The lin-35/ Rb and RNAi pathways cooperate to regulate a key cell cycle transition in C. elegans

BMC Developmental Biology - Tập 7 Số 1 - Trang 1-16 - 2007
Ouellet, Jimmy1, Roy, Richard1
1Department of Biology, McGill University, Montréal, Canada

Tóm tắt

The Retinoblastoma gene product (Rb) has been shown to regulate the transcription of key genes involved in cell growth and proliferation. Consistent with this, mutations in Rb are associated with numerous types of cancer making it a critical tumour suppressor gene. Its function is conferred through a large multiprotein complex that exhibits a dual function in both activation and repression of gene targets. In C. elegans, the Rb orthologue lin-35 functions redundantly with other transcriptional regulators to appropriately specify both vulval and pharyngeal cell fates. In C. elegans the intestinal cells must alter their cell cycle from the mitotic cell divisions typical of embryogenesis to karyokinesis and then endoreplication, which facilitates growth during larval development. While screening for genes that affect the ability of the intestinal cells to appropriately make this cell cycle transition during post-embryonic development, we isolated mutants that either compromise this switch and remain mononucleate, or cause these cells to undergo multiple rounds of nuclear division. Among these mutants we identified a novel allele of lin-35/Rb, while we also found that the components of the synMuv B complex, which are involved in vulval specification, are also required to properly regulate the developmentally-controlled cell cycle transition typical of these intestinal cells during larval development. More importantly, our work uncovered a role for certain members of the pathways involved in RNAi in mediating the efficient transition between these cell cycle programs, suggesting that lin-35/Rb cooperates with these RNAi components. Furthermore, our findings suggest that met-2, a methyltransferase as well as hpl-1 and hpl-2, two C. elegans homologues of the heterochromatin protein HP1 are also required for this transition. Our findings are consistent with lin-35/Rb, synMuv and RNAi components cooperating, probably through their additive effects on chromatin modification, to appropriately modulate the expression of genes that are required to switch from the karyokinesis cell cycle to endoreplication; a highly specified growth pathway in the intestinal epithelium. The lin-35/Rb repressor complex may be required to initiate this process, while components of the RNAi machinery positively reinforce this repression.

Tài liệu tham khảo

citation_journal_title=Cell Cycle; citation_title=The restriction point of the cell cycle; citation_author=MV Blagosklonny, AB Pardee; citation_volume=1; citation_issue=2; citation_publication_date=2002; citation_pages=103-110; citation_doi=10.4161/cc.1.2.108; citation_id=CR1 citation_journal_title=Science; citation_title=Human retinoblastoma susceptibility gene: cloning, identification, and sequence; citation_author=WH Lee, R Bookstein, F Hong, LJ Young, JY Shew, EY Lee; citation_volume=235; citation_issue=4794; citation_publication_date=1987; citation_pages=1394-1399; citation_doi=10.1126/science.3823889; citation_id=CR2 citation_journal_title=Oncogene; citation_title=RB and cell cycle progression; citation_author=C Giacinti, A Giordano; citation_volume=25; citation_issue=38; citation_publication_date=2006; citation_pages=5220-5227; citation_doi=10.1038/sj.onc.1209615; citation_id=CR3 citation_journal_title=Mol Cell Biol; citation_title=RRB1 and RRB2 encode maize retinoblastoma-related proteins that interact with a plant D-type cyclin and geminivirus replication protein; citation_author=RA Ach, T Durfee, AB Miller, P Taranto, L Hanley-Bowdoin, PC Zambryski, W Gruissem; citation_volume=17; citation_issue=9; citation_publication_date=1997; citation_pages=5077-5086; citation_doi=10.1128/MCB.17.9.5077; citation_id=CR4 citation_journal_title=Genes Dev; citation_title=RBF, a novel RB-related gene that regulates E2F activity and interacts with cyclin