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Hands on: Redigering - Biologie

Hands on: Redigering - Biologie



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Hy het 'n verwoestende siekte geërf. 'N Deurbraak deur gen-redigering deur CRISPR het dit stopgesit

Patrick Doherty het vrywillig aangebied vir 'n nuwe mediese ingryping van infusies van gene-redakteurs vir die behandeling van geneties-gebaseerde siektes.

Patrick Doherty was nog altyd baie aktief. Hy het die Himalajas getrek en roetes in Spanje gestap.

Maar so 'n jaar en 'n half gelede het hy spelde en naalde in sy vingers en tone opgemerk. Sy voete het koud geword. En toe het hy uitasem begin raak elke keer as hy met sy hond teen die heuwels van County Donegal in Ierland waar hy woon, opgestap het.

"Ek het op sommige van die groter heuwels opgemerk dat ek 'n bietjie uitasem raak," sê Doherty (65). "Ek het dus besef iets is fout."

Doherty het uitgevind dat hy 'n seldsame, maar verwoestende oorerflike siekte het - bekend as transthyretin amyloidose - wat sy pa doodgemaak het. ’n Misvormde proteïen het in sy liggaam opgebou, wat belangrike weefsels vernietig, soos senuwees in sy hande en voete en sy hart.

Doherty het gesien hoe ander kreupel word en sterf as gevolg van amyloïdose.

'Dit is 'n vreeslike voorspelling,' sê Doherty. "Dit is 'n toestand wat baie vinnig versleg. Dit is net aaklig."

So was Doherty opgewonde toe hy uitvind dat dokters 'n nuwe manier toets om amyloïdose te behandel. Die benadering het 'n revolusionêre geenredigeringstegniek genaamd CRISPR gebruik, wat wetenskaplikes in staat stel om baie presiese veranderinge in DNS aan te bring.

"Ek het gedink: Fantasties. Ek het by die geleentheid gespring," sê Doherty.

Navorsers het Saterdag die eerste data gerapporteer wat aandui dat die eksperimentele behandeling gewerk het, wat veroorsaak het dat vlakke van die vernietigende proteïen in Doherty se liggaam en die liggame van vyf ander pasiënte wat met die benadering behandel is, daal.

'Ek voel fantasties,' sê Doherty. "Dit is net fenomenaal."

Die vooruitgang word nie net vir amyloïdose-pasiënte begroet nie, maar ook as 'n bewys van die konsep dat CRISPR gebruik kan word om baie ander, baie meer algemene siektes te behandel. Dit is 'n nuwe manier om die innoverende tegnologie te gebruik.

"Dit is 'n belangrike mylpaal vir pasiënte," sê Jennifer Doudna van die Universiteit van Kalifornië, Berkeley, wat 'n Nobelprys vir haar werk gedeel het om CRISPR te help ontwikkel.

'Alhoewel dit vroeë data is, toon dit ons dat ons een van die grootste uitdagings kan oorkom met die toepassing van CRISPR tot dusver, wat dit sistemies kan lewer en op die regte plek kan kry,' sê Doudna.

Daar is reeds getoon dat CRISPR pasiënte wat ly aan die verwoestende bloedafwykings, sekelselle en beta -thalassemie help. En dokters probeer dit gebruik om kanker te behandel en om visie te herstel vir mense wat verblind is deur 'n seldsame genetiese afwyking.

Maar daardie eksperimente behels die neem van selle uit die liggaam, die redigeer daarvan in die laboratorium, en die infusie daarvan of die inspuiting van CRISPR direk in selle wat reggemaak moet word.

Die studie waarvoor Doherty vrywillig was, is die eerste waarin dokters bloot die geenredakteur direk by pasiënte infuseer en dit sy eie weg na die regte geen in die regte selle laat vind. In hierdie geval is dit selle in die lewer wat die vernietigende proteïen vervaardig.

"Dit is die eerste voorbeeld waarin CRISPR-Cas9 direk in die bloedstroom ingespuit word - met ander woorde sistemiese toediening - waar ons dit gebruik as 'n manier om 'n weefsel te bereik wat ver van die plek van inspuiting is en dit baie spesifiek gebruik om te redigeer. siekteveroorsakende gene, ”sê John Leonard, die uitvoerende hoof van Intellia Therapeutics, wat die studie borg.

Dokters het miljarde mikroskopiese strukture bekend as nanodeeltjies ingedien wat genetiese instruksies vir die CRISPR-gene-redakteur bevat, by vier pasiënte in Londen en twee in Nieu-Seeland. Die nanodeeltjies is deur hul lewers opgeneem, waar hulle leërs van CRISPR-gene-redakteurs losgelaat het. Die CRISPR -redakteur het die teikengeen in die lewer ingeneem en dit in skywe gesny, wat die produksie van die vernietigende proteïen uitskakel.

Binne weke het die proteïenvlakke wat die siekte veroorsaak, gedaal, veral by die vrywilligers wat 'n hoër dosis gekry het. Navorsers het gerapporteer op die jaarvergadering van die Peripheral Nerve Society en in 'n referaat gepubliseer in Die New England Journal of Medicine.

"Dit is regtig opwindend," sê dr Julian Gillmore, wat die studie lei by die University College London, Royal Free Hospital.

"Dit het die potensiaal om die uitkoms vir hierdie pasiënte wat al vir baie generasies met hierdie siekte in hul familie geleef het, heeltemal 'n rewolusie teweeg te bring. Dit het sommige gesinne na wie ek gekyk het vernietig. Dit is dus ongelooflik," sê Gillmore.

Die pasiënte sal langer gevolg moet word, en meer pasiënte sal behandel moet word, om seker te maak die behandeling is veilig, en bepaal hoeveel dit help, beklemtoon Gillmore. Maar die benadering kan diegene help wat deur amyloïdose getref word wat nie geërf word nie, wat 'n veel meer algemene weergawe van die siekte is, sê hy.

Boonop maak die belowende resultate moontlik die deur oop om dieselfde benadering tot die behandeling van baie ander, meer algemene siektes te gebruik waarvoor selle uit die liggaam verwyder of CRISPR direk ingespuit kan word, insluitend hartsiektes, spierdistrofie en breinsiektes soos as Alzheimer se.

'Dit is regtig 'n nuwe era, terwyl ons dink aan gene-redigering, waar ons kan begin dink oor die toegang tot allerhande verskillende weefsels in die liggaam deur middel van sistemiese toediening,' sê Leonard.

Ander wetenskaplikes wat nie by die navorsing betrokke is nie, stem saam.

"Dit is 'n wonderlike dag vir die toekoms van gene-redigering as 'n medisyne,"
stem saam Fyodor Urnov, 'n professor in genetika aan die Universiteit van Kalifornië, Berkeley. "Ons as 'n spesie kyk na hierdie merkwaardige nuwe program genaamd: our gene-edited future."

