LDR 02878nam a2200301 n 450 001 TD21001844 005 20210410124628.0 049 $aTDMAGDIG 100 $a20190501d2021 --k--ita-50----ba 101 1 $aeng 200 1 $aUNDERSTANDING THE IMPACT OF REPLICATION STRESS ON THE EXPRESSION OF EARLY GENES IN MOUSE EMBRYONIC STEM CELLS$bTesi di dottorato 210 1$cUniversità degli Studi di Milano$d2021-03-30 300 $adiritti: info:eu-repo/semantics/embargoedAccess 300 $aIn relazione con info:eu-repo/semantics/altIdentifier/hdl/2434/814703 328 0$btesi di dottorato$cSettore BIO/11 - Biologia Molecolare$eUniversità degli Studi di Milano 330 $aEmbryonic stem cells (ESCs) are characterized by a rapid cell cycle, which leads to high replication stress (RS) in otherwise unperturbed conditions. The mechanisms that ESCs adopt to cope with their endogenous RS, however, remain to this day elusive. In our recent work we demonstrated that the activation of the checkpoint kinase ATR in response to RS leads to a broad activation of 2-cells stage specific genes in mouse ESCs. This response relies on the up-regulation of Dux, a transcription factor encoded in a macrosatellite sequence repeated in tandem. Dux is repressed by variant Polycomb repressive complex 1 (vPRC1) in unperturbed ESCs, independently from PRC2 presence. Here we demonstrate that RS causes a major rearrangement of both PRC1 and PRC2 in ESCs nuclei, resulting in a major loss of both repressive marks in correspondence to target promoters. Surprisingly, Dux undergoes an increase in vPRC1 occupancy upon RS in an ATR-dependent manner, possibly due to PRC1 involvement in the replication of highly repeated DNA sequences. More interestingly, Dux activation upon RS requires the presence of PRC2. This result is possibly due to PRC2 proved role in the processing of stalled replication forks, which are the main structure signaling RS. In agreement to this data, also the fork remodeling translocases HLTF and ZRANB3 displayed an effect in Dux activation following RS. Taken together, our results show that the up-regulation of 2-cells genes following RS not only requires ATR activation, but also downstream remodeling processes. 689 0 $aSettore BIO/11$b- Biologia Molecolare$cTDR 700 0$aGNOCCHI, ANDREA 702 0$aCOSTANZO, VINCENZO 702 0$aInternal advisor: Y. Doksani ; tutor: V. Costanzo ; phd coordinator: G. Viale 702 0$aVIALE, GIUSEPPE 801 3$aIT$bIT-FI0098 856 4 $uhttp://memoria.depositolegale.it/*/http://hdl.handle.net/2434/814703$2http://hdl.handle.net/2434/814703 856 4 $uhttp://memoria.depositolegale.it/*/http://air.unimi.it/bitstream/2434/814703/2/phd_unimi_R11740.pdf$2http://air.unimi.it/bitstream/2434/814703/2/phd_unimi_R11740.pdf 977 $a CR 997 $aCF FMT $aTD FOR $aTD