一直以來,，科學家認為，端粒（Telomeres）的唯一作用在于保護DNA免受磨損,。瑞士科學家最新研究發(fā)現(xiàn),，端粒的作用不僅如此,，它還能作為合成RNA的模板。相關論文10月4日在線發(fā)表于《科學》上,。
每次染色體進行復制的時候，末端的DNA總是會發(fā)生丟失,。為了防止重要遺傳信息的遺失,，端粒會“犧牲”自我，貢獻出自己的片斷,。長期下來,，端粒就會越來越短。很多科學家相信,，端粒的長短與細胞的壽命有著重要的聯(lián)系,。很多癌細胞之所以能夠長久生存，就是因為它們能夠維持較長的端粒,。另外,，端粒還能夠阻止旁邊的DNA合成RNA。
在最新的研究中,，瑞士實驗癌癥研究所（ISREC）的Joachim Lingner和同事在研究一個與RNA降解有關的蛋白時發(fā)現(xiàn),，該蛋白與端粒相聯(lián)系。隨后,，他們在端粒附近發(fā)現(xiàn)了叢生的RNA,。
法國原子能委員會的分子生物學家Laure Sabatier說，這是一項重大的突破,，從來沒有人會想過,，端粒能夠作為合成RNA的DNA模板。
Lingner表示,，目前尚不清楚該發(fā)現(xiàn)是否能夠為癌癥治療提供新途徑,，端粒附近RNA的作用也還不明了。他說,，實驗表明,，當端粒附近RNA水平升高，端粒的丟失速度會加快,。但這二者之間是否直接相關還有待研究,。（科學網(wǎng) 梅進/編譯）
原始出處:
Published Online October 4, 2007
Science DOI: 10.1126/science.1147182
Submitted on June 28, 2007
Accepted on September 17, 2007
Telomeric Repeat–Containing RNA and RNA Surveillance Factors at Mammalian Chromosome Ends
Claus M. Azzalin 1, Patrick Reichenback 1, Lela Khoriauli 2, Elena Giulotto 2, Joachim Lingner 1*
1 Swiss Institute for Experimental Cancer Research (ISREC), CH-1066 Epalinges, Switzerland.; School of Life Sciences, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.; "Frontiers in Genetics" National Centre for Competence in Research (NCCR), CH-1211 Geneva, Switzerland.
2 University of Pavia, Department of Genetics and Microbiology, 27100 Pavia, Italy.
* To whom correspondence should be addressed.
Joachim Lingner , E-mail: [email protected]
Telomeres, the DNA-protein complexes located at the end of linear eukaryotic chromosomes, are essential for chromosome stability. Until now, telomeres have been considered to be transcriptionally silent. We demonstrate here that mammalian telomeres are transcribed into telomeric repeat containing RNA (TERRA). TERRA molecules are heterogeneous in length, are transcribed from several subtelomeric loci towards chromosome ends and localize to telomeres. We also show that Suppressors with Morphogenetic Defects in Genitalia (SMG) proteins, which are effectors of nonsense mediated RNA decay, are enriched at telomeres in vivo, negatively regulate TERRA association with chromatin and protect chromosome ends from telomere loss. Thus, telomeres are actively transcribed into TERRA, and SMG factors represent a molecular link between TERRA regulation and maintenance of telomere integrity.