Doherty sê dat hy binne weke na die behandeling beter begin voel het en sedertdien aanhou verbeter het.

'Ek voel beslis beter,' het hy aan NPR gesê. "Ek praat met jou van bo in ons huis. Ek het trappe geklim om hier op te klim. Ek sou asemloos gevoel het. Ek is opgewonde."


Agtergrond

Behoorlike ruimtelike tydelike beheer van geenuitdrukking vereis dat die RNA-polimerase II-kompleks fisies assosieer met DNA-bindende transkripsiefaktore en hul koördineerders oor transkripsiefaktor-bindingsplekke (TFBS) in die promotor- en versterkingsgebied van teikengene [1]. Die versterkende funksie en die rol van individuele TFBS het ons begrip van basiese meganismes onderliggend aan die transkripsie van die mens en die ontwikkeling van Cre/laksP muismodelle vir selbeperkte geeninaktivering. Aangesien die meeste volgordevariante (bv. Enkele nukleotiedvariante of SNV's) wat met menslike siektes verband hou, voorkom in 'n nie -koderende volgorderuimte waar TFBS woon [2, 3], kan die begrip van die biologie van TFBS in die orkestrering van geen -transkripsie insig bied in basiese meganismes van siekte [4] ]. Tradisioneel is TFBS-funksie bestudeer in in vitro of in vivo verslaggewertoetse, buite hul normale genomiese konteks. Daar is veral min TFBS aangepas in hul inheemse genomiese omgewing van die muis en byna almal het onnauwkeurige mutasies en genomiese littekens opgelewer (bv. laksP -volgorde) [5,6,7,8]. Die opwekking van sulke muismodelle met konvensionele embryonale stamselgerigtheid is arbeidsintensief en duur, en die resultate kan onseker wees, gegewe die bekende ontslag in die gebruik van TFBS vir teikengeentransskripsie [9].

Die herbestemming van die bakteriële gegroepeerde gereelde interspasiëring van kort palindromiese herhalings (CRISPR)-stelsel as 'n programmeerbare, RNA-gerigte DNA-endonuklease [10, 11] het die presisie-redigering van die muisgenoom [12, 13, 14] aansienlik vereenvoudig en versnel. Die eerste generasie CRISPR-redigering by muise het drie komponente gebruik: 'n endonuklease (Cas9), 'n enkelgeleide RNA (sgRNA) wat Cas9 herhaal na die volgorde wat bewerk moet word en 'n herstelsjabloon, in die algemeen 'n enkelstrengs oligodeoksinukleotied (ssODN) wat ontwerp is om dra klein invoegings, skrapings of substitusies wat tydens die homologie-gerigte herstel (HDR) van die sgRNA-Cas9-geïnduseerde dubbelstrengbreuk [15,16,17] in die doel-DNA-volgorde opgeneem word. Drie-komponent CRISPR het TFBS suksesvol ontwrig in hul inheemse genomiese konteks van muise, wat insig in die teikengeenuitdrukking in 'n in vivo-omgewing [18,19,20] onthul het. HDR-gemedieerde redigering is egter dikwels ondoeltreffend, is beperk tot aktief verdelende selle, word geassosieer met ongewenste kollaterale indelmutasies, en kan gebeurtenisse wat nie teiken nie, kan veroorsaak [21]. 'N Tweede-generasie CRISPR-platform, genaamd basisbewerking [22], is ontwikkel waarin 'n sgRNA 'n Cas9-nikase wat aan 'n sitidien- of adeniendeaminase versmelt word, rig om DNA te teiken vir die installering van basisvervangings sonder die opwekking van 'n dubbelstrengbreuk in DNA of die behoefte aan 'n herstelsjabloon, wat die aflewering vereenvoudig en die hoeveelheid indels verminder. Hierdie twee-komponent platform is gebruik om skeibare TFBS in die muis te wysig met geen waarneembare off-teikens [23]. Basredigering is egter tans beperk tot basisoorgange en kan sogenaamde omstandersubstitusies by naburige basisse binne die redigeringvenster genereer, wat die identifisering van korrek geredigeerde TFBS bemoeilik. Onlangs is 'n nuwe tweekomponente genoombewerkingsplatform, genaamd primêre redigering, ontwikkel waarin 'n Cas9-nickase saamgesmelt is met 'n gemanipuleerde Maloney-leukemie leukemievirus-transkriptase, die gewenste wysigings direk na die teiken-DNA-volgorde kan kopieer vanaf 'n RNA (pegRNA) [24]. Eerste redigering geïnstalleer en gt 175 verskillende bewerkings, insluitend alle moontlike basisvervangings, in verskillende menslike sellyne met beperkte gebeurtenisse buite die teiken [24]. Dus, in beginsel, verteenwoordig prima redigering 'n veelsydige, presisie-geleide platform wat moontlik alle SNV's van kliniese belang kan regstel [24]. Prima redigering is aangemeld in plante [25,26,27], in vroeë stadium muis embrio's [28, 29], en in Drosophila [30]. Daar moet egter nog 'n vergelykende ontleding wees van prima redigering teenoor CRISPR-gemedieerde HDR-redigering in muise wat deur die kiemlyn geteel en vir fenotipes ontleed is. Hier het ons probeer om die doeltreffendheid van primêre redigering teenoor drie-komponent HDR-redigering op 'n enkele TFBS by muise te toets. Resultate demonstreer hoë-getrouheid in vivo prima redigering en 'n onverwagte fenotipe in muise wat 'n enkelbasisvervanging binne 'n TFBS dra.


Genoom Editing en die Christen

Hierdie artikel is aangepas uit 'n gedeelte van die 2018 V. Elving Anderson -lesing in wetenskap en godsdiens deur Jeff Hardin, gehou aan die Universiteit van Minnesota, 5 April 2018. Die volledige lesing kan onderaan hierdie artikel bekyk word.

Oorspronklik gepubliseer Mei 2018

Genoomredigering word deel van die gereedskapstel van moderne bioloë. Ons leef nou in 'n era waarin dit moontlik is om die genome van geteikende menslike selle te wysig (soos om 'n genetiese siekte soos blindheid te genees) of menslike embrio's wat die samestelling van die hele individu sal verander soos hulle ontwikkel. Hierdie omstrede tegnologie laat probleme ontstaan ​​by mense van verskillende wêreldbeskouings, maar ek wil graag argumenteer vir 'n paar beginsels wat spesifiek op die Christelike perspektief van toepassing is. Om te begin, laat ons die raad van die oorlede Christelike genetikus V. Elving Anderson onthou:

Watter innerlike hulpbronne sal individue hê om toekomstige ontdekkings die hoof te bied? Daar word soms beweer dat vrae van die toekoms so uniek sal wees dat die ou waardes onvoldoende sal wees, maar ek het geen basiese vrae gevind wat nie sal baat by die oorweging van 'n Bybelse perspektief nie. [1]

Dit is 'n goeie woord van Elving, wat hierdie woorde in 1978 geskryf het, dekades voordat gene -redigering selfs 'n moontlikheid was.

