生物谷：當(dāng)身體細(xì)胞內(nèi)DNA鏈發(fā)生破損時，通常其修復(fù)不需要很多時間?，F(xiàn)在,，來自瑞典醫(yī)科大學(xué)Karolinska研究所的科學(xué)家發(fā)現(xiàn)了一種能解釋這些修復(fù)過程的新機(jī)制。結(jié)果發(fā)表在Science上,。
這一研究主要針對一種稱為結(jié)合的過程,，它是細(xì)胞核中兩個染色體通過一個稱為cohesin的蛋白聯(lián)合體緊密結(jié)合在一起的現(xiàn)象。在細(xì)胞分裂過程中這起著非常重要的作用,，因為新復(fù)制的染色單體需要結(jié)合在一起,，以等待合適的時機(jī)分離。如果染色單體分離得過早,，則子代細(xì)胞存在染色體數(shù)量錯誤的風(fēng)險,，這在腫瘤細(xì)胞中常被觀測到。
而最近Camilla Sjogren博士和她的研究小組證實,，這一結(jié)合過程在細(xì)胞修復(fù)損傷的染色單體過程中同樣起著重要作用,。結(jié)果顯示，DNA破損能重新激活此過程,，這一發(fā)現(xiàn)和傳統(tǒng)觀點不同,，傳統(tǒng)意義上認(rèn)為結(jié)合過程只在細(xì)胞分裂前的DNA復(fù)制過程中發(fā)生。
科學(xué)家們長期以來驚嘆于復(fù)制得到的染色體分裂的方式,，它們能如此精確的將一半的遺傳物質(zhì)傳遞給其子代細(xì)胞,。而另一個大的研究課題則是細(xì)胞如何修復(fù)受損的DNA，并由此預(yù)防癌癥等疾病的發(fā)生。
Sjogren博士表示：“我們的研究結(jié)果證明,，染色體的分離以及DNA修復(fù)過程部分程度上是通過相同的機(jī)制實現(xiàn)的,。這些發(fā)現(xiàn)為我們提供了對于這兩個基本細(xì)胞學(xué)機(jī)制的深入了解，并且可能對于癌癥的研究有所幫助,。”
（教育部科技發(fā)展中心）
原文鏈接：http://www.physorg.com/news103543773.html
原始出處:
Science 13 July 2007:
Vol. 317. no. 5835, pp. 242 - 245
DOI: 10.1126/science.1140649
Postreplicative Formation of Cohesion Is Required for Repair and Induced by a Single DNA Break
Lena Ström,1 Charlotte Karlsson,1 Hanna Betts Lindroos,1 Sara Wedahl,1 Yuki Katou,2 Katsuhiko Shirahige,2 Camilla Sjögren1*
Sister-chromatid cohesion, established during replication by the protein complex cohesin, is essential for both chromosome segregation and double-strand break (DSB) repair. Normally, cohesion formation is strictly limited to the S phase of the cell cycle, but DSBs can trigger cohesion also after DNA replication has been completed. The function of this damage-induced cohesion remains unknown. In this investigation, we show that damage-induced cohesion is essential for repair in postreplicative cells in yeast. Furthermore, it is established genome-wide after induction of a single DSB, and it is controlled by the DNA damage response and cohesin-regulating factors. We thus define a cohesion establishment pathway that is independent of DNA duplication and acts together with cohesion formed during replication in sister chromatid–based DSB repair.
1 Department of Cell and Molecular Biology, Karolinska Institute, 171 77 Stockholm, Sweden.
2 Gene Research Centre, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, 226-8501 Yokohama, Japan.
* To whom correspondence should be addressed. E-mail: [email protected]
