letters to nature ... Modulation of HIV-1 replication by RNA interference

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... Moultion of HIV-1 replition y RNA interferene Jen-Mr Jque, Krine Triques & Mrio Stevenson Progrm in Moleulr Meiine, University of Msshusetts Meil Shool, 373 Plnttion Street, Worester, Msshusetts

In mmmlin ells, RNAi n e triggere y 21-nuleotie uplexes of smll interfering RNA () 3.

1 ... Moultion of HIV-1 replition y RNA interferene Jen-Mr Jque, Krine Triques & Mrio Stevenson Progrm in Moleulr Meiine, University of Msshusetts Meil Shool, 373 Plnttion Street, Worester, Msshusetts 165, USA... RNA interferene (RNAi) is the proess y whih oulestrne RNA (srna) irets sequene-speifi egrtion of messenger RNA in niml n plnt ells 1,2. In mmmlin ells, RNAi n e triggere y 21-nuleotie uplexes of smll interfering RNA () 3. Here we esrie inhiition of erly n lte steps of HIV-1 replition in humn ell lines n primry lymphoytes y s trgete to vrious regions of the HIV-1 genome. We emonstrte tht syntheti uplexes or plsmi-erive s inhiit HIV-1 infetion y speifilly egring genomi HIV-1 RNA, therey preventing formtion of virl omplementry-dna intermeites. These results emonstrte the utility of RNAi for moulting the HIV replition yle n provie eviene tht genomi HIV-1 RNA, s it exists within nuleoprotein reverse-trnsription omplex, is menle to -meite egrtion. RNAi is uiquitous mehnism of gene regultion in plnts n nimls 4 in whih trget mrnas re egre in sequene-speifi mnner 5. RNAi is initite y the srna-speifi enonulese Dier, whih promotes proessive levge of long srna into oule-strne frgments etween 21 n 25 nuleoties long, terme s 5 8. Smll interfering RNAs re inorporte into protein omplex tht reognizes n leves trget mrnas 9. Introution of srna into mmmlin ells oes not result in effiient Dier-meite genertion of n therefore oes not inue RNAi 1,11. The requirement for Dier in mturtion of s n e ypsse y introuing syntheti 21-nuleotie uplexes, whih inhiits expression of trnsfete n enogenous genes in vriety of mmmlin ells 3. HIV-1 uses RNA intermeites in its replition. Therefore, we exmine whether uplexes speifi for HIV-1 were ple of effeting the egrtion of virl RNAs neessry for ompletion of erly n lte events in the virl replition yle. We irete 21-nuleotie uplexes ginst severl regions of the HIV-1 genome, inluing the virl long terminl repet () n the essory genes vif n nef (Fig. 1). Smll interfering RNA uplexes were o-trnsfete with n HIV-1 moleulr lone (HIV NL- ; ref. 12) into CD4-positive HeL (Mgi) ells 13. Trnsfetion of ells with n infetious moleulr HIV-1 lone repitultes lte events in the virl life yle, inluing proution of virl RNAs, trnsltion of virl proteins n relese of virions. Compre with ells not trnsfete with uplexes, virus proution, mesure 24 h fter trnsfetion, ws reue 3-fol to 5-fol y homologous s (Fig. 1). HIV proution ws inhiite to lesser extent y single mismth s (M, ), wheres HIV-1 NL- M 5' gg pol vif vpr vpu rev tt env M388 nef 3' Env Env 1.33 k.62 k 3' RT HIV NL- 3' HIV NL- HIV YU-2 RT tivity (.p.m. ml ) Mismthes M Phosphorylte PKR PKR (totl) HIV YU-2 Speifiity e NL- YU-2 NL- YU-2 M HIV NL- HIV YU-2 Bright fiel Fluoresene NT NI Figure 1 Smll interfering RNAs inhiit lte events in HIV replition y promoting egrtion of HIV-1 RNA., HIV