{"id":67004,"date":"2026-01-31T00:00:12","date_gmt":"2026-01-30T21:00:12","guid":{"rendered":"https:\/\/bilimvegelecek.com.tr\/?p=67004"},"modified":"2026-01-30T00:06:48","modified_gmt":"2026-01-29T21:06:48","slug":"sicrayan-genler-dnanin-hareketli-parcalari","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2026\/01\/31\/sicrayan-genler-dnanin-hareketli-parcalari","title":{"rendered":"S\u0131\u00e7rayan genler: DNA\u2019n\u0131n hareketli par\u00e7alar\u0131"},"content":{"rendered":"

Muhammet Halim Ta\u015fkesenlio\u011flu
\n<\/strong>Erzurum Teknik \u00dcniversitesi Molek\u00fcler Biyoloji ve Genetik B\u00f6l\u00fcm\u00fc \u00f6\u011frencisi<\/p>\n

Barbara McClintock, 1950\u2019li y\u0131llarda m\u0131s\u0131r bitkisi \u00fczerine yapt\u0131\u011f\u0131 \u00e7al\u0131\u015fmalar s\u0131ras\u0131nda genlerin d\u00fc\u015f\u00fcnd\u00fc\u011f\u00fcm\u00fcz kadar sabit davranmad\u0131\u011f\u0131n\u0131 fark etti. DNA\u2019n\u0131n i\u00e7inde yer de\u011fi\u015ftirip adeta \u201cs\u0131\u00e7rayan\u201d bu gen par\u00e7alar\u0131, o d\u00f6nemin bilim d\u00fcnyas\u0131nda b\u00fcy\u00fck bir \u015fa\u015fk\u0131nl\u0131k yaratm\u0131\u015ft\u0131. Aradan y\u0131llar ge\u00e7tikten sonra, 1988\u2019de Science <\/em>dergisinde yay\u0131mlanan bir \u00e7al\u0131\u015fmada Haig H. Kazazian Jr. ve ekibi bu hareketli genlerin yaln\u0131zca bitkilerde de\u011fil, insan DNA\u2019s\u0131nda da bulundu\u011funu ve baz\u0131 hastal\u0131klar\u0131n ortaya \u00e7\u0131kmas\u0131nda rol oynayabilece\u011fini ortaya koydu.<\/p>\n

McClintock\u2019un a\u00e7t\u0131\u011f\u0131 bu yol, genomu nas\u0131l anlad\u0131\u011f\u0131m\u0131za dair bak\u0131\u015f a\u00e7\u0131m\u0131z\u0131 k\u00f6kl\u00fc bi\u00e7imde de\u011fi\u015ftirdi. Bug\u00fcn biliyoruz ki s\u0131\u00e7rayan genler yani transpozonlar yaln\u0131zca yer de\u011fi\u015ftiren DNA par\u00e7alar\u0131 de\u011fil; genomumuzun yakla\u015f\u0131k %45\u2019ini olu\u015fturan, genlerin ne zaman aktifle\u015fece\u011finden h\u00fccrelerin nas\u0131l davrand\u0131\u011f\u0131na kadar pek \u00e7ok s\u00fcreci etkileyen dinamik unsurlard\u0131r.<\/p>\n

Peki bu genler, DNA \u00fczerinde nas\u0131l yer de\u011fi\u015ftirir?<\/p>\n

S\u0131\u00e7rayan genler nas\u0131l hareket eder?
\n<\/strong>DNA\u2019m\u0131z\u0131n i\u00e7inde yer alan bu \u201cg\u00f6\u00e7ebe\u201d genler, hareket ederken iki farkl\u0131 y\u00f6ntem kullan\u0131r. \u0130lk grup, Barbara McClintock\u2019un da tan\u0131mlad\u0131\u011f\u0131 DNA transpozonlar\u0131d\u0131r. Bu genler, \u201ctranspozaz\u201d ad\u0131 verilen bir enzim yard\u0131m\u0131yla bulunduklar\u0131 yerden kesilerek DNA\u2019n\u0131n ba\u015fka bir b\u00f6lgesine ta\u015f\u0131n\u0131r. Bunu, bir metinden c\u00fcmle kesip ba\u015fka bir sayfaya yap\u0131\u015ft\u0131rmaya benzetebiliriz; bu y\u00fczden bu mekanizma genellikle \u201ckes ve yap\u0131\u015ft\u0131r\u201d olarak adland\u0131r\u0131l\u0131r.<\/p>\n