E in Drosophila; citation_author=W Du, M Vidal, JE Xie, N Dyson; citation_volume=10; citation_issue=10; citation_publication_date=1996; citation_pages=1206-1218; citation_doi=10.1101/gad.10.10.1206; citation_id=CR5 citation_journal_title=Cell; citation_title=lin-35 and lin-53, two genes that antagonize a C. elegans Ras pathway, encode proteins similar to Rb and its binding protein RbAp48; citation_author=X Lu, HR Horvitz; citation_volume=95; citation_issue=7; citation_publication_date=1998; citation_pages=981-991; citation_doi=10.1016/S0092-8674(00)81722-5; citation_id=CR6 citation_journal_title=Oncogene; citation_title=Retinoblastoma family genes; citation_author=W Du, J Pogoriler; citation_volume=25; citation_issue=38; citation_publication_date=2006; citation_pages=5190-5200; citation_doi=10.1038/sj.onc.1209651; citation_id=CR7 citation_journal_title=Oncogene; citation_title=RB, the conductor that orchestrates life, death and differentiation; citation_author=L Khidr, PL Chen; citation_volume=25; citation_issue=38; citation_publication_date=2006; citation_pages=5210-5219; citation_doi=10.1038/sj.onc.1209612; citation_id=CR8 citation_title=E2F-Rb complexes regulating transcription of genes important for differentiation and development; citation_inbook_title=Curr Opin Genet Dev; citation_publication_date=2005; citation_id=CR9; citation_author=M Korenjak; citation_author=A Brehm citation_journal_title=Nature; citation_title=Requirement for a functional Rb-1 gene in murine development; citation_author=AR Clarke, ER Maandag, M van Roon, NM van der Lugt, M van der Valk, ML Hooper, A Berns, H te Riele; citation_volume=359; citation_issue=6393; citation_publication_date=1992; citation_pages=328-330; citation_doi=10.1038/359328a0; citation_id=CR10 citation_journal_title=Nature; citation_title=Effects of an Rb mutation in the mouse; citation_author=T Jacks, A Fazeli, EM Schmitt, RT Bronson, MA Goodell, RA Weinberg; citation_volume=359; citation_issue=6393; citation_publication_date=1992; citation_pages=295-300; citation_doi=10.1038/359295a0; citation_id=CR11 citation_journal_title=Nature; citation_title=Mice deficient for Rb are nonviable and show defects in neurogenesis and haematopoiesis; citation_author=EY Lee, CY Chang, N Hu, YC Wang, CC Lai, K Herrup, WH Lee, A Bradley; citation_volume=359; citation_issue=6393; citation_publication_date=1992; citation_pages=288-294; citation_doi=10.1038/359288a0; citation_id=CR12 citation_journal_title=Genes Dev; citation_title=Cell cycle-dependent and cell cycle-independent control of transcription by the Drosophila E2F/RB pathway; citation_author=DK Dimova, O Stevaux, MV Frolov, NJ Dyson; citation_volume=17; citation_issue=18; citation_publication_date=2003; citation_pages=2308-2320; citation_doi=10.1101/gad.1116703; citation_id=CR13 citation_journal_title=Development; citation_title=lin-35/Rb and ubc-18, an E2 ubiquitin-conjugating enzyme, function redundantly to control pharyngeal morphogenesis in C. elegans; citation_author=DS Fay, E Large, M Han, M Darland; citation_volume=130; citation_issue=14; citation_publication_date=2003; citation_pages=3319-3330; citation_doi=10.1242/dev.00561; citation_id=CR14 citation_journal_title=Dev Biol; citation_title=The coordinate regulation of pharyngeal development in C. elegans by lin-35/Rb, pha-1, and ubc-18; citation_author=DS Fay, X Qiu, E Large, CP Smith, S Mango, BL Johanson; citation_volume=271; citation_issue=1; citation_publication_date=2004; citation_pages=11-25; citation_doi=10.1016/j.ydbio.2004.03.022; citation_id=CR15 citation_journal_title=Dev Cell; citation_title=SynMuv genes redundantly inhibit lin-3/EGF expression to prevent inappropriate vulval induction in C. elegans; citation_author=M Cui, J Chen, TR Myers, BJ Hwang, PW Sternberg, I Greenwald, M Han; citation_volume=10; citation_issue=5; citation_publication_date=2006; citation_pages=667-672; citation_doi=10.1016/j.devcel.2006.04.001; citation_id=CR16 citation_journal_title=Dev Cell; citation_title=lin-35 Rb acts in the major hypodermis to oppose ras-mediated vulval induction in