trgets of s use in this stuy. Smll interfering RNAs ompletely homologous to the trget HIV sequene (HIV NL- ) re shown in lue n those hrouring nuleotie mismthes re shown in yellow., Effet of s on HIV-1 prtile proution., Totl n tive (phosphorylte) PKR levels in trnsfete Mgi ells., Smll interfering RNAs meite sequene-speifi HIV RNA egrtion. The presene of HIV NL- or HIV YU-2 RNA ws etermine y RT PCR using HIV -speifi primers. Beuse of the insertion in HIV NL-, RNAs originting from HIV NL- re 71 nuleoties lrger thn those originting from HIV YU-2. M, moleulr weight mrker (1 p ler, New Engln Biols). e, Effet of s on HIV expression in primry PBLs. NATURE VOL JULY Nture Pulishing Group 435

2 vif with four mismthes () i not inhiit HIV proution (Fig. 1). Ativtion of the srna-tivte protein kinse PKR les to n inhiition of protein trnsltion in sequene-non-speifi mnner reltive to the inuing srna. Ativtion with PKR ws not involve in the inhiition of the negtive-strn RNA virus RSV (respirtory synytil virus) y s 14. Similrly, there ws no signifint inution of tivte PKR (phosphorylte on Thr 446) over levels in non-trnsfete ells y ny of the s (Fig. 1). To further exlue PKR effet, Mgi ells were o-trnsfete with two HIV-1 vrints (HIV-1 NL-, HIV-1 YU-2 ; ref. 15) n with s tht re speifilly trgete to either virus. Beuse of the presene of green fluoresent protein () insertion in, HIV NL- shoul e trgete y the -speifi, wheres HIV YU-2, whih lks insert, shoul e insensitive to. In ition, we exploite sequene ifferenes in the vif genes of these viruses. The ontins four mismthes reltive to the HIV NL- vif gene ut is ompletely homologous to HIV YU-2 vif. Thus, shoul iret the speifi inhiition of HIV YU-2 RNA n not HIV NL- RNA. Beuse of the insertion in HIV NL-, virl RNA proue in ells hrouring oth viruses oul e istinguishe. In the sene of s, oth HIV NL- n HIV YU-2 RNAs were evient in o-trnsfete ells (Fig. 1). However, o-trnsfetion with the resulte in loss of HIV NL- RNA ut not HIV YU-2 RNA. Conversely, the use loss in HIV YU-2 RNA without ffeting HIV NL- RNA (Fig. 1). This sequenespeifi inhiition is inonsistent with sequene-non-speifi PKR effet n inites tht s re inhiiting HIV proution y using the speifi egrtion of virl RNA. We next exmine whether s oul inhiit HIV gene expression ( fluoresene) in primry peripherl loo lymphoytes (PBLs), whih re nturl trgets for HIV-1 infetion. The frequeny of expressing ells ws mrkely reue in ells trnsfete with homologous s (,, nef) reltive to ells trnsfete with mismthe s or non-trnsfete ells (Fig. 1e). The level of HIV NL- RNA, s etermine y polymerse hin retion with reverse trnsription (RT PCR), ws lso mrkely reue in ells trnsfete with homologous s (results not shown). Therefore, the omponents of -tivte RNAi re fully funtionl in ells nturlly trgete y HIV-1 infetion. Upon HIV-1 infetion, genomi virl RNA is introue into the host ell ytoplsm in the form of nuleoprotein omplex, whih omprises virl proteins in ssoition with genomi virl RNA 16. Within this omplex, the virl reverse trnsriptse enzyme irets the synthesis of virl DNA intermeites from the genomi virl RNA templte. Reent stuies with RSV hve inite tht genomi virl RNA, whih is tightly ssoite with nuleopsi protein, is resistnt to s 17. We investigte whether s were le to iret the speifi