As ons Elving se siening oor genoomredigering toepas, kan ons vra: Wat is 'n paar Bybelse parameters om oor mense te dink? Om hierdie vraag te beantwoord, begin ek met 'n stukkie Hebreeuse poësie wat ek elke lente semester met my ontwikkelingsbiologie studente deel, Psalm 139:13-14: “U het my binneste gevorm, U het my saamgebind in my moederskoot…Ek is vreeslik en wonderlik gemaak.” God spreek sy sorg vir elkeen van ons uit, selfs voor ons gebore is, terwyl ons embrio's is. Daarbenewens, mense dra God se beeld. Hulle is sy onder-regente wat sy koninkryksdoeleindes in die wêreld uitvoer. Ons leer dit in die heel eerste hoofstuk van die Bybel (Gen. 1: 26-27): “Hy het hulle gemaak na die beeld van God, man en vrou,” (sien ook Gen. 9: 6). Mense word geroep om tree op as rentmeesters wat omgee vir die skepping (Gen. 1:28, 2:15). Sulke rentmeesterskap kan die versorging van lewende wesens insluit, maar kan ook dink aan genetiese manipulasie insluit.

Boonop word mense volgens Genesis 2: 23-24 voortgebring in 'een-vlees'-verhoudings. Die resultate van hierdie een-vlees verhoudings is geskenke gebore. Soos ons uit Psalm 127 sien, is Kinders 'n gawe van die Here: “Geseënd is die mens wie se pylkoker van hulle vol is.” Boonop verdien mense, veral omdat hulle almal beelddraers is, beskerming, veral die swakkes (Eks. 22:22 Deut. 10:18 Jes. 1:17). Dit laat 'n belangrike vraag ontstaan: Is 'n embrio 'n beelddraer?

Die vraag na die etiese status van 'n menslike embrio is om 'n aantal redes moeilik om so definitief te beantwoord as wat ons sou wou. Een rede vir hierdie moeilikheid is omdat die Bybelse skrywers niks geweet het van blastosiste (embrio's wat nog nie in 'n baarmoeder ingeplant is nie). Die Bybel is 'n voorwetenskaplike dokument, 'n werklikheid wat ons moet erken. Dit beteken dat sy taal hierdie probleem nie oplos met die sekerheid wat ons dalk wil hê nie. Gevolglik verskil opregte Christene oor hierdie onderwerp. Nietemin dink ek dat die meeste Christene die volgende sou bevestig: "Sulke gedeeltes [kan] nie eers vasstel wanneer die menslike lewe begin nie, maar dit vestig God se sorg en betrokkenheid van die begin af."

Oor die kwessie van die status van menslike embrio's, het ek 'n standpunt ingeneem wat ek die "wysheid van onwilligheid" sal noem. Leon Kass, 'n Joodse bio-etikus, het baie jare gelede 'n artikel geskryf, toe Dolly die skaap gekloon is, met die titel, "The Wisdom of Reugnance." Die artikel ondersoek die viscerale reaksies wat betrokke is by die denke oor die kloning van mense en die wysheid wat by sulke reaksies betrokke kan wees. Relevant tot die onderwerp ter sprake, wil ek sê dat daar wysheid is in onwilligheid. As die antwoorde op hierdie vrae effens onderbepaal is deur die Bybelse gegewens, dan is 'n verstandige optrede versigtig. Die Lutherse bio -etikus Gilbert Meilaender stel dit so:

As ons werklik verstom is oor hoe ons die morele status van die menslike subjek wat die onimplantate embrio is, die beste kan beskryf, moet ons nie vorentoe gaan op 'n manier wat metafisiese verwarring en praktiese sekerheid op 'n besondere manier kombineer deur selfs beperkte [gebruik] vir eksperimentele doeleindes goed te keur nie.

Wat Gil suggereer, is dat daar wysheid in onwilligheid is.

Die Bybel gee verdere redes vir onwilligheid. Regdeur die Bybel word die neiging van die mens tot sonde beklemtoon. Die apostel Paulus sê byvoorbeeld: “Want almal het gesondig en dit ontbreek hulle aan die heerlikheid van God” (Rom. 3:23). Ons is almal vatbaar vir sondige gedrag. Selfs voor die katastrofiese gebeure wat in Genesis 3 opgeteken is, het mense egter beperking op hul kennis vereis: God het vir Adam en Eva sekere grense in die tuin gegee (Gen. 2:16-17). God het dus selfs mense beperk voor hulle was ongehoorsaam omdat hulle op sekere maniere beperk moes word. Genesis 3 beskryf die reaksie van die mensdom op God se grense en onthul die gevalle of sondige natuur van mense, 'n werklikheid wat tot ons almal strek. As gevolg hiervan was 'n radikale oplossing nodig, en Jesus van Nasaret, God in menslike gedaante, het vir ons gesterf (Rom. 5: 6-8).

Die mensdom se neiging tot sondige gedrag beteken dat mense die risiko loop om tegnologie te misbruik. Een vorm van misbruik is wat etici dikwels noem kommodifikasieom menslike embrio's in handelsware te maak. Oor hierdie kwessie het Francis Collins gesê:

[Die toepassing van kiembelynmanipulasie sou ons siening van die waarde van menslike lewe verander. As genome verander word om by ouers se voorkeure te pas, word kinders meer soos kommoditeite as kosbare geskenke?

As gevolg van hierdie oorwegings, dink ek dat baie godsdienstige mense uit verskillende tradisies meer skepties is as nie-godsdienstige mense oor die gebruik van hierdie tegnologie. In 'n peiling in 2016 deur die Pew Charitable Trust (sien die grafiek onder die beeldbron) word gerapporteer oor die persentasie volwassenes in die Verenigde State wat 'n godsdiens aanhang en meen dat 'geenbewerking inmeng met die natuur en 'n grens oorskry wat ons nie moet oorsteek nie'. Diegene met sterk godsdienstige verbintenisse was die meeste geneig om saam te stem met die siening dat geenredigering 'n lyn oorsteek, diegene met 'n matige verbintenis het in laer getalle ingestem, en diegene met 'n lae godsdienstige verbintenis het in uiters lae getalle saamgestem. Dit is 'n interessante resultaat. Ek dink dat dit ten minste vanuit die Christelike perspektief gebaseer is op die teologiese bekommernisse wat ek bespreek het: menslike beperkings in die toepassing van tegnologie en wat die Bybel hulle sondigheid noem.