C. elegans; citation_author=TR Myers, I Greenwald; citation_volume=8; citation_issue=1; citation_publication_date=2005; citation_pages=117-123; citation_doi=10.1016/j.devcel.2004.11.015; citation_id=CR17 citation_journal_title=Genes Dev; citation_title=synMuv verite--Myb comes into focus; citation_author=JS Lipsick; citation_volume=18; citation_issue=23; citation_publication_date=2004; citation_pages=2837-2844; citation_doi=10.1101/gad.1274804; citation_id=CR18 citation_journal_title=Genesis; citation_title=The synthetic multivulval genes of C. elegans: functional redundancy, Ras-antagonism, and cell fate determination; citation_author=DS Fay, M Han; citation_volume=26; citation_issue=4; citation_publication_date=2000; citation_pages=279-284; citation_doi=10.1002/(SICI)1526-968X(200004)26:4<279::AID-GENE100>3.0.CO;2-C; citation_id=CR19 citation_journal_title=Mol Cell; citation_title=dpl-1 DP and efl-1 E2F act with lin-35 Rb to antagonize Ras signaling in C. elegans vulval development; citation_author=CJ Ceol, HR Horvitz; citation_volume=7; citation_issue=3; citation_publication_date=2001; citation_pages=461-473; citation_doi=10.1016/S1097-2765(01)00194-0; citation_id=CR20 citation_journal_title=J Cell Sci; citation_title=Molecular mechanisms of E2F-dependent activation and pRB-mediated repression; citation_author=MV Frolov, NJ Dyson; citation_volume=117; citation_issue=Pt 11; citation_publication_date=2004; citation_pages=2173-2181; citation_doi=10.1242/jcs.01227; citation_id=CR21 citation_journal_title=Genes Dev; citation_title=Identification of a Drosophila Myb-E2F2/RBF transcriptional repressor complex; citation_author=PW Lewis, EL Beall, TC Fleischer, D Georlette, AJ Link, MR Botchan; citation_volume=18; citation_issue=23; citation_publication_date=2004; citation_pages=2929-2940; citation_doi=10.1101/gad.1255204; citation_id=CR22 citation_journal_title=Cell; citation_title=Native E2F/RBF complexes contain Myb-interacting proteins and repress transcription of developmentally controlled E2F target genes; citation_author=M Korenjak, B Taylor-Harding, UK Binne, JS Satterlee, O Stevaux, R Aasland, H White-Cooper, N Dyson, A Brehm; citation_volume=119; citation_issue=2; citation_publication_date=2004; citation_pages=181-193; citation_doi=10.1016/j.cell.2004.09.034; citation_id=CR23 citation_journal_title=Mol Cell Biol; citation_title=Transcriptional repression by the retinoblastoma protein through the recruitment of a histone methyltransferase; citation_author=L Vandel, E Nicolas, O Vaute, R Ferreira, S Ait-Si-Ali, D Trouche; citation_volume=21; citation_issue=19; citation_publication_date=2001; citation_pages=6484-6494; citation_doi=10.1128/MCB.21.19.6484-6494.2001; citation_id=CR24 citation_journal_title=Nat Rev Mol Cell Biol; citation_title=HP1 and the dynamics of heterochromatin maintenance; citation_author=C Maison, G Almouzni; citation_volume=5; citation_issue=4; citation_publication_date=2004; citation_pages=296-304; citation_doi=10.1038/nrm1355; citation_id=CR25 citation_journal_title=Proc Natl Acad Sci U S A; citation_title=Does heterochromatin protein 1 always follow code?; citation_author=Y Li, DA Kirschmann, LL Wallrath; citation_volume=99 Suppl 4; citation_publication_date=2002; citation_pages=16462-16469; citation_doi=10.1073/pnas.162371699; citation_id=CR26 citation_journal_title=Development; citation_title=lin-35 Rb and cki-1 Cip/Kip cooperate in developmental regulation of G1 progression in C. elegans; citation_author=M Boxem, S van den Heuvel; citation_volume=128; citation_issue=21; citation_publication_date=2001; citation_pages=4349-4359; citation_id=CR27 citation_journal_title=Curr Biol; citation_title=C. elegans class B synthetic multivulva genes act in G(1) regulation; citation_author=M Boxem, S van den Heuvel; citation_volume=12; citation_issue=11; citation_publication_date=2002; citation_pages=906-911; citation_doi=10.1016/S0960-9822(02)00844-8; citation_id=CR28 citation_journal_title=Development; citation_title=Developmental regulation of a cyclin-dependent kinase inhibitor controls postembryonic