egrtion of genomi virl RNA of HIV-1. The experimentl esign is outline in Fig. 2. Mgi ells were trnsfete with the vrious s n infete with HIV NL- 2 h lter. Trnsfetion of ells with s i not signifintly interfere with virus uptke per se, on the sis of levels of ellssoite p24 t 1 h fter infetion (Fig. 2). The strtegy for nlysis of virl reverse-trnsription intermeites in utely infete ells is outline in Fig. 2. At 1 h fter infetion, genomi virl RNA ws speifilly etete in ells trnsfete with mismthe s n in non-trnsfete ells (, ) ut not trnsfetion p24 (ng per 1 6 ells) HIV infetion h Virl RNA Virl p24 Cell-ssoite p24 Virl DNA Genomi virl RNA priming elongtion + strn elongtion Liner DNA Provirus Mismthes 4 1 +RT RT R U5 gg R U5 N N pol env U3 R A(n) trna primer strong stop DNA Templte swith U5 gg Templte swith R U5 R U3 U5 U5 2 irle R R lu U3 R U5 U3 HIV RNA e Mismthes 3, 24, 18, 12, 6, 7,2 6, 4,8 3,6 2,4 1, DNA (opies per 1 6 ells) f M388 M R/U5 (erly RT) U5/gg (lte RT) R/U5 (2 irle) Integrnts R/lu Figure 2 Smll interfering RNAs lok erly events in HIV replition y promoting egrtion of genomi HIV RNA., Experimentl esign., Levels of trypsin-resistnt HIV gg p24 in -trnsfete ells. Dsh inites no trnsfete into the ells., Strtegy for nlysis of virl nulei i intermeites forme erly fter HIV infetion. Mjor DNA intermeites in virl reverse trnsription re inite. Blue line, virl RNA; re line, virl DNA; open irles n squres, primer-ining sites for initition of minusstrn synthesis n polypurine trts for plus-strn synthesis, respetively. HIV-speifi primers (green rrows) re shown next to the erliest DNA intermeite they mplify. Integrte (provirl) HIV DNA ws mplifie using n HIV -speifi primer (R) n primer irete to lu repets (fille irles) within flnking ellulr DNA., Effet of s on genomi virl RNA. e, Effet of s on formtion of HIV-1 reverse trnsription (RT) intermeites. f, Reue levels of virl integrtion in -trnsfete ells Nture Pulishing Group NATURE VOL JULY 22

3 in ells trnsfete with homologous s (Fig. 2). Beuse genomi virl RNA is the templte for the synthesis of virl DNA intermeites, the synthesis of virl DNAs, etermine 36 h fter infetion, ws rmtilly inhiite in ells trnsfete with homologous s (,, nef) (Fig. 2e). Smll interfering RNAs ering one-nuleotie mismthes (, M388) were prtilly inhiitory reltive to the ering four mismthes (Fig. 2e). Smll interfering RNAs were quite stle in ells: HIV entry ws suppresse to equl levels whether virus ws e 2 h or 4 ys fter trnsfetion (t not shown). Upon ompletion of virl DNA synthesis, virl sequenes integrte into ellulr DNA to form provirus. The level of provirus formtion, s eviene y the presene of juntion sequenes flnking virl n ellulr DNA (Fig. 2e), ws mrkely reue in ells trnsfete with homologous s (,, nef) reltive to ells trnsfete with mismthe () s or non-trnsfete ells (Fig. 2f). Colletively, these stuies inite tht s interrupt erly events in the HIV replition yle y ireting the speifi egrtion of genomi HIV-1 RNA, therey preventing the susequent synthesis of virl reverse-trnsription intermeites n estlishment of the provirus. Expression of s from plsmi templtes offers severl vntges over syntheti s, suh s stle seletion uner RT tivity (.p.m. ml ) Construt TL 3 TL 5 TL Stuffer 5' 5' BstBI 3 19p 5' 5' 5 5' 5' 7 Non-trnsfete Pol + TL Pol + TL 3 