Tolerance of Deregulated G1/S Transcription Depends on Critical G1/S Regulon Genes to Prevent Catastrophic Genome Instability

作者：Caetano Catia; Limbo Oliver; Farmer Sarah; Klier Steffi; Dovey Claire; Russell Paul^*; de Bruin Robertus Antonius Maria

来源：Cell Reports, 2014, 9(6): 2279-2289.

DOI：10.1016/j.celrep.2014.11.039

Expression of a G1/S regulon of genes that are required for DNA replication is a ubiquitous mechanism for controlling cell proliferation; moreover, the pathological deregulated expression of E2F-regulated G1/S genes is found in every type of cancer. Cellular tolerance of deregulated G1/S transcription is surprising because this regulon includes many dosage-sensitive proteins. Here, we used the fission yeast Schizosaccharomyces pombe to investigate this issue. We report that deregulating the MBF G1/S regulon by eliminating the Nrm1 corepressor increases replication errors. Homology-directed repair proteins, including MBF-regulated Ctp1(CtIP), are essential to prevent catastrophic genome instability. Surprisingly, the normally inconsequential MBF-regulated S-phase cyclin Cig2 also becomes essential in the absence of Nrm1. This requirement was traced to cyclin-dependent kinase inhibition of the MBF-regulated Cdc18(Cdc6) replication origin-licensing factor. Collectively, these results establish that, although deregulation of G1/S transcription is well tolerated by cells, nonessential G1/S target genes become crucial for preventing catastrophic genome instability.

• 出版日期2014-12-24