Specific replication factors are targeted by different genotoxic agents to inhibit replication

Abstract

SummaryWhen mammalian cells experience DNA damaging stress, they block DNA replication to avoid erroneous replication of the damaged template. The cells that are unable to respond to DNA damage continue faulty DNA replication that results in incorporation of genomic lesions. To understand the regulation of replication machinery during stress, systemic studies have been carried out but they have been restricted to the evaluation of the mRNA levels and therefore have not been able to identify post-transcriptional changes, vital for immediate blocking of the progressing DNA replication. We have recently discovered that an essential replication factor is downregulated by radiation stress. In this study, we have carried out a systematic evaluation of protein levels of entire replication apparatus after different types of DNA damage. We report that, independent of the status of p53 and retinoblastoma protein, mammalian cells choose targets that are essential for prereplication, preinitiation, and elongation phases of replication. We imposed different kinds of stress to discern whether similar or unique responses are invoked, and we propose a model for inhibition of replication machinery in which mammalian cells target specific essential replication factors based on the experienced stress.2010 IUBMB IUBMB Life, 62(10): 764-775, 2010

CRL4–DDB1–VPRBP ubiquitin ligase mediates the stress triggered proteolysis of Mcm10

“…It is well documented that unwarranted activity of replication genes leads to incorporation of genomic lesions, and our study suggests that CRL4 VprBP ubiquitin ligase may prevent such aberrations (22,56,57). The downregulation of Mcm10 occurs at higher doses of UV radiation and is temporally separated from instantaneous Cdt1 downregulation displaying the cellular resilience in responding to stress (58). Our study suggests that CRL4 VprBP ubiquitin ligase may be involved in regulating the levels of other replication proteins and their identification would help us in completely understanding the role of this E3 ligase in cellular physiology.…”

Direct visualization of replication dynamics in early zebrafish embryos

“…Fish embryos can be used to assess various genotoxic stresses in aquatic environments 16,17) and monitoring DNA replication processes is a sensitive method to quantify the effects of such stresses. 18,19) Given the marked variation in the outcomes of replication labeling among individual 2-2.75 hpf embryos, timing of exposure to genotoxic stresses should be carefully considered to evaluate the effects on replication processes.…”