Pol + TL 5 Pol + TL 7 pdna pol + TL Non-trnsfete pdna RNA Pol BstBI + RT Pol + TL Pol + TL 3 Pol + TL 5 Pol + TL 7 pol + TL 7 Preite RNA Control Non-trnsfete pdna Bright fiel Fluoresene C 19p 19p 19p RT A A A C Pol + TL Pol + TL 3 Pol + TL 5 Pol + TL 7 Figure 3 Inhiition of HIV replition y s erive from plsmi DNA templtes., Strtegy for proution of hirpin s from plsmi vetors. Lineriztion of eh onstrut with Bst BI n trnsfetion into ells with plsmi expressing RNA polymerse (Pol) preits the expression of hirpin RNA with 19-p selfomplementry stem n non-se-pire loops of 3, 5 n 7 nuleoties., Effet of hirpin s on HIV prtile proution. Tl D is ientil to plsmis tht express hirpin exept tht it lks self-omplementry sequenes., hirpin s promote egrtion of HIV RNA. PCR prouts mplifie from HIV NL- serve s ontrol., Inhiition of HIV-1 expression y hirpin s in primry PBLs. seletle mrkers n inuile promoters, whih re fetures tht oul e useful for geneti pprohes to HIV therpy. Therefore, we exmine whether expresse s oul inhiit HIV. Moifying strtegy use previously in plnts 18,19, we onstrute plsmis ontining 19-se pir (p) region of the HIV-1 vif gene in 5 3 n 3 5 orienttions uner the ontrol of promoter (Fig. 3). Virus proution ws etermine 24 h fter three-wy trnsfetion of Mgi ells with n HIV NL- moleulr lone, the linerize hirpin plsmi (Tl ) n vetor expressing RNA polymerse ( Pol). In the presene of RNA polymerse, trnsripts erive from BstBI-linerize expression plsmis woul e preite to omprise sequene from the promoter, 19-p stem of self-omplementry sequenes, 3-, 5- or 7-nuleotie loop n 3 overhng. All three hirpin plsmis ontining 3-, 5- or 7- nuleotie loops potently suppresse virus proution to 2 3-fol reltive to nontrnsfete ells. By omprison, the presene of n ientil plsmi lking sequenes (TL D or ontrol plsmi pdna) h no effet on virus proution in o-trnsfete ells (Fig. 3). This inhiitory effet on virus proution ws reflete y loss of virl RNA (Fig. 3). The hirpin plsmi (TL 7) lso inhiite virl gene expression in primry lymphoytes, wheres there ws no inhiitory effet of the plsmi lking sequenes in these ells (Fig. 3). These results inite tht sequene-speifi RNAi effet n e tivte in estlishe n primry ells y s erive from self-omplementry hirpin-generting plsmis. This provies rtionle for gene-therpy pprohes to HIV tht omplement existing post-trnsriptionl pprohes for inhiiting HIV, inluing riozymes n ntisense RNA (reviewe in ref. 2). The involvement of RNAi in trnsposon silening 21,22 suggests tht RNAi is n nient ntivirl system tht my hve evolve s efene mehnism to protet the host from invsion y moile geneti elements inluing trnsposons n viruses. Severl stuies hve inite tht it is iffiult to inue RNAi in mmmlin ells using long srnas. Although long srnas n moestly inhiit gene expression in mmmlin ells, the effets re not sequene speifi 3,23 n re more onsistent with inhiition y the interferon response. Intriguingly, it is now eoming pprent tht unerlying the non-speifi srna-tivte interferon response in mmmlin ells, there my inee e sequene-speifi RNAi effet tht n e tivte y long srna Silening y long srnas hs now een oserve in vrious ulture mmmlin ells 24,25. The mehnism of silening is onsistent with RNAi euse there is eviene tht the long srnas re proesse to s n trget RNAs re speifilly