A"synthetic"RNA-cont rolled"trans lational "acti vatorRed$region$ of$taRNA is$complementary$ to$red$region$of$crRNAWhen$taRNA is$ added,$it$can$bind$the$ red$region$and$free$the$ RBSFinishing"from"last"cla ss…A"synthetic"RNA-cont rolled"trans lational "acti vatortaRNA triggers$translation$ of$the$attached$ geneThis"class"(part"1):"Post-transcriptional"controlRather$than$control$transcription,$we’re$going$ to$control$how$a$transcript$ is$read,$degraded,$processed,$etc.We$can$also$ control$whether$ a$protein$ itself$ is$ activated$ or$inactivated.We$will$ discuss$ canonical$ examples:1) Alternative$ Splicing2) MicroRNAs$(miR NAs )$ and$Small-interfering$ RNAs$(siRNAs)3) Long$non-coding$RNAs4) Posttr anslational$ controlMales :$ exons$1,$2,$3,$5,$and$6$joined.$Females :$ exons$ 1,$2,$3,$and$4$joined.The $intron$upstream$from$exon$4$has$a$tract$that$doesn’t$match$the$conse nsus $sequence$ for$splicing.$ Therefore,$U2AF$proteins$ (part$of$the$ spliceosome)$ don’t$bind$unless$ another$activator$helps$U2AF$bind.$This$activator,$called$Transformer$(Tra)$allows$the$ splicing$ complex$to$ assemble$ at$Exon$4,$including$ it$ in$ the$splicing$reaction.$At$the$end$of$ Exon$4$is$ a$ polyadenylation signal$ that$causes$ cleavage$ of$the$mRNA$at$that$point.Cis factors?Trans$ factors?Alternative"splicing"natural"example:" Fly"sex"determination"gene"dsxFemale$genitals$ only$develop$if$ the$ female$splice$ for m$is$present.$Differ ences$in$brain$structure$and$behavior$are$also$caused$by$the$different$forms.MicroRNA"exampleThis $dictates $ the $onset $of$larval$stages $of$development$ in$worm.MicroRNA"general"mechanismRISC$=$RNA-induced$ silencing$ complexCleavage$ if$complete$complementationBl ocki ng$of$translati on$if$incomplete$complementationMicroRNA"general"mechanismRISC$=$RNA-induced$ silencing$ complexWhat$is$the$advantage$of$a$miR NA?• Easily$ programmable:$se quence$is$based$ on$watson-crick$pairing• Regulates $ multiple$ targets• Occupies$little$ space$in$the$genomeCleavage$ if$complete$complementationBl ocki ng$of$translati on$if$incomplete$complementationMicroRNA"lin-4Translational$ inhibition$ and/or$mRNA$ degradation$ by$speeding$ up$ deadenylationCis factors?Trans$ factors?siRNA general"mechanismSimilar$to$miRNA pathway,$but$designed$ for$targeting$ viruses,$ a$signature$of$which$is$dsRNACis factors?Trans$ factors?siRNA engineering /therapy"platform"example968 NATURE MATERIALS | VOL 12 | NOVEMBER 2013 | www.nature.com/naturematerialsphagocyte system (MPS)18,30. Opsonization and subsequent uptake by the MPS is a common pathway by which delivery systems are cleared from the blood and prevented from reaching their targets. A common strategy for minimizing interaction with serum pro-teins involves shielding the surface of delivery vehicles with hydro-philic polymers, usually polyethylene glycol (PEG)18,31. PEGylation Ta b l e 1 | RNAi-based drugs in clinical trials.Drug Target Delivery system Disease Phase Status Company ClinicalTrials.gov identifierALN–VSP02 KSP and VEGF LNP Solid tumours I Completed Alnylam PharmaceuticalsNCT01158079siRNA–EphA2–DOPCEphA2 LNP Advanced cancers I Recruiting MD Anderson Cancer CenterNCT01591356Atu027 PKN3 LNP Solid tumours I Completed