biostudies-literatureAbe TEuropean Research CouncilTelethonItalian Association for Cancer Research153-64https://www.ebi.ac.uk/biostudies/studies/S-EPMC4194320biostudies-literatureUnknown22Transient induction or suppression of target genes is useful to study the function of toxic or essential genes in cells. Here we apply a Tet-On 3G system to DT40 lymphoma B cell lines, validating it for three different genes. Using this tool, we then show that overexpression of the chicken BRC4 repeat of the tumor suppressor BRCA2 impairs cell proliferation and induces chromosomal breaks. Mechanistically, high levels of BRC4 suppress double strand break-induced homologous recombination, inhibit the formation of RAD51 recombination repair foci, reduce cellular resistance to DNA damaging agents and induce a G2 damage checkpoint-mediated cell-cycle arrest. The above phenotypes are mediated by BRC4 capability to bind and inhibit RAD51. The toxicity associated with BRC4 overexpression is exacerDNA repairHigh levels of BRC4 induced by a Tet-On 3G system suppress DNA repair and impair cell proliferation in vertebrate cells.PMC4194320GGP1216010637242928Branzei DAbe TfalseHigh levels of BRC4 induced by a Tet-On 3G system suppress DNA repair and impair cell proliferation in vertebrate cells.Transient induction or suppression of target genes is useful to study the function of toxic or essential genes in cells. Here we apply a Tet-On 3G system to DT40 lymphoma B cell lines, validating it for three different genes. Using this tool, we then show that overexpression of the chicken BRC4 repeat of the tumor suppressor BRCA2 impairs cell proliferation and induces chromosomal breaks. Mechanistically, high levels of BRC4 suppress double strand break-induced homologous recombination, inhibit the formation of RAD51 recombination repair foci, reduce cellular resistance to DNA damaging agents and induce a G2 damage checkpoint-mediated cell-cycle arrest. The above phenotypes are mediated by BRC4 capability to bind and inhibit RAD51. The toxicity associated with BRC4 overexpression is exacer2014-01-01T00:00:00Z2014 Oct2026-05-07T04:50:33.457Z2025-05-29T20:05:04.403ZS-EPMC41943202521846710.1016/j.dnarep.2014.08.003