Suchergebnisse

The repair of DNA breaks takes place in the context of chromatin and thus involves the activity of chromatin remodelers. The nucleosome acetyltransferase of H4 (NuA4) remodeler complex enables DNA break repair by relaxing flanking chromatin. Here, we show that MRG domain binding protein (MRGBP), a member of this complex, acts as a general inhibitor of DNA double-strand break repair. Upon its downregulation, repair is generally increased. This is particularly evident for the stimulation of early events of homologous recombination. Thus, MRGBP has an opposing role to the main catalytic subunits of the NuA4 complex. Our data suggest that MRGBP acts by limiting the activity of this complex in DNA repair, specifically by narrowing the extent of DNA-end resection. ; This work was funded by a R+D+I grant from the Spanish Ministry of Economy and Competitivity (SAF2016-74855-P) and by the European Union Regional Funds (FEDER). GR-L was supported by the Regional Government of Andalucía (Junta de Andalucía) with a contract of the program 'GARANTÍA JUVENIL EN LA UNIVERSIDAD DE SEVILLA'. CABIMER is supported by the regional government of Andalucía (Junta de Andalucía).

The epithelial-to-mesenchymal transition (EMT) and its reversion (MET) are related to tumor cell dissemination and migration, tumor circulating cell generation, cancer stem cells, chemoresistance, and metastasis formation. To identify chromatin and epigenetic factors possibly involved in the process of EMT, we compare the levels of expression of epigenetic genes in a transformed human breast epithelial cell line (HMEC-RAS) versus a stable clone of the same cell line expressing the EMT master regulator ZEB1 (HMEC-RAS-ZEB1). One of the factors strongly induced in the HMEC-RAS-ZEB1 cells was Transducin beta-like 1 (TBL1), a component of the NCoR complex, which has both corepressor and coactivator activities. We show that TBL1 interacts with ZEB1 and that both factors cooperate to repress the promoter of the epithelial gene E-cadherin (CDH1) and to autoactivate the ZEB1 promoter. Consistent with its central role, TBL1 is required for mesenchymal phenotypes of transformed breast epithelial and breast cancer cell lines of the claudin-low subtype. Importantly, a high expression of the TBL1 gene correlates with poor prognosis and increased proportion of metastasis in breast cancer patients, indicating that the level of TBL1 expression can be used as a prognostic marker. ; This work was funded by the Spanish Ministry of Economy and Competitiveness (BFU2014-53543-P and BFU2017-85420-R to J.C.R.), the Junta de Andalucía (BIO-321), and the European Union (FEDER). CABIMER is a Center partially funded by the Junta de Andalucía.