egre. Our results inite tht 21-nuleotie s promote HIV RNA egrtion in primry lymphoytes, suggesting tht the mjor trget ell for HIV replition possesses funtionl omponents of the -inue silening omplex tht meites speifi levge of trget RNA 2. Future stuies shoul etermine whether sequene-speifi RNAi tht is inepenent of the interferon response n e tivte ginst HIV y long srnas. A Methos Synthesis of The following RNA oligonuleoties were purhse from Dhrmon: (5 -GGAAA GCUAAGGACUGGTT-3 ); (5 -AGCACACAAGUAGACCCUGTT-3 ; :5 -CGGCACUAGCAGCAATT-3 ); (5 GAAAGCUAGGGGAUGGU UTT-3 ); (5 -CGGCACUAACAGCAATT-3 ); (5 -GACCAA GGAAGAUGGCATT-3) ; M388 (5 -GACCAAGGGAGAUGGCATT-3 ); nef (5 -GUGCCUGGCUAGAAGCACATT-3 ); (5 -AGACCAGAUCUGAGCCUG GTT-3 ); n M (5 -AGACCAGAUAUGAG CCUGGTT-3 ). Plsmis The promoter ws moifie in the plsmi PCRsript (Strtgene) to form pcr. Oligonuleoties orresponing to nuleoties 5,323 5,342 of HIV-1 vif (Gennk ession numer M19921) were inserte t the Srf I site of pcr. Pol omprises RNA polymerse from Esherihi oli BL21 (DE3) lone into pdna 3.1 (Invitrogen). NATURE VOL JULY Nture Pulishing Group 437

4 Cells n trnsfetions Mgi ells were grown in DMEM ontining 1% fetl ovine serum (FBS). PHAtivte, elutrite PBLs were ulture in RPMI ontining 1% FBS n 64 U ml 21 of interleukin-2 (ICN). Mgi ells were trnsfete with oligofetmine (GIBCO) y the mnufturer s protool in the presene of 1 mg HIV plsmi n/or 6 pmol of oligonuleoties. Trnsfetion effiienies were 75 85%. For PHA-tivte PBLs, ells were eletroporte using Gene Pulser pprtus (Bio-R) t 25 V, 96 mf, resistne R ¼ 1 with 5 mg plsmi n/or 2 pmol. Trnsfetion effiienies were 3 5% of vile ells. Three-wy trnsfetions with expression plsmis omprise.1 mg Pol,.5 mg ptl n.5 mg pnl (Mgi ells), or.5 mgpol, 2 mg TL n 2 mg pnl (for primry lymphoytes). Trnsfete ells were entrifuge (1,2g) on DAKO silnize slies n exmine uner right-fiel illumintion or fluoresene (wvelength 516 nm) on Zeiss Axiopln 2 mirosope. PCR nlysis Rel-time PCR ws performe s previously reporte 27. Prouts were mplifie from 5 to 2 ml of extrhromosoml DNA in 5-ml retions ontining 1 HotStrt Tq uffer (Qigen), 2 nm NTPs, 4 nm primers n 1.5 U HotStrt Tq. Two- juntions were mplifie y the primers R (5 -TAGACCAGATCT GAGCCTGGGA -3 ) n U5 (5 -GTAGTTCTGCCAATCAGGG AAG -3 ). Erly prouts were mplifie y the primers R (5 -TCTCTGGTTAGACCAGATCTG-3 ) n U5 (5 - GTCTGAGGGATCTCTAGTTAC-3 ), n lte prouts were mplifie with U5 (5 - GGGAGCTCTCTGGCTAACT-3 )ngg (5 -GGATTAA CTGCGAATCGTTC-3 ) primers. The oligonuleotie proe for rel-time PCR ws s previously reporte 27. Virl ssys For RT PCR, 1 2 mg RNA ws reverse trnsrie n mplifie y PCR using the primers N (5 -GACAGGGCTTGGAAAGG-3 ) n N (5 -TTAGCAGTTCTGAA GTACTC-3 ) s esrie previously 28. The integrtion ssy ws performe on DNAzolextrte totl DNA (Invitrogen) using the Alu primer SB74 (5 -TGCTGGGATTACAG GCGTGAG-3 ) n primer R for the first roun of PCR (25 yles). Neste PCR ws performe uner the sme onitions using primers M667 (5 -GGCTAACTAGGGAA CCCACTG-3 ) n AA55 (5 -CTGCTAGAGATTTTCCACACTGAC-3 ). For virus proution, virl p24 (psi) ws mesure y enzyme-linke immunosorent ssy oring to the mnufturer s protool (Bekmn-Coulter). Reverse trnsription tivity ws mesure s previously reporte 28. PKR ssy We eletrophorese 2 mg of whole-ell lystes in triple etergent lysis uffer on 1% SDS polyrylmie gel n eletrotrnsferre to nitroellulose memrne (Amershm Hyon C þ ). The memrne ws proe with phospho-thr 446 PKR-speifi ntioy or PKR-speifi ntioy (Upstte Biotehnology). Reeive 25 Mrh; epte 7 June 22; oi:1.138/nture896. Pulishe online 26 June Shrp, P. A. RNA interferene 21. Genes Dev. 15, (21). 