The repair of DNA double strand breaks (DSB) through non-homologous end joining (NHEJ) or homologous recombination (HR) is a finely regulated process. Genetic and molecular impedances in either of the pathways affect the fate of the DSB repair and can lead to extended chromosome rearrangements, triggering inheritable genetic instability and tumorigenesis. Recent findings indicated that formation of DNA:RNA hybrids at DSB sites might interfere with DSB repair and DNA damage response. Here we characterized the role of budding yeast DNA:RNA helicase Sen1, orthologous of the human Senataxin/SETX, in DSB repair. Chromatin immunoprecipitation analyses showed that Sen1 is recruited to one HO-induced DSB, contributing to remove DNA:RNA hybrids nearby the lesion. Along with the increased DNA:RNA hybrids, the binding of Rpb3, a subunit of the RNA polymerase II complex, is also prolonged in Sen1-depleted cells. Remarkably, the persistent DNA:RNA hybrids cause abrupt Mre11 and Dna2 dependent resection of the DSB, in the absence of Sen1. By specific genetic backgrounds, we found that Sen1 depletion leads to faster ectopic recombination repair of a DSB and, surprisingly, to elevated NHEJ and chromosome translocations. In line with the increased NHEJ, KU binding at the DSB is also prolonged in Sen1-depleted cells. In summary, our data suggest molecular mechanism through which Sen1 removes DNA:RNA hybrids at DSB in order to prevent non-canonical resection initiation, also limiting KU persistence at DSB and dangerous NHEJ events. We believed that these results in yeast might contribute to explain molecularly pathologic phenotypes, recently described in human cells depleted of Senataxin.

Sen1/SETX helicase limits DNA:RNA hybrids at DNA double strand breaks and determines faithful repair through end joining and homologous recombination / C.C. Rawal, L. Zardoni, M. Di Terlizzi, G. Liberi, A. Pellicioli. ((Intervento presentato al convegno Jacques Monod Conference : Genome instability: when RNA meets chromatin tenutosi a Roscoff , France nel 2019.

Sen1/SETX helicase limits DNA:RNA hybrids at DNA double strand breaks and determines faithful repair through end joining and homologous recombination

M. Di Terlizzi;G. Liberi;A. Pellicioli
2019-09

Abstract

The repair of DNA double strand breaks (DSB) through non-homologous end joining (NHEJ) or homologous recombination (HR) is a finely regulated process. Genetic and molecular impedances in either of the pathways affect the fate of the DSB repair and can lead to extended chromosome rearrangements, triggering inheritable genetic instability and tumorigenesis. Recent findings indicated that formation of DNA:RNA hybrids at DSB sites might interfere with DSB repair and DNA damage response. Here we characterized the role of budding yeast DNA:RNA helicase Sen1, orthologous of the human Senataxin/SETX, in DSB repair. Chromatin immunoprecipitation analyses showed that Sen1 is recruited to one HO-induced DSB, contributing to remove DNA:RNA hybrids nearby the lesion. Along with the increased DNA:RNA hybrids, the binding of Rpb3, a subunit of the RNA polymerase II complex, is also prolonged in Sen1-depleted cells. Remarkably, the persistent DNA:RNA hybrids cause abrupt Mre11 and Dna2 dependent resection of the DSB, in the absence of Sen1. By specific genetic backgrounds, we found that Sen1 depletion leads to faster ectopic recombination repair of a DSB and, surprisingly, to elevated NHEJ and chromosome translocations. In line with the increased NHEJ, KU binding at the DSB is also prolonged in Sen1-depleted cells. In summary, our data suggest molecular mechanism through which Sen1 removes DNA:RNA hybrids at DSB in order to prevent non-canonical resection initiation, also limiting KU persistence at DSB and dangerous NHEJ events. We believed that these results in yeast might contribute to explain molecularly pathologic phenotypes, recently described in human cells depleted of Senataxin.
Settore BIO/11 - Biologia Molecolare
Sen1/SETX helicase limits DNA:RNA hybrids at DNA double strand breaks and determines faithful repair through end joining and homologous recombination / C.C. Rawal, L. Zardoni, M. Di Terlizzi, G. Liberi, A. Pellicioli. ((Intervento presentato al convegno Jacques Monod Conference : Genome instability: when RNA meets chromatin tenutosi a Roscoff , France nel 2019.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/754368
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