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The mechanism of RNAi assembly andsi...

Colmenares, Serafin Uro, III.

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The mechanism of RNAi assembly andsiRNA generation in fission yeast centromeres.

Record Type:	Language materials, printed : Monograph/item
Title/Author:	The mechanism of RNAi assembly andsiRNA generation in fission yeast centromeres./
Author:	Colmenares, Serafin Uro, III.
Description:	134 p.
Notes:	Adviser: Danesh Moazed.
Contained By:	Dissertation Abstracts International68-05B.
Subject:	Biology, Cell. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3264935
ISBN:	9780549035558

The mechanism of RNAi assembly andsiRNA generation in fission yeast centromeres.
Colmenares, Serafin Uro, III.

The mechanism of RNAi assembly andsiRNA generation in fission yeast centromeres. - 134 p.

Adviser: Danesh Moazed.

Thesis (Ph.D.)--Harvard University, 2007.

RNA interference, or RNAi, is a highly-conserved gene silencing mechanism mediated by base-pairing interactions of small, interfering RNAs, or siRNAs, to specifically target homologous gene products. This mechanism has been adapted to regulate diverse cellular processes through degradation or translational inhibition of mRNAs in a post-transcriptional manner or by recruitment of a transcriptionally-repressive heterochromatic structure. In fission yeast, centromere function requires RNAi components Ago1 (Argonaute), Dcr1 (Dicer), and Rdp1 (RNA-dependent RNA polymerase) that drive formation of heterochromatin structure at pericentric regions. The identification of Ago1 and the heterochromatic protein Chp1 as components of the RNA-induced Initiation of Transcriptional gene Silencing complex (RITS) provided the first physical evidence directly linking heterochromatin with RNAi. Recruitment of the RITS complex is a prerequisite for efficient dimethylation of histone H3 lysine 9 and localization of heterochromatic structural proteins like the HP1 homolog Swi6 that are absolutely required for heterochromatin formation in fission yeast. Initiation of heterochromatin assembly requires bi-directional transcription of centromeric domains that provide precursors for siRNA synthesis. However, the mechanisms of Rdp1 and Dcr1 function in this pathway and their coordination with RITS activity remain largely unknown. This study describes the purification of the RDRC, or RNA-dependent RNA polymerase complex, that contains Rdp1, a putative helicase Hrr1, and a poly-A polymerase member Cid12. RDRC, RITS, and Dcr1, are shown to interact whereas non-coding centromeric RNAs are implicated as assembly platforms for RNAi complexes. Finally, siRNA generation by Dcr1 and double-stranded RNA synthesis by RDRC are reconstituted in vitro and shown to be coupled processes. The findings of this study define mechanisms of double-stranded RNA formation and siRNA generation central to RNAi in a transcriptional mode of gene silencing.

ISBN: 9780549035558Subjects--Topical Terms:

1017686
Biology, Cell.

The mechanism of RNAi assembly andsiRNA generation in fission yeast centromeres.
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035 $a (UMI)AAI3264935
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100 1 $a Colmenares, Serafin Uro, III. $3 1285757
245 1 4 $a The mechanism of RNAi assembly andsiRNA generation in fission yeast centromeres.
300 $a 134 p.
500 $a Adviser: Danesh Moazed.
500 $a Source: Dissertation Abstracts International, Volume: 68-05, Section: B, page: 2755.
502 $a Thesis (Ph.D.)--Harvard University, 2007.
520 $a RNA interference, or RNAi, is a highly-conserved gene silencing mechanism mediated by base-pairing interactions of small, interfering RNAs, or siRNAs, to specifically target homologous gene products. This mechanism has been adapted to regulate diverse cellular processes through degradation or translational inhibition of mRNAs in a post-transcriptional manner or by recruitment of a transcriptionally-repressive heterochromatic structure. In fission yeast, centromere function requires RNAi components Ago1 (Argonaute), Dcr1 (Dicer), and Rdp1 (RNA-dependent RNA polymerase) that drive formation of heterochromatin structure at pericentric regions. The identification of Ago1 and the heterochromatic protein Chp1 as components of the RNA-induced Initiation of Transcriptional gene Silencing complex (RITS) provided the first physical evidence directly linking heterochromatin with RNAi. Recruitment of the RITS complex is a prerequisite for efficient dimethylation of histone H3 lysine 9 and localization of heterochromatic structural proteins like the HP1 homolog Swi6 that are absolutely required for heterochromatin formation in fission yeast. Initiation of heterochromatin assembly requires bi-directional transcription of centromeric domains that provide precursors for siRNA synthesis. However, the mechanisms of Rdp1 and Dcr1 function in this pathway and their coordination with RITS activity remain largely unknown. This study describes the purification of the RDRC, or RNA-dependent RNA polymerase complex, that contains Rdp1, a putative helicase Hrr1, and a poly-A polymerase member Cid12. RDRC, RITS, and Dcr1, are shown to interact whereas non-coding centromeric RNAs are implicated as assembly platforms for RNAi complexes. Finally, siRNA generation by Dcr1 and double-stranded RNA synthesis by RDRC are reconstituted in vitro and shown to be coupled processes. The findings of this study define mechanisms of double-stranded RNA formation and siRNA generation central to RNAi in a transcriptional mode of gene silencing.
590 $a School code: 0084.
650 4 $a Biology, Cell. $3 1017686
650 4 $a Biology, Genetics. $3 1017730
650 4 $a Chemistry, Biochemistry. $3 1017722
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710 2 $a Harvard University. $3 528741
773 0 $t Dissertation Abstracts International $g 68-05B.
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791 $a Ph.D.
792 $a 2007
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3264935