Silence Therapeutics NCT00938574TKM–080301 PLK1 LNP Cancer I Recruiting Tekmira PharmaceuticalNCT01262235TKM–100201 VP24, VP35, Zaire Ebola L-polymeraseLNP Ebola-virus infection I Recruiting Tekmira PharmaceuticalNCT01518881ALN–RSV01 RSV nucleocapsid Naked siRNA Respiratory syncytial virus infectionsII Completed Alnylam PharmaceuticalsNCT00658086PRO-040201 ApoB LNP Hypercholesterolaemia I Te r m i n a t e d Tekmira PharmaceuticalNCT00927459ALN–PCS02 PCSK9 LNP Hypercholesterolaemia I Completed Alnylam PharmaceuticalsNCT01437059ALN–TTR02 TTR LNP Transthyretin-mediated amyloidosisII Recruiting Alnylam PharmaceuticalsNCT01617967CALAA-01 RRM2 Cyclodextrin NP Solid tumours I Active Calando PharmaceuticalsNCT00689065TD101 K6a (N171K mutation) Naked siRNA Pachyonychia congenita I Completed Pachyonychia Congenita ProjectNCT00716014AGN211745 VEGFR1 Naked siRNA Age-related macular degeneration, choroidal neovascularizationII Te r m i n a t e d Allergan NCT00395057QPI-1007 CASP2 Naked siRNA Optic atrophy, non-arteritic anterior ischaemic optic neuropathyI Completed Quark PharmaceuticalsNCT01064505I5NP p53 Naked siRNA Kidney injury, acute renal failureI Completed Quark PharmaceuticalsNCT00554359Delayed graft function, complications of kidney transplantI, II Recruiting Quark PharmaceuticalsNCT00802347PF-655 (PF-04523655)RTP801 (Proprietary target)Naked siRNA Choroidal neovascularization, diabetic retinopathy, diabetic macular oedemaII Active Quark PharmaceuticalsNCT01445899siG12D LODER KRAS LODER polymer Pancreatic cancer II Recruiting Silenseed NCT01676259Bevasiranib VEGF Naked siRNA Diabetic macular oedema, macular degenerationII Completed Opko Health NCT00306904SYL1001 TRPV1 Naked siRNA Ocular pain, dry-eye syndromeI, II Recruiting Sylentis NCT01776658SYL040012 ADRB2 Naked siRNA Ocular hypertension, open-angle glaucomaII Recruiting Sylentis NCT01739244CEQ508 CTNNB1 Escherichia coli-carrying shRNAFamilial adenomatous polyposisI, II Recruiting Marina Biotech UnknownRXi-109 CTGF Self-delivering RNAi compoundCicatrix scar prevention I Recruiting RXi Pharmaceuticals NCT01780077ALN–TTRsc TTR siRNA–GalNAc conjugateTransthyretin-mediated amyloidosisI Recruiting Alnylam PharmaceuticalsNCT01814839ARC-520 Conserved regions of HBV DPC HBV I Recruiting Arrowhead Research NCT01872065DPC, dynamic polyconjugate; LNP, lipid nanoparticle; NP, nanoparticle; shRNA, short hairpin RNA.INSIGHT | REVIEW ARTICLESNATURE MATERIALS DOI: 10.1038/NMAT3765REVIEW ARTICLES | INSIGHTNATURE MATERIALS DOI: 10.1038/NMAT3765© 2013 Macmillan Publishers Limited. All rights reservedLong"non-coding"RNA:"a"complex "resear ch"problemncRNAs to recruit RNA binding proteins, one of the largest protein classes in the mam-malian proteome, to gene promoters hugely expands the regulatory repertoire available to the transcriptional programme29.Long ncRNAs also act as co-factors to modulate transcription factor activity. For example, in mice, the ncRNA Evf2 is transcribed from an ultraconserved distal enhancer and recruits the binding and action of the transcription factor DLX2 to this same enhancer to induce expression of adjacent protein-coding genes30 (FIG. 2c). Many similar enhancers are transcribed in cells in which they are