The Legube lab is interested in deciphering the function of chromatin during DNA double strand break (DSB) repair. This aspect of DSB repair is yet mostly unexplored, mainly because until recently, no system was available to induce DSBs at well identified loci, a prerequisite to study how chromatin influences repair. We have developed a system (the DIvA cell line), based on a restriction enzyme fused to the ligand-binding domain of oestrogen receptor (AsiSI-ER), in order to generate multiples sequence-specific DSBs. 4OHT treatment of this cell line triggers AsiSI nuclear localization and the rapid induction of ~150 DSBs on the human genome. Since it induces unambiguously positioned DSBs, one can use ChIP-chip/seq to draw high resolution profiles of DSB-induced chromatin modification and DNA repair complexes around breaks. Using this system, combined to these genome wide approaches we have been able to comprehensively characterize the chromatin landscape assembled at DSBs (Iacovoni et al, 2010; Clouaire et al, 2018), and the changes of chromosome conformation induced by DSBs (Aymard et al, 2017, Arnould et al, in press). Moreover we have recently provided evidence that transcribing chromatin displays specialized repair mechanisms compared to silent loci (Aymard et al, 2014, Aymard et al, 2017, Cohen et al, 2018, Marnef et al, 2019).

We will support Dr Tej Pandita for his NIH proposal, by providing help and advice for the use of the DIvA cell line. Moreover we will on our side, assess the effect of heat shock on the ability of the DSB to cluster, using both high throughput microscopy and 4C-seq/Hi-C approaches (as in Aymard et al, 2017), as well as the impact of temperature on translocation frequency (as in Cohen et al, 2018).

Giulia Guarguaglini graduated in Biological Sciences at Sapienza University of Rome. She has long-standing experience in the study of signaling networks in cell division and cancer, developed first while studying the mitotic roles of the Ran GTPase network during her PhD in the laboratories of Dr Lavia (CNR, Rome) and Dr Mattaj (EMBL, Heidelberg) (Battistoni, Guarguaglini et al., J Cell Sci 1997; Carazo-Salas, Guarguaglini et al., Nature, 1999; Guarguaglini et al., Cell Growht Diff. 2000; Gruss et al., Cell, 2001). She then joined a leading laboratory in the mitotic field, led by Prof. Nigg at the MPI for Biochemistry (Munich, DE) and focussed on the study of mitotic kinases (Guarguaglini et al., Mol. Biol. of the Cell, 2005; Tachibana et al., EMBO Rep, 2005). Back to Italy thanks to a Marie Curie Re-integration Grant, she coordinates since 2006 a research unit at IBPM-CNR, where she has recently been appointed a Senior researcher position. The unit has since then focussed on the Aurora-A kinase, in particular on its function as a complex with its activator TPX2, contributing an original view about the role of the complex in cell division and tumorigenesis (De Luca et al., Cell cycle, 2006; De Luca et al., Oncogene 2008; Asteriti et al., BBA Reviews on Cancer 2010 and Molecular Cancer 2011; Giubettini et al., J Cell Sci 2011; Gallini et al., Curr Biol, 2016; Polverino et al., Curr Biol, 2021). She is pursuing studies of the Aurora-A/TPX2 complex in tumorigenesis and anti-cancer therapy (Asteriti et al., Oncotarget, 2014 and 2017; Naso et al., Cells, 2020) and has recently extended these studies to other Aurora-A complexes of relevance in cancer, i.e. the Aurora-A/MYCN complex in neuroblastoma, as well as to Aurora-A non-mitotic roles (Naso et al., Oncogene, 2021; Boi et al., IJMS, 2021). Since 2009 she also co-directs the IBPM imaging platform.