cell cycle progression in Caenorhabditis elegans; citation_author=Y Hong, R Roy, V Ambros; citation_volume=125; citation_issue=18; citation_publication_date=1998; citation_pages=3585-3597; citation_id=CR29 citation_journal_title=Development; citation_title=Organ-specific cell division abnormalities caused by mutation in a general cell cycle regulator in C. elegans; citation_author=I Kostic, R Roy; citation_volume=129; citation_issue=9; citation_publication_date=2002; citation_pages=2155-2165; citation_id=CR30 citation_journal_title=Science; citation_title=Systematic genetic analysis with ordered arrays of yeast deletion mutants; citation_author=AH Tong, M Evangelista, AB Parsons, H Xu, GD Bader, N Page, M Robinson, S Raghibizadeh, CW Hogue, H Bussey, B Andrews, M Tyers, C Boone; citation_volume=294; citation_issue=5550; citation_publication_date=2001; citation_pages=2364-2368; citation_doi=10.1126/science.1065810; citation_id=CR31 citation_journal_title=Genes Dev; citation_title=A complex of LIN-5 and GPR proteins regulates G protein signaling and spindle function in C elegans; citation_author=DG Srinivasan, RM Fisk, H Xu, S van den Heuvel; citation_volume=17; citation_issue=10; citation_publication_date=2003; citation_pages=1225-1239; citation_doi=10.1101/gad.1081203; citation_id=CR32 citation_journal_title=Nature; citation_title=Functional genomic analysis of C. elegans chromosome I by systematic RNA interference; citation_author=AG Fraser, RS Kamath, P Zipperlen, M Martinez-Campos, M Sohrmann, J Ahringer; citation_volume=408; citation_issue=6810; citation_publication_date=2000; citation_pages=325-330; citation_doi=10.1038/35042517; citation_id=CR33 citation_journal_title=Genetics; citation_title=lin-8, which antagonizes C. elegans Ras-mediated vulval induction, encodes a novel nuclear protein that interacts with the LIN-35 Rb protein; citation_author=EM Davison, MM Harrison, AJ Walhout, M Vidal, B Horvitz; citation_volume=171; citation_issue=3; citation_publication_date=2005; citation_pages=1017-31; citation_doi=10.1534/genetics.104.034173; citation_id=CR34 citation_journal_title=Proc Natl Acad Sci U S A; citation_title=Negative regulation of nuclear divisions in Caenorhabditis elegans by retinoblastoma and RNA interference-related genes; citation_author=A Grishok, PA Sharp; citation_volume=102; citation_issue=48; citation_publication_date=2005; citation_pages=17360-17365; citation_doi=10.1073/pnas.0508989102; citation_id=CR35 citation_journal_title=Trends Genet; citation_title=Stop making nonSense: the C. elegans smg genes; citation_author=SE Mango; citation_volume=17; citation_issue=11; citation_publication_date=2001; citation_pages=646-653; citation_doi=10.1016/S0168-9525(01)02479-9; citation_id=CR36 citation_journal_title=Embo J; citation_title=E2Fs link the control of G1/S and G2/M transcription; citation_author=W Zhu, PH Giangrande, JR Nevins; citation_volume=23; citation_issue=23; citation_publication_date=2004; citation_pages=4615-4626; citation_doi=10.1038/sj.emboj.7600459; citation_id=CR37 citation_journal_title=Gene; citation_title=Linking cyclins to transcriptional control; citation_author=O Coqueret; citation_volume=299; citation_issue=1-2; citation_publication_date=2002; citation_pages=35-55; citation_doi=10.1016/S0378-1119(02)01055-7; citation_id=CR38 citation_journal_title=Genes Dev; citation_title=The Rb/E2F pathway: expanding roles and emerging paradigms; citation_author=JW Harbour, DC Dean; citation_volume=14; citation_issue=19; citation_publication_date=2000; citation_pages=2393-2409; citation_doi=10.1101/gad.813200; citation_id=CR39 citation_journal_title=Curr Opin Cell Biol; citation_title=A revised picture of the E2F transcriptional network and RB function; citation_author=O Stevaux, NJ Dyson; citation_volume=14; citation_issue=6; citation_publication_date=2002; citation_pages=684-691; citation_doi=10.1016/S0955-0674(02)00388-5; citation_id=CR40 citation_journal_title=Mol Cell Biol; citation_title=Functional inactivation of the retinoblastoma protein requires sequential modification by at least