Daar is verdere redes om ons toepassings van tegnologie te beperk. Die natuurlike impuls van sommige wetenskaplikes wat hierdie tegnologie ontwikkel het, is om dit oral te neem. Tydens die besprekings van die Nasionale Akademie van Wetenskappe en die Nasionale Akademie vir Geneeskunde het die briljante molekulêre bioloog George Church gesê: "As daar getoon word dat hierdie oplossings vir ernstige siektes veilig en doeltreffend is, waarom sal klein of groot verbeterings wat die regstellings vergesel onaanvaarbaar wees?" Die kerk stel voor dat ons, terwyl ons besig is om 'n siekte op te los, die verbetering van die genomiese ekwivalent van 'n klein "fixeer -boonste gedeelte" nie verder neem nie? Die kerk stel 'n belangrike vraag: moet ons tegnologie beskou as 'n onvermydelike goed wat altyd positiewe resultate sal lewer?

Die tegnologie wat tot verbetering kan lei, kan egter in teorie ook lei tot die verbetering in die verkeerde hande. Baie dink nie aan hierdie moontlikheid nie. Miskien is ek geneig om hieroor te dink omdat ek pas Aldous Huxley se roman herlees het Dapper nuwe wêreld (1932), waarin tegnologieë gebruik word vir presies sulke verbeterings.

Hierdie oorwegings lei my na 'n paar voorstelle vir Christene in hul denke oor genome -redigering. Eerstens, deur na te dink hoe ons tegnologie op die embrio moet toepas, ons moet daarna streef om die embrio as 'n pasiënt en 'n doel, 'n verwese geskenk te behandel, eerder as 'n middel, in alle stadiums van ontwikkeling. Tweedens, ons moet twee realiteite van ons verhouding met tegnologie in balans bring. Aan die een kant word Christene geroep om lief te hê, wat beteken dat ons tegnologie behoort te gebruik om siektes te voorkom. Aan die ander kant moet ons versigtig wees vir buitensporige tegnologiese optimisme, veral as die gebruik van tegnologie belangrike Christelike waardes skend. Hierdie oorwegings is duidelik in spanning met mekaar, maar ons moet poog om die twee waarhede teen mekaar te balanseer.

Ek sluit af met 'n aanhaling van 'n held van die Christelike geloof wat vroeg in 2018 oorlede is, die Christelike evangelis Billy Graham. In 1998 het Billy Graham 'n TED Talk gehou, waartydens hy gesê het: "Die probleem is nie tegnologie nie. Die probleem is die persoon of persone wat dit gebruik." As Christene dink ek ons ​​moet dit wat Billy gesê het ernstig opneem. Om oor Billy se woorde te reflekteer, laat my met 'n diep gevoel dat ons nederig moet wees deur te dink dat ons hierdie tegnologieë reg gaan gebruik. Om terug te keer na die woorde van Elving Anderson: "Dit alles moet getemper word met die nederigheid dat daar perke is aan die veranderinge wat genetika kan bring."

Dit is my gebed dat ons, terwyl ons hierdie kwessies binne die Christelike gemeenskap en binne die breër samelewing bespreek, sal nadink oor wat dit beteken om mens te wees. Gegewe 'n beter begrip van wat dit beteken om mens te wees, kan ons verdere vrae vra: Wat is die toepaslike gebruike van tegnologie? Wat moet ons van tegnologie verwag? As Christen glo ek uiteindelik dat die fundamentele probleme waarmee ons as mense te kampe het, nie geneties of biologies is nie. Ons diepste probleme is eerder geestelik. Dit is my hoop dat Christene en ander hierdie waarheid en die implikasies daarvan in die bespreking kan bring, aangesien ons poog om die uitdagende onderwerp van genoomredigering beter te verstaan.


3. Molekulêre inosien in metabolisme en sein

Purienukleotiede dien as energiebronne, kofaktore vir metaboliese ensieme en seinmolekules. Gevolglik is molekulêre inosien 'n sentrale intermediêre in purien biosintetiese en degradasie weë (Figuur 2), terwyl dit ook 'n belangrike rol speel in neuronale sein.

Purienmetabolisme. Inosine dien as 'n sentrale tussenproduk in anaboliese en kataboliese paaie van purien.

Die de novo purien sintetiese weg behels 10 ensieme wat puriene opeenvolgend op die ribose -eenheid bou van fosforibosylpyrofosfaat (PRPP) [29]. Inosienmonofosfaat (IMP) is die eerste purienproduk van hierdie pad. Hoogs prolifererende selle soos tumorselle neem 'n energie-intensiewe de novo biosintetiese pad aan om IMP te bou. Die metaboliese ensieme van die de novo sintetiese pad word ooruitgedruk in verskeie kankers [30,31,32,33], en die tumor mikro-omgewing is ryk aan puriennukleotiede [34]. Ensieme betrokke by foliensuurmetabolisme, soos dihidrofolaatreduktase (DHFR), speel 'n noodsaaklike en beperkende rol in de novo purienbiosintese. As gevolg hiervan dien inhibeerders van die de novo purien sintetiese pad, soos antifolate, as chemoterapie-middels teen verskeie kankers [35].

Die bergingsweg is 'n purien-anaboliese pad wat ensieme met die de novo purien-sintetiese pad deel en IMP herwin om die vlakke van adenosien- en guanosien-nukleotiede aan te vul. Inosien monofosfaat dehidrogenase (IMPDH) en hipoksantien fosforibosyltransferase (HPRT) is die belangrikste ensieme van die purien bergingsweg. IMPDH skakel IMP om na xantienmonofosfaat (XMP), 'n onmiddellike voorloper van guanosienmonofosfaat (GMP). Die uitdrukking van IMPDH word verryk in menslike leukemiese selle en verskeie ander kankers [36,37]. Doelstelling van IMPDH is 'n moontlike terapeutiese strategie vir leukemie [38]. Net so is die teiken van HPRT met substraatanaloë soos 6-merkaptopurien effektief teen verskeie kankers en outo-immuun siektes [39,40].

In die purienafbraakweg word inosien wat uit adenosien geproduseer word, deur purienukleosiedfosforylase (PNP) omgeskakel na hipoksantien, wat verder afgebreek word na uriensuur [41]. Die verbetering van die purienafbrekingsweë is nog 'n strategie om die poel puriene van vinnig prolifererende selle te verminder [42].

Menslike inosientrifosfatase (ITPase) is 'n alomteenwoordige ensiem wat inosinetrifosfaat (ITP/dITP) na inosienmonofosfaat (IMP/dIMP) hidroliseer [43]. Funksionele verlies van ITPase kan lei tot die inkorporering van inosiene in RNA's en DNA's. ITPase-nul muis embrionale selle toon verrykte inosienbasisinhoud in RNA's, maar nie in DNA nie [44], waar dit vermoedelik deur DNA-herstelmeganismes verwyder word. By mense is resessiewe ITPase -mutasies betrokke by pediatriese enkefalopatieë wat gekenmerk word deur 'n gebrek aan ontwikkeling, aanvalle, hartafwykings en katarakte [45].

