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Silence at the End: How Drosophila Regulates Expression and Transposition of Telomeric Retroelements.
Journal of Molecular Biology ( IF 5.6 ) Pub Date : 2020-06-05 , DOI: 10.1016/j.jmb.2020.06.004
Stefano Cacchione 1 , Giovanni Cenci 2 , Grazia Daniela Raffa 1
Affiliation  

The maintenance of chromosome ends in Drosophila is an exceptional phenomenon because it relies on the transposition of specialized retrotransposons rather than on the activity of the enzyme telomerase that maintains telomeres in almost every other eukaryotic species. Sequential transpositions of Het-A, TART, and TAHRE (HTT) onto chromosome ends produce long head-to-tail arrays that are reminiscent to the long arrays of short repeats produced by telomerase in other organisms. Coordinating the activation and silencing of the HTT array with the recruitment of telomere capping proteins favors proper telomere function. However, how this coordination is achieved is not well understood. Like other Drosophila retrotransposons, telomeric elements are regulated by the piRNA pathway. Remarkably, HTT arrays are both source of piRNA and targets of gene silencing thus making the regulation of Drosophila telomeric transposons a unique event among eukaryotes. Herein we will review the genetic and molecular mechanisms underlying the regulation of HTT transcription and transposition and will discuss the possibility of a crosstalk between piRNA-mediated regulation, telomeric chromatin establishment, and telomere protection.



中文翻译:

尽头沉默:果蝇如何调节端粒端粒元件的表达和转座。

果蝇染色体末端的维持是一种特殊现象,因为它依赖于专门的逆转座子的转座,而不是维持几乎所有其他真核物种中端粒的端粒酶的活性。Het-ATARTTAHRE(HTT)在染色体末端的顺序转座产生长的头对尾阵列,让人想起端粒酶在其他生物中产生的短重复序列。将HTT阵列的激活和沉默与端粒封端蛋白的募集相协调,有利于端粒的正常功能。但是,如何实现这种协调还没有很好的理解。像其他果蝇逆转座子,端粒元件受piRNA途径调节。值得注意的是,HTT阵列既是piRNA的来源,也是基因沉默的目标,因此使果蝇端粒转座子的调控成为真核生物中的独特事件。在本文中,我们将回顾HTT转录和转座调控的遗传和分子机制,并讨论piRNA介导的调控,端粒染色质建立和端粒保护之间发生串扰的可能性。

更新日期:2020-07-14
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