2. Hutvgner, G. & Zmore, P. D. RNAi: nture hors oule-strn. Curr. Opin. Genet. Dev. 12, (22). 3. Elshir, S. M. et l. Duplexes of 21-nuleotie RNAs meite RNA interferene in ulture mmmlin ells. Nture 411, (21). 4. Fire, A. et l. Potent n speifi geneti interferene y oule-strne RNA in Cenorhitis elegns. Nture 391, (1998). 5. Zmore, P. D., Tushl, T., Shrp, P. A. & Brtel, D. P. RNAi: oule-strne RNA irets the ATPepenent levge of mrna t 21 to 23 nuleotie intervls. Cell 11, (2). 6. Elshir, S. M., Lenekel, W. & Tushl, T. RNA interferene is meite y 21- n 22-nuleotie RNAs. Genes Dev. 15, (21). 7. Hmmon, S. M., Bernstein, E., Beh, D. & Hnnon, G. J. An RNA-irete nulese meites posttrnsriptionl gene silening in Drosophil ells. Nture 44, (2). 8. Bernstein, E., Cuy, A. A., Hmmon, S. M. & Hnnon, G. J. Role for ientte rionulese in the initition step of RNA interferene. Nture 49, (21). 9. Nyknen, A., Hley, B. & Zmore, P. D. ATP requirements n smll interfering RNA struture in the RNA interferene pthwy. Cell 17, (21). 1. Cplen, N. J., Fleenor, J., Fire, A. & Morgn, R. A. srna-meite gene silening in ulture Drosophil ells: tissue ulture moel for the nlysis of RNA interferene. Gene 252, (2). 11. Ui-Tei, K., Zenno, S., Miyt, Y. & Sigo, K. Sensitive ssy of RNA interferene in Drosophil n Chinese hmster ulture ells using firefly luiferse gene s trget. FEBS Lett. 479, (2). 12. Welker, R., Hrris, M., Crel, B. & Krusslih, H. G. Virion inorportion of humn immunoefiieny virus type 1 is meite y iprtite memrne-trgeting signl: nlysis of its role in enhnement of virl infetivity. J. Virol. 72, (1998). 13. Kimpton, J. & Emermn, M. Detetion of replition-ompetent n pseuotype humn immunoefiieny virus with sensitive ell line on the sis of tivtion of n integrte - gltosise gene. J. Virol. 66, (1992). 14. Bitko, V. & Brik, S. Phenotypi silening of ytoplsmi genes using sequene-speifi oulestrne short interfering RNA n its pplition in the reverse genetis of wil type negtive-strn RNA viruses. BMC Miroiol. 1, (21). 15. Li, Y. et l. Moleulr hrteriztion of humn immunoefiieny virus type 1 lone iretly from unulture humn rin tissue: Ientifition of replition-ompetent n -efetive virl genomes. J. Virol. 65, (1991). 16. Moore, J. & Stevenson, M. New trgets for inhiitors of HIV-1 replition. Nture Rev. Mol. Cell Biol. 1, 4 49 (2). 17. Bitko, V. & Brik, S. An enoplsmi retiulum-speifi stress-tivte spse (spse-12) is implite in the poptosis of A549 epithelil ells y respirtory synytil virus. J. Cell Biohem. 8, (21). 18. Wng, M. B. & Wterhouse, P. M. High-effiieny silening of -gluuronise gene in rie is orrelte with repetitive trnsgene strutureut is inepenent of DNA methyltion. Plnt Mol. Biol. 43, (2). 19. Vrshwesley, S. et l. Construt esign for effiient, effetive n high-throughput gene silening in plnts. Plnt J. 27, (21). 2. Dornurg, R. & Pomerntz, R. J. HIV-1 gene therpy: promise for the future. Av. Phrmol. 49, (2). 