In purinergiese sein bemiddel nukleotiede neurotransmissie deur te dien as seinmolekules vir purien- en pirimidienreseptorfamilies [46]. Adenosiene tree op as neurotransmitters in beide perifere en sentrale senuweestelsels [47], en inosien oefen soortgelyke effekte uit as adenosien, wat A1, A2A en A3 adenosienreseptore aktiveer [48]. Die toediening van inosien is neurobeskermend by rotte met rugmurgbesering, moontlik deur die metaboliet daarvan, uraat [49]. Deur te funksioneer as 'n intrasellulêre seinmolekule, dien inosine ook as 'n antidepressant by muise [50], bevorder aksonale uitgroei en verbeter die gedragsuitkoms na beroerte [51,52].

Orale toediening van inosine is ondersoek in kliniese toetse om neurologiese toestande soos Parkinson se siekte (PD) te behandel. Inosien toediening verhoog die uraatvlakke in serum en serebrospinale vloeistof (CSF), wat neurobeskerming bied deur radikale opruiming [53,54,55]. In PD-pasiënte kan inosientoediening die vordering van verstandelike gestremdheid vertraag, maar 'n fase 3-proef is voortydig beëindig aangesien die verwagte doeltreffendheid nie nagekom is nie [56]. Inosien pranobex (IP), 'n inosienderivaat, is bekend vir sy immunomodulerende en antivirale eienskappe [57] en word ondersoek vir die behandeling van COVID-19 by bejaarde pasiënte vir die versterkende effekte van IP op limfosietproliferasie, sitokienproduksie en natuurlike sitotoksisiteit van moordenaarselle [58].


Hands on: Redigering - Biologie

Dr. Carl June se laboratorium aan die Universiteit van Pennsylvania lyk soos enige ander sentrum vir biologiese navorsing. Daar is netjiese rye werkblaaie met swart bedekking, geflankeer deur rakke met bokse pipette en proefbuise. Daar is ad hoc -tekens wat die verskillende werkstasies aandui. En daar gons na -dokters rond, kalibreer skale, kyk broeikaste en smeer oplossings en monsters op klein glasplate.

Op die een of ander manier, wat June hier probeer doen, op die agtste verdieping van die Smilow Center for Translational Research in Philadelphia met glas, is alles behalwe normaal. Hy het 'n loopbaan opgebou om die kans vir mense met ondraaglike eindstadiumsiekte te verbeter, en nou, in die splinternuwe selverwerkingslaboratorium van die universiteit, berei hy hom voor om sy mees ambisieuse studie nog te begin: hy &# 8217s gaan probeer om 18 mense met hardnekkige kankers te behandel, en hy’s gaan dit doen met behulp van CRISPR, die mees omstrede nuwe hulpmiddel in medisyne.

Net vier jaar gelede ontwikkel deur twee groepe—Jennifer Doudna, 'n molekulêre en selbioloog aan die Universiteit van Kalifornië, Berkeley, saam met Emmanuelle Charpentier, nou by die Max Planck Instituut in Berlyn en Feng Zhang, 'n biomediese ingenieur by die Broad Institute van Harvard en MIT—CRISPR laat wetenskaplikes toe om maklik en goedkoop feitlik enige stukkie DNS in enige spesie te vind en te verander. Net in 2016 is dit gebruik om die gene van groente, skape, muskiete en allerhande selmonsters in laboratoriums te wysig. Nou, selfs soos sommige wetenskaplikes om geduld en uiters versigtigheid vra, is daar 'n wêreldwye wedloop om die grense van CRISPR se vermoëns te verskuif.

Die uiteindelike doel van Junie is om die grootste potensiaal van CRISPR te toets: sy vermoë om siektes by mense te behandel. Voordat ons in die donker vlieg toe ons geenveranderinge aanbring, sê hy van vroeëre pogings tot genetiese knoeiery. “Met CRISPR het ek tot die gevolgtrekking gekom dat hierdie tegnologie in mense getoets moet word.” Die proef, wat oor 'n paar maande sal begin om pasiënte te behandel, is die eerste wat hierdie kragtige tegniek op hierdie manier gebruik. Dit verteenwoordig die mees uitgebreide manipulasie van die menslike genoom wat ooit probeer is.

Binnekort sal 18 proefpasiënte in Junie die eerste mense ter wêreld word wat met CRISPR ’d -selle behandel word - in hierdie geval word selle geneties geredigeer om kanker te beveg. Soos baie mense met kanker, het die pasiënte ook nie meer die opsies nie. As gevolg van die werk van Doudna, Charpentier en Zhang, sal die span van June hul T -selle, 'n soort immuunsel, onttrek en CRISPR gebruik om drie gene in die selle te verander, wat dit in wese in supervegters verander. Die pasiënte sal dan weer met die kankerbestrydende T-selle toegedien word om te sien of hulle doen wat hulle veronderstel is om te doen: om kankergewasse te soek en te vernietig.

Baie hoop hang af van die uitslag van die verhoor, maar of dit slaag of misluk, dit sal wetenskaplikes van kritiese inligting voorsien oor wat reg en verkeerd kan gaan wanneer hulle probeer om die genetiese kode by mense te herskryf. Die hoop is dat studies soos Junie se CRISPR -terapeutiese potensiaal sal uitwerk, wat sal lei tot die ontwikkeling van radikale nuwe terapieë, nie net vir mense met die kanker wat bestudeer word nie, maar ook vir almal, sowel as vir genetiese siektes soos sekel selanemie en sistiese fibrose en chroniese toestande soos tipe 2 -diabetes en Alzheimer. Dit klink dalk vergesog, maar studies soos hierdie is ’n enorme eerste stap in daardie rigting.

Die gebruik van CRISPR op mense is nog steeds baie kontroversieel, deels omdat dit so maklik is. Die feit dat dit wetenskaplikes in staat stel om enige geen doeltreffend te redigeer - vir sommige kankers, maar ook moontlik vir 'n aanleg vir rooi hare, om oorgewig te wees, om goed te wees in wiskunde - maak etici bekommerd oor wat kan gebeur as dit in die verkeerde hande beland. . Die National Institutes of Health (NIH), verreweg die grootste borg van wetenskaplike navorsing ter wêreld, finansier tans nie studies met CRISPR oor menslike embrio's nie. En enige nuwe manier om gene in menslike selle te verander, moet etiek en veiligheidsgoedkeuring deur die NIH kry, ongeag wie daarvoor betaal. (Die NIH is ook gekant teen die gebruik van CRISPR op sogenaamde kiemlynselle-dié in 'n eier, sperm of embrio-aangesien sulke veranderinge permanent en oorerflik sou wees.)