\u0130kinci grup RNA transpozonlar\u0131d\u0131r, ba\u015fka bir deyi\u015fle retrotranspozonlard\u0131r. Bu genler DNA\u2019dan direkt kesilmez, bunun yerine kendi bilgilerinin bir RNA kopyas\u0131n\u0131 olu\u015ftururlar. Sonra bu olu\u015fan kopya, \u201cters transkriptaz\u201d isimli bir enzim taraf\u0131ndan tekrardan DNA\u2019ya d\u00f6n\u00fc\u015ft\u00fcr\u00fcl\u00fcr ve genomun ba\u015fka bir b\u00f6lgesine entegre edilir. Sonu\u00e7ta, orijinal gen yerinde kal\u0131r ama onun bir kopyas\u0131 DNA\u2019n\u0131n farkl\u0131 bir noktas\u0131nda yer edinir.<\/p>\n

\"\"<\/p>\n

\u015eekil 1. Retrotranspozon ve DNA transpozonunun hareket mekanizmalar\u0131n\u0131n \u015fematik kar\u015f\u0131la\u015ft\u0131rmas\u0131. Orijinal g\u00f6rsel: Kelvinsong, \u201cTransposable elements (2).png\u201d, CC BY-SA 4.0. T\u00fcrk\u00e7eye \u00e7evrilmi\u015f ve d\u00fczenlenmi\u015ftir.<\/p>\n

\u00d6zetle, DNA transpozonlar\u0131 hareket ederken \u201ckes-yap\u0131\u015ft\u0131r\u201d mekanizmas\u0131n\u0131 kullan\u0131r. Buna kar\u015f\u0131l\u0131k, RNA transpozonlar\u0131 ise \u201ckopyala-yap\u0131\u015ft\u0131r\u201d y\u00f6ntemiyle \u00e7o\u011falarak DNA \u00fczerinde yer de\u011fi\u015ftirirler. Bu temel farkl\u0131l\u0131k, genetik bozukluklar\u0131n ve \u00e7e\u015fitli mutasyon t\u00fcrlerinin DNA\u2019m\u0131zda nas\u0131l meydana geldi\u011fini ve yay\u0131ld\u0131\u011f\u0131n\u0131 anlamak a\u00e7\u0131s\u0131ndan hayati bir \u00f6neme sahiptir. Bu iki mekanizma aras\u0131ndaki hareket farkl\u0131l\u0131klar\u0131 \u015eekil 1\u2019de g\u00f6sterilmi\u015ftir.<\/p>\n

Genetik \u00e7e\u015fitlilikten hastal\u0131\u011fa: s\u0131\u00e7rayan genlerin dinamik etkisi
\n<\/strong>DNA\u2019da yer alan transpozonlar yaln\u0131zca genetik \u00e7e\u015fitlilik yaratmaz, bunun yan\u0131 s\u0131ra canl\u0131lar\u0131n \u00e7evreye uyum sa\u011flama yeteneklerini de etkiler. Nitekim, Batzer ve Deininger\u2019in 2002\u2019de Genome Research\u2019te <\/em>yapt\u0131\u011f\u0131 \u00e7al\u0131\u015fma, bizlere bu genlerin ki\u015filer aras\u0131ndaki genetik farkl\u0131l\u0131klar\u0131 b\u00fcy\u00fck \u00f6l\u00e7\u00fcde art\u0131rd\u0131\u011f\u0131n\u0131 ve yeni genlerin ya da gen kombinasyonlar\u0131n\u0131n (rekombinasyon) ortaya \u00e7\u0131kmas\u0131na sebep oldu\u011funu g\u00f6sterdi. Yine paralel bir do\u011frultuda 2023 y\u0131l\u0131nda bioRxiv preprint<\/em>\u2019te Jubierre Zapater ve ekibinin ortaya koydu\u011fu \u00e7al\u0131\u015fma ile PGBD5 adl\u0131 genin, eski bir s\u0131\u00e7rayan gen enziminden evrimle\u015fti\u011fi ve memelilerde beyin geli\u015fiminde kilit bir rol \u00fcstlendi\u011fi ortaya kondu.<\/p>\n

