{"id":4290,"date":"2019-12-09T19:52:03","date_gmt":"2019-12-09T16:52:03","guid":{"rendered":"http:\/\/blog.ulubat.org\/?p=4290"},"modified":"2019-12-09T22:04:30","modified_gmt":"2019-12-09T19:04:30","slug":"gen-duzenleme-teknolojilerinde-yeni-bir-boyut-prime-editing","status":"publish","type":"post","link":"https:\/\/blog.ulubat.org\/index.php\/genel\/gen-duzenleme-teknolojilerinde-yeni-bir-boyut-prime-editing\/","title":{"rendered":"Gen D\u00fczenleme Teknolojilerinde Yeni Bir Boyut: Prime Editing"},"content":{"rendered":"\n
\"\"<\/figure>\n\n\n\n

2012 y\u0131l\u0131nda Jennifer Doudna\u2019n\u0131n CRISPR\/Cas9 sistemini ke\u015ffinden\nsonra, gen d\u00fczenleme teknolojileri g\u00fcn\u00fcm\u00fcz\u00fcn en pop\u00fcler konular\u0131ndan biri\nhaline geldi. Bir\u00e7ok bilim insan\u0131n\u0131n ilgisini \u00e7eken bu teknolojiler, y\u0131llard\u0131r\nd\u00fcnyan\u0131n \u00f6nde gelen laboratuvarlar\u0131nda \u00e7al\u0131\u015f\u0131lmakta ve yeni y\u00f6ntemler\ngeli\u015ftirilmesi ama\u00e7lanmaktad\u0131r.<\/p>\n\n\n\n

MIT (Massachusetts Institute of Technology) ve Harvard \u00dcniversitesi \u00f6\u011fretim \u00fcyesi David Liu liderli\u011findeki ara\u015ft\u0131rmac\u0131lar\u0131n yapt\u0131klar\u0131 \u00e7al\u0131\u015fmalar, bu teknolojilere yeni bir boyut kazand\u0131racak nitelikte. Yaz\u0131m\u0131zda, \u201cPrime Editing\u201d ad\u0131 verilen bu yeni CRISPR teknolojisini ele alaca\u011f\u0131z.<\/p>\n\n\n\n

Prime Editing; insan h\u00fccreleri \u00fczerinde genetik d\u00fczenlemeler yap\u0131lmas\u0131na imkan veren, hassas, verimli ve \u00e7ok y\u00f6nl\u00fc bir teknolojidir. Bu teknoloji, biyolojik ve tedaviye y\u00f6nelik ara\u015ft\u0131rmalarda genetik d\u00fczenleme kapsam\u0131n\u0131 geli\u015ftirecek nitelikte olup genetik mutasyonlar\u0131n sebep oldu\u011fu hastal\u0131klar\u0131n yakla\u015f\u0131k %90\u2019\u0131n\u0131n tedavisini m\u00fcmk\u00fcn k\u0131lmaktad\u0131r.<\/p>\n\n\n\n

Prime Editing Teknolojisi<\/strong><\/p>\n\n\n\n

Prime Editing,  iki \u00f6nemli protein (Cas9 ve revers transkriptaz) ile pegRNA’n\u0131n kombinasyonundan olu\u015fmaktad\u0131r.<\/em><\/p>\n\n\n\n

Cas9 enzimi<\/em><\/strong>, DNA’n\u0131n sadece bir\nzincirine ba\u011flan\u0131p istenilen k\u0131sm\u0131 kesmek amac\u0131yla modifiye edilmi\u015ftir. Revers\ntranskriptaz (RT) enzimi<\/strong> ise RNA tasla\u011f\u0131n\u0131 kopyalayarak yeni DNA’y\u0131 meydana\ngetirme g\u00f6revini \u00fcstlenmi\u015ftir.<\/em><\/p>\n\n\n\n

pegRNA<\/em><\/strong> (prime editing guide RNA),\nCas9 ve RT’yi kesilmek istenen zincire g\u00f6t\u00fcrmektedir. Laboratuvarda \u00fcretilen\npegRNA’lar iki \u00f6nemli yap\u0131y\u0131 i\u00e7ermektedir:<\/em><\/p>\n\n\n\n

  1. Ba\u011flanma b\u00f6lgesi:<\/em><\/strong> DNA zincirine ba\u011flanan k\u0131s\u0131md\u0131r. Zinciri, yeni bazlar\u0131n eklenmesi i\u00e7in haz\u0131rlamaktad\u0131r.<\/em><\/li>
  2. D\u00fczenlenmi\u015f sekans:<\/em><\/strong> Zincirde istenilen de\u011fi\u015fikli\u011fi kodlayacak olan RNA bazlar\u0131ndan olu\u015fan k\u0131s\u0131md\u0131r.<\/em><\/li><\/ol>\n\n\n\n

    Sistemi olu\u015fturan ana yap\u0131lar ve onlar\u0131n g\u00f6revlerinden\nbahsettikten sonra yap\u0131lan i\u015fleme gelecek olursak:<\/em><\/p>\n\n\n\n