Om sy studie te befonds, kon June steun trek van Sean Parker, die voormalige Facebook -uitvoerende beampte en Silicon Valley -entrepreneur agter Napster. Parker het onlangs die Parker Institute for Cancer Immunotherapy van $ 250 miljoen gestig, 'n samewerking tussen ses groot kankersentrums, en Junie se studie is die eerste ambisieuse onderneming. 'Ons moet groot, ambisieuse weddenskappe neem om die behandeling van kanker te bevorder,' sê Parker. “Ons’re probeer om die pad te lei in die doen van meer aggressiewe, voorpunt-dinge wat nie befonds kon kry as ons nie daar was nie.”

Dit om nie te sê dat die studie van June ’s hierdie kanker noodwendig sal genees nie. Of dit is terug na die tekenbord, sê hy, of almal gaan vorentoe en bestudeer 'n wye verskeidenheid ander siektes wat moontlik opgelos kan word. In werklikheid is albei dinge waarskynlik waar.

Selfs as die studie van Junie nie werk soos hy hoop nie, is kenners dit steeds eens dat dit 'n kwessie van maande - nie jare nie - sal wees voordat ander privaat befondsde menslike studies in die VSA en in die buiteland van stapel gestuur word. An ongoing patent battle over who owns the lucrative technology hasn’t stopped investors from pouring millions into CRISPR companies. So simple and inexpensive is the technique, and so frenzied is the medical community about its potential, that it would be foolish to bet on anything else. “With a technology like CRISPR,” says Doudna, “you’ve lit a fire.”

A Year of Progress
CRISPR’s journey from lab bench to cancer treatment may seem quick. After all, as recently as a couple of years ago only a minuscule number of people even knew what clustered regularly interspaced short palindromic repeats—that’s longhand for CRISPR—was. But the technology is at least hundreds of millions of years old. It was bacteria that originally used CRISPR, as a survival mechanism to fend off infection by viruses. The ultimate freeloaders, viruses never bothered developing their own reproductive system, preferring instead to insert their genetic material into that of other cells—including bacteria. Bacteria fought back, holding on to snippets of a virus’ genes when they were infected. The bacteria would then surround these viral DNA fragments with a genetic sequence that effectively cut them out altogether.

Bacteria have been performing that clever evolutionary stunt for millennia, but it wasn’t until the early 2000s that food scientists at a Danish yogurt company realized just how clever the bacterial system was when they noticed that their cultures were turning too sour. They discovered that the cultures were CRISPRing invaders, altering the taste considerably. It made for bad dairy, but the scientific discovery was immediately recognized as a big one.

About a decade later, in 2012, Doudna and Charpentier tweaked the system to make it more standardized and user-friendly, and showed that not just bacterial DNA but any piece of DNA has this ability. That was a game changer. Scientists have been mucking with plant, animal and human DNA since its structure was first discovered by James Watson and Francis Crick in 1953. But altering genes, especially in deliberate, directed ways, has never been easy. “The idea of gene correction is not new at all,” says June. “But before CRISPR it just never worked well enough so that people could do it routinely.”

Within months of Doudna’s and Charpentier’s discovery, Zhang showed that the technique worked to cut human DNA at specified places. With that, genetics changed overnight. Now scientists had a tool allowing them, at least in theory, to wield unprecedented control over any genome, making it possible to delete bits of DNA, add snippets of genetic material and even insert entirely new pieces of code.

Now, that theoretical potential took shape in a remarkable array of real-world applications. CRISPR produced the first mushroom that doesn’t brown, the first dogs with DNA-boosted cells giving them a comic-book-like musculature, and a slew of nutritionally superior crops that are already on their way to market. There are even efforts to use CRISPR’d mosquitoes to fight Zika and malaria.

On the human side, progress has been even more dramatic. In a lab, scientists have successfully snipped out HIV from infected human cells and demonstrated that the process works in infected mice and rats as well. They’re making headway in correcting the genetic defect behind sickle-cell anemia, which stands to actually cure the disease. They’re making equally promising progress in treating rare forms of genetic blindness and muscular dystrophy. And in perhaps the most controversial application of CRISPR to date, in 2016 the U.K. approved the first use of the technology in healthy human embryos for research.

At the Francis Crick Institute in London, developmental biologist Kathy Niakan is using CRISPR to try to understand one of the more enduring mysteries of human development: what goes wrong at the earliest stages, causing an embryo to die and a pregnancy to fail. To be clear, Niakan will not attempt to implant the embryos in a human her research is experimental, and the embryos are destroyed seven days after the studies begin.

Like Niakan, June is looking for answers to one of human biology’s more vexing problems: why the immune system, designed to fight disease, is nearly useless against cancer. It’s an issue that’s kept him up at night since 2001, when his wife, not responding to the many treatments she tried, died of ovarian cancer.

“This trial is about two things: safety and feasibility,” he says. It’s about testing whether it’s even possible to successfully edit these immune cells to make them do—in human bodies, not a petri dish—what he wants them to do. Either way, the study will yield critical information, paving the way for eventual new treatment options that are more targeted, less brutal and far smarter against tumors than systemwide chemotherapy will ever be.

As much as has been done in 2016, this is only the beginning of a kind of medicine that stands to effectively change the course of human history. “CRISPR is an empowering technology with broad applications in both basic science and clinical medicine,” says Dr. Francis Collins, director of the NIH. “It will allow us to tackle problems that for a long time we probably felt were out of our reach.”

The Hurdles Ahead
Because it’s so easy to use, Zhang, along with the other CRISPR pioneers, says careful thought should be given to where and how it gets employed. “For the most part I don’t think we are getting ahead of ourselves with the CRISPR applications,” he says. “What we need to do is really engage the public, to make sure people understand what are the really exciting potential applications and what are the immediate limitations of the technology, so we really are applying it and supporting it in the right way.”

Regulatory scrutiny is a given with CRISPR, and any new tool for rewriting human DNA requires federal approval. For the current Penn trial, June got the green light from the NIH Recombinant DNA Advisory Committee, established in the 1980s to assess the safety of any first-in-humans gene-therapy trials. While there are still dangers involved in any kind of gene therapy—the changes may happen in unexpected places, for example, or the edits may have unanticipated side effects—scientists have learned more about the best way to make the genetic changes, and how to deliver them more safely. So far, animal studies show CRISPR provides enough control that unexpected negative effects are rare—at least so far.

The role of regulatory oversight is less clear when the technique is used to alter food crops. Even before June’s patients get infused with CRISPR’d T cells, farmers in Argentina and Minnesota will plant the world’s first gene-edited crops for market. CRISPR provides an unparalleled ability to insert almost any trait into plants—drought or pest resistance, more of this vitamin or less of that nutritional villain du jour. Dupont, for instance, is putting the finishing touches on its first drought-resistant corn, and biotech company Calyxt has created a potato that doesn’t produce cancerous compounds when fried it’s also planting its first crop of soy plants modified to produce higher amounts of healthy oleic-acid fats.