21. Ketting, R. F., Hverkmp, T. H., vn Luenen, H. G. & Plsterk, R. H. Mut-7 of C. elegns, require for trnsposon silening n RNA interferene, is homolog of Werner synrome helise n RNseD. Cell 99, (1999). 22. Tr, H., Hill, R. J., Mello, C. C., Priess, J. R. & Kohr, Y. pos-1 enoes ytoplsmi zin-finger protein essentil for germline speifition in C. elegns. Development 126, 1 11 (1999). 23. Cplen, N. J., Prrish, S., Imni, F., Fire, A. & Morgn, R. A. Speifi inhiition of gene expression y smll oule-strne RNAs in inverterte n verterte systems. Pro. Ntl A. Si. USA 98, (21). 24. Billy, E., Bronni, V., Zhng, H., Muller, U. & Filipowiz, W. Speifi interferene with gene expression inue y long, oule-strne RNA in mouse emryonl tertorinom ell lines. Pro. Ntl A. Si. USA 98, (21). 25. Pison, P. J., Cuy, A. A. & Hnnon, G. J. Stle suppression of gene expression y RNAi in mmmlin ells. Pro. Ntl A. Si. USA 99, (22). 26. Yng, S., Tutton, S., Piere, E. & Yoon, K. Speifi oule-strne RNA interferene in unifferentite mouse emryoni stem ells. Mol. Cell. Biol. 21, (21). 27. Shrkey, M. et l. Persistene of episoml HIV-1 infetion intermeites in ptients on highly tive ntiretrovirl therpy. Nture Me. 6, (2). 28. Brihek, B. & Stevenson, M. Quntittive ompetitive RNA PCR for quntittion of virion ssoite HIV-1 RNA. Methos 12, (1997). Aknowlegements We thnk A. Mnn for reserh support, C. Mello n P. Zmore for isussions, B. Mellor for preprtion of the figures, n T. Pinkos for mnusript preprtion. We lso knowlege ssy support provie y the University of Msshusetts Center for AIDS Reserh. HIV YU-2 ws otine through the AIDS Reserh n Referene Regent Progrm, Division of AIDS, Ntionl Institute of Allergy n Infetious Diseses, Ntionl Institutes of Helth (NIH), from B. Hhn n G. Shw. This stuy ws supporte y grnts from the NIH n the Jenner Fountion to M.S. Competing interests sttement The uthors elre tht they hve no ompeting finnil interests. Corresponene n requests for mterils shoul e resse to M.S. (e-mil: mrio.stevenson@umssme.eu).... E3 uiquitin ligse tht reognizes sugr hins Yukiko Yoshi*, Tomoki Chi, Fuminori Tokung, Hiroshi Kwskik, Kzuhiro Iwi, Toshiki Suzuki, Yukishige Ito{, Koji Mtsuok#, Minoru Yoshi q, Keiji Tnk & Tshi Ti* * Deprtments of Tumor Immunology n Moleulr Onology, Tokyo Metropolitn Institute of Meil Siene, Bunkyo-ku, Tokyo , Jpn CREST, Jpn Siene n Tehnology Corportion (JST), Sitm , Jpn, Deprtment of Moleulr Cell Biology, Grute Shool of Meiine, Osk City University, Osk , Jpn k Kihr Institute for Biologil Reserh, Grute Shool of Integrte Siene, Yokohm City University, Yokohm, Kngw , Jpn { Syntheti Cellulr Chemistry Lortory, n q Chemil Genetis Lortory, RIKEN, Wko, Sitm , Jpn # Deprtment of Funtionl Mterils Siene, Sitm University, Sitm, , Jpn... N-glyosyltion of proteins in the enoplsmi retiulum (ER) hs entrl role in protein qulity ontrol 1 3. Here we report tht N-glyn serves s signl for egrtion y the Skp1 Cullin1 Fx2 Ro1 (SCF Fx2 ) uiquitin ligse omplex. The F- ox protein Fx2 (ref. 4) ins speifilly to proteins tthe to Nture Pulishing Group NATURE VOL JULY 22

Title of Experiment: Author, Institute and address:

Title of Experiment: Author, Institute and address: Title of Experiment: Trsfetion of murine mrophge RAW264.7 ells with METAFECTENE PRO. Author, Institute n ress: Ptrizi Pellegtti n Frneso Di Virgilio. Deprtment of Experimentl n Dignosti Meiine, Setion