    1. Prime editor kompleksi (Cas9\/RT), pegRNA rehberli\u011fi ile  de\u011fi\u015fiklik yap\u0131lmak istenen zincire ba\u011flan\u0131r.<\/em><\/li>
    2. Cas9 zincirde istenilen k\u0131sm\u0131 keser. <\/em><\/li>
    3. Revers transkriptaz, pegRNA \u00fczerindeki d\u00fczenlenmi\u015f sekansa uygun DNA’y\u0131 sentezler ve kesilen k\u0131sma ekler.<\/em><\/li>
    4. H\u00fccresel endon\u00fckleaz enzimi, DNA’dan kesilmi\u015f olan par\u00e7ay\u0131 eksize eder ve yeni eklenmi\u015f olan par\u00e7ay\u0131 zincire sabitler.<\/em><\/li>
    5. Bu a\u015famada yaln\u0131zca bir zincirde istenilen de\u011fi\u015fiklik yap\u0131lm\u0131\u015ft\u0131r. Fakat yanl\u0131\u015f-e\u015flenme olmamas\u0131 i\u00e7in kar\u015f\u0131 zincirde de de\u011fi\u015fiklik yap\u0131lmas\u0131 gerekmektedir. Bunun i\u00e7in prime editor kompleksi, farkl\u0131 bir pegRNA rehberli\u011fiyle DNA’n\u0131n kar\u015f\u0131 zincirine y\u00f6nlendirilir.<\/em><\/li>
    6. Cas9, bu zincirde de istenilen k\u0131sm\u0131 keser.<\/em><\/li>
    7. Zincirde a\u00e7\u0131lan \u00e7entik, d\u00fczenlenmi\u015f DNA’ya g\u00f6re (ilk d\u00fczenlenen zincir) kendisini tamamlar.<\/em><\/li>
    8. T\u00fcm bu i\u015flemler sonucunda, iki zinciri de d\u00fczenlenmi\u015f DNA elde edilir.<\/em><\/li><\/ol>\n\n\n\n
      \"\"<\/figure>\n\n\n\n

      Bu y\u00f6ntemin, CRISPR\/Cas9 teknolojisine g\u00f6re en \u00f6nemli\n\u00fcst\u00fcnl\u00fc\u011f\u00fc; DNA’n\u0131n yaln\u0131zca bir zincirini kesmesinden \u00f6t\u00fcr\u00fc hedef\nhassasiyetinin fazla ve hedef d\u0131\u015f\u0131 etkisinin az olmas\u0131d\u0131r.  Klasik CRISPR\/Cas9 y\u00f6nteminde DNA’n\u0131n iki\nipli\u011fi birden kesilmekte ve sonras\u0131nda yeni baz ekleme i\u015flemi, h\u00fccrenin kendi\ntamir mekanizmas\u0131nca ger\u00e7ekle\u015fmektedir. Prime editing teknolojisinde ise DNA\nsarmal\u0131n\u0131n sadece tek ipli\u011fi kesilmekte olup di\u011fer zincir, de\u011fi\u015fikli\u011fin yap\u0131ld\u0131\u011f\u0131\nzincire g\u00f6re d\u00fczenlenmektedir. Ancak bu \u00fcst\u00fcnl\u00fcklerinin yan\u0131nda prime editing\nsisteminin, klasik CRISPR\/Cas9 teknolojisinin yapabildi\u011fi kadar b\u00fcy\u00fck DNA\npar\u00e7alar\u0131n\u0131 ekleme ve kesip atma i\u015flemlerinde yetersiz kald\u0131\u011f\u0131 belirtilmelidir.<\/p>\n\n\n\n

      Prime editing ile insan\nh\u00fccre serileri \u00fczerinde yap\u0131lan \u00e7al\u0131\u015fmalarda orak h\u00fccreli anemide meydana gelen\nT-A (timin-adenin) de\u011fi\u015fimi ve Tay-Sachs hastal\u0131\u011f\u0131na sebep olan d\u00f6rt\nbaz\u0131n delesyonu gibi genetik mutasyonlar ba\u015far\u0131yla d\u00fczeltilmi\u015ftir. <\/p>\n\n\n\n

      Prime editing teknolojisi \u00fczerine yap\u0131lacak \u00e7al\u0131\u015fmalar\u0131n artmas\u0131yla birlikte, insanlarda hastal\u0131\u011fa sebep olan bir\u00e7ok genetik mutasyona kar\u015f\u0131 tedaviler geli\u015ftirilece\u011fi \u00f6ng\u00f6r\u00fclmektedir. T\u0131p d\u00fcnyas\u0131 olarak bizler de yeni \u00e7al\u0131\u015fmalar\u0131 merakla bekliyor ve heyecanla  takip ediyoruz…<\/p>\n\n\n\n

      Kaynaklar<\/strong><\/p>\n\n\n\n

      1. Anzalone AV, et al.\nSearch-and-replace genome editing without double-strand breaks or donor DNA.\nNature. Online October 21, 2019.<\/li>
      2. New CRISPR genome editing system offers a wide range of versatility in\nhuman cells, Broad Institute. broadinstitute.org<\/li><\/ol>\n","protected":false},"excerpt":{"rendered":"

        2012 y\u0131l\u0131nda Jennifer Doudna\u2019n\u0131n CRISPR\/Cas9 sistemini ke\u015ffinden sonra, gen d\u00fczenleme teknolojileri g\u00fcn\u00fcm\u00fcz\u00fcn en pop\u00fcler konular\u0131ndan biri haline geldi. Bir\u00e7ok bilim<\/p>\n","protected":false},"author":144,"featured_media":4298,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[1],"tags":[271],"acf":[],"views":1761,"_links":{"self":[{"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/posts\/4290"}],"collection":[{"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/users\/144"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/comments?post=4290"}],"version-history":[{"count":5,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/posts\/4290\/revisions"}],"predecessor-version":[{"id":4300,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/posts\/4290\/revisions\/4300"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/media\/4298"}],"wp:attachment":[{"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/media?parent=4290"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/categories?post=4290"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.ulubat.org\/index.php\/wp-json\/wp\/v2\/tags?post=4290"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}