These edits involve deleting or amping up existing genes—not adding new ones from other species—and the U.S. Department of Agriculture has said this kind of gene-edited food crop is not significantly different from unaltered crops and therefore does not need to be regulated differently.

In the coming months, the National Academy of Sciences is expected to issue guidelines that might address some of the challenges posed by CRISPR, focusing on how and when to proceed with developing new disease treatments. The report is expected to launch much-needed discussion in the scientific community and among the public as well. Whether more regulation will eventually be required likely depends on how far scientists push the limits of their editing—and how comfortable consumers and advocacy groups are with those studies.

As CRISPR goes mainstream in medicine and agriculture, profound moral and ethical questions will arise. Few would argue against using CRISPR to treat terminal cancer patients, but what about treating chronic diseases? Or disabilities? If sickle-cell anemia can be corrected with CRISPR, should obesity, which drives so many life-threatening illnesses? Who decides where that line ought to be drawn?

Questions like these weigh heavily on June and all of CRISPR’s pioneering scientists. “Having this technology enables humans to alter human evolution,” says Doudna. “Thinking about all the different ways it can be employed, both for good and potentially not for very good, I felt it would be irresponsible as someone involved in the earliest stages of the technology not to get out and talk about it.”

Last year, Doudna invited other leaders in genetics to a summit to address the immediate concerns about applying CRISPR to human genes. The group agreed to a voluntary temporary moratorium on using CRISPR to edit the genes of human embryos that would be inserted into a woman and brought to term, since the full array of CRISPR’s consequences isn’t known yet. (Any current research using human embryos, including Niakan’s, is lab-only.)

For researchers like June and Niakan, Doudna and Zhang, and others, proceeding carefully with CRISPR is the only way forward. But proceed they will. The sooner more answers emerge, the sooner CRISPR can mature and begin to deliver on its promise. “There are thousands of applications for CRISPR,” says June. “The sky is the limit. But we have to be careful.”


Editing the Building Blocks of Life, Using a New Technique

In a bustling laboratory, Biology 410 students are clustered into groups of two or three, pipetting fluids into tiny test tubes. The scene isn’t unusual for an upper level course in a science classroom, but these students are doing something previously unseen in undergraduate courses: editing genomes.


Biological Sciences Professor John Steele (left) and Biology 410 students Patrick Quinn (middle) and Rachel Parry (right) in the classroom. Using the CRISPR /Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR associated gene 9)-based techniques, students in Biology Professor John Steele’s classes and labs have been editing the genetic material of cells, inserting coding sequences for fluorescent proteins, correcting or inserting disease-causing mutations, or mutations that affect other cell functions, or studying pathways using CRISPR -based modifiers of gene expression.

Dr. Steele received his Ph.D. and did his post-doctoral work in neurodegeneration labs, looking at a spectrum of diseases such as Alzheimer’s, Huntington’s, and Parkinson’s, as well as several rare neurological diseases. The cell death involved in those diseases is caused by a buildup of proteins—an apparent inability to activate the autophagy pathway, or the cells’ way of maintaining themselves.

In his BIOL 410 class this semester, students are using CRISPR -based methods to control expression of genes in human embryonic kidney cells, then studying how the loss or overabundance of the genes effect the autophagy pathway—leading to more understanding about what causes neurodegenerative diseases.

Dr. Steele brought these CRISPR techniques to HSU when he was hired in Fall 2016. Until several years ago, before the technique was developed, genome editing would have cost tens of thousands of dollars and taken six weeks or more. Now, with CRISPR -based methods, genome-editing tools can be easily produced by students in his lab courses for around $20 and completed in a week.

Because of the low cost and relative simplicity of the CRISPR techniques, Dr. Steele has given it classroom applications new to undergraduate programs.

The way CRISPR edits genomes is closely related to fundamental biology teachings. Students in entry-level courses are learning the principles that make CRISPR function, and then will be able to apply those principles in a hands-on way in later courses. And he’d like to introduce CRISPR even earlier in biology students’ educations.

“From a pedagogical standpoint, it’s a really effective way to teach the central dogma of genetics,” Steele says. “ CRISPR will be the foundational research tool of the gene editing field and students need to learn how to work with these tools now.”


Biochemistry senior Michael Martinez looks at cells in the CRISPR lab. It’s also a highly marketable skill. Recent graduates have already landed jobs in academic and private laboratories based partly upon their experience with CRISPR -based methods.

As part of his curriculum, Steele asks students to propose research ideas using the highly adaptable CRISPR process.

Patrick Quinn, a Psychology graduate student, is seeking to use CRISPR to manipulate expression of multiple genes at a time, improving his understanding of schizophrenia and other neurodevelopmental disorders.

Biochemistry Senior Michael Martinez, who says he “pretty much kicked down John’s office door and said let me work here” when he learned of Dr. Steele’s CRISPR lab, is researching the how overabundance of the protein tau alters cellular processes in human embryonic kidney cells, similar to Steele’s work. Interested in the building blocks of life, Martinez originally wanted to design tools like CRISPR —now he can use it to conduct research at a scale previously unattainable.


Online Forum: Simulated, or Hands On Science Learning?

Can a student who completes a virtual dissection of a fetal pig get the same level of experience as a student who performs a live dissection? Do you think simulations can replace hands-on science experiments? From your experience, what are the advantages and disadvantages of both? Leave your comments, have your say, read posts .

About 17 percent of the 17,000 schools that offer Advanced Placement courses provide them online. The online offerings allow home-schooled students, for example, or those at schools that don’t provide their own AP courses to access the advanced classes.

Generally, such online courses work well, Packer says, but AP science classes, which have laboratory requirements, have encountered roadblocks. A panel studying simulations for online AP science courses such as biology, chemistry, and physics found that simulations alone couldn’t provide the experiences needed.

Currently, the College Board provides conditional authorization to AP science courses with only virtual lab components. As the College Board works to overhaul its curriculum for those science courses, however, the provisional authorization will become a thing of the past, says Michael Kabbaz, its senior director of college and university services.

AP biology is first on the list for revamping. By the 2011-12 school year, no conditional authorization will be permitted.

Still, Kabbaz says that since technology is constantly changing, there is a possibility that virtual simulations may be able to meet the requirements in the future. “We’ll be as eager as anyone else to see what develops,” he says. “The ideal scenario will probably involve a mix” of simulated and hands-on experiments, he adds.

Zipporah Miller, the associate executive director of professional programs and conferences for the Arlington, Va.-based National Science Teachers Association, says virtual experiments alone can’t equal real-world labs. “The simulation should be used only as a reinforcement,” she says. “If they go through the simulation, they may get the right answer on an AP exam, but they may not have the experience to apply that knowledge in the real world.”

Some virtual AP providers argue that simulations are being used by everyone from medical students to the military and can suffice. But others are trying to incorporate real lab experiences into their online courses.

