Loqs-PD and R2D2 Define Independent Pathways for RISC Generation in Drosophila

Overview

Journal Nucleic Acids Res

Publisher Oxford University Press

Specialty Biochemistry

Date 2011 Jan 20

PMID 21245036

Citations 46

Authors

Julia V Hartig

Klaus Forstemann

Affiliations

Soon will be listed here.

Abstract

In Drosophila, siRNAs are classified as endo- or exo-siRNAs based on their origin. Both are processed from double-stranded RNA precursors by Dcr-2 and then loaded into the Argonaute protein Ago2. While exo-siRNAs serve to defend the cell against viruses, endo-siRNAs restrict the spread of selfish DNA in somatic cells, analogous to piRNAs in the germ line. Endo- and exo-siRNAs display a differential requirement for double-stranded RNA binding domain proteins (dsRBPs): R2D2 is needed to load exo-siRNAs into Ago2 while the PD isoform of Loquacious (Loqs-PD) stimulates Dcr-2 during the nucleolytic processing of hairpin-derived endo-siRNAs. In cell culture assays, R2D2 antagonizes Loqs-PD in endo-siRNA silencing and Loqs-PD is an inhibitor of RNA interference. Loqs-PD can interact via the C-terminus unique to this isoform with the DExH/D-helicase domain of Drosophila Dcr-2, where binding of R2D2 has also been localized. Separation of the two pathways is not complete; rather, the dicing and Ago2-loading steps appear uncoupled, analogous to the corresponding steps in miRNA biogenesis. Analysis of deep sequencing data further demonstrates that in r2d2 mutant flies, siRNAs can be loaded into Ago2 but not all siRNA classes are equally proficient for this. Thus, the canonical Ago2-RISC loading complex can be bypassed under certain circumstances.

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References

Okamura K, Lai E . Endogenous small interfering RNAs in animals. Nat Rev Mol Cell Biol. 2008; 9(9):673-8. PMC: 2729316. DOI: 10.1038/nrm2479. View

Liu X, Jiang F, Kalidas S, Smith D, Liu Q . Dicer-2 and R2D2 coordinately bind siRNA to promote assembly of the siRISC complexes. RNA. 2006; 12(8):1514-20. PMC: 1524895. DOI: 10.1261/rna.101606. View

Ye X, Paroo Z, Liu Q . Functional anatomy of the Drosophila microRNA-generating enzyme. J Biol Chem. 2007; 282(39):28373-28378. DOI: 10.1074/jbc.M705208200. View

Lee Y, Nakahara K, Pham J, Kim K, He Z, Sontheimer E . Distinct roles for Drosophila Dicer-1 and Dicer-2 in the siRNA/miRNA silencing pathways. Cell. 2004; 117(1):69-81. DOI: 10.1016/s0092-8674(04)00261-2. View

Miyoshi K, Okada T, Siomi H, Siomi M . Characterization of the miRNA-RISC loading complex and miRNA-RISC formed in the Drosophila miRNA pathway. RNA. 2009; 15(7):1282-91. PMC: 2704077. DOI: 10.1261/rna.1541209. View

Brennecke J, Aravin A, Stark A, Dus M, Kellis M, Sachidanandam R . Discrete small RNA-generating loci as master regulators of transposon activity in Drosophila. Cell. 2007; 128(6):1089-103. DOI: 10.1016/j.cell.2007.01.043. View

Forstemann K . Transposon defense in Drosophila somatic cells: a model for distinction of self and non-self in the genome. RNA Biol. 2010; 7(2):158-61. DOI: 10.4161/rna.7.2.11059. View

Kawamura Y, Saito K, Kin T, Ono Y, Asai K, Sunohara T . Drosophila endogenous small RNAs bind to Argonaute 2 in somatic cells. Nature. 2008; 453(7196):793-7. DOI: 10.1038/nature06938. View

Okamura K, Robine N, Liu Y, Liu Q, Lai E . R2D2 organizes small regulatory RNA pathways in Drosophila. Mol Cell Biol. 2010; 31(4):884-96. PMC: 3028645. DOI: 10.1128/MCB.01141-10. View

10.

Haase A, Jaskiewicz L, Zhang H, Laine S, Sack R, Gatignol A . TRBP, a regulator of cellular PKR and HIV-1 virus expression, interacts with Dicer and functions in RNA silencing. EMBO Rep. 2005; 6(10):961-7. PMC: 1369185. DOI: 10.1038/sj.embor.7400509. View

11.

Lim D, Kim J, Kim S, Carthew R, Lee Y . Functional analysis of dicer-2 missense mutations in the siRNA pathway of Drosophila. Biochem Biophys Res Commun. 2008; 371(3):525-30. PMC: 2924196. DOI: 10.1016/j.bbrc.2008.04.118. View

12.

Blumenstiel J, Hartl D . Evidence for maternally transmitted small interfering RNA in the repression of transposition in Drosophila virilis. Proc Natl Acad Sci U S A. 2005; 102(44):15965-70. PMC: 1276106. DOI: 10.1073/pnas.0508192102. View

13.

Liu Q, Rand T, Kalidas S, Du F, Kim H, Smith D . R2D2, a bridge between the initiation and effector steps of the Drosophila RNAi pathway. Science. 2003; 301(5641):1921-5. DOI: 10.1126/science.1088710. View

14.

Le T, Yu M, Williams B, Goel S, Paul S, Beitel G . CaSpeR5, a family of Drosophila transgenesis and shuttle vectors with improved multiple cloning sites. Biotechniques. 2007; 42(2):164, 166. PMC: 1955475. DOI: 10.2144/000112386. View

15.

Park J, Liu X, Strauss T, McKearin D, Liu Q . The miRNA pathway intrinsically controls self-renewal of Drosophila germline stem cells. Curr Biol. 2007; 17(6):533-8. DOI: 10.1016/j.cub.2007.01.060. View

16.

Forstemann K, Horwich M, Wee L, Tomari Y, Zamore P . Drosophila microRNAs are sorted into functionally distinct argonaute complexes after production by dicer-1. Cell. 2007; 130(2):287-97. PMC: 2686109. DOI: 10.1016/j.cell.2007.05.056. View

17.

Lipardi C, Paterson B . Identification of an RNA-dependent RNA polymerase in Drosophila involved in RNAi and transposon suppression. Proc Natl Acad Sci U S A. 2009; 106(37):15645-50. PMC: 2736140. DOI: 10.1073/pnas.0904984106. View

18.

Daher A, Longuet M, Dorin D, Bois F, Segeral E, Bannwarth S . Two dimerization domains in the trans-activation response RNA-binding protein (TRBP) individually reverse the protein kinase R inhibition of HIV-1 long terminal repeat expression. J Biol Chem. 2001; 276(36):33899-905. DOI: 10.1074/jbc.M103584200. View

19.

Kim V, Han J, Siomi M . Biogenesis of small RNAs in animals. Nat Rev Mol Cell Biol. 2009; 10(2):126-39. DOI: 10.1038/nrm2632. View

20.

Marques J, Kim K, Wu P, Alleyne T, Jafari N, Carthew R . Loqs and R2D2 act sequentially in the siRNA pathway in Drosophila. Nat Struct Mol Biol. 2009; 17(1):24-30. PMC: 2919300. DOI: 10.1038/nsmb.1735. View