N\u00f6ronal sisteme bakt\u0131\u011f\u0131m\u0131zda ise beyinde yer alan ve bir s\u0131\u00e7rayan gen olan LINE-1\u2019in; sinir h\u00fccrelerinin geli\u015fimi s\u0131ras\u0131nda (\u00f6zellikle do\u011fum \u00f6ncesi ve hemen sonras\u0131) etkinle\u015ferek, her bireyin beyninde \u015fahs\u0131na \u00f6zg\u00fc olan genetik bir \u201cmozaik\u201d yap\u0131 olu\u015fturmas\u0131na sebep oldu\u011funu g\u00f6r\u00fcyoruz. E\u011fer ki bu s\u00fcre\u00e7 h\u00fccre kontrol\u00fcn\u00fcn d\u0131\u015f\u0131na \u00e7\u0131karsa DNA yap\u0131s\u0131 bozulabilir, hasarlar olu\u015fabilir ve hatta \u201cAlzheimer ve ALS\u201d gibi n\u00f6rolojik rahats\u0131zl\u0131klara sebep olabilir. Biliminsanlar\u0131, transpozonlar\u0131n n\u00f6ronal sistem i\u00e7erisindeki y\u00fcksek etkinli\u011finin nedeninin h\u00fccre kayb\u0131 ve sinir h\u00fccrelerindeki iltihaplanmalardan kaynakland\u0131\u011f\u0131n\u0131 d\u00fc\u015f\u00fcn\u00fcyor.<\/p>\n

Bazen de kanser h\u00fccrelerinde s\u0131\u00e7rayan genlerden kaynaklanan kontrol kaybetme etkileri g\u00f6r\u00fcl\u00fcyor. Buna en iyi \u00f6rnek; 2017\u2019de Burns ve arkada\u015flar\u0131 taraf\u0131ndan, Nature Reviews Cancer <\/em>dergisinde yay\u0131mlanan ve s\u0131\u00e7rayan genlerin DNA\u2019ya rastgele eklenmesi sonucu di\u011fer genlerin i\u015flevlerini negatif y\u00f6nde etkileyerek, kontrols\u00fcz \u00e7o\u011falmaya (kanserle\u015fme) neden oldu\u011funu g\u00f6steren ara\u015ft\u0131rmad\u0131r. \u00d6zellikle pankreas kanserinde, tedaviye diren\u00e7 g\u00f6steren h\u00fccrelerde bu d\u00fczensiz gen hareketlerinin pay\u0131 b\u00fcy\u00fckt\u00fcr.<\/p>\n

Yine de, belirtmek gerekir ki bu genler her zaman bir hastal\u0131k sebebi ya da bir tehdit unsuru de\u011fildir. Transpozonlar bazen, h\u00fccredeki protein \u00fcretimini y\u00f6neten perde arkas\u0131ndaki d\u00fczenleyicilerdir. Bazen de olu\u015fturduklar\u0131 RNA molek\u00fclleri ile genlerin nerede, ne zaman ve ne kadar aktif kalaca\u011f\u0131n\u0131 ayarlayan h\u00fccre i\u00e7i g\u00f6revlilerdir. Transpozonlar\u0131n DNA dizilerine entegre olarak yeni kombinasyonlar olu\u015fturmas\u0131, \u00e7e\u015fitli protein t\u00fcrlerinin \u00fcretilmesini ve canl\u0131lar\u0131n \u00e7evresel ko\u015fullara daha iyi uyum sa\u011flamas\u0131n\u0131 kolayla\u015ft\u0131r\u0131r (do\u011fal se\u00e7ilim). Ve unutulmamal\u0131d\u0131r ki, bu genler canl\u0131 ya\u015fam\u0131n\u0131n evrilmesinde ve \u00e7e\u015fitlenmesinde biyolojik bir ger\u00e7ektir.<\/p>\n