two distinct cyclin-cdk complexes; citation_author=AS Lundberg, RA Weinberg; citation_volume=18; citation_issue=2; citation_publication_date=1998; citation_pages=753-761; citation_doi=10.1128/MCB.18.2.753; citation_id=CR41 citation_journal_title=Cell; citation_title=Cdk phosphorylation triggers sequential intramolecular interactions that progressively block Rb functions as cells move through G1; citation_author=JW Harbour, RX Luo, A Dei Santi, AA Postigo, DC Dean; citation_volume=98; citation_issue=6; citation_publication_date=1999; citation_pages=859-869; citation_doi=10.1016/S0092-8674(00)81519-6; citation_id=CR42 citation_journal_title=Development; citation_title=Drosophila myb exerts opposing effects on S phase, promoting proliferation and suppressing endoreduplication; citation_author=CA Fitzpatrick, NV Sharkov, G Ramsay, AL Katzen; citation_volume=129; citation_issue=19; citation_publication_date=2002; citation_pages=4497-4507; citation_id=CR43 citation_journal_title=Cell; citation_title=Exit from G1 and S phase of the cell cycle is regulated by repressor complexes containing HDAC-Rb-hSWI/SNF and Rb-hSWI/SNF; citation_author=HS Zhang, M Gavin, A Dahiya, AA Postigo, D Ma, RX Luo, JW Harbour, DC Dean; citation_volume=101; citation_issue=1; citation_publication_date=2000; citation_pages=79-89; citation_doi=10.1016/S0092-8674(00)80625-X; citation_id=CR44 citation_journal_title=Curr Biol; citation_title=Fluctuations in cyclin E levels are required for multiple rounds of endocycle S phase in Drosophila; citation_author=PJ Follette, RJ Duronio, PH O'Farrell; citation_volume=8; citation_issue=4; citation_publication_date=1998; citation_pages=235-238; citation_doi=10.1016/S0960-9822(98)70089-2; citation_id=CR45 citation_journal_title=Cell; citation_title=Endoreplication cell cycles: more for less; citation_author=BA Edgar, TL Orr-Weaver; citation_volume=105; citation_issue=3; citation_publication_date=2001; citation_pages=297-306; citation_doi=10.1016/S0092-8674(01)00334-8; citation_id=CR46 citation_journal_title=Development; citation_title=Dp1 is required for extra-embryonic development; citation_author=MJ Kohn, RT Bronson, E Harlow, NJ Dyson, L Yamasaki; citation_volume=130; citation_issue=7; citation_publication_date=2003; citation_pages=1295-1305; citation_doi=10.1242/dev.00355; citation_id=CR47 citation_journal_title=Plant Cell; citation_title=The balance between cell division and endoreplication depends on E2FC-DPB, transcription factors regulated by the ubiquitin-SCFSKP2A pathway in Arabidopsis; citation_author=JC del Pozo, S Diaz-Trivino, N Cisneros, C Gutierrez; citation_volume=18; citation_issue=9; citation_publication_date=2006; citation_pages=2224-2235; citation_doi=10.1105/tpc.105.039651; citation_id=CR48 citation_journal_title=Nature; citation_title=Extra-embryonic function of Rb is essential for embryonic development and viability; citation_author=L Wu, A de Bruin, HI Saavedra, M Starovic, A Trimboli, Y Yang, J Opavska, P Wilson, JC Thompson, MC Ostrowski, TJ Rosol, LA Woollett, M Weinstein, JC Cross, ML Robinson, G Leone; citation_volume=421; citation_issue=6926; citation_publication_date=2003; citation_pages=942-947; citation_doi=10.1038/nature01417; citation_id=CR49 citation_journal_title=Embo J; citation_title=Critical role of active repression by E2F and Rb proteins in endoreplication during Drosophila development; citation_author=L Weng, C Zhu, J Xu, W Du; citation_volume=22; citation_issue=15; citation_publication_date=2003; citation_pages=3865-3875; citation_doi=10.1093/emboj/cdg373; citation_id=CR50 citation_journal_title=Curr Opin Genet Dev; citation_title=Control of developmental timing in Caenorhabditis elegans; citation_author=V Ambros; citation_volume=10; citation_issue=4; citation_publication_date=2000; citation_pages=428-433; citation_doi=10.1016/S0959-437X(00)00108-8; citation_id=CR51 citation_journal_title=Cell; citation_title=MicroRNA pathways in flies and worms: growth, death, fat, stress, and timing; citation_author=V