Cheryl Vedoe, the president and chief executive officer of the virtual-course provider Apex Learning, says her Seattle-based company has embraced the AP panel’s findings by formulating real-world lab experiments that online students can do mostly on their own. For example, students who take Apex’s online AP biology course will also receive lab kits. A typical kit for an experiment on osmosis and diffusion might contain, among other items, dialysis tubing, glucose test strips, a digital scale, and instructions to add a self-bought potato, Vedoe says.

The Apex AP biology course also comes with simulations of the experiment and a video to support the hands-on lab exercise, she says. The model will work well for both biology and physics, but chemistry is a bit different, Vedoe says. Working with chemicals can be dangerous, so Apex is producing two versions of the AP chemistry course. One includes hands-on experiments that must be performed in a laboratory setting under the supervision of an adult—a scenario easier to envision for students taking the course at a school. The College Board is expected to officially authorize that course. The other version will include only simulations and may be the best option for some home-schooled students, Vedoe says.

“Colleges and universities will recognize the student has completed the course,” she says, “but they may require them to take the lab portion of the course when they arrive.”


The Long View On Gene Editing

The CRISPR-Cas9 genome editing system is transforming bioengineering. We asked one of the technology&rsquos creators, Jennifer Doudna, what comes next.

This article was produced for Kavli Prize by Scientific American Custom Media, a division separate from the magazine's board of editors.

It began as an effort to understand how microbes fight viral infections. Within their chromosomes bacteria store snippets of DNA taken from the viruses they encounter. These fragments, which are tagged by a set of DNA segments called CRISPRs (clustered regulatory interspaced short palindromic repeats), serve as a record of past infections, and allow bacteria to become immune to future infections.

For Jennifer Doudna, an HHMI investigator and professor of chemistry as well as biochemistry and molecular biology at the University of California, Berkeley, the big question was, how did the system work? The answer lay with an enzyme named Cas9. Doudna and her team found that when armed with an RNA copy of one of the viral mug shots, the Cas9 enzyme could recognize and disable viruses that carried a matching sequence.

Once she understood this system, Doudna set out to harness it. By feeding the Cas9 enzyme a guide RNA of her choosing, Doudna found that she could edit target DNA much more easily and accurately than with existing methods. A Cas9-directed incision could inactivate a target gene. It could also provide an insertion site for new DNA, such as an altered version of the target gene.

The description of this CRISPR- Cas9 system—published in Science in 2012—launched a revolution in biology and biotechnology. In just seven years, CRISPR has become an essential research tool and the inspiration for scores of new start-ups. The technology has the potential to transform basic science, improve agricultural crops and cure genetic diseases. At the same time, it raises ethical questions about how to handle a technology that has the power to alter human evolution.

In 2018, Doudna and two of her colleagues, Professors Emmanuelle Charpentier at the Max Planck Institute for Infection Biology and Virginijus Siksnys at Vilnius University, were awarded the Kavli Prize in Nanoscience for their work on CRISPR-Cas9.

Now, Doudna outlines the next big questions that need to be addressed before CRISPR can reach its full potential.

What is CRISPR 2.0, and how do we develop it?

One big issue with CRISPR technology is how we can ensure the accuracy and the efficiency of genome editing, meaning the exact changes that are introduced into DNA. Right now, scientists can trigger targeted changes to DNA at a particular place in the genome, but we have a harder time ensuring the exact kind of change that gets introduced. A couple of things that are in the pipeline right now, not just in my own lab, but generally in the field: One is to develop what are called base-editing versions of CRISPR-Cas proteins. This means developing ways of using these programmable enzymes, not to cut DNA, but actually to trigger a chemical change to a particular DNA base in a sequence. With these base-editing molecules, we could reduce opportunities for the cell to make an undesired change. This is the kind of very specific manipulation of a DNA sequence that could, in principle, cure a disease-causing mutation in a cell.

Illustration by Falconieri Visuals

Can we turn CRISPR-Cas9 against infectious disease?

There’s been a lot of interest in asking the question, at least in a research setting. Could you harness the adaptive immune functions of CRISPR-Cas systems for protecting other kinds of cells from viruses? I think that is not too likely, at least in its present form, because viruses have a remarkable ability to adapt and evolve resistance to targeting mechanisms, such as the one used by CRISPR-Cas. On the other hand, do I think that there may be ways to target bacteria that are infectious agents in people? Absoluut. One of the forefronts of the field is to explore how we could use CRISPR-Cas systems to target some of the bacteria that are harmful to people.

Can we turn to microbes to find alternative gene-editing tools?

One of the amazing questions in biology is, what are all of the microbes that populate our planet? Many scientists, including my colleague, Jillian Banfield here at University of California, Berkeley, are studying microbes in the environment by sequencing their DNA and piecing together information about their lifestyles, community partners and environmental niches. That’s something where I think a biochemist and structural biologist like myself can engage with experts in DNA metagenomics to try to understand the molecular pathways in these organisms. Some of these pathways provide a defense against viruses, like CRISPR systems do. CasX is a newer iteration of CRISPR-Cas that can be programmed to find and cut DNA just like Cas9. But it’s a lot smaller, and it has a completely different molecular shape, so it may be easier to deliver it into cells and ensure that it does the accurate editing necessary for clinical use.

How can we ensure gene editing benefits everyone?

Very soon, we will be faced with many opportunities for manipulating DNA—not only in individuals but also in the cells that can transmit changes to future generations. Given that, I’d like to see a lot more opportunities for public interaction with scientists and more opportunities to explore the broader implications of gene editing. How does it affect the inequalities that we see across society? How does it affect people’s decisions about reproduction and genetic disease? How do we even define genetic disease? What do we consider to be health versus disease? Those kinds of questions need to be openly debated.

To hear the complete podcast with Jennifer Doudna, watch the video below.

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International Hands-on Training on Genome Editing Technologies

The International Crops Research Institute for the Semi-Arid Tropics (ICRISAT) and Asia-Pacific Association of Agricultural Research Institutions (APAARI) under its programme on Asia Pacific Consortium on Agricultural Biotechnology and Bioresources (APCoAB) jointly announces the call for applications for its international hands-on training program on “Genome Editing Technologies”. ICRISAT is an International non-profit agricultural research institute with sate of the art facilities on agri-biotechnology research supporting innovation, development and applications of broad range of biotechnological solutions spreading across various domains from basic research to product translation. Under the aegis BioNcube, a BIRAC-BioNEST Ag-biotech incubator at ICRISAT and APCoAB programme of APAARI the training course is being organized during October 14 – 25, 2019 at ICRISAT, Patancheru, Hyderabad, India-502 324.

Toepassing

Applications are invited from researchers who are familiar with basic molecular and cell biology techniques and want to learn genome editing applications in agriculture using the most recent and advanced CRISPR system.


Kyk die video: Bindegewebe 1. Teil (Augustus 2022).