Sonu\u00e7 olarak, s\u0131\u00e7rayan genler genomun sessiz par\u00e7alar\u0131 olmay\u0131p; bazen genleri a\u00e7\u0131p kapatan, bazen hastal\u0131klar\u0131n ortaya \u00e7\u0131kmas\u0131na yol a\u00e7an, bazen uyum sa\u011flamay\u0131 kolayla\u015ft\u0131r\u0131p bazen de genetik \u00e7e\u015fitlilik yaratan DNA\u2019n\u0131n g\u00f6r\u00fcnmez d\u00fczenleyicileridir.<\/p>\n

S\u0131\u00e7rayan genlerin gelece\u011fi
\n<\/strong>S\u0131\u00e7rayan genler \u00fczerine yap\u0131lan \u00e7al\u0131\u015fmalar, bug\u00fcn genetik biliminin en merak uyand\u0131ran alanlar\u0131ndan biri olmaya devam ediyor. Bu gizemli DNA par\u00e7alar\u0131, anla\u015f\u0131lan o ki ilerleyen y\u0131llarda da biliminsanlar\u0131n\u0131n ilgisini \u00e7ekmeye devam edecek. \u00d6zellikle hastal\u0131klar\u0131n ortaya \u00e7\u0131k\u0131\u015f\u0131ndaki rolleri ve h\u00fccrelerdeki h\u0131zl\u0131 genetik de\u011fi\u015fimlere olan etkileri, onlar\u0131 modern biyolojinin en \u00e7ok konu\u015fulan konular\u0131ndan biri h\u00e2line getiriyor.<\/p>\n

Genetik sabitlik anlay\u0131\u015f\u0131n\u0131 (genlerin DNA \u00fczerinde sabit oldu\u011funu savunan d\u00fc\u015f\u00fcnce) y\u0131kan bu ke\u015fif, ak\u0131llarda \u015fu soruyu b\u0131rak\u0131yor: \u201cE\u011fer genler bu kadar hareketliyse, sabit kal\u0131p, miras olarak aktar\u0131lan ne olabilir?\u201d Bu, genetik biliminin belki de en temel tart\u0131\u015fmalar\u0131ndan birini yeniden g\u00fcndeme ta\u015f\u0131yor. Kal\u0131t\u0131m yaln\u0131zca genlerle mi a\u00e7\u0131klanmal\u0131, yoksa DNA\u2019n\u0131n kendi i\u00e7 hareketlili\u011fi de bu miras\u0131n bir par\u00e7as\u0131 m\u0131 say\u0131lmal\u0131?<\/p>\n

Art\u0131k biliyoruz ki transpozonlar yaln\u0131zca ge\u00e7mi\u015fi \u015fekillendirmedi, biyoteknolojinin ve t\u0131bb\u0131n gelece\u011fine y\u00f6n vererek, gen terapisi ve gen d\u00fczenleme teknolojilerinde ilham al\u0131nabilecek do\u011fal bir model oldular. CRISPR gibi teknolojiler, g\u00fcn\u00fcm\u00fczde gen d\u00fczenlemede \u00e7\u0131\u011f\u0131r a\u00e7sa da; yar\u0131n\u0131n yeni ara\u00e7lar\u0131, transpozonlar\u0131n do\u011fal \u201cs\u0131\u00e7rama\u201d mekanizmalar\u0131n\u0131 \u00f6rnek alarak DNA\u2019ya m\u00fcdahale edebilme yetkinli\u011fini bizlere kazand\u0131rabilir. Ve bu yetkinli\u011fin sayesinde, DNA\u2019ya kontroll\u00fc bir \u015fekilde yeni par\u00e7alar ekleyebilen biyolojik ara\u00e7lar\u0131n varl\u0131\u011f\u0131n\u0131 hayal etmemek elde de\u011fildir. Bu bulgular ki\u015fiselle\u015ftirilmi\u015f t\u0131p ve genetik ba\u015fta olmak \u00fczere ya\u015fam bilimlerinin pek \u00e7ok alan\u0131nda bizlere e\u015fik atlatacakt\u0131r<\/p>\n

