title: Survival of the replication checkpoint deficient cells requires MUS81-RAD52 function.
abstract: In checkpoint-deficient cells, DNA double-strand breaks (DSBs) are produced during replication by the structure-specific endonuclease MUS81. The mechanism underlying MUS81-dependent cleavage, and the effect on chromosome integrity and viability of checkpoint deficient cells is only partly understood, especially in human cells. Here, we show that MUS81-induced DSBs are specifically triggered by CHK1 inhibition in a manner that is unrelated to the loss of RAD51, and does not involve formation of a RAD51 substrate. Indeed, CHK1 deficiency results in the formation of a RAD52-dependent structure that is cleaved by MUS81. Moreover, in CHK1-deficient cells depletion of RAD52, but not of MUS81, rescues chromosome instability observed after replication fork stalling. However, when RAD52 is down-regulated, recovery from replication stress requires MUS81, and loss of both these proteins results in massive cell death that can be suppressed by RAD51 depletion. Our findings reveal a novel RAD52/MUS81-dependent mechanism that promotes cell viability and genome integrity in checkpoint-deficient cells, and disclose the involvement of MUS81 to multiple processes after replication stress.
authors.affiliation: Section of Experimental and Computational Carcinogenesis, Department of Environment and Primary Prevention, Istituto Superiore di Sanità, Rome, Italy.
authors.forename: Ivana
authors.initials: I
authors.lastname: Murfuni
authors.forename: Giorgia
authors.initials: G
authors.lastname: Basile
authors.forename: Shyamal
authors.initials: S
authors.lastname: Subramanyam
authors.forename: Eva
authors.initials: E
authors.lastname: Malacaria
authors.forename: Margherita
authors.initials: M
authors.lastname: Bignami
authors.forename: Maria
authors.initials: M
authors.lastname: Spies
authors.forename: Annapaola
authors.initials: A
authors.lastname: Franchitto
authors.forename: Pietro
authors.initials: P
authors.lastname: Pichierri
mesh_terms: D059447:Cell Cycle Checkpoints / Q000235:genetics; D002470:Cell Survival / Q000235:genetics; D043171:Chromosomal Instability / Q000235:genetics; D053903:DNA Breaks, Double-Stranded; D004261:DNA Replication / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000096:biosynthesis* / Q000235:genetics; D004720:Endonucleases / Q000096:biosynthesis* / Q000235:genetics; D005786:Gene Expression Regulation; D015894:Genome, Human; D057809:HEK293 Cells; D006801:Humans; D051135:Rad51 Recombinase / Q000235:genetics; D051721:Rad52 DNA Repair and Recombination Protein / Q000096:biosynthesis* / Q000235:genetics; D011995:Recombination, Genetic; D016196:S Phase / Q000235:genetics
chemical_list: D004268:DNA-Binding Proteins; C497194:RAD52 protein, human; D051721:Rad52 DNA Repair and Recombination Protein; D051135:Rad51 Recombinase; D004720:Endonucleases; C498772:MUS81 protein, human