40.s1.59] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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92
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Li C, Vagin VV, Lee S, Xu J, Ma S, Xi H, Seitz H, Horwich MD, Syrzycka M, Honda BM, Kittler ELW, Zapp ML, Klattenhoff C, Schulz N, Theurkauf WE, Weng Z, Zamore PD. Collapse of germline piRNAs in the absence of Argonaute3 reveals somatic piRNAs in flies. Cell 2009; 137:509-21. [PMID: 19395009 DOI: 10.1016/j.cell.2009.04.027] [Citation(s) in RCA: 416] [Impact Index Per Article: 27.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2009] [Revised: 02/24/2009] [Accepted: 04/10/2009] [Indexed: 10/20/2022]
Abstract
Piwi-interacting RNAs (piRNAs) silence transposons in animal germ cells. piRNAs are thought to derive from long transcripts spanning transposon-rich genomic loci and to direct an autoamplification loop in which an antisense piRNA, bound to Aubergine or Piwi protein, triggers production of a sense piRNA bound to the PIWI protein Argonaute3 (Ago3). In turn, the new piRNA is envisioned to produce a second antisense piRNA. Here, we describe strong loss-of-function mutations in ago3, allowing a direct genetic test of this model. We find that Ago3 acts to amplify piRNA pools and to enforce on them an antisense bias, increasing the number of piRNAs that can act to silence transposons. We also detect a second, Ago3-independent piRNA pathway centered on Piwi. Transposons targeted by this second pathway often reside in the flamenco locus, which is expressed in somatic ovarian follicle cells, suggesting a role for piRNAs beyond the germline.
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93
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Seitz H. Redefining microRNA targets. Curr Biol 2009; 19:870-3. [PMID: 19375315 DOI: 10.1016/j.cub.2009.03.059] [Citation(s) in RCA: 269] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Revised: 03/23/2009] [Accepted: 03/26/2009] [Indexed: 01/28/2023]
Abstract
Animal microRNAs (miRNAs) guide proteins to repress the translation of target mRNAs via imperfect base pairing between the miRNA and the target. Computational analyses suggest that each miRNA regulates tens or hundreds of targets [1, 2], yet genetic studies usually show that the repression of a few targets plays a physiological role [3-5]. The extent of miRNA-mediated repression (which rarely exceeds 2-fold [1, 2]) is also surprisingly lower than most well-tolerated, intrinsic variations in gene expression [6, 7]. Although miRNA targets are well conserved among closely related species, they differ greatly between more distant animals [8]. The prevailing view is that miRNAs "tune" expression of most of their targets [1, 2]. Here, I propose an alternative hypothesis that could resolve these three paradoxes: many computationally identified miRNA targets may actually be competitive inhibitors of miRNA function, preventing miRNAs from binding their authentic targets by sequestering them. Depending on the prevalence of this type of miRNA:mRNA interaction, this new conception of miRNA regulation could have profound implications on our assumptions about miRNA function.
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94
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Seitz H, Ghildiyal M, Zamore PD. Argonaute loading improves the 5' precision of both MicroRNAs and their miRNA* strands in flies. Curr Biol 2008; 18:147-51. [PMID: 18207740 DOI: 10.1016/j.cub.2007.12.049] [Citation(s) in RCA: 133] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 12/18/2007] [Accepted: 12/19/2007] [Indexed: 10/22/2022]
Abstract
MicroRNAs (miRNAs) are short regulatory RNAs that direct repression of their mRNA targets. The miRNA "seed"-nucleotides 2-7-establishes target specificity by mediating target binding. Accurate processing of the miRNA 5' end is thought to be under strong selective pressure because a shift by just one nucleotide in the 5' end of a miRNA alters its seed sequence, redefining its repertoire of targets (Figure 1). Animal miRNAs are produced by the sequential cleavage of partially double-stranded precursors by the RNase III endonucleases Drosha and Dicer, thereby generating a transitory double-stranded intermediate comprising the miRNA paired to its partially complementary miRNA* strand. Here, we report that in flies, the 5' ends of miRNAs and miRNA* strands are typically more precisely defined than their 3' ends. Surprisingly, the precision of the 5' ends of both miRNA and miRNA* sequences increases after Argonaute2 (Ago2) loading. Our data imply that either many miRNA* sequences are under evolutionary pressure to maintain their seed sequences-that is, they have targets-or that secondary constraints, such as the sequence requirements for loading small RNAs into functional Argonaute complexes, narrow the range of miRNA and miRNA 5' ends that accumulate in flies.
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95
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Ghildiyal M, Seitz H, Horwich MD, Li C, Du T, Lee S, Xu J, Kittler ELW, Zapp ML, Weng Z, Zamore PD. Endogenous siRNAs derived from transposons and mRNAs in Drosophila somatic cells. Science 2008; 320:1077-81. [PMID: 18403677 DOI: 10.1126/science.1157396] [Citation(s) in RCA: 476] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Small interfering RNAs (siRNAs) direct RNA interference (RNAi) in eukaryotes. In flies, somatic cells produce siRNAs from exogenous double-stranded RNA (dsRNA) as a defense against viral infection. We identified endogenous siRNAs (endo-siRNAs), 21 nucleotides in length, that correspond to transposons and heterochromatic sequences in the somatic cells of Drosophila melanogaster. We also detected endo-siRNAs complementary to messenger RNAs (mRNAs); these siRNAs disproportionately mapped to the complementary regions of overlapping mRNAs predicted to form double-stranded RNA in vivo. Normal accumulation of somatic endo-siRNAs requires the siRNA-generating ribonuclease Dicer-2 and the RNAi effector protein Argonaute2 (Ago2). We propose that endo-siRNAs generated by the fly RNAi pathway silence selfish genetic elements in the soma, much as Piwi-interacting RNAs do in the germ line.
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96
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Beismann H, Finck M, Seitz H. Standardisation of methods for GMO Monitoring on a European level. J Verbrauch Lebensm 2008. [DOI: 10.1007/s00003-007-0241-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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97
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Finck M, Seitz H, Beismann H. Concepts for General Surveillance: VDI Proposals Standardisation and Harmonisation in the Field of GMO-Monitoring. J Verbrauch Lebensm 2006. [DOI: 10.1007/s00003-006-0062-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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98
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Abstract
MicroRNAs (miRNAs) are tiny regulators of gene expression that are processed from longer primary transcripts. In this issue, Han et al. (2006) report some of the structural features of the primary transcript that ensure that the Drosha-DGCR8 enzyme complex liberates precisely the correct precursor sequence, enabling production of a fully functional miRNA.
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99
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Kovacs L, Papadopulos N, Kloeppel M, Schwenzer K, Seitz H, Biemer E. Opportunities and Limitations of Computer-Aided Surgical Reconstruction after Complex Facial Burn Injuries. J Reconstr Microsurg 2006. [DOI: 10.1055/s-2006-947886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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100
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Kovacs L, Papadopulos N, Kloeppel M, Schwenzer K, Seitz H, Biemer E. Quality of Life and Patient Satisfaction after Breast Reconstruction: Free TRAM vs. Expansion/Implant. J Reconstr Microsurg 2006. [DOI: 10.1055/s-2006-947945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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