McClintock\u2019un bir as\u0131r \u00f6nce fark etti\u011fi bu ke\u015fif bize baz\u0131 \u015feyleri hat\u0131rlat\u0131yor: \u201cBir s\u0131\u00e7ray\u0131\u015fla ba\u015flar her \u015fey. \u0130kincisinde evrilir. \u00dc\u00e7\u00fcnc\u00fcs\u00fcnde\u2026 belki de biz anlar\u0131z.\u201d<\/p>\n

KAYNAKLAR<\/strong><\/p>\n

– Batzer, M. A., & Deininger, P. L. (2002). Alu repeats and human genomic diversity. Genome Research, 12(4), 463\u2013471.<\/p>\n

– Morgan, G. T., et al. (2005). Transposable elements and the evolution of the eukaryotic genome. Cytogenetic and Genome Research, 110(1\u20134), 49\u201357.<\/p>\n

– Richardson, S. R., et al. (2014). Active retrotransposons in the human brain: Neuronal mosaicism and disease. Nature Neuroscience, 17(5), 791\u2013797.<\/p>\n

– Saleh, A., et al. (2019). Transposable elements and neuroinflammation. Frontiers in Neurology, 10, 894<\/p>\n

– Burns, K. H., & Boeke, J. D. (2017). Human transposon activity and cancer. Nature Reviews Cancer, 17(7), 415\u2013424.<\/p>\n

– Zhou, W., et al. (2022). Transposon-induced genomic instability drives pancreatic cancer evolution. Nature Genetics, 54(12), 1907\u20131918.<\/p>\n

– Jubierre Zapater, J., et al. (2023). A transposase-derived gene required for human brain development. bioRxiv, preprint. doi:10.1101\/2023.05.10.540200<\/p>\n

– Sibley, C. R., et al. (2023). Transposable elements drive transcript diversification through alternative splicing in mammals. Nature Communications, 14(1), 2678.<\/p>\n","protected":false},"excerpt":{"rendered":"

Muhammet Halim Ta\u015fkesenlio\u011flu Erzurum Teknik \u00dcniversitesi Molek\u00fcler Biyoloji ve Genetik B\u00f6l\u00fcm\u00fc \u00f6\u011frencisi Barbara McClintock, 1950\u2019li y\u0131llarda m\u0131s\u0131r bitkisi \u00fczerine yapt\u0131\u011f\u0131 \u00e7al\u0131\u015fmalar s\u0131ras\u0131nda genlerin d\u00fc\u015f\u00fcnd\u00fc\u011f\u00fcm\u00fcz kadar sabit davranmad\u0131\u011f\u0131n\u0131 fark etti. DNA\u2019n\u0131n i\u00e7inde yer de\u011fi\u015ftirip adeta \u201cs\u0131\u00e7rayan\u201d bu gen par\u00e7alar\u0131, o d\u00f6nemin bilim d\u00fcnyas\u0131nda b\u00fcy\u00fck bir \u015fa\u015fk\u0131nl\u0131k yaratm\u0131\u015ft\u0131. Aradan y\u0131llar ge\u00e7tikten sonra, 1988\u2019de Science dergisinde yay\u0131mlanan bir […]<\/p>\n","protected":false},"author":4383,"featured_media":67006,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[10405,38,535,510],"tags":[10424,10423],"class_list":["post-67004","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-262-sayi","category-dergi-sayilari","category-forum","category-surekli-bolumler","tag-muhammed-halim-taskesenlioglu","tag-sicrayan-genler"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t