Ambros; citation_volume=113; citation_issue=6; citation_publication_date=2003; citation_pages=673-676; citation_doi=10.1016/S0092-8674(03)00428-8; citation_id=CR52 citation_journal_title=Trends Genet; citation_title=Heterochronic genes and the temporal control of C. elegans development; citation_author=V Ambros, EG Moss; citation_volume=10; citation_issue=4; citation_publication_date=1994; citation_pages=123-127; citation_doi=10.1016/0168-9525(94)90213-5; citation_id=CR53 citation_journal_title=Annu Rev Genet; citation_title=Temporal pattern formation by heterochronic genes; citation_author=F Slack, G Ruvkun; citation_volume=31; citation_publication_date=1997; citation_pages=611-634; citation_doi=10.1146/annurev.genet.31.1.611; citation_id=CR54 citation_journal_title=Biol Bull; citation_title=Heterochronic genes in development and evolution; citation_author=F Slack, G Ruvkun; citation_volume=195; citation_issue=3; citation_publication_date=1998; citation_pages=375-376; citation_doi=10.2307/1543152; citation_id=CR55 citation_journal_title=Mol Cell Biol; citation_title=Structure and function analysis of LIN-14, a temporal regulator of postembryonic developmental events in Caenorhabditis elegans; citation_author=Y Hong, RC Lee, V Ambros; citation_volume=20; citation_issue=6; citation_publication_date=2000; citation_pages=2285-2295; citation_doi=10.1128/MCB.20.6.2285-2295.2000; citation_id=CR56 citation_journal_title=Dev Biol; citation_title=The lin-4 regulatory RNA controls developmental timing in Caenorhabditis elegans by blocking LIN-14 protein synthesis after the initiation of translation; citation_author=PH Olsen, V Ambros; citation_volume=216; citation_issue=2; citation_publication_date=1999; citation_pages=671-680; citation_doi=10.1006/dbio.1999.9523; citation_id=CR57 citation_journal_title=Dev Biol; citation_title=The timing of lin-4 RNA accumulation controls the timing of postembryonic developmental events in Caenorhabditis elegans; citation_author=R Feinbaum, V Ambros; citation_volume=210; citation_issue=1; citation_publication_date=1999; citation_pages=87-95; citation_doi=10.1006/dbio.1999.9272; citation_id=CR58 citation_journal_title=Cell; citation_title=Posttranscriptional regulation of the heterochronic gene lin-14 by lin-4 mediates temporal pattern formation in C. elegans; citation_author=B Wightman, I Ha, G Ruvkun; citation_volume=75; citation_issue=5; citation_publication_date=1993; citation_pages=855-862; citation_doi=10.1016/0092-8674(93)90530-4; citation_id=CR59 citation_journal_title=Cell; citation_title=Genes and mechanisms related to RNA interference regulate expression of the small temporal RNAs that control C. elegans developmental timing; citation_author=A Grishok, AE Pasquinelli, D Conte, N Li, S Parrish, I Ha, DL Baillie, A Fire, G Ruvkun, CC Mello; citation_volume=106; citation_issue=1; citation_publication_date=2001; citation_pages=23-34; citation_doi=10.1016/S0092-8674(01)00431-7; citation_id=CR60 citation_journal_title=Cell; citation_title=Functional proteomics reveals the biochemical niche of C. elegans DCR-1 in multiple small-RNA-mediated pathways; citation_author=TF Duchaine, JA Wohlschlegel, S Kennedy, Y Bei, D Conte, K Pang, DR Brownell, S Harding, S Mitani, G Ruvkun, JR Yates, CC Mello; citation_volume=124; citation_issue=2; citation_publication_date=2006; citation_pages=343-354; citation_doi=10.1016/j.cell.2005.11.036; citation_id=CR61 citation_journal_title=Cell; citation_title=Mut-7 of C. elegans, required for transposon silencing and RNA interference, is a homolog of Werner syndrome helicase and RNaseD; citation_author=RF Ketting, TH Haverkamp, HG van Luenen, RH Plasterk; citation_volume=99; citation_issue=2; citation_publication_date=1999; citation_pages=133-141; citation_doi=10.1016/S0092-8674(00)81645-1; citation_id=CR62 citation_journal_title=Genes Dev; citation_title=Transcriptional silencing of a transgene by RNAi in the soma of C. elegans; citation_author=A Grishok, JL Sinskey, PA Sharp; citation_volume=19; citation_issue=6; citation_publication_date=2005; citation_pages=683-696; citation_doi=10.1101/gad.1247705; citation_id=CR63 citation_journal_title=Chromosome Res; citation_title=The roles of histone modifications and small RNA in centromere function; citation_author=K Ekwall; citation_volume=12; citation_issue=6; citation_publication_date=2004; citation_pages=535-542; citation_doi=10.1023/B:CHRO.0000036584.40567.e5; citation_id=CR64 citation_journal_title=Science; citation_title=RNA polymerase II is required for RNAi-dependent heterochromatin assembly; citation_author=H Kato, DB Goto, RA Martienssen, T Urano, K Furukawa, Y Murakami; citation_volume=309; citation_issue=5733; citation_publication_date=2005; citation_pages=467-469; citation_doi=10.1126/science.1114955; citation_id=CR65 citation_journal_title=Science; citation_title=Regulation of heterochromatic silencing and histone H3 lysine-9 methylation by RNAi; citation_author=TA Volpe, C Kidner, IM Hall, G Teng, SI Grewal, RA Martienssen; citation_volume=297; citation_issue=5588; citation_publication_date=2002; citation_pages=1833-1837; citation_doi=10.1126/science.1074973; citation_id=CR66 citation_journal_title=Nature; citation_title=The role of RNA interference in heterochromatic silencing; citation_author=Z Lippman, R Martienssen; citation_volume=431; citation_issue=7006; citation_publication_date=2004; citation_pages=364-370; citation_doi=10.1038/nature02875; citation_id=CR67 citation_journal_title=Genetica; citation_title=SU(VAR)3-9 is a conserved key function in heterochromatic gene silencing; citation_author=G Schotta, A Ebert, G Reuter; citation_volume=117; citation_issue=2-3; citation_publication_date=2003; citation_pages=149-158; citation_doi=10.1023/A:1022923508198; citation_id=CR68 citation_journal_title=EMBO Rep; citation_title=A heterochromatin protein 1 homologue in Caenorhabditis elegans acts in germline and vulval development; citation_author=F Couteau, F Guerry, F Muller, F Palladino; citation_volume=3; citation_issue=3; citation_publication_date=2002; citation_pages=235-241; citation_doi=10.1093/embo-reports/kvf051; citation_id=CR69 citation_journal_title=Embo J; citation_title=Chromatin regulation and sumoylation in the inhibition of Ras-induced vulval development in Caenorhabditis elegans; citation_author=G Poulin, Y Dong, AG Fraser, NA Hopper, J Ahringer; citation_volume=24; citation_issue=14; citation_publication_date=2005; citation_pages=2613-2623; citation_doi=10.1038/sj.emboj.7600726; citation_id=CR70 citation_journal_title=Genome Biol; citation_title=Loss of LIN-35, the Caenorhabditis elegans ortholog of the tumor suppressor p105Rb, results in enhanced RNA interference; citation_author=B Lehner, A Calixto, C Crombie, J Tischler, A Fortunato, M Chalfie, AG Fraser; citation_volume=7; citation_issue=1; citation_publication_date=2006; citation_pages=R4; citation_doi=10.1186/gb-2006-7-1-r4; citation_id=CR71 citation_journal_title=Nature; citation_title=Somatic misexpression of germline P granules and enhanced RNA interference in retinoblastoma pathway mutants; citation_author=D Wang, S Kennedy, D Conte, JK Kim, HW Gabel, RS Kamath, CC Mello, G Ruvkun; citation_volume=436; citation_issue=7050; citation_publication_date=2005; citation_pages=593-597; citation_doi=10.1038/nature04010; citation_id=CR72 citation_journal_title=Rna; citation_title=Interacting endogenous and exogenous RNAi pathways in Caenorhabditis elegans; citation_author=RC Lee, CM Hammell, V Ambros; citation_volume=12; citation_issue=4; citation_publication_date=2006; citation_pages=589-597; citation_doi=10.1261/rna.2231506; citation_id=CR73 citation_journal_title=Genes Dev; citation_title=fzr-1 and lin-35/Rb function redundantly to control cell proliferation in C. elegans as revealed by a nonbiased synthetic screen; citation_author=DS Fay, S Keenan, M Han; citation_volume=16; citation_issue=4; citation_publication_date=2002; citation_pages=503-517; citation_doi=10.1101/gad.952302; citation_id=CR74 citation_journal_title=Genetics; citation_title=The genetics of Caenorhabditis elegans; citation_author=S Brenner; citation_volume=77; citation_issue=1; citation_publication_date=1974; citation_pages=71-94; citation_id=CR75